Hydraulic device for a drive train of a motor vehicle

Abstract

A hydraulic device (2) for a drive train (1) of a motor vehicle, comprising a hydraulic circuit (3) into which at least one assembly (6-9) of the drive train (1) can be or is integrated, wherein the at least one assembly (6-9) can be supplied with a working fluid by the hydraulic circuit (3) for tempering and / or actuating the assembly (6-9), wherein the hydraulic circuit (3) has a first sub-circuit (4) and a second sub-circuit (5), wherein a control device (12) of the hydraulic device (2) is designed to adjust a supply of the second sub-circuit (5) with the working fluid in a current operating state depending on a supply state of the hydraulic circuit (3) with the working fluid and a tempering state of at least one assembly (6-9) of the second sub-circuit (5) and / or a type of assembly (6-9) of the second sub-circuit (5), characterized in thatthat the control device (12) is designed to determine the temperature control state of the at least one assembly (6-9) based on a heat capacity of the assembly (6-9) of the second sub-circuit (5) and / or the first sub-circuit (4).

Description

[0001] The invention relates to a hydraulic device for a drive train of a motor vehicle, comprising a hydraulic circuit into which at least one assembly of the drive train can be or is integrated, wherein the at least one assembly can be supplied with a working fluid by the hydraulic circuit for tempering and / or actuating the assembly.

[0002] Hydraulic devices for motor vehicle drivetrains are generally known from the state of the art. Hydraulic systems are particularly suitable due to their high power density and highly flexible options for actuating and cooling components. One advantage is that, for example, the hydraulic oil can serve both as a coolant and a lubricant. Such drivetrains and hydraulic devices are becoming increasingly complex due to ongoing developments, requiring the supply of a larger number of units, actuators, and components, while simultaneously meeting ever-increasing expectations for efficiency. Accordingly, appropriate programs must be provided on electronic control units for implementation. Modifications to existing systems are therefore also complex.

[0003] However, the hydraulic medium usable in the so-called oil sump or reservoir, which can also be referred to as the working fluid, is limited, primarily due to space constraints. Weight due to large oil volumes also plays a role. Current technology primarily uses variable-displacement pumps rather than fixed-displacement pumps. This increases efficiency, and higher drive speeds prevent unnecessary excess oil from being pumped. While in the past, components were generally fully supplied by constant cooling / lubrication, today direct or indirect means are generally created to direct the available oil to where it is needed most.

[0004] The requirements for the accuracy of calculating and balancing requirements, as well as the control of distribution, are becoming increasingly complex. Efficiency is directly linked to the oil requirement to be produced and thus to the accuracy of the calculation of requirements. This is done carefully, taking into account the risk of undersupply. Since direct control options always involve additional components and costs, attempts are being made to find a functioning constant distribution for components in the form of a distribution path. Overall, hydraulic control systems and cooling oil networks are therefore designed to their limits, and there is hardly any reserve potential.

[0005] If additional components are to be integrated into the drive train that are also to be supplied by the hydraulic device, this is usually not possible, as the described hydraulic device is already designed to its limits for the integrated components, meaning that the supply of additional components to be integrated cannot be guaranteed across all realized operating situations. The integration of additional components and the resulting additional leakage can push the hydraulic device to its delivery limits, at least in certain operating situations. This poses a risk of thermal overload of individual components, especially in undersupplied operating conditions.

[0006] Typically, this requires the integration or addition of additional components into the hydraulic device, requiring a complex new development or redesign of the hydraulic device. This is because altering the existing network of the hydraulic device is highly complex and changes made can have unintended or unforeseeable effects. This results in considerable effort in terms of the design, layout, and control of the hydraulic device. Another option would be to increase the basic delivery capacity of the hydraulic device across all operating situations, for example, by increasing the idle speed of a drive device that drives a delivery device of the hydraulic device, such as a pump.However, this would reduce the efficiency of the drive system and thus of the drive train across all operating situations, which does not meet the constant demand for efficiency in the operation of the drive train.

[0007] Hydraulic devices for motor vehicles are known from the documents DE 10 2008 006 165 A1, DE 10 2007 051 525 A1, DE 10 2014 224 820 A1, DE 10 2016 107 187 A1 and DE 10 2005 028 848 A1.

[0008] The invention is based on the object of providing an improved hydraulic device for a drive train of a motor vehicle.

[0009] The object is achieved by a hydraulic device having the features of claim 1. Advantageous embodiments are the subject of the subclaims.

[0010] As described above, the invention relates to a hydraulic device for a drive train of a motor vehicle. The hydraulic device has a hydraulic circuit into which at least one component of the drive train can be or is integrated. The at least one component can be supplied with a working fluid through the hydraulic circuit for tempering and / or actuating the component. In other words, the at least one component is integrated into the hydraulic circuit so that the working fluid can be supplied to the at least one component. By supplying the component with the working fluid, actuating functions and / or tempering functions, in particular cooling of the component, can be performed.

