阅读说明：本技术 用于运送机动车的流体回路中的流体的方法和流体泵 (Method and fluid pump for conveying a fluid in a fluid circuit of a motor vehicle ) 是由 阿达尔沙·干乍纳 克里斯蒂安·比尼克 于 2017-09-05 设计创作，主要内容包括：本发明涉及一种用于运送机动车的流体回路中的流体的方法和流体泵。其中,借助流体泵(10)将流体回路(4)中的流体(6)的流体压力(p)调节到目标压力(p-(目标)),并且其中,以无压力传感器的方式确定流体(6)的实际压力(p-(实际))。(The invention relates to a method and a fluid pump for conveying a fluid in a fluid circuit of a motor vehicle. Wherein a fluid pressure (p) of a fluid (6) in a fluid circuit (4) is adjusted to a target pressure (p) by means of a fluid pump (10) Target ) And wherein the actual pressure (p) of the fluid (6) is determined in a pressure-sensorless manner Practice of )。)

1. Method for conveying a fluid (6) of a fluid circuit (4) by means of an electric fluid pump (10), in particular an oil pump, of a motor vehicle,

-wherein a fluid pressure (p) of a fluid (6) in the fluid circuit (4) is adjusted to a target pressure (p) by means of the fluid pump (10)_Target) And is and

-itDetermining the actual pressure (p) of the fluid (6) without a pressure sensor_{Practice of})，

According to the temperature (T) of the fluid_Oil) To determine the fluid viscosity (η),

depending on the operating temperature (T) of the pump electronics (26) of the fluid pump (10) by means of a heat transfer model (34)_B) To determine the fluid temperature (T)_Oil)。

2. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

determining an actual pressure (p) of the fluid (6) from operational data of the fluid pump (10)_{Practice of})。

3. The method according to claim 1 or 2,

it is characterized in that the preparation method is characterized in that,

according to a load torque (M) of the fluid pump (10)_Load(s)) And the fluid viscosity (η) of the fluid (6) to determine the actual pressure (p)_{Practice of})。

4. The method of claim 3, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

by the actual torque (M) of the electric motor (12) of the fluid pump (6)_{Practice of}) A dynamic torque (M) related to the dynamic characteristics of the fluid (6)_{Dynamic state}) To determine said load torque M_{Negative pole}And (4) loading.

5. The method of claim 4, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

determining the dynamic torque (M) from a stepped torque boost during a start-up process of the fluid pump (6)_{Dynamic state})。

6. The method of any one of claims 1 to 5,

it is characterized in that the preparation method is characterized in that,

adaptively adjusting the targetPressure (p)_Target)。

7. The method of claim 6, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

applying a Kalman filter for setting the target pressure (p)_Target)。

8. Electric fluid pump (10) for conveying a fluid (6) of a fluid circuit (4) of a motor vehicle, in particular of a motor vehicle transmission, having pump electronics (26) and a pump controller (28) which is provided and set up for carrying out the method according to one of claims 1 to 7.

9. The fluid pump (10) of claim 8,

it is characterized in that the preparation method is characterized in that,

the fluid circuit (4) is implemented without a pressure sensor.

10. The fluid pump (10) of claim 8 or 9,

it is characterized in that the preparation method is characterized in that,

the pump controller (28) is signal-connected to a controller (22) of the fluid circuit (4).

11. A motor vehicle transmission having a fluid circuit (4) and a fluid pump (10) according to any one of claims 8 to 10.

Technical Field

The present invention relates to the field of pumps, preferably to the field of electrically or electrically operated or driven (fluid) pumps, and to a method for conveying fluid of a fluid circuit with an electrically driven fluid pump in a motor vehicle, in particular in a motor vehicle transmission. The invention also relates to a fluid pump operating according to said method and to a motor vehicle transmission having such a fluid pump. A fluid pump is understood here to mean, in particular, an auxiliary pump or a main pump, in particular an oil pump, in or for a motor vehicle.

