Operating two pump units of a motor vehicle

Abstract

The invention relates to a method for operating two pump units (28, 29) of a motor vehicle. The method comprises the steps of: providing a drive motor configured to drive an axle of a motor vehicle and a first pump unit (28); and providing an electric pump motor (39) configured to drive a second pump unit (29) independently of the rotational speed of the drive motor, wherein either the first pump unit (28) or the second pump unit (29) or both pump units (28, 29) are driven simultaneously, so that sufficient fluid is supplied to at least one component for its cooling and / or lubrication.

Description

The invention relates to a method for operating two pump assemblies of a motor vehicle.Electric drives for passenger cars (passenger cars) can have various architectures and designs. This results in different requirements for a lubrication and cooling circuit of the respective electric drive. From JP6664302 B2 a vehicle drive device is known which comprises a first oil passage supplying an oil discharged from a first hydraulic pump to a rotor as cooling oil. The first oil passage further supplies the oil to a power transmission mechanism as lubricating oil. Further, the vehicle driving device includes a second oil passage that supplies an oil discharged from a second hydraulic pump to a stator as cooling oil.An oil volume flow requirement for different components of the electric drive is naturally not always dependent on the same parameters alone. Particular attention is thereby required for an architecture which provides for very demanding performance classes equal to two drive motors. The doubling of the necessary lubricating and cooling power associated therewith in the first approach would obviously result in a doubling of the necessary cooling and lubricant volume flows. With pump sizes that are usually designed, therefore, two pumps would have to be operated in parallel and in part simultaneously. The use of purely electrically drivable pumps in addition in this case means that these must be switched on and operated at all times as soon as the electric vehicle is in motion.An object of the present invention can be seen in providing an alternative concept according to requirements for the provision of a lubricating oil and cooling oil supply, in particular for electric vehicle drives. The object is achieved by the subject matters of the independent claims. Advantageous embodiments are the subject matter of the dependent claims, the following description and the figures.To solve this problem, it is proposed according to the present invention to provide a proportion of the respective momentarily required fluid volume flow of a component to be cooled and / or lubricated by means of an oil pump that is driven in a manner proportional to the rotational speed and mechanically. The remaining proportion of this fluid volume flow requirement can be covered by an electrically controlled pump which is independent of the rotational speed of the mechanically rotating parts. In this sense, according to one aspect of the invention, a method for operating two pump assemblies of a motor vehicle is provided. The motor vehicle is in particular a vehicle which is driven by an engine, for example an automobile (e.g. a passenger car with a weight of less than 3.5 t), motorcycle, motor scooter, moped, bicycle, e-bike or pedelec (acronym for Pedal Electric Cycle), bus or truck (e.g. with a weight of more than 3.5 t).According to the method, a drive motor is provided which is configured to drive an axle of a motor vehicle and a first pump assembly. The drive motor may be an electric motor. Alternatively, an internal combustion engine can also be used. Depending on the design, a separate transmission with a transmission ratio can be installed between the drive motor and the first pump assembly, or a shaft of a transmission already present in the electric final drive can be used for a speed conversion if the drive motor is an electric motor of an electric final drive. The first pump assembly is configured in particular to suck in a fluid (e.g. oil) on its suction side and to discharge it on its pressure side so that it reaches a component, in particular to one or more cooling and lubrication points. In other words, the first pump assembly can be incorporated into a fluid circuit for cooling and / or lubricating at least one component. Accordingly, the size of the mechanically operated pump assembly must be designed depending on the "consumers" or components that are to be cooled and / or lubricated. This mechanically operated first pump assembly can be driven, for example, by an intermediate shaft of a gear drive or transmission of the electric final drive, which is generally provided with two gear pairs. Directly on the rotor, the rotational speed range would be too high (up to about 18000 1 / min) and would have to be reduced; directly on the output shafts for the wheel drive, the rotational speed range would be too low (up to about 2000 1 / min).Furthermore, an electric pump motor is provided, which is configured to drive a second pump assembly independently of a rotational speed of the drive motor. However, the electric pump motor need not be