[0011] The invention is based on the finding that the hydraulic circuit has a first sub-circuit and a second sub-circuit, wherein a control device of the hydraulic device is designed to adjust a supply of the second sub-circuit with the working fluid in a current operating state as a function of a supply state of the hydraulic circuit with the working fluid, in particular a volume flow of the working fluid in the current operating state, and a temperature control state of at least one assembly of the second sub-circuit and / or a type of assembly of the second sub-circuit.

[0012] The invention thus fundamentally proposes the basic division of the hydraulic circuit into a first sub-circuit and a second sub-circuit. The supply state of the second sub-circuit can be adjusted depending on the current supply state of the hydraulic circuit. In other words, it can be checked in the current operating state whether the hydraulic circuit as a whole is sufficiently supplied with working fluid to supply all components, i.e., the assemblies of the first and second sub-circuits, of the hydraulic circuit, or whether there is an undersupply in the current operating state.

[0013] If the hydraulic circuit is undersupplied with working fluid, the supply to the second sub-circuit can be stopped, i.e., partially limited or shut off. This allows, particularly with regard to the problem described above, the second sub-circuit to contain components that have been additionally integrated into the hydraulic device or into the hydraulic circuit provided by the hydraulic device. These components can be supplied if the supply is sufficient, and if the supply is insufficient, the supply to the first sub-circuit is given priority. The first sub-circuit can thus also be considered the "old system" and the second sub-circuit the "new system."It must be ensured that the components arranged in the first sub-circuit or supplied by it remain sufficiently supplied and that the additionally integrated components can be supplied if the supply status of the hydraulic circuit permits this.

[0014] In particular, the temperature control state of the second sub-circuit or of the assemblies in the second sub-circuit and / or the type of assemblies in the second sub-circuit can be taken into account. If, for example, the current supply state of the hydraulic circuit does not allow for complete supply to all assemblies in both sub-circuits, the temperature control state of the assemblies in the second sub-circuit and their type can be taken into account. In particular, this makes it possible to accept that the temperature control state of at least one assembly in the second sub-circuit changes, for example that the assembly heats up. This allows the heating of the assembly in the second sub-circuit due to a current undersupply of the second sub-circuit to be accepted, but that the assemblies in the first sub-circuit can be sufficiently supplied with working fluid.

[0015] Different temperature or heating levels of the assembly in the second sub-circuit can be accepted, depending on the type of assembly and the resulting excess temperature. This ensures that the assemblies in the first sub-circuit can be adequately supplied in all operating states of the hydraulic device. Since the hydraulic device or the hydraulic circuit may originally have been designed exclusively to supply the assemblies in the first sub-circuit, the supply to the second sub-circuit must be limited accordingly in operating states in which the supply to the hydraulic circuit is not additionally sufficient for the assembly in the second sub-circuit, particularly as long as this is possible due to the temperature control state or the type of assembly in the second sub-circuit.

[0016] Advantageously, it is therefore not necessary to redesign and program the entire hydraulic device and provide new controls. Instead, the existing system can continue to be used, and the new components to be integrated can be integrated into the second sub-circuit. If an oversupply condition exists, all components or all assemblies can be supplied. If the hydraulic device is operated in an operating state in which there is an undersupply of all assemblies, the supply to the second sub-circuit is reduced as necessary and as far as possible due to the type of assemblies and their temperature control state.This advantageously ensures that the efficiency of the hydraulic device is not reduced and can even be further increased, since ultimately more components can be supplied than before in most operating states, and in operating states in which the supply is insufficient, the supply to the second sub-circuit is reduced. Since such operating states rarely or usually do not exist for an extended period of time, but rather represent, for example, temporary states, such as standstill states, the temporary undersupply can be "bridged" by the temperature control state and the type of assembly in the second sub-circuit and the resulting temporary undersupply of the second sub-circuit.

[0017] As described, the temperature control state of at least one component of the second sub-circuit can be taken into account and the supply to the second sub-circuit can be adjusted accordingly. In the hydraulic device, it is provided that the control device is designed to determine the temperature control state of the at least one component based on a heat capacity of the component of the second sub-circuit and / or the first sub-circuit. In principle, it is thus possible to determine the temperature control states for all components of the hydraulic circuit or of the components supplied by the hydraulic circuit of the hydraulic device. The temperature control state is determined based on a heat capacity of the respective component. Depending on the heat capacity, the control device can determine how the current temperature control state of the component will change in the event of an undersupply.The assembly can therefore be understood and used as a “heat buffer”.

