DEMAND-BASED OIL SUPPLY FOR MULTIPLE DRIVE COMPONENTS

Abstract

Method for the demand-based oil supply of a plurality of drive components in a motor vehicle with a branched oil supply network having at least one electrically controllable valve, wherein the plurality of drive components have at least one wet-running electric machine and / or a transmission, and wherein the method comprises at least the following steps: supplying the oil supply network with an oil as a coolant and / or lubricant for the plurality of drive components; and controlling the at least one valve depending on a predefined control criterion.

Description

[0001] The present disclosure relates to a method and an oil supply device for the demand-based oil supply of several drive components in a motor vehicle.

[0002] In electric vehicles, the oil supply is currently provided by a pressurized oil system that delivers oil in a fixed distribution to several drive components requiring cooling and / or lubrication. This is disadvantageous for several reasons.

[0003] On the one hand, the cooling and lubrication requirements of the drive components are subject to significant changes during operation, particularly depending on temperature, speed, or load point. To ensure an adequate oil supply even under adverse operating conditions, the oil supply has so far been oversized. Furthermore, fundamental differences in the oil requirements of the individual drive components must be taken into account, necessitating a rigid prioritization of the oil supply for each component, the design of which is complex due to the variable operating conditions.

[0004] Further challenges arise with compact drive components that offer little space for oil supply. This is particularly true for modern, low-profile electric drives. Consequently, narrow oil lines can easily lead to insufficient oil supply to drive components under low temperatures (e.g., -40°C) due to the reduced viscosity of the oil, which must be avoided. At the same time, drive components whose cooling requirements exceed their lubrication needs may experience oversupply, which can also be undesirable. Therefore, a fixed design of the pressurized oil system suffers overall efficiency disadvantages, depending on the operating point.

[0005] In light of the problems described, one objective of the present disclosure is to improve the oil supply to several drive components in a motor vehicle, particularly with regard to efficiency and reliability.

[0006] The problem is solved by the subject matter of the independent claims. The dependent claims contain further developments of the disclosure.

[0007] The problem is then solved according to one aspect of the disclosure by a method for the demand-based oil supply of several drive components in a motor vehicle with a branched oil supply network which has at least one electrically controllable valve, wherein the several drive components preferably have at least one wet-running electric machine and / or a transmission, and wherein the method comprises at least the following steps: supplying the oil supply network with an oil as a coolant and / or lubricant for the several drive components; and controlling the at least one valve of the oil supply network depending on a predefined control criterion.

[0008] The oil supply can be selectively restricted or enabled by controlling one or more valves in the oil supply network for one or more drive components. For example, the oil supply can be restricted for drive components whose supply is not necessary under certain current operating conditions, such as low load. This can achieve efficiency gains, since in regular operation there is very often no or only a very low active cooling or lubrication requirement, and the oil supply is therefore unnecessary, at least temporarily.

[0009] Furthermore, the method enables the advantageous prioritization of drive components whose lubrication and / or cooling requirements must be met particularly reliably under certain operating conditions. For example, in highly viscous oil conditions resulting from low temperatures, drive components with high lubrication requirements can be supplied more intensively by restricting the oil supply to drive components with lower lubrication requirements using suitable valve control in the oil supply network. The available supply capacity can thus be specifically focused on the drive components with the highest lubrication needs. In this way, a potential undersupply of these drive components can be countered flexibly and adaptively, depending on the respective operating conditions.

[0010] A particular advantage of the proposed solution is that the oil supply can be smaller than with previous rigid hydraulic oil systems. For example, the oil pump's power output can be reduced because, under high loads due to high viscosity oil, the pump no longer needs to supply all drive components simultaneously. Consequently, the efficiency of the oil supply is increased.

[0011] At the same time, reliability is also improved because, for example, highly viscous oil can be reliably conveyed to a relevant drive component even with unfavorable pipe geometries in the oil supply network or longer oil lines.