Background

Electrical fluid pumps and in particular also so-called auxiliary pumps or auxiliary pumps are used, for example, for conveying oil as a (hydraulic) fluid for control tasks or for cooling, for example, moving parts or components of hybrid or electrically driven vehicles (motor vehicles), which are driven by an internal combustion engine. Such oil pumps usually produce a (closed) oil circuit (fluid circuit) with a pressure flow and a volume flow on the basis of their delivery characteristics.

Auxiliary or additional pumps, which are driven, for example, electrically or electrically, are often also used for at least temporarily lubricating or additionally lubricating the drive train of a motor vehicle transmission, in particular an automatic transmission. The transported oil is also used for cooling components or additional components of the drive train of such a motor vehicle. Furthermore, the auxiliary pump or the additional pump can implement or support extended driving functions of the motor vehicle, such as, for example, a coasting or start-stop function.

For control and/or regulation purposes, such fluid pumps usually have pump electronics that can be controlled and/or regulated by means of a pump controller, with which the operating point of the electric motor is set. For this purpose, the (hydraulic) fluid pressure of the fluid in the fluid circuit is monitored, in particular, by means of a pump controller. To this end, the fluid circuit typically has a (fluid) pressure sensor which detects a current value of the actual pressure of the fluid in the fluid circuit and transmits it to the pump controller. The pump controller compares the detected actual pressure with a desired target pressure and actuates the fluid pump or its motor in dependence on the comparison. In particular, the fluid pressure is set here by adjusting the delivery flow of the fluid pump to a desired target pressure.

DE 10345449 a1 discloses a device for conveying fluid in a motor vehicle transmission. The known device comprises a pressure sensor coupled to the fluid circuit, which in operation detects the actual fluid pressure (actual pressure) of the fluid circuit and transmits it to a regulator (pump controller) of the fluid pump. The regulator is also coupled to a sensor that detects a driving state of the vehicle. The regulator determines a threshold value (target pressure) to which the detected fluid pressure is compared, according to the vehicle running state.

Pressure sensors for such (fluid) pressure regulation (Closed-Loop-Regelung) are error-prone and are associated with relatively high operating and manufacturing costs. Furthermore, the cable guides (wire harnesses) between the fluid pressure sensors in the fluid circuit and the pump controllers of the fluid pump, which are required for the signal transmission of the actual pressure, lead to additional structural weight and increased production costs.

EP 2290264 a2 describes a motor vehicle transmission having a device for conveying fluid, which has a fluid circuit with a fluid pump. The motor vehicle transmission has a continuously variable rotational speed changing device. The (transmission) controller calculates a target pressure required for this purpose as a function of the moment of inertia and the input torque of the rotational speed changing device during a shifting operation in which a shift between two transmission gears of the motor vehicle transmission is carried out. The calculated target pressure is sent to a pump controller, which drives the fluid pump accordingly.

Such a pressure control without a pressure sensor (Open-Loop-Steuerung) can be established relatively inexpensively. However, due to the lack of regulation, an effective delivery of fluid cannot be ensured, thereby adversely affecting the efficiency of the fluid pump or the motor vehicle transmission.

Disclosure of Invention

The object of the present invention is to provide a particularly suitable method for conveying a fluid of a fluid circuit using an electric fluid pump of a motor vehicle. The object of the invention is also to specify a fluid pump operating according to such a method and a motor vehicle transmission having such a fluid pump.

According to the invention, this object is achieved in terms of method by means of the features of claim 1, in terms of a fluid pump by means of the features of claim 10, and in terms of a motor vehicle transmission by means of the features of claim 13. Advantageous embodiments and improvements are the subject matter of the respective dependent claims.

The method according to the invention is suitable and designed for conveying a fluid of a fluid circuit using an electric fluid pump of a motor vehicle.