[0018] If, for example, an undersupply condition occurs in which the hydraulic circuit is not supplied with sufficient working fluid to supply all assemblies in the first and second sub-circuits, a targeted undersupply can be set, specifically in the second sub-circuit. This undersupply can be designed so that the temperature control of the assemblies does not become critical. This can be determined based on the heat capacity of the assembly. Depending on the heat capacity, for example how much heat the assembly can absorb before a limit temperature is reached, a certain undersupply can be tolerated without the component or assembly becoming critically hot. The heat capacity is determined, for example, by the mass and the material of the assembly.Once the undersupply condition is over, the excess temperature that built up during the undersupply period can be reduced by resupplying the module previously used as a heat buffer.

[0019] Specifically, it can also be considered in the first sub-circuit whether the supply to the module of the first sub-circuit could be reduced in the current operating state. If, for example, the first sub-circuit still has excess capacity in the current operating state, this can be used to supply the module of the second sub-circuit better or for longer, so that excess capacity is not unnecessarily maintained in the first sub-circuit while the second sub-circuit is undersupplied. In this case, it can also be determined whether at least one module of the first sub-circuit allows a temperature control state in which a, for example, slight, undersupply of the first sub-circuit can be tolerated. In other words, the heat capacities of all modules can be used to determine the temperature control state of the modules.This allows the requirements of the individual components in the first and second subcircuits to be determined, and the supply to the first and second subcircuits to be adjusted accordingly. However, as far as possible, the supply to the first subcircuit should be maintained, and any undersupply should be compensated for by the second subcircuit. Depending on the type of individual components in the first and second subcircuits, at least one component in the first subcircuit may be undersupplied, as this is easily possible, for example, due to its nature—for example, its current usage status in the current operating state—or its heat capacity.

[0020] The hydraulic circuit can have a common inlet, in particular from a pressure generating device, at which inlet the hydraulic circuit is divided into the first sub-circuit and the second sub-circuit, wherein a distribution device is provided at the inlet, which is designed to limit the supply to the second sub-circuit. The distribution device can, for example, be designed as a flow restrictor or as a valve. The valve can be provided either as a control valve or as a digital slide. The digital slide can also be operated in PWM mode, so that the flow rate in the second sub-circuit can ultimately be specifically adjusted. As described, this can be used to determine how the working fluid is distributed between the first sub-circuit and the second sub-circuit.Particularly in certain operating conditions, such as severe undersupply, the second subcircuit can be closed, so that the working fluid supplied to the hydraulic circuit at the inlet, for example, via the pressure generation device, is completely directed into the first subcircuit. Various intermediate states are possible in which the working fluid can be distributed arbitrarily between the first subcircuit and the second subcircuit.

[0021] In a special embodiment, it can be provided that a supply power of the hydraulic device is designed only for the first sub-circuit and that the first sub-circuit competes with the second sub-circuit when the second sub-circuit is open. As described, the first sub-circuit and the second sub-circuit are connected, for example, to the common inlet. If the distribution device for the second sub-circuit is at least partially open, the working fluid supplied to the inlet is distributed between the first sub-circuit and the second sub-circuit. As described, the distribution ratio can be controlled based on the closed state of the distribution device or the control state of the distribution device. As a result, the working fluid is distributed between the first sub-circuit and the second sub-circuit, so that the first sub-circuit and the second sub-circuit compete with one another.

[0022] As described, the supply capacity is only designed for the first sub-circuit so that the first sub-circuit can be guaranteed to receive a sufficient supply in all operating states. By integrating the second sub-circuit into the existing system of the hydraulic device, i.e., adding the second sub-circuit in addition to the first sub-circuit, a targeted strategy is required to supply both sub-circuits with the supply capacity previously only designed for the first sub-circuit. In other words, the hydraulic device is originally designed in such a way that a total cooling capacity is only sufficient for the first sub-circuit in all operating states. Thus, after integrating the second sub-circuit across all operating states, operating states can arise in which the hydraulic circuit as a whole is undersupplied.

[0023] In such undersupply conditions, as described, the supply to the second sub-circuit is reduced in order not to impair the supply to the first sub-circuit. This can be done, in particular, to bridge such operating conditions as long as the temperature control state and / or the type of components in the second sub-circuit permit. Advantageously, an existing concept for a hydraulic device can therefore be used and does not need to be modified in terms of the design with regard to the supply power and the components integrated therein. Instead, the second sub-circuit is coupled to the inlet and can thus utilize the entire network of the existing hydraulic device. For the first sub-circuit, no changes to the control, supply, construction or other design changes are necessary.However, in situations where the supply power is insufficient for all components, the supply to the second sub-circuit is limited, so that there is generally no negative impact on the first sub-circuit. This ensures, in particular, that existing control systems, designs, and the like do not need to be changed, thus eliminating the need for a complex redesign of the entire hydraulic system.