[0012] The control criterion used for the valves can be generally defined as dependent on various operating parameters, which are continuously recorded and evaluated against one or more threshold values ​​to determine the respective oil supply requirement for one or more drive components. The control can be implemented in a separate control module for the oil supply or be an integral part of the drive control system for one or more drive components.

[0013] Preferably, the control of one or more valves is carried out at least as a function of a measured temperature, in particular in such a way that a valve in question is switched to a closed position when a predefined temperature threshold is undershot, in order to restrict and in particular completely prevent the oil supply to a drive component with lower lubrication requirements in favor of other drive components with higher supply priority.

[0014] The measured temperature can, for example, represent the temperature of the oil in the oil supply network. More generally, the measured temperature can also represent the ambient temperature of the vehicle or, more generally, the operating temperature of at least one of the drive components. These temperatures can, at least indirectly, also represent the oil temperature.

[0015] According to a further embodiment, the control criterion is defined as a function of the load condition of at least one of the drive components. In this way, the oil supply to drive components with low loads can be restricted with increased efficiency, while simultaneously increasing the supply to drive components with higher loads. The load condition can be detected, in particular, by the rotational speed and / or torque of a drive component. Corresponding operating parameters can refer to the load condition of exactly one drive component or simultaneously represent the load for several drive components. The operating parameters can, for example, be read from a central motor control unit.

[0016] Valve control is preferably electronic, achieved through switching commands. Specifically, a valve closes upon receiving a switching command and opens in the absence of a command, or remains open if already open. The one or more valves of the oil supply network are therefore preferably always in the open position without any circuitry or energization, ensuring the oil supply to the drive component connected to the relevant network branch even in the event of a valve control failure. The valves can, for example, be biased in the open position, allowing them to automatically move from the closed to the open position in the absence of a switching command. Preferably, the valves of the oil supply network are designed as solenoid valves that are only closed when energized.

[0017] The valves of the oil supply network can each be controlled binary, meaning they can be switched between a fully open position (unimpeded oil flow through the valve) and a fully closed position (no oil flow through the valve possible). However, intermediate positions are also conceivable, which merely restrict oil flow but do not completely prevent it. In this way, the control system can be designed with tolerances that may be desirable for reliably maintaining the oil supply to all drive components.

[0018] According to a further embodiment, the oil supply to a first subset of the drive components, preferably at least the electric motor and / or the transmission, is restricted or completely shut off by controlling at least one valve, while the oil supply to a second subset of the drive components is maintained at a constant or increased level. For example, the first subset of drive components can be connected to one or more branches of the oil supply network, the oil flow to which is interrupted by closing at least one valve. The oil supply to the drive components of the second subset connected via other branches, however, is maintained or even improved. In this way, the oil supply for certain drive components can be flexibly prioritized over other drive components.

[0019] Preferably, the oil supply network comprises an oil circuit that is supplied by an oil pump to continuously circulate the oil as a coolant and / or lubricant through the various drive components. The oil temperature of the circuit is regulated to maintain a predetermined temperature range, thus ensuring both the cooling function and the desired lubrication properties. Oil temperature control is particularly important when the electric machine is cooled solely by the oil circuit, i.e., when no additional water cooling is provided.

[0020] Another aspect of the disclosure relates to an oil supply device for the demand-based oil supply of several drive components of a motor vehicle with a branched oil supply network, which has at least one electrically controllable valve for influencing an oil flow in the oil supply network, wherein the several drive components comprise at least one wet-running electric machine and / or a transmission, and wherein the oil supply device is configured to be operated according to a method according to one of the described embodiments.

[0021] According to one embodiment, at least some of the drive components are each assigned an electrically controlled valve of the oil supply network. Each of the valves is configured to selectively restrict or enable the oil supply to the assigned drive component. For this purpose, the valves are controlled depending on the predefined control criterion, as described above in connection with the method.