According to the method, a pressure regulation (closed-loop regulation) is provided for actuating the fluid pump as a function of the current (hydraulic) fluid pressure (operating pressure) of the fluid in the fluid circuit. For this purpose, the actual pressure and the target pressure of the fluid are determined and compared with one another. Depending on the comparison, the fluid pump or its electric motor is controlled in such a way that the fluid pressure in the fluid circuit is adjusted to the target pressure on the basis of the variable delivery flow. In this case, a pressure-free determination or detection of the actual pressure is provided, which means that the actual pressure is not monitored by the (fluid) pressure sensor of the fluid circuit.

In other words, it is possible to implement the fluid circuit without expensive (fluid) pressure sensors. Thus reducing the manufacturing and operating costs of the fluid circuit. Furthermore, the cabling between the pressure sensor and the fluid pump can thus be reduced, which on the one hand enables maintenance and repair costs to be reduced and on the other hand enables structural weight and structural dimensions to be saved. This is advantageous, therefore, for expanding the operating range of the motor vehicle.

The fluid pump is, for example, an electric water pump, preferably an electric auxiliary pump or an auxiliary pump for a motor vehicle, in particular an oil pump for lubricating and/or controlling a transmission part of a motor vehicle transmission. The fluid to be delivered is here suitably a (transmission) oil, for example ATF oil (Automatic transmission fluid), and is also used, for example, for cooling components or additional components of the drive train of such a motor vehicle. The term oil is understood here to mean, in particular, without being limited to mineral oils. Instead, fully or partially synthetic oils, silicone oils or other oily liquids, such as, for example, hydraulic fluids or cooling lubricants, can also be used.

The fluid pump expediently comprises a pump controller and pump electronics, with which the electric motor is preferably controlled and/or regulated in a field-oriented manner. The electric motor is preferably implemented as a brushless dc motor, which is operated with a three-phase current of the pump electronics. The rotor of the electric motor is connected to the pump rotor in a rotationally fixed manner, so that in operation fluid is conveyed from the pump inlet (low-pressure side, suction side) to the pump outlet (pressure side). In an alternative embodiment, the pump electronics controls and/or regulates a plurality of electric pump drives. This is advantageous, for example, in the application of direct-shift transmissions (DSG), in which pump electronics control a plurality of electrically driven auxiliary drives for generating pressure.

In a suitable development, the actual pressure of the fluid is determined from operating data of the fluid pump. In particular, the pump controller monitors operating data of the fluid pump detected during operation. In this way, a pressure-sensor-less determination of the actual pressure can be achieved in a simple and cost-effective manner.

In a conceivable embodiment, for determining the actual pressure, in particular the operating parameters are used to determine the load torque of the fluid pump and the fluid viscosity of the fluid. The load torque of the fluid pump is essentially a static torque which the fluid pump or the pump rotor must exert against the fluid pressure present in the fluid circuit, in particular during a steady state or steady state of the fluid circuit after the fluid pump has been started. In other words, the load torque is proportional to the actual pressure, and in particular, the load torque has a linear correlation with the actual pressure. The scaling factor which forms the correlation between the load torque and the actual pressure is here related to the fluid viscosity of the transported fluid. This allows a simple determination of the actual pressure with knowledge of the load torque and the fluid viscosity.

In a suitable embodiment, the load torque is determined by the difference between the actual torque of the electric motor of the fluid pump and the dynamic torque of the dynamic behavior of the fluid. The actual torque of the electric motor corresponds here substantially to the total torque to be applied during operation for conveying the fluid. The actual torque may 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 is dependent on the actual torque applied. The actual three-phase current has a correlation with the magnet temperature or the coil temperature of the stator, so that the magnet temperature or the coil temperature is also appropriately detected.

