MOBILE WORK MACHINE, ESPECIALLY AREA CONVEYOR

Description

[0001] The invention relates to a mobile work machine, in particular an industrial truck, with at least one hydraulic consumer, wherein a hydraulic pump is provided which supplies the consumer with hydraulic fluid, wherein an electronic control device is provided which is connected to a volume flow sensor arranged in a delivery line of the hydraulic pump, wherein the electronic control device is designed to determine the volume flow delivered by the hydraulic pump on the basis of the signal from the volume flow sensor.

[0002] In mobile work machines, such as industrial trucks, it is known that when one or more hydraulic consumers are activated, the hydraulic pump supplying the consumers with hydraulic fluid, which can be designed as a fixed-displacement pump with a constant delivery volume or as a variable-displacement pump with a variable delivery volume, is operated in such a way that the hydraulic pump provides an excess of hydraulic energy, so that the supply of the controlled consumers can be ensured under all operating conditions. Due to the excess of hydraulic energy, the energy that exceeds the demand of the controlled consumers must be throttled to the tank, for example by means of a pressure compensator. This results in energy losses and undesirable heating of the hydraulic fluid.Load-sensing controls and speed controls of the hydraulic pump are used, with empirical values for wear and production variations of the hydraulic pump being kept as a surplus.

[0003] In mobile work machines, such as industrial trucks, it is also known to arrange a volume flow sensor, such as a volume flow meter, in a delivery line of the hydraulic pump. This sensor can be used to determine the exact volume flow delivered by the hydraulic pump to supply the controlled consumers. The volume flow of the hydraulic pump determined by the volume flow sensor is used to regulate the pump motor speed and, in the case of a variable displacement pump, to adjust the pump. This means that when one or more consumers are activated, the hydraulic pump always only delivers the volume flow requested by the consumers, thus minimizing energy losses.

[0004] Volume flow meters based on a measuring turbine, in which the speed of a measuring wheel, for example an impeller, rotating in the hydraulic fluid is measured, are well suited as volume flow sensors for use in mobile work machines, such as industrial trucks. Such volume flow sensors based on a measuring turbine require less installation space than gear-based volume flow sensors and, compared to gear-based volume flow sensors, have a high measurement dynamic and low flow losses, and are more cost-effective. The disadvantage of a volume flow sensor based on a measuring turbine is that the measurement result of the volume flow sensor depends on the current viscosity of the hydraulic fluid during the measurement process, since the hydraulic fluid used, with its viscosity properties in combination with the temperature of the hydraulic fluid, has a significant influence on the measurement result.The reason for this is that a volume flow sensor based on a measuring turbine is calibrated at a specific viscosity. As the viscosity of the hydraulic fluid decreases, a volume flow sensor designed as a measuring turbine detects volume flows that are too low, which leads to excessive volume flows delivered by the hydraulic pump via the pump control of the hydraulic pump and the associated energy losses. As the viscosity of the hydraulic fluid increases, a volume flow sensor designed as a measuring turbine detects volume flows that are too high, which leads to excessive volume flows delivered by the hydraulic pump via the pump control of the hydraulic pump and the associated energy losses, and the controlled consumers are therefore undersupplied. In the case of a consumer designed as a hydraulic steering device, an undersupply of the steering device with pressure medium must be avoided.

[0005] During operation of a mobile work machine, such as an industrial truck, the hydraulic fluid is typically subject to significant temperature fluctuations, resulting in correspondingly large deviations in the measurement results of a volume flow sensor designed as a measuring turbine. If the temperature-viscosity behavior of the hydraulic fluid used is known, the current viscosity of the hydraulic fluid can be determined by measuring the current temperature of the hydraulic fluid. The measurement result of the volume flow sensor designed as a measuring turbine can be corrected using a correction factor to reduce the effects of the viscosity of the hydraulic fluid used on the measurement result of the volume flow sensor designed as a measuring turbine.This dependence on temperature-viscosity behavior is problematic in practice, as it can change, for example, due to aging of the hydraulic fluid or due to mixing with other hydraulic fluids after repairs or maintenance. As a result, the correction factor stored in an electronic control device that determines the volume flow delivered by the hydraulic pump from the volume flow sensor signal is no longer correct. This leads to the volume flow of the hydraulic pump determined by the volume flow sensor deviating from the actual volume flow delivered by the hydraulic pump. Using the volume flow determined by the volume flow sensor to control the hydraulic pump can result in corresponding energy losses or an undersupply of the controlled consumers.

[0006] From DE 100 21 823 A1 a generic mobile work machine with the features of the preamble of patent claim 1 is known.

[0007] US 11 209 029 B2 discloses a hydraulic power unit system.

