Method and fluid pump for pumping a fluid in a fluid circuit of a motor vehicle

Abstract

Method for conveying a fluid (6) of a fluid circuit (4) with an electric motor fluid pump (10) of a motor vehicle, - in which the fluid pump (10) and the fluid circuit (4) are part of a motor vehicle manual transmission, - in which a controller (22) of the fluid circuit (4) is coupled to a pump controller (28) of the fluid pump (10) via signal technology, - in which the pump controller (28) performs pressure control for the fluid circuit (4) by means of the fluid pump (10), in which a) an actual pressure (p ist ) of the fluid (6) is determined without a pressure sensor by the pump controller (28) based on operating parameters of the fluid pump (10), b) operating parameters of the fluid circuit (4) that are not related to the fluid pump are transmitted from the controller (22) to the pump controller (28), c) a target pressure (p soll) is predicted by the pump controller (28) and compared by evaluating the operating parameters transmitted by the controller (22), and d) the actual pressure (p ist ) to the target pressure (p soll ) is regulated.

Description

[0001] The invention lies in the field of pumps, preferably in the field of electric or electromotor-driven (fluid) pumps, and relates to a method for conveying a fluid in a fluid circuit using an electromotor-driven fluid pump in a motor vehicle, in particular in a motor vehicle transmission. It further relates to a fluid pump operating according to such a method and to a motor vehicle transmission having such a fluid pump. A fluid pump is understood here to mean, in particular, an auxiliary or main pump, in particular an oil pump, in or for a motor vehicle.

[0002] An electric fluid pump, and in particular a so-called auxiliary or supplementary pump, is used, for example, to pump oil as a (hydraulic) fluid for control tasks or for cooling, particularly for moving parts or components, for example, in a vehicle (motor vehicle) powered by an internal combustion engine, hybrid technology, or electrically. Due to its pumping characteristics, such an oil pump typically creates a (closed) oil circuit (fluid circuit) with a pressure and volume flow.

[0003] An auxiliary or supplementary pump, driven electrically or by an electric motor, is often also used for at least temporary lubrication or additional lubrication of transmission components of a motor vehicle transmission, particularly an automatic transmission. The pumped oil also serves to cool the components or additional components of the drivetrain of such a motor vehicle. Furthermore, the auxiliary or supplementary pump enables or supports extended driving functions of the motor vehicle, such as coasting or a start-stop function.

[0004] For control and / or regulation, such a fluid pump usually has pump electronics that can be controlled and / or regulated using a pump controller, with which the operating point of the electric motor is set. For this purpose, in particular the (hydraulic) fluid pressure of the fluid in the fluid circuit is monitored by the pump controller. For this purpose, the fluid circuit typically has a (fluid) pressure sensor that records the current value of the actual pressure of the fluid in the fluid circuit and feeds it to the pump controller. The pump controller compares the recorded actual pressure with a desired target pressure and controls the fluid pump or its electric motor depending on the comparison. In particular, the fluid pressure is set to the desired target pressure by adjusting the flow rate of the fluid pump.

[0005] DE 103 45 449 A1 discloses a device for pumping a fluid in a motor vehicle transmission. The known device comprises a pressure sensor coupled to a fluid circuit, which, during operation, detects a real fluid pressure in the fluid circuit (actual pressure) and feeds it to a controller (pump controller) of a fluid pump. The controller is further coupled to a sensor that detects a vehicle's driving condition. Based on the vehicle's driving condition, the controller determines a threshold value (target pressure) with which the detected fluid pressure is compared.

[0006] Pressure sensors for such (fluid) pressure control systems (closed-loop control) are error-prone and associated with comparatively high operating and manufacturing costs. Furthermore, the cable routing (cable harness) required for transmitting the actual pressure signal between the fluid pressure sensor in the fluid circuit and the pump controller of the fluid pump results in additional weight and increased manufacturing costs.

[0007] EP 2 290 264 A2 describes a motor vehicle transmission with a device for conveying a fluid, comprising a fluid circuit with a fluid pump. The motor vehicle transmission has a continuously variable speed change device. During a shifting operation, in which two gears of the motor vehicle transmission are switched between, a (transmission) controller calculates a required target pressure based on a moment of inertia and an input torque of the speed change device. The calculated target pressure is sent to a pump controller, which controls the fluid pump accordingly.