The actual torque to be applied is composed of the pressure-dependent load torque and the dynamic torque prestored, in particular as a control reserve. The dynamic torque includes, on the one hand, the known, structurally dependent mass moment of inertia of the pump rotor and the system moment of inertia, which is dependent on the fluid viscosity and the temperature of the fluid to be conveyed. The actual torque is monitored during operation as an operating parameter by the pump controller, so that the load torque desired for the actual pressure determination can be determined in a simple manner and in a simple manner by means of subtraction given a dynamic torque.

In an advantageous embodiment, a stepped torque rise (torque gradient) is determined during the starting process of the fluid pump in order to determine the dynamic torque. The torque increase occurring at the start-up or start-up of the fluid pump is constant with respect to the fluid pressure of the fluid circuit and essentially describes the dynamic behavior of the fluid (system moment of inertia). This makes it possible to: the value of the dynamic torque known from the start-up of the fluid pump is subtracted from the static torque for the steady-state (running) state of the fluid pump. Thereby, the influence due to the viscosity of the fluid can be eliminated from the load torque defined by the fluid pressure (actual pressure).

The load torque, which is therefore substantially known, is proportional to the actual pressure to be determined by means of a factor dependent on the viscosity of the fluid. In operation of the fluid pump, a temperature change of the fluid circuit and thus of the fluid guided in the fluid circuit is possible. The temperature range to be controlled or taken into account in the fluid circuit is for example between-40 ℃ and +130 ℃. It should also be taken into account here that the fluid used has a certain or specific (fluid) viscosity which is temperature-dependent and decreases with increasing temperature, i.e. the viscosity is greater at lower temperatures than at higher temperatures.

In a suitable development, the fluid viscosity is determined as a function of the fluid temperature, in particular the temperature of the fluid in the fluid circuit. In the fluid used, the value of the viscosity of the fluid for a given temperature is known, for example, from a data table. In this way, the corresponding fluid viscosity can be determined in a simple manner by determining the fluid temperature. For this purpose, the pump controller has, for example, a stored table or characteristic curve, with which the corresponding value of the fluid viscosity is assigned to the fluid temperature value. For this purpose, the fluid circuit has, for example, an integrated (fluid) temperature sensor.

In a preferred embodiment, the fluid circuit is implemented without a temperature sensor, wherein the fluid temperature is determined by means of a heat transfer model as a function of the operating temperature of the pump electronics of the fluid pump. The temperature sensor of the fluid circuit is eliminated, thereby making the fluid circuit particularly inexpensive. In this case, the operating temperature of the pump electronics is monitored as an operating parameter of the fluid pump. The fact that the pump electronics and the fluid are at least partially in thermal contact with one another is thereby used in an advantageous and simple manner. The thermal contact is described at least approximately by means of a transfer model.

The operating temperature is, for example, the barrier layer temperature of the semiconductor switch of the pump electronics or the temperature of the circuit board (PCB board) carrying the pump electronics. With the transfer model, it is therefore possible to determine a value for the temperature of the fluid in the fluid circuit as a function of the operating temperature, with which value it is thus possible to determine the (actual) fluid viscosity.

By knowing the fluid viscosity and the load torque, it is thus possible to determine the value of the actual pressure in the fluid circuit simply and without a pressure sensor. In particular, the actual pressure is determined only by operating parameters of the fluid pump, which are monitored by the pump controller for error-free operation of the fluid pump. This allows a particularly simple, cost-effective and advantageous determination of the actual pressure.

In accordance with an additional or further aspect of the method according to the invention, it is provided that the target pressure is set adaptively. The target pressure is preferably set by means of an operating parameter of the fluid circuit that is independent of the fluid pump. For this purpose, the controller of the fluid circuit is signaled to the pump controller, for example via a (bus) interface. In other words, the actual pressure is determined and/or set in particular as a function of an operating parameter of the fluid pump, and the target pressure is determined and/or set in particular as a function of an operating parameter of the fluid circuit.