[0024] In particular, the control device can be designed to supply the first sub-circuit and the second sub-circuit with working fluid in an oversupply state and to at least partially limit the supply to the second sub-circuit at least temporarily in an undersupply state. As described, a pressure generating device or a flow generating device, in particular a pump, which is provided for supplying the hydraulic circuit with working fluid, can be driven by a drive device of the motor vehicle. In this case, the delivery rate of working fluid into the hydraulic circuit is therefore dependent on the current operating state of the drive train. Depending on the speed of the drive device, a different quantity or a different volume flow of working fluid will be available to the hydraulic circuit.Thus, oversupply conditions can occur in which a larger volume flow of working fluid is available than would be necessary to supply the components in the first subcircuit and the second subcircuit. In such oversupply conditions, the control device will supply the first subcircuit and the second subcircuit with working fluid.

[0025] In contrast, in an undersupply state, for example when the drive train is at a standstill and the speed of the drive device is operated below a speed level necessary for a sufficient supply of the hydraulic circuit with working fluid, the control device can at least temporarily limit the supply to the second sub-circuit, in particular for the duration of the undersupply state. During the undersupply state, the assemblies or individual assemblies of the second sub-circuit will build up an excess temperature. The extent of the excess temperature can be determined based on the parameters of the individual assemblies, for example their heat capacity and / or their type. Here, the excess temperature that the respective assembly can tolerate can be determined depending on the mass or material of the individual assembly and its use or type.

[0026] In this case, the control device can be designed to limit the supply to the second sub-circuit depending on the heat capacity of at least one component in the second sub-circuit. If, for example, there is a component in the second sub-circuit which, by its nature and due to its heat capacity, has a comparatively high tolerance to excess temperature, the control device can reduce the supply of working fluid to the second sub-circuit. The heat capacity of the component and its type can, in particular, indicate how long the component can withstand an undersupply without being damaged. The temperature tolerance can be determined as precisely as necessary, for example, as is required for the operation of the hydraulic device across all occurring operating states.This makes it possible to reduce the supply of working fluid in the second sub-circuit, since the excess temperature can be bridged by the assembly for a certain period of time.

[0027] According to a further embodiment, it can be provided that the control device is designed to carry out at least one module-specific protective measure, in particular derating of an electrical machine, in the undersupply state. As described, various modules can be provided in the second sub-circuit. First, the control device determines which module has which heat capacity and how the temperature control state of the module will change depending on an intended undersupply of the second sub-circuit. In the example of an electrical machine that has a comparatively high mass and, depending on the material of the electrical machine, thus has a high heat capacity compared to other modules, it is initially possible to supply the electrical machine as a module of the second sub-circuit with a reduced volume flow of working fluid.

[0028] In such an undersupply state, the electrical machine will build up excess temperature. The control device can, for example, execute a module-specific protective measure once an excess temperature limit has been reached. In the example of the electrical machine, this can be derating, so that less power is provided by the electrical machine for the current amount of excess temperature, so that less heating of the electrical machine is to be expected. The extent of the module-specific protective measure can occur in different stages or levels, so that initially a protective function can take place as a reduced scope of functions, for example reduced power, and in at least one further stage a partial or complete shutdown of the module can take place.The example described can be extended to all other assemblies; for example, the assembly can be designed as a coupling device which, as an assembly-specific protective measure, has a change in the opening state, for example, can be opened to reduce further temperature entry into the assembly.

[0029] In a further development of the hydraulic device, it can be provided that the control device is designed to adjust a supply to the first sub-circuit in a current operating state depending on the supply state of the hydraulic circuit and a temperature control state of at least one component of the first sub-circuit and / or the second sub-circuit and / or a type of assembly of the first sub-circuit and / or the second sub-circuit. In this further development, the evaluation of the supply state or the evaluation of the robustness of the components with regard to excess temperatures can also be extended to the first subsystem or the first sub-circuit. Depending on the type of assemblies in the first sub-circuit and in the second sub-circuit as well as the temperature control state of the assemblies of the first and second sub-circuits, it can be determined which sub-circuit still has sufficient capacity for excess temperatures.

[0030] If, for example, a wheelset is located in the first sub-circuit which is not yet operating at its temperature limit, the supply of working fluid to the first sub-circuit can initially be reduced so that the wheelset is heated even further. This allows the freed-up capacity to be used for the second sub-circuit or other components in the first sub-circuit. Ultimately, this ensures that all components can be utilized to their tolerable temperature limits, so that the maximum cooling capacity of the hydraulic device can be exploited. Together with the reduction in the functional scope of individual components, this ensures that all components are ultimately operated at their temperature limit, for example before individual components required in the current operating state have to be switched off.The individual assemblies can be supplied individually, meaning that the amount of working fluid supplied to each assembly can be individually adjusted. If such adjustability is not available, the most critical component can be determined for each subcircuit, for example, the assembly most likely to reach the overtemperature limit.