[0008] Such pressure sensorless pressure controls (open-loop control) are comparatively inexpensive to manufacture. However, due to the lack of closed-loop control, effective fluid delivery is not guaranteed, which adversely affects the efficiency of the fluid pump or the vehicle transmission.

[0009] DE 10 2008 043 127 A1 discloses a fuel supply system for internal combustion engines in which a target pressure in a fuel line is set using dynamic pre-control. Remaining deviations between the actual pressure and the target pressure are compensated by a regulator.

[0010] DE 10 2010 001 150 A1 discloses a method for controlling the delivery rate of a feed pump, wherein a target delivery rate is specified and the feed pump is controlled based on the target delivery rate, the temperature of the pumped fluid and a pressure difference between a suction opening and a discharge opening.

[0011] DE 196 47 940 A1 describes a hydraulic actuator comprising a hydraulic pump with a drive, the drive being equipped with a sensor for detecting its power consumption. The hydraulic pump can be controlled depending on the drive's power consumption.

[0012] DE 10 2014 009 770 A1 discloses a method for conveying a fluid using an electric motor-driven fluid pump. According to the method, a synchronization speed and a base duty cycle are set that deviate from a target duty cycle, with the base duty cycle being adjusted to the target duty cycle based on an induction voltage of the electric motor. Data is stored in order to set an optimized voltage and duty cycle when the electric motor is restarted.

[0013] The invention is based on the object of providing a particularly suitable method for conveying a fluid in a fluid circuit using an electric motor-driven fluid pump of a motor vehicle. The invention is further based on the object of providing a fluid pump operating according to such a method and a motor vehicle transmission having such a fluid pump.

[0014] With regard to the method, the object is achieved according to the invention by the features of claim 1, with regard to the fluid pump by the features of claim 8, and with regard to the motor vehicle transmission by the features of claim 9. Advantageous embodiments and further developments are the subject of the respective subclaims.

[0015] The method according to the invention is suitable and configured for conveying a fluid of a fluid circuit with an electromotive fluid pump of a motor vehicle.

[0016] According to the method, pressure control is provided to control the fluid pump based on the current (hydraulic) fluid pressure of the fluid in the fluid circuit (operating pressure) (closed-loop control). For this purpose, an actual pressure and a target pressure of the fluid are determined and compared. Depending on the comparison, the fluid pump or its electric motor is controlled in such a way that, based on the variable flow rate, the fluid pressure in the fluid circuit is adjusted to the target pressure. In this case, a pressure sensor-free determination or detection of the actual pressure is provided, which means that the actual pressure is not monitored by a (fluid) pressure sensor in the fluid circuit.

[0017] In other words, it is possible to implement the fluid circuit without a costly (fluid) pressure sensor. This reduces the manufacturing and operating costs of the fluid circuit. Furthermore, wiring between a pressure sensor and the fluid pump is eliminated, thus reducing maintenance and repair costs on the one hand, and reducing weight and size on the other. This subsequently has a beneficial effect on the vehicle's range.

[0018] The fluid pump is, for example, an electric motor water pump, preferably an electric motor auxiliary or supplementary pump for the motor vehicle, in particular an oil pump for lubricating and / or controlling transmission components of a motor vehicle transmission. The pumped fluid is expediently (gear) oil, for example ATF oil (automatic transmission fluid), and is also used, for example, to cool the components or additional components of a drive train of such a motor vehicle. The term oil is not to be understood as being restricted to mineral oils. Rather, a fully synthetic or semi-synthetic oil, a silicone oil, or other oil-like fluids such as a hydraulic fluid or a cooling lubricant can also be used.

[0019] The fluid pump suitably comprises pump electronics with a pump controller, with which the electric motor is preferably controlled and / or regulated in a field-oriented manner. The electric motor is preferably designed as a brushless DC motor, which is operated with a three-phase current from the pump electronics. A rotor of the electric motor is connected in a rotationally fixed manner to a pump rotor, so that during operation the fluid is pumped from a pump inlet (low-pressure, suction side) to a pump outlet (pressure side). In an alternative embodiment, the pump electronics controls and / or regulates several electric motor pump drives. This is advantageous, for example, in an application in a direct-shift transmission (DSG), in which the pump electronics actuates several electric motor auxiliary drives to generate pressure.