In a possible application, the fluid pump and the fluid circuit are part of a (motor vehicle) transmission (automatic transmission, dual clutch transmission), wherein the controller sends information about the engine speed and/or the shifting situation to the pump controller. Such information only indirectly affects fluid pressure, but enables prediction of a demand profile or target pressure. In other words, the target pressure is adjusted in a particularly prospective manner in order to be set adaptively. For this purpose, mechanisms and methods for machine learning (big data, auto-learning) are integrated, for example, in the pump controller. The pump controller is thereby adapted and configured for predictively and adaptively determining the value of the target pressure as a function of known, previously occurring driving or gear shifting conditions. This is advantageous, therefore, for expanding the effectiveness and efficiency of the fluid pump or fluid circuit and of a motor vehicle transmission equipped with the fluid pump or fluid circuit.

In a suitable development, a kalman filter is used to set the target pressure. In particular, in the case of applications in a manual transmission, the variance of the dependency of the desired shifting process on the detected operating parameters of the fluid circuit and/or the fluid pump and the current vehicle parameters (vehicle speed, engine speed). Hereby it is achieved that the prediction of the target pressure is performed according to an easily implementable kalman filter. Thus, the state estimation or target pressure estimation can be achieved in a simple manner. In other words, the pump controller basically learns the shift strategy based on the operating parameters and the vehicle parameters.

In particular, algorithms utilizing kalman filters produce linear quadratic estimates for the target pressure (LQE). For this purpose, previously occurring driving or shifting situations are converted into an estimate for the (future) required target pressure by means of bayesian conclusions and evaluation according to a probability function. Since the deviation (variance) of the driving or shifting situation is relatively small, a relatively accurate and precise prediction of the target pressure can be achieved.

The electric fluid pump according to the invention is suitable and designed for conveying a fluid of a fluid circuit of a motor vehicle, in particular in a motor vehicle transmission. The fluid pump has integrated pump electronics and a pump controller (control unit) which is provided and set up for carrying out the method according to the invention described above. The pump controller is therefore specifically designed to regulate the fluid pressure of the fluid in the fluid circuit to a target pressure during operation of the pump and to determine the actual pressure of the fluid required for the regulation in a pressure-sensor-free manner.

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 in the form of operating software (firmware) is implemented in a programming technique, so that the method (if necessary in the case of interaction with a vehicle user) is carried out automatically when the operating software in the microcontroller is implemented.

Within the scope of the invention, the controller may alternatively also be formed by non-programmable electronic components, 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 the mechanisms of circuit technology.

The fluid pump operated in this way is therefore suitable and designed for closed-loop control of the fluid pressure in a fluid circuit without a pressure sensor. This enables a particularly inexpensive fluid pump with a reduced number of components to be realized. Furthermore, a particularly efficient operation of the fluid pump is ensured with the highest possible efficiency.

In an advantageous embodiment, the fluid circuit is implemented without a pressure sensor. This means that the fluid circuit does not have a (fluid) pressure sensor for detecting the actual pressure. This saves signal lines between the fluid circuit and the fluid pump, which advantageously results in a weight reduction and thus a cost saving.

In a suitable embodiment, the pump controller is coupled to the controller of the fluid circuit using signaling technology. This enables the target pressure to be set adaptively according to the indicator that is independent of the pump.

In a preferred application, the fluid pump and the fluid circuit coupled thereto are part of a motor vehicle transmission. The fluid pump is preferably an electrically driven auxiliary pump or an additional pump. This results in a low-cost motor vehicle transmission with fewer components.

Drawings

Embodiments of the present invention are described in detail below with reference to the accompanying drawings. In which are shown, in a simplified and schematic illustration:

FIG. 1 illustrates a hydraulic system of a motor vehicle transmission having a fluid circuit and an electrically powered fluid pump;

FIG. 2 shows an interface model of a pump controller of a fluid pump, an

Fig. 3 shows a graph of the actual torque of the fluid pump during the starting process.