[0031] For this purpose, it can advantageously be provided that the control device is designed to predict a supply requirement of at least one assembly and / or a future temperature control state of at least one assembly. For this purpose, models tailored to the individual assemblies can be used, for example. For example, it is possible to model how the individual assemblies behave, in particular how they heat up, in a current operating state when a supply of working fluid is provided. For example, it is possible to determine for an electrical machine as an assembly how it is currently or in the future operated, so that it is possible to determine what its future temperature control state can be expected. Likewise, it is possible to take into account what the requirements of the electrical machine will be in the current operating state or a subsequent future operating state.This allows the control system to ultimately determine for all modules what requirements they will have in a future operating state, so that the supply to the sub-circuits or modules can be adjusted accordingly.

[0032] In a further embodiment, the control device can be configured to change the supply state of the hydraulic circuit, in particular by increasing the idle speed of a drive device. As described above, the basic supply of the hydraulic circuit should not be increased across all operating states, but rather, particularly in exceptional situations and thus at short notice, an increase in the supply state should be possible as an emergency measure.

[0033] For example, if all other means have already been exhausted, in particular if the tolerance for excess temperatures of the individual components has been set based on their heat capacity and / or type, so that no further excess temperatures can occur on the components' side, the supply level of the hydraulic circuit can be increased in such relatively rare exceptional situations. For this purpose, the control device can, for example, increase the idle speed of the drive device, thereby also increasing the supply level of working fluid to the hydraulic circuit.In particular, this can only be carried out as long as the increased power is required to supply the modules, for example when the operating state changes again or when the modules are again in a temperature control state due to the increase in the supply state in which the absorption of excess temperature is again possible due to their heat capacity and / or the type of module.

[0034] According to a further embodiment, the hydraulic device can have an electrically controllable auxiliary pump or be connected to such a pump, wherein the control device is designed to increase the supply state of the hydraulic circuit as needed by controlling the auxiliary pump, in particular temporarily. The auxiliary pump can be provided, for example, for operating states in which the supply to the hydraulic circuit is in an undersupply state. If, for example, instead of or in addition to increasing the idling speed of the drive device, the supply to the hydraulic circuit is to be increased, for example temporarily, the auxiliary pump can be electrically controlled, i.e. operated electrically, in order to increase the delivery rate of working fluid into the hydraulic circuit. The electrically controllable auxiliary pump thus makes it possible, in particular, to bridge critical supply states for a short time.

[0035] In addition to the hydraulic device, the invention relates to a motor vehicle comprising such a hydraulic device. Furthermore, the invention relates to a method for controlling the operation of a hydraulic device for a drive train of a motor vehicle, in particular a previously described hydraulic device, which hydraulic device comprises a hydraulic circuit into which at least one component of the drive train is integrated, wherein the at least one component can be supplied with a working fluid by the hydraulic circuit for tempering and / or actuating the component, wherein the hydraulic circuit has a first sub-circuit and a second sub-circuit, wherein a supply of the second sub-circuit with the working fluid in a current operating state depends on a supply state of the hydraulic circuit, in particular a volume flow of the working fluid in the current operating state,and a temperature control state of at least one assembly of the second sub-circuit and / or a type of assembly of the second sub-circuit is set. ,

[0036] All advantages, details, and features described with regard to the hydraulic device are fully applicable to the motor vehicle and the method. The method can be carried out, in particular, with a previously described hydraulic device.

[0037] The invention is explained below using exemplary embodiments with reference to the figures. The figures are schematic representations and show: Fig. 1 a hydraulic device for a drive train of a motor vehicle; and Fig. 2 a flowchart of a method for controlling an operation of a hydraulic device.

[0038] Fig. 1 shows a schematic representation of a drive train 1 for a motor vehicle (not shown in more detail), having a hydraulic device 2. The hydraulic device 2 has a hydraulic circuit 3, which is divided into a first sub-circuit 4 and a second sub-circuit 5. In the first sub-circuit 4, purely by way of example, a first assembly 6 and a second assembly 7 are arranged, which in this exemplary embodiment can be designed as a gear set and as a clutch device. In the second sub-circuit 5, also purely by way of example, a third assembly 8 and a fourth assembly 9 are arranged, which can be designed, for example, as an electric machine and a separating clutch. The number of assemblies 6-9 and their design can be selected or changed as desired. The assemblies 6-9 and their assignment to the first sub-circuit 4 or the second sub-circuit 5 can be changed as desired.In other words, the assemblies 6-9 can be designed as other assemblies. Likewise, additional assemblies 6-9 or fewer assemblies 6-9 can be provided.