[0020] According to the invention, the actual pressure of the fluid is determined based on operating data from the fluid pump. In particular, the pump controller monitors the operating data of the fluid pump recorded during operation. This enables a simple and cost-effective determination of the actual pressure without the need for a pressure sensor.

[0021] In one conceivable embodiment, to determine the actual pressure, in particular a load torque of the fluid pump and a fluid viscosity of the fluid are determined using the operating parameters. The load torque of the fluid pump is essentially the static torque that the fluid pump or pump rotor must generate with respect to the fluid pressure prevailing in the fluid circuit, in particular during a stable or steady-state state of the fluid circuit after the fluid pump has started up. In other words, this load torque is proportional to the actual pressure; in particular, the load torque has a linear relationship with the actual pressure. The proportionality factor, which forms the relationship between the load torque and the actual pressure, depends on the fluid viscosity of the pumped fluid. This makes it possible to easily determine the actual pressure with knowledge of the load torque and the fluid viscosity.

[0022] In a practical embodiment, the load torque is determined from the difference between the actual torque of the electric motor of the fluid pump and a dynamic torque of the dynamic properties of the fluid. The actual torque of the electric motor essentially corresponds to the total torque required to pump the fluid during operation. The actual torque can be monitored by the pump controller as an operating parameter of the fluid pump. For this purpose, for example, the actual three-phase current for energizing the stator windings is monitored, which correlates with the actual torque applied. The actual three-phase current is dependent on the magnet or coil temperature of the stator, so this is also expediently recorded.

[0023] The actual torque to be applied is composed of the pressure-dependent load torque and the dynamic torque, which is primarily reserved as a control reserve. The dynamic torque comprises, on the one hand, a known, design-dependent mass moment of inertia of the pump rotor and a system moment of inertia, which depends on the fluid viscosity and temperature of the fluid to be pumped. The actual torque is monitored as an operating parameter by the pump controller during operation, so that for a given dynamic torque, the load torque desired for determining the actual pressure can be easily determined by calculating the difference.

[0024] In an advantageous embodiment, a step-like torque increase (torque gradient) is determined during a start-up process of the fluid pump to determine the dynamic torque. The torque increase occurring when starting or running up the fluid pump is invariant with respect to the fluid pressure of the fluid circuit and essentially describes the dynamic properties of the fluid (system moment of inertia). This makes it possible to subtract the dynamic torque value known from the start of the fluid pump from the static torque for the steady-state (operating) state of the fluid pump. This allows the effects caused by the fluid viscosity to be eliminated from the load torque defined by the fluid pressure (actual pressure).

[0025] The essentially known load torque is proportional to the actual pressure to be determined by means of a fluid viscosity-dependent factor. During operation of the fluid pump, temperature changes in the fluid circuit and thus in the fluid conveyed within it are possible. The temperature range to be controlled or considered in the fluid circuit is, for example, between -40°C and +130°C. It should also be considered that the fluid used has a certain or specific (fluid) viscosity, which is temperature-dependent and decreases with increasing temperature; i.e., it is greater at lower temperatures than at higher temperatures.

[0026] In a suitable development, the fluid viscosity is determined based on a fluid temperature, in particular the temperature of the fluid in the fluid circuit. For a fluid used, the fluid viscosity value for a given temperature is known, for example, from a data sheet. This makes it easy to determine the corresponding fluid viscosity by determining the fluid temperature. For this purpose, the pump controller has, for example, a stored table or a characteristic curve with which a corresponding fluid viscosity value is assigned to a fluid temperature value. For this purpose, the fluid circuit has, for example, an integrated (fluid) temperature sensor.

[0027] In a preferred embodiment, the fluid circuit is designed without a temperature sensor, with the fluid temperature being determined using a thermal transfer model based on the operating temperature of the fluid pump's pump electronics. This eliminates the need for a temperature sensor in the fluid circuit, making the fluid circuit particularly cost-effective. The operating temperature of the pump electronics is monitored as an operating parameter of the fluid pump. This advantageously and simply exploits the fact that the pump electronics and the fluid are at least partially in thermal contact with each other. This thermal contact is at least approximately described by the transfer model.

[0028] The operating temperature can be, for example, the junction temperature of a semiconductor switch in the pump electronics or the temperature of a printed circuit board (PCB) carrying the pump electronics. Using the transfer model, a value for the temperature of the fluid in the fluid circuit can be determined based on the operating temperature, which can then be used to determine the (actual) fluid viscosity.