In all the figures, parts and parameters corresponding to each other have the same reference numerals throughout.

Detailed Description

The hydraulic system 2 shown in fig. 1 is suitable and designed for operating and lubricating a motor vehicle transmission, in particular a manual transmission, of a motor vehicle, not shown. For this purpose, the hydraulic system 2 comprises a fluid or oil circuit 4, shown in dashed lines, for conducting a (hydraulic) fluid 6, in particular a (transmission) oil. For conveying the oil 6 in the oil circuit 4, the hydraulic system 2 has two fluid pumps or oil pumps 8 and 10. The oil pump 8 is designed here as a main pump, while the oil pump 10 is designed as an auxiliary or additional pump of the oil circuit 4.

The oil pump 8 is coupled to an internal combustion engine of the motor vehicle and can be functionally driven by means of the internal combustion engine for conveying the oil 6. The oil pump 10 is electrically operated and has a driven electric motor 12. The electric motor 12 is embodied, for example, as a brushless direct current motor and has a rotatably mounted rotor which is coupled to the pump rotor in a rotationally fixed manner.

The oil circuit 4 has a high-pressure branch (primary circuit) 4a and a low-pressure branch (secondary circuit) 4 b. In this exemplary embodiment, the high-pressure branch 4a has two hydraulically controllable valves 14, with which a clutch 16 of the motor vehicle transmission can be actuated accordingly during the course of a shifting operation. The oil pump 8 is connected to the high-pressure branch 4a on the outlet side. Via a pressure-limiting valve 18, the oil pump 8 is fluidically coupled to the low-pressure branch 4 b. The oil pump 10 is guided on the outlet side (pressure side) of the oil pump 8 by means of a check valve 20.

In operation of the hydraulic system 2, the oil pump 10 delivers oil 6 into the high-pressure branch 4a when the delivery volume of the oil pump 8 is smaller than a threshold value. The delivery volume of the oil pumps 8 and 10 is monitored in this case, in particular, via the fluid pressure or oil pressure p of the oil 6 in the oil circuit 4.

In order to monitor and regulate the oil pressure p in the oil circuit 4, a control unit 22 of the fluid circuit is provided, which is signaled, for example, to an engine control unit of the internal combustion engine and/or to a transmission control unit of the manual transmission. In this case, the control unit 22 monitors the oil pressure p for actuating the valve 14 in the region of the connection 24. On the other hand, the oil pump 10 has pump electronics 26 with a pump controller 28, which determines the oil pressure p in the region of the interface 30. In other words, the controller 22 monitors, among other things, the oil pressure p in the main pressure branch 4a, while the pump controller 28 monitors the oil pressure p in the auxiliary pressure branch 4 b.

The operation of the oil pump 10 is explained in detail below with reference to fig. 2. A schematic interface model of the pump controller 28 with the controller 22 is shown in fig. 2. The pump controller 28 and the controller 22 are coupled to one another by means of a bus interface 32.

In operation, the pump controller 28 is configured in particular to perform a pressure regulation for the oil circuit 4In which the actual pressure p of the oil 6_{Practice of}Is adjusted to a target pressure p_Target. In conjunction with this comparison, the rotational speed of the electric motor 12 or of the oil pump 10, and thus the delivery volume, is set by the pump controller 28. The pump controller 28 determines the actual pressure p of the oil 6 without a pressure sensor_{Practice of}That is, the oil circuit 4 does not have a pressure sensor coupled to the pump controller 28.