[0039] The drive train 1 can specifically be designed as an all-wheel-drive hybrid drive train, although it is also possible to design the drive train 1 as a purely electric drive train 1. The clutch device of the assembly 7 can, for example, be designed as a friction clutch or as a dual clutch, or can represent both, or can include both systems.

[0040] Essentially, the hydraulic circuit 3 has an inlet 10 to which the two subcircuits 4, 5 are connected. In other words, the hydraulic circuit 3 divides at the inlet 10 into the first subcircuit 4 and the second subcircuit 5. The inlet 10 is supplied, for example, by a pressure generating device 11 or flow generating device, which is designed, for example, as a pump. The pressure generating device 11 can, in particular, be mechanically driven by a drive device of the drive train 1, so that the delivery rate of the pressure generating device 11 depends on the drive speed of the drive device of the drive train 1.

[0041] The hydraulic device 2 further comprises a control device 12, which is fundamentally designed to control the operation of the hydraulic device 2. The hydraulic device 2, in particular the hydraulic circuit 3, can, for example, be designed only for the first sub-circuit 4 with regard to the cooling capacity that can be achieved in the hydraulic circuit 3. This means that the construction, control, and design of the hydraulic circuit 3, with regard to its cooling capacity, is only designed so that the first sub-circuit 4 can be fully supplied across all operating states of the drive train 1. The assemblies 8, 9 in the second sub-circuit 5 can thus be understood as additionally integrated assemblies 8, 9, for whose supply the hydraulic circuit 3 does not have sufficient capacity in all operating states.

[0042] The control device 12 is designed to adjust the supply to the second sub-circuit 5 depending on the type of assemblies 8, 9 of the second sub-circuit 5 and their temperature control state. For this purpose, a distribution device 13, which is designed, for example, as a valve, is arranged in the second sub-circuit 5. Depending on the supply state of the hydraulic circuit 3, the control device 12 thus changes the supply to the second sub-circuit 5. If an oversupply state exists in a current operating state, i.e. if the quantity of working fluid, for example oil, provided by the pressure generating device 11 is sufficient to supply all assemblies 6-9 of the two sub-circuits 4, 5, the control device 12 can open the distribution device 13 so that the working fluid can flow into or through both sub-circuits 4, 5.

[0043] However, if, depending on the current operating state, an undersupply condition occurs, for example, a standstill state of the drive train 1 or of the motor vehicle having the drive train 1, in which the rotational speed mechanically transmitted from the drive device to the pressure generation device 11 is insufficient to generate a sufficient volume flow of the working fluid to supply all assemblies 6-9, the control device 12 adjusts the distribution device 13 such that the supply to the second sub-circuit 5 is limited. Depending on the current supply situation, the control device 12 can also completely close the distribution device 13 so that the second sub-circuit 5 is no longer supplied with working fluid.

[0044] For this purpose, the control device 12 determines the requirements of the assemblies 6-9 and their temperature control status. Optionally, the type of assembly 6-9 can be considered, since different types of assemblies 6-9 have different usage conditions and different tolerances to excess temperatures. Specifically, the heat capacity of each assembly 6-9 can be determined. From this, the control device 12 determines which assembly 6-9 can tolerate which excess temperature in the current operating state. This can bridge a temporary undersupply of the hydraulic circuit 3.

[0045] For this purpose, the assemblies 8, 9 in the second sub-circuit 5 build up excess temperature because their supply of working fluid is reduced due to the control of the distribution device 13 by the control device 12. The control device 12 determines how long the assemblies 8, 9 can tolerate such an undersupply or which overtemperature the assemblies 8, 9 can tolerate. Once the undersupply state is over, for example the drive train 1 is moved from the standstill state so that the delivery rate from the pressure generating device 11 also increases again, the control device 12 can control the distribution device 13 accordingly differently so that the undersupply in the second sub-circuit 5 is eliminated and the assemblies 8, 9 can again be sufficiently supplied in order to reduce the previously entered overtemperature.

[0046] Furthermore, it is possible for the control device 12 to protect the assemblies 8, 9 in the undersupply state using an assembly-specific protective measure. For this purpose, for example, the assembly 8 designed as an electric machine can be operated in a derating state, so that the temperature ingress into the assembly 8 is reduced. Likewise, the assembly 9 designed as a clutch device can be opened to prevent any further temperature ingress into the assembly 9, in the example of an all-wheel drive clutch. If the excess temperature of the assembly 8, 9 is too high, the control device 12 can also initiate a complete shutdown.