[0029] By knowing the fluid viscosity and load torque, a simple, pressure-sensor-free determination of the actual pressure in the fluid circuit is possible. In particular, the actual pressure is determined solely by the operating parameters of the fluid pump, which are already monitored by the pump controller to ensure error-free operation. This enables a particularly simple, low-effort, and advantageous determination of the actual pressure.

[0030] The target pressure is adjusted adaptively. According to the invention, the target pressure is adjusted using operating parameters of the fluid circuit that are external to the fluid pump. For this purpose, for example, a controller of the fluid circuit is connected to the pump controller via a (bus) interface. In other words, the actual pressure is determined and / or adjusted, in particular, based on operating parameters of the fluid pump, and the target pressure is determined and / or adjusted, in particular, based on operating parameters of the fluid circuit.

[0031] According to the invention, the fluid pump and the fluid circuit are part of a (motor vehicle) manual transmission (automatic transmission, dual-clutch transmission), wherein the controller sends information about an engine speed and / or a gear shift status to the pump controller. Such information only indirectly influences the fluid pressure, but enables a prediction of the requirement profile or the target pressure. In other words, the target pressure is set in a particularly proactive manner for adaptive adjustment. For this purpose, means and methods for machine learning (big data, auto-learning), for example, are integrated into the pump controller. As a result, the pump controller is suitable and configured to proactively and adaptively determine a value for the target pressure based on known, previously occurred driving or gear shift situations.This subsequently has a beneficial effect on the efficiency and effectiveness of the fluid pump or fluid circuit as well as the motor vehicle transmission equipped with it.

[0032] In a practical further development, a Kalman filter is used to adjust the target pressure. Particularly in an application in a manual transmission, the variance of the expected gear shifts depending on the recorded operating parameters of the fluid circuit and / or the fluid pump as well as the existing vehicle parameters (vehicle speed, engine speed, etc.) is comparatively small. This makes it possible to predict the target pressure using an easy-to-implement Kalman filter. This enables a simple state estimation or target pressure estimation. In other words, the pump controller essentially learns the gear shift strategy based on the operating parameters and the vehicle parameters.

[0033] The Kalman filter algorithm generates a linear quadratic estimation (LQE) for the target pressure. For this purpose, previously encountered driving or gearshift situations are converted into an estimate of the (future) required target pressure using Bayesian inference and estimations based on a probability function. Since the deviations (variance) of the driving or gearshift situations are comparatively small, this enables comparatively accurate and precise predictions of the target pressure.

[0034] The electromotive fluid pump according to the invention is suitable and configured for pumping a fluid in a fluid circuit of a motor vehicle, in particular in a motor vehicle transmission. The fluid pump comprises integrated pump electronics and a pump controller (control unit) that is provided and configured to carry out the method according to the invention described above. The pump controller is thus specifically configured to regulate the fluid pressure of the fluid in the fluid circuit to a desired pressure during pump operation and to determine the actual fluid pressure required for regulation without the use of a pressure sensor.

[0035] In a preferred embodiment, the controller is formed at least in its core by a microcontroller with a processor and a data memory in which the functionality for carrying out the method according to the invention is implemented in the form of operating software (firmware) so that the method - if necessary in interaction with a vehicle user - is carried out automatically when the operating software is executed in the microcontroller.

[0036] Within the scope of the invention, the controller can alternatively also be formed by a non-programmable electronic component, for example an ASIC (application-specific integrated circuit) or an FPGA (field programmable gate array), in which the functionality for carrying out the method according to the invention is implemented using circuitry.

[0037] The fluid pump operated with this method is thus suitable and configured for pressure-sensorless closed-loop control of the fluid pressure in the fluid circuit. This enables a particularly cost-effective fluid pump with reduced component count. Furthermore, particularly effective operation of the fluid pump with the highest possible efficiency is ensured.

[0038] The fluid circuit is designed without a pressure sensor. This means that the fluid circuit does not have a (fluid) pressure sensor to detect the actual pressure. This eliminates the need for signal lines between the fluid circuit and the fluid pump, which advantageously translates into a reduction in (structural) weight and thus cost savings.

[0039] The pump controller is signal-linked to a fluid circuit controller. This enables adaptive adjustment of the target pressure based on external indicators.