[0022] The oil supply network generally has several branches radiating from a central main line, which is supplied with oil via the main line. Preferably, each drive component whose oil supply is to be selectively modified by valve control is connected to exactly one branch. The respective branch has an electrically controlled valve, which, as described above, can be assigned to the drive component connected to the branch and primarily serves to selectively influence the oil supply to that drive component. However, it should be understood that if individual drive components are isolated from the oil supply by valve control, the remaining drive components can be supplied with a higher degree of oil. The influence of the valve control can therefore extend beyond the assigned drive components.

[0023] The oil supply network preferably has an oil circuit with an oil pump to pump oil as a coolant and / or lubricant through the several drive components, wherein a cooling circuit, separate from the oil circuit and fluidically isolated from the oil circuit, is provided, which is connected to the oil circuit by means of a heat exchanger to control the temperature of the oil.

[0024] The drive components can be formed by elements of the electric machine, such as a stator, a rotor, or a radial shaft seal of the rotor. The oil supply for these and other drive components can be separately switchable by connecting each drive component to its own branch of the oil supply network, which is equipped with a separately controllable valve. In extreme cases, all drive components can be connected to the oil supply network via a single valve-controlled branch. However, to reduce complexity, valve-controlled branches can be omitted for drive components whose oil supply is not expected to be restricted at all. The oil supply to several drive components with similar oil requirements can also be controlled by a single valve.

[0025] Preferably, drive components with active lubrication requirements are only connected to the oil supply network via a valve-controlled line branch if these drive components already have passive lubrication.

[0026] The described aspects of the disclosure can advantageously be implemented in a motor vehicle comprising an oil supply device according to one of the described embodiments and several drive components connected to the oil supply device for oil supply. The drive components preferably include at least one wet-running electric motor and / or a transmission. Furthermore, other drive components can be connected to the oil supply device, e.g., a parking lock, a differential lock, or other examples mentioned herein.

[0027] Further features of the described aspects are disclosed in the claims, the figures, and the figure description. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the figure description and / or in the figures alone, are disclosed not only in the combinations specified, but also in other combinations or on their own.

[0028] The drawings are purely examples of: Fig. 1 a schematic sectional view of a drive unit for a motor vehicle with several drive components and an oil supply unit according to a first embodiment; Fig. 2 a circuit diagram of an oil supply device according to a second embodiment; Fig. 3 a circuit diagram of an oil supply device according to a third embodiment; and Fig. 4. A flowchart of a procedure for operating an oil supply facility.

[0029] In the figures, identical and functionally equivalent elements are provided with the same reference symbols.

[0030] In Fig. Figure 1 shows a drive unit 1 for a motor vehicle. The drive unit 1 comprises several drive components, wherein in Fig. Figure 1 shows an electric machine 2 and a gearbox 3 in more detail. Furthermore, the drive unit 1 includes an inverter 12 electrically coupled to the electric machine 2, which is configured to control and monitor the electric machine 2 and to ensure a demand-based torque supply and speed control of the vehicle's electric drivetrain. The inverter 12 is specifically responsible for the torque and speed control of the electric machine 2. In addition, the inverter 12 converts the direct current voltage from the vehicle's battery, which supplies electrical energy to the electric machine 2, into alternating current. The electric machine 2 is enclosed by an electric machine housing 4, and the gearbox 3 is enclosed by a gearbox housing 5.The electric machine 2 has a stator 6 and a rotor 7 that can rotate about an axis of rotation relative to the stator 6. A hollow shaft 8 extends centrally through the rotor 7, by means of which the torque generated by the electric machine 2 can be transmitted to the gearbox 3. Stator winding heads 9 are located at the end faces of the stator 6. Rotor winding heads 10 are located at the end faces of the rotor 7. Electrical terminals 11 are arranged at the stator winding heads 9 of the stator 6, via which the stator 6 is connected to the inverter 12.

[0031] In order to translate the torque provided by the electric machine 2 as required, the transmission 3 has at least one transmission stage, wherein this at least one transmission stage is achieved by means of respective gears 13, which are in Fig. 1. These are only hinted at, but will be implemented.