configured, like the drive motor, to drive the axle of the motor vehicle. In particular, the electric pump motor can be designed and dimensioned smaller than the drive motor. The second pump assembly, like the first pump assembly, is in particular configured to suck in a fluid (e.g. oil) on its suction side and to discharge it on its pressure side, so that it reaches in particular the same cooling and lubrication points to which the first pump assembly can also convey fluid. In other words, the second pump assembly can also be incorporated into the fluid circuit for cooling and / or lubricating at least one component. Either the first pump assembly can be driven, so that sufficient fluid is conveyed to the at least one component for cooling and / or lubrication thereof. The second pump assembly does not have to be driven in this case. Alternatively, the second pump assembly can be driven, so that sufficient fluid is conveyed to the at least one component for cooling and / or lubrication thereof. The first pump assembly does not have to be driven in this case, which is the case, for example, when the vehicle is stationary. Furthermore, both pump assemblies can be driven simultaneously, so that sufficient fluid is conveyed to the at least one component for cooling and / or lubrication thereof.Depending on various preferences and requirements for energy requirements for driving the two pump assemblies, the second pump assembly can be operated with electric drive at predominantly low vehicle speeds up to standstill of the vehicle with applied drive torques. Furthermore, the first pump assembly with mechanical drive can be operated at predominantly medium and higher vehicle speeds, wherein the electrically driven second pump assembly is only rarely required in order to supply additional oil volume flow.In this sense, in a first operating mode, the first pump can be driven by means of the drive motor, so that the first pump delivers fluid to the at least one component for cooling and / or lubrication thereof if a rotational speed of the drive motor exceeds a defined rotational speed threshold value. The rotational speed of the drive motor can be understood to mean, for example, the rotational speed of a rotor shaft if the drive motor is an electric motor, wherein it is conceivable in the sense of the present invention that the defined rotational speed threshold value can also be zero, for example. In a second operating mode, the second pump can be driven by means of the electric pump motor, so that the second pump delivers fluid to the at least one component for cooling and / or lubrication thereof if the rotational speed of the drive motor does not exceed the defined rotational speed threshold value. The speed threshold value can be defined depending on the individual case. An optimization can be carried out, for example, using consumption simulation calculations as a function of requirements for routes to be traveled and for the relevant vehicle. For example only, the speed threshold may be set to wheel speeds corresponding to a vehicle speed of about 50 mph. However, this is not mandatory in any way and may further depend on loads that do not exceed a slope of about 1-2%.In particular, depending on various preferences and specifications for an energy requirement for the drive of the second pump assembly, the latter can be operated with electric drive at predominantly low vehicle speeds and low rotational speeds of the drive motor associated therewith, up to standstill of the vehicle with applied drive torques. In this sense, according to one embodiment, it is provided that, if the rotational speed of the drive motor does not exceed the defined rotational speed threshold value, the first pump assembly is not driven by means of the drive motor, but rather only the second pump assembly is driven by means of the electric pump motor, so that the second pump assembly delivers sufficient fluid to the at least one component for cooling and / or lubrication thereof in order to meet a fluid volume flow requirement of the at least one component.Furthermore, the oil pump with mechanical drive can be operated at predominantly medium and higher vehicle speeds, wherein the electrically driven oil pump is only rarely required to supply additional oil volume flow. In particular, the electrically driven pump assembly is not required in the case of long-lasting quasi-stationary driving conditions such as overland and freeway driving. In this sense, according to a further embodiment, it is provided that the second pump assembly is not driven by means of the electric pump motor, but only the first pump assembly is driven by means of the drive motor in order to convey fluid to the at least one component for cooling and / or lubrication thereof, if the first pump assembly can cover a fluid volume flow requirement of the at least one component. This makes it possible to save electrical energy, since the mechanically driven first pump assembly generally achieves a better overall efficiency with the same hydraulic power.For the life-compatible design of components, the dwell times of driving states, classified in driving speed with associated drive torque, are preferably used, which can also be used for the design of the