[0008] US 2014 / 165692 A1 discloses a method for recalibrating pressure sensors and position sensors in a hydraulic system of a mobile work machine.

[0009] US 2011 / 126608 A1 discloses a hydraulic system with pressure sensors and a recalibration of the pressure sensors.

[0010] DE 10 2009 056 673 B4 discloses a hydraulic system and a method for calibrating a pressure sensor.

[0011] The present invention is based on the object of providing a working machine of the type mentioned at the outset which enables compensation for the viscosity dependence of the measurement result of a volume flow sensor and allows consideration of a change in the temperature-viscosity behavior of the hydraulic fluid during use of the working machine.

[0012] This object is achieved according to the invention in that the electronic control device is designed to carry out a calibration of the volume flow sensor installed in the working machine, wherein the control device is designed, during the calibration of the volume flow sensor, to compare the volume flow determined by means of the volume flow sensor with an actuation of the consumer detected by means of a sensor device, in particular with an actuation speed of the consumer detected by means of a sensor device.

[0013] The electronic control device, which determines the volume flow delivered by the hydraulic pump based on the signal from the volume flow sensor, is thus designed to calibrate the volume flow sensor installed in the working machine. Calibrating the volume flow sensor installed in the working machine using the electronic control device makes it possible to perform an internal calibration of the volume flow sensor at regular or irregular intervals while the working machine is in operation. This makes it easy to account for changes in the temperature-viscosity behavior of the hydraulic fluid during use of the working machine, and to compensate for the viscosity dependence of the measurement result of the volume flow sensor even if the temperature-viscosity behavior of the hydraulic fluid changes during use of the working machine.The calibration of the volume flow sensor installed in the working machine thus makes it possible to minimize the deviations of the measured value, i.e. the determined volume flow of the hydraulic pump, of the volume flow sensor from the actual volume flow of the pump, so that with an appropriate pump control based on the volume flow of the hydraulic pump determined with the volume flow sensor, energy losses can be reduced and an undersupply of the controlled consumers can be avoided.

[0014] According to an advantageous embodiment of the invention, the control device is connected to a temperature sensor that detects the temperature of the hydraulic fluid, wherein the control device is configured to correct the signal supplied by the volume flow sensor using a correction factor. The temperature-viscosity behavior of the hydraulic fluid and its changes during use of the work machine can be easily taken into account using a correction factor in order to be able to determine the volume flow of the hydraulic pump from the signal of the volume flow sensor in the electronic control device.

[0015] According to the invention, the control device is designed to calibrate the volume flow sensor and compare the volume flow determined by the volume flow sensor with an actuation of the consumer detected by a sensor device, in particular with an actuation speed of the consumer detected by a sensor device. During the calibration of the volume flow sensor, the volume flow determined by the signal from the volume flow sensor is thus compared with the resulting actuation of the consumer detected by the sensor device, for example, the movement, or with the resulting actuation speed of the consumer detected by the sensor device, for example, the movement speed.

[0016] For this purpose, according to an advantageous embodiment of the invention, the control device is designed, during calibration of the volume flow sensor, to determine the actual volume flow delivered by the hydraulic pump from the actuation of the consumer detected by the sensor device, in particular the actuation speed of the consumer detected by a sensor device, and to compare the volume flow determined by the volume flow sensor with the actual volume flow determined by the sensor device. From the actuation of the consumer or the actuation speed of the consumer, given known geometric properties of the consumer, for example a hydraulic cylinder or a hydraulic motor, the actual volume flow of the hydraulic pump can be easily calculated.Deviations between the volume flow of the hydraulic pump determined by means of the volume flow sensor and the actual volume flow actually delivered by the hydraulic pump determined by means of the sensor device can thus be determined in a simple manner, so that the volume flow determined by means of the volume flow sensor can be compared with the actual volume flow of the hydraulic pump detected by means of the sensor device and the processing of the signal of the volume flow sensor can be changed in such a way that the volume flow determined by means of the volume flow sensor corresponds to the actual volume flow.

[0017] According to an advantageous embodiment of the invention, the control device is configured to adjust the correction factor during calibration of the volume flow sensor. By appropriately changing and adjusting the correction factor during calibration of the volume flow sensor, it can be easily achieved that the volume flow determined by the volume flow sensor corresponds to the actual volume flow delivered by the hydraulic pump.

[0018] According to an advantageous embodiment of the invention, the consumer is designed as a hydraulic steering device, and the sensor device is designed as a steering sensor, in particular a steering angle sensor. The steering sensor is preferably designed to detect an actuation speed of a hydraulic steering cylinder of the steering device. When calibrating the volume flow sensor during operation of the work machine, in particular, the volume flow determined by the volume flow sensor is compared with the resulting steering movement or steering movement speed of a steering cylinder of the steering device detected by the steering sensor.