[0032] To cool and lubricate the drive components of the drive unit 1 during operation, an oil circuit 15 is provided, in which oil 16 is circulated as a cooling and lubricating fluid for the electric machine 2 and the gearbox 3. The oil circuit 15 forms an oil supply system for the drive unit 1.

[0033] The oil circuit 15 extends partially through the electric machine housing 4, where it forms an oil jacket 25. Specifically, the oil circuit 15 extends through a jacket of the electric machine 2, allowing the oil flowing through the oil circuit 15 to act as a cooling fluid and thus cool the electric machine 2. The oil flowing in the oil jacket 25 absorbs heat from the stator 6, thereby cooling the stator 6. Because the stator 6 is cooled, it can in turn absorb heat from the rotor 7, thus cooling the rotor 7 as well. Consequently, the entire electric machine 2 is cooled via heat conduction through the oil jacket 25.

[0034] The oil 16 is pumped in the oil circuit 15 by means of an electric oil pump 17. In the oil circuit 15, the oil 16 is pumped into a gear reservoir 18 of the gearbox 3. At least one of the gears 13 of the gearbox 3 can extend into the gear reservoir 18, whereby oil 16 can be drawn from the gear reservoir 18 by means of this gear 13 extending into the gear reservoir 18 and, when this gear 13 rotates, distributed to other gears 13 of the gearbox 3. Thus, the gearbox 3 is lubricated by means of the oil 16 collected in the gear reservoir 18.

[0035] In the oil circuit 15, the oil 16 can be pumped into the hollow shaft 8, from which it can flow out through radial bores 19, or in particular be sprayed out, thus impacting the stator winding heads 9 and, optionally, the rotor winding heads 10. This allows the stator winding heads 9 and, optionally, the rotor winding heads 10 to be cooled by the oil 16 exiting the hollow shaft 8. The oil 16 can also be pumped, or in particular sprayed, radially outwards onto the stator winding heads 9 and the electrical connections 11 to cool them. The oil 16 sprayed onto the stator winding heads 9, as well as the oil 16 from the gears 13 of the gearbox 3, can collect in an electric motor reservoir 20 of the electric motor housing 4. This electric motor reservoir 20 can also be referred to as an oil sump.The oil 16 also serves to lubricate a B-bearing 21 of the drive unit 1, as well as a B-side radial shaft seal 22 of the drive unit 1.

[0036] Furthermore, a cooling water circuit 14 is provided, in which water is used as the cooling fluid. The cooling water circuit 14 is fluidically separated from the oil circuit 15 and connected to the oil circuit 15 via an oil-water heat exchanger 23 in order to extract excess heat from the oil circuit 15 to maintain the cooling function.

[0037] Continuous oil flow in the oil circuit 15 can lead to undesirable oil dynamics and oil droplets within the hollow shaft 8, the machine compartment of the electric machine 2, and especially in an air gap between the rotor 7 and the stator 6. The resulting oil friction can be detrimental to the efficiency of the electric machine 2.

[0038] However, the oil flow in the oil circuit 15 can be adjusted as needed by controlling a switching valve 24. In the exemplary embodiment of Fig. In the present drive unit 1, the switching valve 24 is arranged in a branch of the oil circuit 15, so that the oil flow into the hollow shaft 8 of the rotor 7 and the gearbox 3 can be restricted or completely stopped by closing the switching valve 24. Oil friction losses can be reduced in this way, and an efficiency gain can be achieved. This efficiency gain is particularly noticeable during normal operation, since motor vehicles are more frequently operated at low loads compared to peak loads. In this low-load operation, only a comparatively small amount of cooling power is required for the drive components of the drive unit 1. Furthermore, it should be noted that in the present drive unit 1, the gear set of the gearbox 3 is passively lubricated by the respective gear movements through the gearbox reservoir 18, and therefore there is no risk of insufficient lubrication even if it is temporarily disconnected from the actively lubricating oil circuit 15.