The pump controller 28 determines the current actual pressure p by evaluating the detected and monitored operating data of the oil pump 10_{Practice of}The value of (c). For this purpose, during operation, the pump controller 28 detects the phase current I of the pump electronics 26 for driving the electric motor 12_M. Phase currents (three-phase currents) I_MIs fed to the stator or phase windings of the motor 12, thereby generating a rotating magnetic field that rotates the rotor. The pump controller 28 also detects the actual torque M of the oil pump 10 generated in operation as a result thereof_{Practice of}And the operating temperature T of the pump electronics 26_B。

To determine the actual pressure p_{Practice of}The pump controller 28 evaluates the load torque M of the oil pump 10 occurring during operation_Load(s)And the (fluid) viscosity η of the oil 6. Here, the load torque M_Load(s)Is a static torque, which is the actual pressure p of the oil pump 10 relative to the oil circuit 4 that is necessary in the steady state of the oil pump, i.e. at a stable operating point after the starting process_{Practice of}Applied in order to carry the oil 6. Load torque M_Load(s)By a scaling factor related to the oil viscosity eta and the actual pressure p to be determined_{Practice of}And (4) coupling.

Load torque M_Load(s)In this case, it can be detected by the pump controller 28 not directly as an operating parameter of the oil pump 10. However, the load torque M_Load(s)Actual torque M to be applied included in motor 12 of oil pump 10_{Practice of}In (1). Actual torque M_{Practice of}Whereby the load torque M_Load(s)And dynamic torque M_{Dynamic state}And adding the components to form the composition.

Dynamic torque M retained as a control reserve for oil pump 10_{Dynamic state}In particular, oils are described6 dynamic characteristics. Dynamic torque M_{Dynamic state}This includes, on the one hand, the known, structurally dependent mass moment of inertia of the pump rotor and the system moment of inertia, which is a function of the oil viscosity η and (oil) T of the oil 6 to be delivered_OilIt is related.

For determining dynamic torque M_{Dynamic state}The pump controller 28 detects the actual torque M during the start-up or starting process_{Practice of}Where the oil pump 10 accelerates from standstill to an operating rotational speed.

Fig. 3 shows the actual torque M during the starting process for opening the pressure-limiting valve 18_{Practice of}Exemplary time profile of (a). In the schematic graph of fig. 3, the abscissa axis (x-axis) represents the time t, and the ordinate axis (y-axis) represents the actual torque M_{Practice of}。

At time t₀The oil pump 10 is started. As is shown in fig. 3, it is clear that a stepped or step-like torque increase or torque gradient occurs here. At a subsequent time t₁The starting process is terminated and the desired operating speed or operating torque is reached.

The torque increase occurring at the start or start of the oil pump is constant in this case with respect to the oil pressure p of the oil circuit 4 and essentially describes the oil 6 dynamics (system moment of inertia). Thereby, basically by passing through at time t₀A step height or torque gradient in the range of (a) yields a dynamic torque M_{Dynamic state}。

Thereby, the dynamic torque M_{Dynamic state}The pump controller 28 may determine when the oil pump 10 is started. Thus, for determining the actual pressure p_{Practice of}Load torque M of importance_Load(s)Can be determined as the actual torque p_{Practice of}And dynamic torque M_{Dynamic state}Simple differencing of (1).

Load torque M_Load(s)With the actual torque p occurring in the oil circuit 4_{Practice of}The scaling factor between is related to the oil viscosity η. Oil viscosity eta is a function of the oil temperature T in the oil circuit 4_OilAnd (4) changing. During operation of the hydraulic system 2, a temperature change of the oil 6 in the oil circuit 4 occurs and thus a corresponding oil viscosity ηAnd (4) changing. Preferably, a corresponding table or characteristic curve of the material or fluid properties of the oil 6 is stored in the memory of the pump controller 28, in order to specify a particular oil temperature T in each case_OilCorresponding values for the oil viscosity η are assigned.

In this example, the oil temperature T_OilThis is determined by the pump controller 28 in a temperature-sensorless manner, i.e. without a measurement or sensor signal of a temperature sensor in the oil circuit 6. For this purpose, the pump controller 28 evaluates the detected operating temperature T of the pump electronics 26_B. In this case, for example, the barrier layer temperature of the semiconductor switches of the inverter of the pump electronics 26 or the temperature of the circuit board (PCB) carrying the pump electronics 26 is taken as the operating temperature T_BTo monitor. In this case, a transmission 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 is assigned_BAssociated with the oil temperature T in the oil circuit 4_OilThe value of (c).