electric and mechanical oil pumps. In this sense, according to a further embodiment, it is provided that the first pump assembly and / or the second pump assembly are driven as a function of dwell times of driving states of the motor vehicle, wherein the size ratio with respect to the fluid delivery volume between the two pump assemblies is preferably defined.The drive motor can be an electric drive motor which is installed in an electric final drive. An electric final drive is a drive system in which one or more electric motors are used to drive the wheels of a vehicle via an axle directly or via a transmission drive. Electric final drives are used in electric vehicles (BEVs), hybrid vehicles (HEVs), and plug-in hybrid vehicles (PHEVs). Electric axle drives use electric motors or electric drive motors as the drive source. These electric motors may be mounted on the wheels or placed in other parts of the vehicle and transmit their energy to the wheels via a driveshaft. In contrast to vehicles with internal combustion engines and transmissions, power transmission in the electric final drive is generally carried out without the use of a conventional transmission. Electric motors can deliver high torque over a wide speed range, reducing the need for sophisticated transmission systems.An oil volume flow requirement for the various components of the electric final drive is naturally not always dependent on the same parameters alone. For example, the oil volume flow requirement of a stator of the electric drive motor of the electric final drive predominantly depends on a phase current or a requested torque, but less on the rotational speed of a rotor shaft of the electric drive motor or of the attached wheel drive of the motor vehicle. In other words, the stator requires predominantly more oil at higher torques. In response, the electrically operated second oil pump may be used at low speeds (or travel speeds) predominantly for stator cooling, but less for lubricating mechanical, power-transmitting components. In this sense, according to a further embodiment, it is provided that the drive motor is an electric drive motor which is installed in an electric final drive. Furthermore, if the rotational speed of the drive motor does not exceed the defined rotational speed threshold value, the second pump assembly is driven by means of the electric pump motor, so that the second pump assembly delivers fluid to a stator of the electric drive motor in order to cool the stator.Other components require predominantly more oil at higher rotational speeds, for example a rotor of the electric drive motor of the electric final drive. The mechanically operated oil pump can be used at high or higher rotational speeds (or travel speeds) predominantly for rotor cooling and for lubricating and cooling the mechanical components which transmit power. In this sense, according to a further embodiment, it is provided that, when the rotational speed of the drive motor exceeds the defined rotational speed threshold value, the first pump assembly is driven by means of the electric drive motor, so that the first pump assembly delivers fluid to power-transmitting mechanical components of the electric final drive. The power-transmitting mechanical components can be, for example, a rotor (in particular its rotor shaft or its bearing) of the electric drive motor of the electric final drive.Still other components require predominantly more oil at higher power, e.g., bearings or gear meshes in a transmission of the electric final drive. In other words, the oil volume flow requirement of bearings and gear meshes of the electric final drive predominantly depends on the transmitted power and therefore on the rotational speed and the requested torque. An increased power requirement arises in particular in the case of transient short-term changes in state of the motor vehicle, for example during passing processes or hill climbing. In this context, it is proposed that the electrically driven second pump assembly is additionally operated in the event of these transient changes in state in order to cover the resulting increased cooling requirement for the electric final drive. The electrically driven oil pump is thus used to supply additional oil volume flow. In this sense, according to a further embodiment, it is provided that, if the first pump assembly cannot alone cover the fluid volume flow requirement of the at least one component, the second pump assembly is driven by means of the electric pump motor in order to convey additional fluid to the at least one component for cooling and / or lubrication thereof, so that the first pump assembly and the second pump assembly together cover the fluid volume flow requirement of the at least one component. In other words, a first proportion of the respective instantaneous oil volume flow requirement is provided by a pump assembly which is driven in a manner proportional to the rotational speed and mechanically. A remaining second proportion of the oil volume flow requirement is covered by an electrically controlled pump assembly which is independent of the rotational speed of the mechanically rotating parts. Finally, the switch-on duration of the electric auxiliary pump can thus be