[0039] Fig. Figure 2 shows a schematic circuit diagram of an oil supply device according to a second embodiment. It includes an oil circuit 15 with an oil sump 20 and an oil pump 17 controlled by a control signal SP for pumping the oil through the oil circuit 15. The oil circuit 15 branches to a first inlet E1 for a first drive component and a second inlet E2 for a second drive component. The drive components are in Fig. 2 not shown. The branches defined by the inlets E1 and E2 correspond to the returns R1 and R2, which empty into the oil sump 20; that is, the first drive component is connected between the inlet E1 and the return R1, and the second drive component is connected between the inlet E2 and the return R2. The oil present in the oil sump 20 can optionally be drained via an oil drain plug 26, particularly for maintenance-related oil changes. The oil circuit 15 also includes an oil filter 28, which can be bypassed by opening a bypass valve 29. This is particularly useful if the permeability of the oil filter 28 is restricted and the oil pump 17 would consequently be subjected to excessive load. Until the oil filter 28 is replaced, the supply to the drive components connected to the inlets E1 and E2 can be maintained by opening the bypass valve 29.

[0040] The oil supply to inlet E2 can be selectively restricted and then enabled again by controlling the switching valve 24. Inlet E1, however, is not switchable and is therefore always supplied with oil as long as the oil pump 17 is activated for oil delivery.

[0041] The temperature of the oil circuit 27 is measured by means of a temperature sensor 27 and used as an oil temperature signal ST to control the cooling circuit 14, which extracts excess heat energy from the oil circuit 15 via the oil-water heat exchanger 23 as required. A coolant pump (not shown) and a cooling device for cooling the coolant circulated by the cooling circuit 14 are located between an inlet IK and a return RK of the cooling circuit 14.

[0042] Fig. Figure 3 shows a schematic circuit diagram of an oil supply device according to a third embodiment. This differs from the second embodiment according to Fig. 2 by additional inlets E3, E4, E5, and E6. Additionally, each branch of the oil circuit 15 corresponding to a respective inlet is switchable, namely by switching valves 24, 30, 31, 32, 33, and 34. The switching valves 24 and 30 to 34 can each be controlled independently of one another. The drive components connected to the inlets E1 to E5 (not shown) can be selectively closed, in particular by selectively actuating the switching valves 24, 30, 31, 32, 33, and 34 by switching signals, in order to restrict the oil supply to the drive components. The switching valves 24, 30, 31, 32, 33, and 34 are preferably each designed as solenoid valves that are closed by active energizing in response to associated switching commands, but otherwise remain passively open.For example, the drive components connected to the inlets E1 to E5 could consist of a stator, a rotor, a radial shaft seal of the rotor, a gearbox, a parking lock, and a differential lock. However, other drive components are conceivable and can, in particular, be integrated into a common drive unit.

[0043] Fig. Figure 4 schematically shows a flowchart of a process 100 for operating an oil supply facility according to one of the procedures related to the Fig.The embodiments described in Sections 1 to 3 are for use in one or more drive units in a motor vehicle (not shown). Method 100 comprises a step 110 in which the oil present in the oil circuit 15 is set into continuous flow by means of the oil pump 17. The oil pump is preferably operated continuously when the motor vehicle is in use, which simplifies pump control and reduces wear. In a step 120, it is checked at least once, but preferably at regular intervals, whether a control criterion is met that indicates a modified switching configuration for the switching valves 24 and 30 to 34. For this purpose, several operating parameters, including an oil temperature and at least one rotational speed of a drive component with associated threshold values, are compared.If at least one of these threshold values ​​is undershot, no more oil flows from the oil circuit 15 into those drive components that do not require cooling or lubrication due to the low temperature or load, as a result of the actuation of at least one switching valve 24 or 30 to 34. This occurs in step 130 by generating switching commands for one or more of the switching valves 24 and 30 to 34. The respective valves are each closed from their open default position, thereby interrupting the oil supply to the drive components connected to the respective valves. The valves can, for example, be solenoid valves that are energized in response to a switching command in order to actuate a closing element of the switching valve to a closing movement and thereby improve the oil supply to other drive components. Reference symbol list 1 Drive unit 2 electric machine 3 gearboxes 4 electric machine housings 5 Gearbox housing 6 Stator 7 Rotor 8 Hollow shaft 9 Stator winding head 10 Rotor winding head 11 electrical connections 12 Inverter 13 gears 14 Cooling circuit 15 Oil circuit 16 Oil 17 Oil pump 18 Gearbox reservoir 19 radial bores 20 E-machine reservoir 21 B-warehouses 22 Radial shaft seal 23 heat exchangers 24 switching valve 25 Oilcoat 26 Oil drain plug 27 Oil temperature sensor 28 oil filters 29 Bypass 100 Flowchart 110 Apply oil 120 Examination Tax Criterion 130 Controlling a switching valve R1 First oil return R2 Second oil return E1 First oil inlet E2 Second oil inlet RK coolant return IK Coolant Inlet SP oil pump signal ST oil temperature signal