[0040] According to the invention, the fluid pump and the fluid circuit coupled to it are part of a motor vehicle transmission. The fluid pump is preferably an electric motor-driven auxiliary or supplementary pump. This results in a motor vehicle transmission with reduced components and a lower cost.

[0041] An exemplary embodiment of the invention is explained in more detail below with reference to a drawing. The drawings show, in simplified and schematic representations: Fig. 1 a hydraulic system of a motor vehicle transmission with a fluid circuit and with an electromotive fluid pump, Fig. 2 an interface model of a pump controller of the fluid pump, and Fig. 3 a diagram of an actual torque of the fluid pump during a start-up process.

[0042] Corresponding parts and sizes are always provided with the same reference symbols in all figures.

[0043] The Fig. The hydraulic system 2 shown in Figure 1 is suitable and configured for actuating and lubricating a motor vehicle transmission (not shown in detail), in particular a manual transmission, of a motor vehicle. For this purpose, the hydraulic system 2 comprises a fluid or oil circuit 4, shown in dashed lines, for conveying a (hydraulic) fluid 6, in particular a (transmission) oil. To pump the oil 6 in the oil circuit 4, the hydraulic system 2 has two fluid or oil pumps 8 and 10. The oil pump 8 is designed as a main pump, and the oil pump 10 as an auxiliary or supplementary pump of the oil circuit 4.

[0044] The oil pump 8 is coupled to an internal combustion engine of the motor vehicle and can be functionally driven by the internal combustion engine to pump the oil 6. The oil pump 10 is designed as an electric motor and has a driving electric motor 12. The electric motor 12 is designed, for example, as a brushless DC motor and has a rotatably mounted rotor, which is rotationally fixedly coupled to a pump rotor.

[0045] The oil circuit 4 has a high-pressure branch (primary circuit) 4a and a low-pressure branch (secondary circuit) 4b. In this exemplary embodiment, the high-pressure branch 4a has two hydraulically controllable valves 14, each of which can be used to actuate a clutch 16 of the motor vehicle transmission during a gearshift. The oil pump 8 is connected to the outlet side of the high-pressure branch 4a. The oil pump 8 is fluidly coupled to the low-pressure branch 4b via a pressure relief valve 18. The oil pump 10 is guided to the outlet side (pressure side) of the oil pump 8 by means of a check valve 20.

[0046] During operation of the hydraulic system 2, the oil pump 10 pumps the oil 6 into the high-pressure branch 4a when the delivery volume of the oil pump 8 is less than a threshold value. The delivery volume of the oil pumps 8 and 10 is monitored in particular via the fluid or oil pressure p of the oil 6 in the oil circuit 4.

[0047] To monitor and regulate the oil pressure p in the oil circuit 4, a controller (control unit) 22 of the fluid circuit is provided, which is connected in terms of signal technology, for example, to an engine control unit of the internal combustion engine and / or a transmission control unit of the manual transmission. The controller 22 monitors the oil pressure p in the area of ​​an interface 24 to control the valves 14. The oil pump 10 also has pump electronics 26 with a pump controller 28, which determines the oil pressure p in the area of ​​an interface 30. In other words, the controller 22 monitors, in particular, the oil pressure p in the main pressure branch 4a, and the pump controller 28 monitors the oil pressure p in the secondary pressure branch 4b.

[0048] The operation of the oil pump 10 is described below using the Fig. 2 is explained in more detail. In the Fig. Figure 2 shows a schematic interface model of the pump controller 28 with the controller 22. The pump controller 28 and the controller 22 are signal-coupled via a bus interface 32.

[0049] During operation, the pump controller 28 is designed according to the invention to carry out a pressure control for the oil circuit 4, in which an actual pressure p ist of the oil 6 to a target pressure p soll Based on the comparison, the speed, and thus the delivery volume, of the electric motor 12 or the oil pump 10 are adjusted by the pump controller 28. The pump controller 28 determines the actual pressure p ist of the oil 6 is pressure sensorless, which means that the oil circuit 4 does not have a pressure sensor coupled to the pump controller 28.

[0050] The pump controller 28 determines the value for the current actual pressure p istby evaluating recorded and monitored operating data of the oil pump 10. For this purpose, the pump controller 28 records a phase current I during operation M the pump electronics 26 to drive the electric motor 12. The phase current (three-phase current) I M is fed to a stator or phase winding of the electric motor 12, generating a rotating magnetic field that causes the rotor to rotate. The pump controller 28 further records the actual torque M generated during operation. ist the oil pump 10 and an operating temperature T B the pump electronics 26.