[0047] Furthermore, the control device 12 can also consider the requirements and the temperature control states of the assemblies 6, 7 in the first subcircuit 4. If capacity is still available in the assemblies 6, 7 in the undersupply state, for example, the gear set is still below an overtemperature, more working fluid can be fed into the second subcircuit 5. This can be permitted until the assemblies 6, 7 have built up an overtemperature corresponding to their temperature control state. In the specific example of the electric machine, a high heat capacity can be realized due to the comparatively high mass and material of the electric machine, which can absorb comparatively high overtemperatures or large amounts of heat.

[0048] This ensures that, even if the hydraulic circuit 3 is not originally intended for the additional supply of the second sub-circuit 5, operating states in which an undersupply then exists can be bridged by absorbing excess temperatures based on the heat capacity of the assemblies 8, 9, so that the hydraulic circuit 3 can still additionally supply the second sub-circuit 5. In particular, excess temperatures built up in the undersupply state can be dissipated again in subsequent oversupply states. If all components of the hydraulic circuit 3 have already reached their tolerable excess temperature, it is possible to increase the delivery rate of the pressure generation device 11, either by means of an electrically controllable additional pump or by increasing the speed of the drive device.

[0049] Fig. Figure 2 shows a schematic flow of the process which has already been described in relation to Fig.1. The method starts schematically in a block 14, in which the supply state of the hydraulic circuit 3 is determined, in particular by means of the control device 12. In this case, it can be determined in particular whether an oversupply state or an undersupply state exists. If an oversupply state exists, it is not necessary for the control device 12 to intervene, so that the distribution device 13 can remain open so that both sub-circuits 4, 5 are supplied. If an undersupply state exists, a branch can be made from block 14 to a block 15, in which the requirements of the individual assemblies 6-9 or the sub-circuits 4, 5 are determined. Subsequently, in a block 16, the temperature control state of at least one assembly 6-9 can be determined.For this purpose, the heat capacity and type of the individual assemblies 6-9 can be included in block 17, so that it can be determined which of the assemblies 6-9, in particular the assemblies 8, 9 of the second subcircuit 5, can tolerate which excess temperature. For this purpose, for example, based on the heat capacity, it can be determined what amount of heat can be introduced into the second subcircuit 5 in order to ensure the supply of working fluid from the first subcircuit 4 even in the undersupply state.

[0050] For example, excess temperature may occur due to heat absorption by the assemblies 8, 9, which, however, can be tolerated by the assemblies 8, 9. To this end, the control device 12, in a block 18, adjusts the distribution device 13 such that a sufficient supply to the assemblies 6, 7 is maintained in the first subcircuit 4 and, if excess capacity exists, the additional working fluid is fed to the second subcircuit 5. Likewise, the control device 12 can cause the distribution device 13 to close completely, so that the working fluid is fed exclusively to the first subcircuit 4.

[0051] The described method can be carried out continuously, so that the control device 12 checks the supply status according to block 14 in every operating state. Depending on the excess temperature or temperature control conditions that occur, the heat capacities and type of the assemblies 6-9, as well as the resulting requirements, redistribution may be possible so that, for example, the assemblies 6, 7 are adequately supplied with their cooling capacity even in critical operating situations. If, for example, it turns out that the assemblies 6, 7 are sufficiently temperature-controlled and could tolerate further excess temperatures, but the assemblies 8, 9 have already reached their limits, the cooling capacity of the first sub-circuit 4 can be reduced by opening the distribution device 13 and the cooling capacity in the second sub-circuit 5 can be increased instead.

[0052] If all components have reached their tolerable limit of excess temperature, the control device 12 can reduce the performance of the assemblies 8, 9 in block 18; for example, at least one assembly-specific protective measure can be implemented. In the case of the electric machine, this can be a derating function of the electric machine. If the assembly-specific protective measures, in particular switching off or opening the assemblies 8, 9, do not provide sufficient capacity with regard to the cooling performance of the hydraulic circuit 3 to bridge the current operating state, it is possible for the control device 12 to further increase the supply of working fluid to the hydraulic circuit 3 in block 18. For this purpose, an electrically controllable auxiliary pump can be operated, if available, which increases the delivery rate in the hydraulic circuit 3.It is also possible to increase the drive speed of the drive device to which the pressure generating device 11 is mechanically coupled, so that the delivery capacity is increased.