In combination with the oil temperature T thus determined_OilThe oil viscosity η is then obtained, from which the load torque M can be determined_Load(s)With the actual pressure p occurring in the oil circuit 4_{Practice of}A scaling factor in between. This makes it possible in a simple manner to determine the actual pressure p in the oil circuit 4 by the pump controller 28 solely on the basis of operating parameters of the oil pump 10_{Practice of}The value of (c).

Target pressure p required for pressure-regulating oil pump 10_TargetAs determined by the controller 22 of the oil circuit 4. In particular, the target pressure p_TargetThe value of (b) is dynamic and adaptive, in particular adapted to the respective transmission or driving situation of the motor vehicle by means of a kalman filter.

In this embodiment, the target pressure p is predicted, for example, by the pump controller 28_TargetAnd is adjusted or rationalized by evaluating operating parameters (vehicle parameters) transmitted by the controller 22 that are independent of the oil pump. For this purpose, the control unit 22 transmits, for example, the sum of the engine speed v and the shift state S and the oil temperature T_OilThe value of (c). The pump controller 28 is designed for machine learning, for example, in order toAchieving a desired target pressure p or a demand profile based on the received engine speed v and the shift condition S_TargetAnd (4) predicting. In other words, a prospective pressure regulation in the oil circuit 4 is carried out as a function of known, previously occurring driving conditions or shifting conditions. This ensures a particularly efficient and operationally reliable operation of the motor vehicle transmission.

Here, the shifting behavior is not directly influenced. By means of a Kalman filter, preferably only for the actual pressure p_{Practice of}A correction is made, however, here the actual pressure requirement is not affected. Preferably, a signal-technical processing of various vehicle interfaces (e.g. road section profile, road gradient, traffic …) and an accompanying, moderate target pressure p are provided_TargetOr the actual pressure p_{Practice of}And (4) adjusting. For example, in the case of a high traffic flow, it is possible to predict an increased frequency of the shifting process. The pump controller 28 thus adjusts the oil pressure p, for example, slightly higher, in order to optimize the shifting process to be carried out by means of the reserve thus available.

The present invention is not limited to the above-described embodiments. But other variants of the invention can also be deduced therefrom by those skilled in the art without departing from the subject matter of the invention. In particular, all individual features described in connection with the embodiments may also be combined with one another in other ways without departing from the subject matter of the invention.

The method according to the invention is therefore not limited to the hydraulic system 2 (as shown in fig. 1). It is thus possible, for example, for the hydraulic system 2 to have no higher-order pressure regulating device or no pressure limiting valve 18. It is also conceivable to apply the method to a water pump of a motor vehicle. It is important that the associated actual pressure p of the fluid 6 to be conveyed is determined without a pressure sensor_{Practice of}。

List of reference numerals

2 Hydraulic system

4 fluid/oil circuit

4a main pressure branch

4b auxiliary pressure branch

6 fluid/oil

8 fluid pump/oil pump/main pump

10 fluid pump/oil pump/auxiliary pump

12 electric motor

14 valve

16 clutch

18 pressure limiting valve

20 check valve

22 controller

24 interface

26 pump electronic device

28 Pump controller

30 interface

32 bus interface

34 transfer model

p fluid pressure/oil pressure

p_{Practice of}Actual pressure

p_TargetTarget pressure

l_MPhase current

M_{Practice of}Actual torque

M_Load(s)Load torque

M_{Dynamic state}Dynamic torque

T_OilFluid/oil temperature

T_BOperating temperature

Eta fluid viscosity/oil viscosity

time t

t₀、t₁Time of day

v engine speed

S Shift Condition