significantly reduced, in particular in the case of longer-lasting travel distances. This also results in a more cost-effective construction for the electric drive unit of the pump.Exemplary embodiments of the invention are explained in more detail below with reference to the schematic drawing, wherein identical or similar elements are provided with the same reference numerals. This shows FIG. 1 shows a top view of a drive train of a motor vehicle, FIG. 2 shows a hydraulic circuit diagram of cooling and lubrication points of an electric final drive of the drive train according to FIG. 1, FIG. 3 ashows a hydraulic circuit diagram of a part of a fluid circuit with an electrically driven pump assembly and with a mechanically driven pump assembly and configured as a dry sump variant, FIG. 3 b shows a hydraulic circuit diagram of a part of a fluid circuit with a simple electrically driven pump and with a simple mechanically driven pump and configured as a wet sump variant, FIG. 4 shows a speed-torque diagram which shows dwell times of driving states of a vehicle in a field, FIG. 5 shows a first diagram of a control of oil volume flows of the two pump assemblies as a function of input variables according to the various requirements of the cooling and lubricating points according to FIG. 2, FIG. 5 shows a second diagram of a control of oil volume flows of the two pump assemblies as a function of input variables according to the various requirements of the cooling and lubricating points according to FIG. 2, and FIG. 6 shows a third diagram of a control of oil volume flows of the two pump assemblies as a function of input variables according to the various requirements of the cooling and lubricating points according to FIG. 2,FIG. 1 shows, purely by way of example, a motor vehicle 1, which can be, for example, a passenger car (passenger car) or a commercial vehicle. The motor vehicle 1 has a drive train 2 explained in more detail below, which in the exemplary embodiment according to FIG. 1 optionally enables an all-wheel drive that can be switched on and switched off. The drive train 2 comprises a drive unit 3. The drive unit 3 comprises, in the exemplary embodiment shown, an engine 4, for example an internal combustion engine or an electric motor. The electric motor can optionally be operated in a motor mode for driving the motor vehicle 1 and in a generator mode for charging a battery 5. The drive unit 3 further comprises a transmission 6. The drive unit 3 in the embodiment shown permanently drives two front wheels 8 and 9 via a front differential 7 which are mounted on a front axle 10.As an alternative or in addition to the described front axle drive, the drive train 2 can have an electrical axle drive 11 which can be switched on and off, if appropriate. In the exemplary embodiment shown, the electric final drive 11 comprises a first electric motor 12 (drive motor) and a second electric motor 13 (drive motor). The battery 5 provides electric power for the operation of the first electric motor 12 and the second electric motor 13. The first electric motor 12 may drive a first side shaft 15 via a first transmission 14 (e.g., a 2-speed transmission). A first rear wheel 16 is mounted on the first side shaft 15 in a rotationally fixed manner, which first rear wheel rotates with the first side shaft 15. The second electric motor 13 may drive a second side shaft 18 via a second transmission 17 (e.g., a 2-speed transmission). A second rear wheel 19 is mounted on the second side shaft 18 in a rotationally fixed manner, which second rear wheel rotates with the second side shaft 18. In the exemplary embodiment according to FIG. 1, the electric motor 12 and the second electric motor 13 are the same electric motors, wherein the electric motors 12, 13 are arranged in an axis-symmetrical manner with respect to one another in order to be able to drive a divided axis with the first side shaft 15 and the second side shaft 18.The electric final drive 11, in particular its first and second electric motors 12, 13 and the first and second gears 14, 17, has a plurality of elements 22 to 26 which have to be cooled and / or lubricated, which is illustrated by FIG. 2. For this purpose, at least one of two pump assemblies 28, 29 (cf. FIG. 3 a ) can convey a fluid (e.g. an oil) via a heat exchanger 20 and a pressure filter 21 to various elements 22 to 26 or cooling and lubrication points of the electric final drive 11, in particular to gear sets 22 of the transmissions 14, 17 and to a rotor 23, a first bearing 24, a second bearing 25 and to a stator 26 of the electric motors 12, 13. After the fluid has passed the aforementioned cooling and lubrication points 22 to 26, it is collected in an oil tank 27 in the form of an oil sump 30 and sucked in again by the at least one pump assembly 28, 29, so that a closed fluid circuit is produced (FIG. 3 a ).FIG. 3 ashows in a hydraulic circuit diagram of a part of a fluid circuit configured as a dry sump variant that the first pump assembly 28 comprises a first pump 31, a second pump 32 and a third pump 33. The first electric motor 12 and / or the second electric motor 13 (FIG. 1 ) may drive the first pump 31, the second pump 32, and the third pump 33. The first pump assembly 28 can be