Claims

[1] Method for supplying oil to several drive components (E1, E2) in a motor vehicle on demand with a branched oil supply network (15) which has at least one electrically controllable valve (24), wherein the several drive components (E1, E2) preferably have at least one wet electric machine (2) and / or a transmission (3), and wherein the method comprises at least the following steps: - Supplying the oil supply network (15) with an oil (16) as a coolant and / or lubricant for the several drive components (110); and - Control of at least one valve (24) depending on a predefined control criterion (120, 130). [2] Method according to claim 1, wherein the control is carried out depending on a measurement temperature, in particular an oil temperature (ST), an ambient temperature and / or an operating temperature of at least one of the drive components (E1, E2). [3] Method according to claim 1 or 2, wherein the control is carried out depending on a load state of at least one of the drive components (E1, E2), in particular a rotational speed and / or a torque. [4] Method according to any of the preceding claims, wherein the control comprises: - Closing of at least one valve (24) in response to a switching command; and / or - Opening of at least one valve (24) in the absence of a switching command, preferably automatically. [5] Method according to one of the preceding claims, wherein the control is carried out in such a way that the oil supply of a first subset of the drive components (E2), preferably at least the electric machine (2) and / or the gearbox (3), is restricted, and wherein the oil supply of a second subset of the drive components (E1) is maintained with a constant or increased supply level. [6] Method according to one of the preceding claims, wherein the oil supply network has an oil circuit (15) which is supplied by means of an oil pump (17) to convey the oil (16) as a coolant and / or lubricant through the several drive components (E1, E2), wherein an oil temperature (ST) of the oil circuit (15) is controlled to maintain a predetermined temperature range, in particular wherein the electric machine (2) is cooled at least substantially exclusively by the oil circuit (15). [7] Oil supply device for the demand-based oil supply of several drive components (E1, E2) of a motor vehicle with a branched oil supply network (15) which has at least one electrically controllable valve (24), wherein the several drive components (E1, E2) comprise at least one wet-running electric machine (2) and a transmission (3), and wherein the oil supply device is configured to be operated according to a method according to one of the preceding claims. [8] Oil supply device according to claim 7, wherein at least some of the drive components (E1, E2) are each assigned an electrically controllable valve (24, 30) of the oil supply network (15), and wherein each of the valves (24, 30) is configured to selectively restrict the oil supply to the assigned drive component (E1, E2). [9] Oil supply device according to claim 7 or 8, wherein the oil supply network has an oil circuit (15) with an oil pump (17) to supply oil (16) as a coolant and / or lubricant through the multiple drive components (E1, E2), wherein a cooling circuit (14) is provided which is fluidically separate from the oil circuit (15) and is connected to the oil circuit (15) by means of a heat exchanger to control a temperature (ST) of the oil (16). [10] Motor vehicle comprising an oil supply device according to one of claims 7 to 9 and several drive components (E1, E2) connected to the oil supply device to be supplied with oil (16), wherein the several drive components (E1, E2) comprise at least one wet electric machine (2) and a transmission (3).

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