[0051] To determine the actual pressure p ist the pump controller 28 evaluates a load torque M occurring during operation Last of the oil pump 10 and a (fluid) viscosity η of the oil 6. The load torque M Lastis the static torque which the oil pump 10 in a steady state, that is to say in a stable operating point after a start-up process, relative to the actual pressure p ist of the oil circuit 4 to pump the oil 6. The load torque M Last is determined by a proportionality factor dependent on the oil viscosity η with the actual pressure p ist coupled.

[0052] The load torque M Last cannot be directly detected by the pump controller 28 as an operating parameter of the oil pump 10. The load torque M Last However, the actual torque to be applied is M ist of the electric motor 12 of the oil pump 10. The actual torque M ist is composed additively of the load torque M Last and a dynamic torque M dyn together.

[0053] The dynamic torque M retained as control reserve of the oil pump 10dyn describes in particular the dynamic properties of the oil 6. The dynamic torque M dyn This includes, on the one hand, a known, design-dependent, mass moment of inertia of the pump rotor and a system moment of inertia, which depends on the oil viscosity η and an (oil) temperature T Öl of the oil to be extracted 6.

[0054] To determine the dynamic torque M dyn the pump controller 28 records the course of the actual torque M ist during a start-up or startup process in which the oil pump 10 is accelerated from a standstill to an operating speed.

[0055] In the Fig. 3 is an example of a time course of the actual torque M ist during a start-up process in which the pressure relief valve 18 is open. In the schematic diagram of the Fig. 3 is a time t on the abscissa axis (x-axis) and the actual torque M ist plotted on the ordinate axis (y-axis).

[0056] At a time t0, the oil pump 10 is started. As shown in the Fig. As can be clearly seen in Figure 3, a sudden or step-like torque increase or torque gradient occurs. At a delayed time t1, the starting process is completed and a desired operating speed or operating torque is reached.

[0057] The torque increase occurring when starting or running the oil pump is invariant with respect to the oil pressure p of the oil circuit 4 and essentially describes the dynamic properties of the oil 6 (system moment of inertia). This results in the dynamic torque M dyn essentially by the jump height or the torque gradient in the area around the time t0.

[0058] As a result, the dynamic torque M dyn when the oil pump 10 starts up, can be determined by the pump controller 28. As a result, the pressure p ist relevant load torque M Last as a simple subtraction of the actual torque M ist with the dynamic torque M dyn determinable.

[0059] The proportionality factor between the load torque M Last and the actual pressure p occurring in the oil circuit 4 ist depends on the oil viscosity η. The oil viscosity η varies with the oil temperature T Öl in the oil circuit 4. During operation of the hydraulic system 2, temperature changes of the oil 6 in the oil circuit 4 and thus corresponding changes in the oil viscosity η occur. Preferably, a corresponding table or characteristic curve of the material or fluid properties of the oil 6 is stored in a memory of the pump controller 28, so that a specific oil temperature TÖl a corresponding value of the oil viscosity η is assigned.

[0060] In this embodiment, the oil temperature T Öl by the pump controller 28 without a temperature sensor, i.e. without a measurement or sensor signal from a temperature sensor in the oil circuit 6. For this purpose, the pump controller 28 evaluates the detected operating temperature T B of the pump electronics 26. The operating temperature T B For example, a junction temperature of a semiconductor switch of an inverter of the pump electronics 26 or a temperature of a printed circuit board (PCB) carrying the pump electronics 26 is monitored. A transfer model 34, for example in the form of a table or a characteristic curve, is stored in the pump controller 28, with which the detected operating temperature T B a value for the oil temperature T Öl in oil circuit 4.

[0061] Based on the thus determined oil temperature T Öl This results in the oil viscosity η, which determines the proportionality factor between the load torque M Last and the actual pressure p occurring in the oil circuit 4 ist This makes it possible in a simple manner for the pump controller 28 to determine the value for the actual pressure p based solely on the operating parameters of the oil pump 10. ist in oil circuit 4.

[0062] The target pressure p required for pressure control of the oil pump 10 soll is determined by the controller 22 of the oil circuit 4. In particular, the value of the target pressure p soll This is done dynamically and adaptively, in particular by means of a Kalman filter, to the respective transmission or driving situation of the vehicle.