referred to as a mechanically driven pump assembly. When the first pump 31 and the second pump 32 are driven by the first electric motor 12 and / or by the second electric motor 13, the first pump 31 and the second pump 32 suck oil from the oil tank 27 via two oil filters 34 and convey it into an oil reservoir 35. When the third pump 33 is driven by the first electric motor 12 and / or by the second electric motor 13, the third pump 33 sucks oil from the oil reservoir 35 and conveys it via the heat exchanger 20 and the pressure filter 21 to the cooling and lubricating points 22 to 26 described above (FIG. 2 ). The first pump assembly 28 can be, but does not have to be, arranged within the electric final drive 11.FIG. 3 afurther shows that the second pump assembly 29 has a fourth pump 36, a fifth pump 37 and a sixth pump 38 and an electric pump motor 39. The electric pump motor 39 may drive the fourth pump 36, the fifth pump 37, and the sixth pump 38. The second pump unit 29 can be referred to as an electrically driven pump unit. When the fourth pump 36 and the fifth pump 37 are driven by the electric pump motor 39, the fourth pump 36 and the fifth pump 37 suck and discharge oil from the oil tank 27 via two oil filters 34, into the oil reservoir 35, When the sixth pump 38 is driven by the electric pump motor 39, the sixth pump 38 sucks and discharges oil from the oil reservoir 35 via the heat exchanger 20 and the pressure filter 21 to the cooling and lubricating points 22 to 26 described above (FIG. 2 ). The second pump assembly 29 can be arranged, but does not have to be arranged, within the electric final drive 11.FIG. 3 bshows, in the case of a hydraulic circuit diagram of a part of a fluid circuit designed as a wet sump variant (i.e. without an oil reservoir 35) with a simple electrically driven pump 31, wherein a first electric motor 12 and / or second electric motor 13 (FIG. 1 ) can drive the pump 31. In this case, the pump 31 draws in oil from the oil tank 27 via an oil filter 34 and delivers the oil via the heat exchanger 20 and the pressure filter 21 to the cooling and lubricating points 22 to 26 described above (FIG. 2 ).Furthermore, the fluid circuit shown in FIG. 3 bcomprises a further simple pump 38, which is driven here by the electric pump motor 39. In this case, the pump 38 draws in oil from the oil tank 27 via an oil filter 34 and delivers the oil via the heat exchanger 20 and the pressure filter 21 to the cooling and lubricating points 22 to 26 described above (FIG. 2 ).FIG. 4 illustrates dwell times of driving states in fields, classified on the basis of a rotational speed n and a drive torque T of the motor vehicle 1 according to FIG. 1, which is driven by the electric final drive 11. The different hatchings of the fields stand for different dwell times, i.e. how long the motor vehicle 1 dwells in the relevant rotational speed-drive torque state, wherein in principle the darker the field, the longer the dwell time. Dwell times or dwell times for forward travel and reverse travel as well as for acceleration and deceleration of the motor vehicle 1 are shown. Based on a consideration of the time components that elapse with the moving motor vehicle 1, a defined portion of an overall required oil volume flow for cooling and / or lubrication of the cooling and lubrication points 22 to 26 of the electric drive drive 11 can be covered by the speed-dependent, mechanically operated second pump assembly 29.However, an oil volume flow requirement for the various components 22 to 26 of the electric final drive 11 is naturally not always dependent on the same parameters alone. For example, the oil volume flow requirement of the stator 26 of the electric motors 12, 13 of the electric final drive 11 predominantly depends on a phase current or a requested drive torque T, but less on the rotational speed n of the rotor shaft of the electric motors 12, 13 or of the attached wheel drive of the motor vehicle 1. Furthermore, for example, the oil volume flow demand from the bearings 24, 25 and gear meshes 22 of the electric final drive 11 predominantly depends on the transmitted power and therefore on the rotational speed n and the required drive torque T. In a manner matched to the respective oil volume flow requirement of the respective cooling and lubrication point 22 to 26, the two pump assemblies 28, 29 can be driven individually or jointly, which is explained in more detail below with reference to FIGS. 5, 6 to 7.On the left-hand side of FIGS. 5, 6 to 7, the input variables of the controller are shown. In FIG. 6, these material inputs are in the form of a first fluid volume flow Vshift 1, which can be conveyed by the first pump assembly 28 in the direction of the components 22 to 26 which are to be cooled and / or lubricated, and in the form of a second fluid volume flow Vshift 2, which can be conveyed by the second pump assembly 29 in the direction of the components 22 to 26 which are to be cooled and / or lubricated. FIG. 7 shows signal inputs in the form of the drive torque T and the rotational speed n as input variables. FIG. 5 combines the input variables Vshift 1 and Vshift 2 from FIG. 6 and T and n from FIG. 7 and adds as a further input variable whether the motors 12, 13 