[0053] The described method is particularly intended to bridge undersupply conditions that temporarily occur in selected operating states of the drive train 1, so that the excess capacities of the hydraulic circuit 3 not available for supplying the second sub-circuit can be bridged by targeted utilization of the thermal capacities of the assemblies 8, 9 of the second sub-circuit 5. Advantageously, it is therefore not necessary to modify or design the hydraulic device 2 such that its cooling capacity is also sufficient to supply the additional assemblies 8, 9 in the second sub-circuit 5, in particular across all operating states. Instead, in individual operating states, for example standstill states, the fact that the assemblies 8, 9 can tolerate a certain excess temperature, in particular depending on their thermal capacity, is exploited. Reference symbol 1 drivetrain 2 hydraulic device 3 Hydraulic circuit 4 first subcircuit 5 second subcircuit 6-9 Assembly 10 Entrance 11 Pressure generating device 12 Control device 13 Distribution device 14-18 blocks

Claims

[1] A hydraulic device (2) for a drive train (1) of a motor vehicle, comprising a hydraulic circuit (3) into which at least one assembly (6-9) of the drive train (1) can be or is integrated, wherein the at least one assembly (6-9) can be supplied with a working fluid by the hydraulic circuit (3) for tempering and / or actuating the assembly (6-9), wherein the hydraulic circuit (3) has a first sub-circuit (4) and a second sub-circuit (5), wherein a control device (12) of the hydraulic device (2) is designed to adjust a supply of the second sub-circuit (5) with the working fluid in a current operating state depending on a supply state of the hydraulic circuit (3) with the working fluid and a tempering state of at least one assembly (6-9) of the second sub-circuit (5) and / or a type of assembly (6-9) of the second sub-circuit (5), characterized bythat the control device (12) is designed to determine the temperature control state of the at least one assembly (6-9) based on a heat capacity of the assembly (6-9) of the second sub-circuit (5) and / or the first sub-circuit (4). [2] Hydraulic device (2) according to claim 1, characterized by that the hydraulic circuit (3) has a common inlet (10), at which inlet (10) the hydraulic circuit (3) is divided into the first partial circuit (4) and the second partial circuit (5), wherein a distribution device (13) is provided at the inlet (10) which is designed to limit the supply to the second partial circuit (5). [3] Hydraulic device (2) according to one of the preceding claims, characterized bythat a supply power of the hydraulic device (2) is designed only for the first partial circuit (4) and the first partial circuit (4) competes with the second partial circuit (5) when the second partial circuit (5) is open. [4] Hydraulic device (2) according to one of the preceding claims, characterized by in that the control device (12) is designed to supply the first sub-circuit (4) and the second sub-circuit (5) with working fluid in an oversupply state and to at least partially limit the supply of the second sub-circuit (5) at least temporarily in an undersupply state. [5] Hydraulic device (2) according to one of the preceding claims, characterized by that the control device (12) is designed to limit the supply of the second partial circuit (5) depending on the heat capacity of at least one assembly (6-9) of the second partial circuit (5). [6] Hydraulic device (2) according to claim 4 or 5, characterized by that the control device (12) is designed to carry out at least one module-specific protective measure in the undersupply state. [7] Hydraulic device (2) according to one of the preceding claims, characterized by in that the control device (12) is designed to adjust a supply of the first partial circuit (4) in a current operating state as a function of the supply state of the hydraulic circuit (3) and a temperature control state of at least one assembly (6-9) of the first partial circuit (4) and / or of the second partial circuit (5) and / or of a type of assembly (6-9) of the first partial circuit (4) and / or of the second partial circuit (5). [8] Hydraulic device (2) according to one of the preceding claims, characterized bythat the control device (12) is designed to predict a need for a supply of at least one assembly (6-9) and / or a future temperature control state of at least one assembly (6-9). [9] Hydraulic device (2) according to one of the preceding claims, characterized by that the control device (12) is designed to change the supply state of the hydraulic circuit (3). [10] Hydraulic device (2) according to one of the preceding claims, characterized by an electrically controllable auxiliary pump, wherein the control device (12) is designed to increase the supply state of the hydraulic circuit (3) as required by controlling the auxiliary pump. [11] Motor vehicle comprising a hydraulic device (2) according to one of the preceding claims. [12] A method for controlling the operation of a hydraulic device (2) for a drive train (1) of a motor vehicle according to one of claims 1 to 10, which hydraulic device (2) comprises a hydraulic circuit (3) into which at least one assembly (6-9) of the drive train (1) is integrated, wherein the at least one assembly (6-9) can be supplied with a working fluid by the hydraulic circuit (3) for tempering and / or actuating the assembly (6-9), wherein the hydraulic circuit (3) has a first sub-circuit (4) and a second sub-circuit (5), wherein a supply of the second sub-circuit (5) with the working fluid is adjusted in a current operating state depending on a supply state of the hydraulic circuit (3) and a tempering state of at least one assembly (6-9) of the second sub-circuit (5) and / or a type of assembly (6-9) of the second sub-circuit (5), characterized bythat the temperature control state of the at least one assembly (6-9) is determined based on a heat capacity of the assembly (6-9) of the second sub-circuit (5) and / or the first sub-circuit (4).

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