[0063] In this embodiment, the target pressure p sollpredicted by the pump controller 28 and compared or verified by evaluating non-oil pump operating parameters (vehicle parameters) transmitted by the controller 22. For this purpose, the controller 22 transmits, for example, the values ​​of an engine speed v and a gear shift status S as well as the oil temperature T Öl . The pump controller 28 is configured for machine learning, so that, for example, based on the received engine speed v and the gear change status S, a prediction of the requirement profile or the desired target pressure p soll In other words, based on known, previously occurring driving or shifting situations, a predictive pressure control in the oil circuit 4 is carried out. This ensures particularly effective and reliable operation of the vehicle transmission.

[0064] This does not directly influence the switching behavior. The Kalman filter preferably only corrects the actual pressure p ist The actual pressure requirement is not affected. Preferably, the signal processing of various vehicle interfaces (e.g. route profile, gradient, traffic, ...) and the associated, moderate, adjustment of the target or actual pressure p soll or p ist For example, in high traffic conditions, it is possible to predict an increased frequency of gearshifts. As a result, the pump controller 28 regulates, for example, to a slightly increased oil pressure p, so that the resulting reserve optimizes the upcoming gearshifts.

[0065] The invention is not limited to the exemplary embodiment described above. Rather, other variants of the invention can also be derived therefrom by those skilled in the art without departing from the scope of the invention. In particular, all individual features described in connection with the exemplary embodiment can also be combined with one another in other ways without departing from the scope of the invention.

[0066] Thus, the method according to the invention is not limited to a - as in the Fig. 1. For example, it is possible that the hydraulic system 2 does not have a higher-level pressure control device or a pressure relief valve 18. It is also conceivable to apply the method to a water pump of a motor vehicle. It is essential that the assigned actual pressure p ist of the pumped fluid 6 is determined without a pressure sensor.

Claims

[1] Method for conveying a fluid (6) of a fluid circuit (4) with an electromotive fluid pump (10) of a motor vehicle, - in which the fluid pump (10) and the fluid circuit (4) are part of a motor vehicle manual transmission, - in which a controller (22) of the fluid circuit (4) is signal-coupled to a pump controller (28) of the fluid pump (10), - in which the pump controller (28) carries out a pressure control for the fluid circuit (4) by means of the fluid pump (10), in which a) an actual pressure (p ist ) of the fluid (6) is determined without a pressure sensor by the pump controller (28) based on operating parameters of the fluid pump (10), b) operating parameters of the fluid circuit (4) that are not related to the fluid pump are transmitted from the controller (22) to the pump controller (28), c) a target pressure (p soll) is predicted by the pump controller (28) and adjusted by evaluating the operating parameters transmitted by the controller (22), and d) the actual pressure (p ist ) to the target pressure (p soll ) is regulated. [2] Method according to claim 1, characterized by that the actual pressure (p ist ) based on a load torque (M Last ) of the fluid pump (10) and a fluid viscosity (η) of the fluid (6). [3] Method according to claim 2 characterized by that the load torque (M Last ) from a difference of an actual torque (M ist ) of the electric motor (12) of the fluid pump (6) and a dynamic torque (M dyn ) of the dynamic properties of the fluid (6). [4] Method according to claim 3, characterized by that the dynamic torque (M dyn ) is determined by means of a step-like torque increase during a start-up process of the fluid pump (6). [5] Method according to one of claims 2 to 4, characterized by that the fluid viscosity (η) is determined based on a fluid temperature (T Öl ) is determined. [6] Method according to claim 5, characterized by that the fluid temperature (T Öl ) by means of a thermal transfer model (34) based on an operating temperature (T B ) of a pump electronics (26) of the fluid pump (10). [7] Method according to one of claims 1 to 6, characterized by that to adjust the target pressure (p soll ) a Kalman filter is used. [8] Electromotive fluid pump (10) for conveying a fluid (6) of a fluid circuit (4) of a motor vehicle, in particular in a motor vehicle transmission, with pump electronics (26) and with a pump controller (28) which is provided and set up to carry out a method according to one of claims 1 to 7, wherein the fluid circuit (4) is designed without a pressure sensor, and wherein the pump controller (28) is coupled in terms of signal technology to a controller (22) of the fluid circuit (4). [9] Motor vehicle transmission with a fluid circuit (4) with a fluid pump (10) according to claim 8.

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