and 39, respectively, are running or standing or are switched on or off ("on / off").On the right-hand side of FIGS. 5, 6 to 7, the output variables of the controller are shown. In FIGS. 5 and 6, these are material exits in the form of fluid volume flow requirements Vev 3, Vev 4 and Vev 5. In detail, a first fluid volume flow demand Vegr 3 is shown, which is required for cooling and / or lubricating components, the fluid volume flow demand of which predominantly depends on a phase current or the required drive torque T, but less on the rotational speed n of the rotor 23 or of the rotor shaft thereof or of the attached wheel drive of the motor vehicle 1. On the other hand, a second fluid volume flow demand Vegr 4 is shown, which is required for cooling and / or lubricating components, the fluid volume flow demand of which predominantly depends on the rotational speed n of the rotor 23 or of the attached wheel drive of the motor vehicle 1. An example of such a component is, for example, the rotor 23 or its rotor shaft. Further shown is a third fluid volume flow demand Vshift 5 required for cooling and / or lubricating components, the fluid volume flow demand of which depends on a transmitted power and therefore on the rotational speed n and the required drive torque T, e.g. the transmissions 14, 17 with their gear meshes 22 or the bearings 24 and 25.The rectangular box of FIGS. 5, 6 to 7 respectively shows how the fluid volume flow requirements Vev 3, Vev 4 and Vev 5 can be met. Quite generally, the two pump assemblies 28, 29 can be driven in such a way that they can individually or jointly cover the fluid volume flow requirements Vcv 3, Vcv 4 and Vcv 5. The first fluid volume flow Vshift 1, supplied by the mechanically driven first pump assembly 28, and the second oil volume flow Vshift 2, supplied by the electrically driven second pump assembly 29, are distributed in a controlled manner by a suitable logic module 40 (the central box with the arrows) to the different components 22 to 26 as required. As can be seen in FIGS. 5 and 6, the fluid volume requirement Vcv is preferably supplied by the oil volume flow Vcv 1 or the fluid volume requirement Vcv 3 is supplied by the oil volume flow Vcv 2 respectively. As already explained, there are different "consumers" of oil requirements, namelycomponents that require predominantly more oil at more torque T (e.g. the stator 26),components which predominantly require more oil at a higher rotational speed n (e.g. the rotor 23), andcomponents that require predominantly more oil at more power (e.g., the gear meshes 22 of the transmissions 14, 17).Since the three types of components 22 to 26 listed above occur in the electric final drive 11, the logic unit 40 controls the oil supply by an optimal drive of the mechanically driven first pump assembly 28 and / or of the electrically driven second pump assembly 29 for all states of the motor vehicle 1.In particular, the first pump assembly 28 and the second pump assembly 29 may or may not be driven as a function of the rotational speed n. For this purpose, a rotational speed threshold value ns can be established. If the rotational speed n of at least one of the drive motors 12, 13 exceeds the defined rotational speed threshold value ns, then the first pump assembly 28 can be driven by means of the relevant drive motor 12, 13, so that the first pump assembly 28 delivers fluid to the cooling and lubricating points 22 to 26 for cooling and / or lubrication thereof. This is advantageous at predominantly medium and higher vehicle speeds. In the case of long-lasting quasi-stationary driving conditions such as cross country and highway driving, the electrically driven second pump assembly 29 is not required and is not driven, but only the first pump assembly 28 by means of the drive motor 12, 13.However, if the rotational speed n of at least one of the two drive motors 12, 13 does not exceed the defined rotational speed threshold value ns, then the second pump assembly 29 can be driven by means of the electric pump motor 39 so that the second pump assembly 29 delivers fluid to the cooling and lubrication points, in particular to the stator 26 for cooling thereof. This is advantageous at predominantly low vehicle speeds up to standstill of the motor vehicle 1 in the case of applied drive torques. If the rotational speed threshold value ns is exceeded and the first pump assembly 28 cannot alone cover the fluid volume flow requirements Vcv 3, Vcv 4, Vcv 5 then the second pump assembly 29 is additionally driven by means of the electric pump motor 39 in order to convey additional fluid to the cooling and lubricating points 22 to 26 for their cooling and / or lubrication, in particular to the bearings 24, 25 and to the gear mesh 22 of the transmissions 14, 17. as a result, the first pump assembly 28 and the second pump assembly 29 together cover the fluid volume flow requirements Vcv 3, Vcv 4, Vcv 5.Reference numerals denote reference numeralsn rotational speed ns rotational speed threshold value T drive torque Vshift 1 first fluid volume flow Vshift 2 second fluid volume flow Vshift 3 first fluid volume flow demand Vshift 4 second fluid volume flow demand Vshift 5 third fluid volume flow demand 1 motor vehicle 2 drive train 3 drive unit 4 motor 5 battery 6 transmission 7 differential transmission 8 front wheel 9 front wheel 10 front axle 11 electric final drive 12 first electric motor 13 second electric motor 14 first transmission 15 first side shaft 16 first rear wheel 17 second transmission 18 second side shaft 19 second rear wheel 20 heat exchanger 21 pressure filter 22 gear meshes 23 rotor 24 bearing 25 bearing 26 stator 27 oil tank 28 first pump assembly 29 second pump assembly 30 oil sump 31 first pump 32 second pump 33 third pump 34 oil filter 35 oil reservoir 36 fourth pump 37 fifth pump 38 sixth pump 39 electric pump motor 40 logic moduleReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedJP6664302B2

[0002]

Claims

Method for operating two pump assemblies (28, 29) of a motor vehicle (1), the method comprising the steps of - providing a drive motor (12; 13) which is configured to drive an axle (15;18) of a motor vehicle (1) and a first pump assembly (28), and - providing an electric pump motor (39) which is configured to drive a second pump assembly (29) independently of a rotational speed of the drive motor (12; 13), wherein either the first pump assembly (28) or the second pump assembly (29) or both pump assemblies (28, 29) are driven simultaneously, such that sufficient fluid is conveyed to at least one component (22 to 26) for cooling and / or lubrication thereof.Method according to claim 1, wherein - the first pump assembly (28) is driven by means of the drive motor (12; 13), such that the first pump assembly (28) delivers fluid to the at least one component (22 to 26) for cooling and / or lubrication thereof, if a rotational speed (n) of the drive motor (12; 13) exceeds a defined rotational speed threshold value (ns), and - the second pump assembly (29) is driven by means of the electric pump motor (39), such that the second pump assembly (29) delivers fluid to the at least one component (22 to 26) for cooling and / or lubrication thereof, if the rotational speed (n) of the drive motor (12; 13) does not exceed the defined rotational speed threshold value (ns).Method according to claim 2, wherein, if the rotational speed (n) of the drive motor (12; 13) does not exceed the defined rotational speed threshold value (ns), - the first pump assembly (28) is not driven by means of the drive motor (12; 13), but only - the second pump assembly (29) is driven by means of the electric pump motor (39), so that the second pump assembly (29) delivers sufficient fluid to the at least one component (22 to 26) for cooling and / or lubrication thereof in order to cover a fluid volume flow requirement (Vcv 3, Vcv 4, Vcv 5) of the at least one component (22 to 26).Method according to one of the preceding claims, wherein - the second pump assembly (29) is not driven by means of the electric pump motor (39), but only - the first pump assembly (28) is driven by means of the drive motor (12; 13) in order to convey fluid to the at least one component (22 to 26) for cooling and / or lubrication thereof if the first pump assembly (28) can cover a fluid volume flow requirement (Vcv 3, Vcv 4, Vcv 5) of the at least one component (22 to 26).Method according to one of the preceding claims, wherein the first pump assembly (28) and / or the second pump assembly (29) are driven as a function of dwell times of driving states of the motor vehicle (1).Method according to one of the preceding claims, wherein - the drive motor (12; 13) is an electric drive motor which is installed in an electric final drive (11), and - the second pump assembly (29) is driven by means of the electric pump motor (39), such that the second pump assembly (29) delivers fluid to a stator (26) of the electric drive motor (11) in order to cool the stator (26) if the rotational speed (n) of the drive motor (12; 13) does not exceed the defined rotational speed threshold value (n s).Method according to claim 6, wherein, when the rotational speed (n) of the drive motor (12; 13) exceeds the set rotational speed threshold value (ns), the first pump assembly (28) is driven by means of the electric drive motor (12; 13), so that the first pump assembly (28) delivers fluid to power-transmitting mechanical components (23) of the electric final drive (11) in order to cool and / or lubricate these components (23).The method according to claim 7, wherein one of the power transmitting mechanical components is a rotor (23) of the electric drive motor (12; 13).Method according to one of the preceding claims, wherein, if the first pump assembly (28) cannot cover the fluid volume flow requirement (Vcv 3, Vcv 4, Vcv 5) of the at least one component (22 to 26) alone, the second pump assembly (29) is driven by means of the electric pump motor (39) in order to convey additional fluid to the at least one component (22 to 26) for cooling and / or lubrication thereof, so that the first pump assembly (28) and the second pump assembly (29) together cover the fluid volume flow requirement (Vcv 3, Vcv 4, Vcv 5) of the at least one component (22 to 26).Method according to claim 9, wherein the at least one component is a bearing (24, 25) or a gear mesh (22) of a transmission (14; 17) of the electric final drive (11).

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