[0019] According to an advantageous embodiment of the invention, the consumer is designed as a hydraulic lifting drive of a load-handling device, and the sensor device is designed as a lifting height sensor. The lifting height sensor is preferably designed to detect an actuation speed of a hydraulic lifting cylinder of the lifting drive. When calibrating the volume flow sensor during operation of the work machine, the volume flow determined by the volume flow sensor is compared with the resulting lifting movement or lifting speed of a lifting cylinder of the lifting drive or the load-handling device detected by the lifting height sensor.

[0020] According to an advantageous embodiment of the invention, the consumer is designed as a hydraulic tilt drive of a lifting mast, and the sensor device is designed as a tilt sensor, in particular a tilt angle sensor. The tilt sensor is preferably designed to detect an actuation speed of a hydraulic tilt cylinder of the tilt drive. When calibrating the volume flow sensor during operation of the work machine, the volume flow determined by the volume flow sensor is compared with the resulting tilt movement or tilt speed of a tilt cylinder of the tilt drive or of the lifting mast detected by the tilt sensor.

[0021] According to an advantageous embodiment of the invention, the control device is designed to calibrate the volume flow sensor in operating states in which a singular actuation of a single consumer occurs. The calibration of the volume flow sensor is thus preferably carried out in operating states that offer a clear and singular actuation of only a single consumer, for example, lifting with the lifting drive at maximum lifting speed. This allows the actuation speed of the consumer to be easily determined using the sensor device and suitable distance and time measurement, and the actual volume flow of the hydraulic pump can be calculated by converting this.

[0022] According to an advantageous embodiment of the invention, the control device can be configured to calibrate the volume flow sensor in operating states in which multiple consumers are actuated simultaneously. If the calibration of the volume flow sensor is performed with multiple consumers actuated simultaneously, the associated movements of all actuated consumers are advantageously recorded in order to determine the actuation speed of all actuated consumers and, by converting this, to calculate the actual volume flow of the hydraulic pump.

[0023] According to an advantageous embodiment of the invention, the volume flow sensor is designed as a measuring turbine with an impeller driven by the volume flow. Such a measuring turbine requires little installation space, offers high measurement dynamics, and low flow losses, and is cost-effective. Through the inventive calibration of the measuring turbine during use of the working machine, the measuring turbine can be used to measure the volume flow of the hydraulic pump with high accuracy, even if the temperature-viscosity behavior of the hydraulic fluid changes during use of the working machine.

[0024] According to an advantageous embodiment of the invention, the control device is designed to use the volume flow of the hydraulic pump determined by means of the volume flow sensor as a parameter for controlling the delivery volume of the hydraulic pump. With the calibration of the volume flow sensor according to the invention, small deviations between the volume flow of the hydraulic pump determined by means of the volume flow sensor and the actual volume flow actually delivered by the hydraulic pump can be achieved when the work machine is in use. With this, with appropriate pump control based on the volume flow determined by the volume flow sensor, the volume flow delivered by the hydraulic pump can be adjusted with high precision to the volume flow requested by the consumers. This reduces energy losses and reliably prevents undersupply of the controlled consumers.

[0025] The invention has a number of advantages.

[0026] The invention enables precise determination of the flow rate delivered by the hydraulic pump. Using precise flow rate determination, the hydraulic pump's output can be precisely adjusted to the requirements of the controlled consumers, thus reducing the machine's energy consumption.

[0027] By using the volume flow of the hydraulic pump determined by means of the volume flow sensor as a control variable / parameter for a pump control, variations in the pump delivery rate due to tolerances of the hydraulic pump and, if applicable, its delivery volume adjustment are compensated and do not have to be kept in reserve, which also saves energy.

[0028] The invention with the calibration of the volume flow sensor during use of the working machine enables the use of a volume flow sensor based on a measuring turbine with its advantages while simultaneously minimizing its disadvantages due to the viscosity dependence of the measuring method.

[0029] With the invention and the calibration of the volume flow sensor in use of the working machine, disturbing influences such as wear of the hydraulic pump, changes in the viscosity properties of the hydraulic fluid, mixing or changing of the hydraulic fluid in the pump control or regulation can be easily compensated.

[0030] With the invention, a sufficient hydraulic energy supply of a hydraulic steering device can be achieved in a simple manner with the volume flow determination by means of a volume flow sensor, which results in advantages when the steering device is designed as an electro-hydraulic steering system.

[0031] If a sensor device is used for the calibration of the volume flow sensor that is already installed for other functions in the mobile work machine, for example a lifting height sensor, a tilt sensor of a lifting mast and / or a steering sensor, no additional sensor device needs to be installed for the calibration and the calibration of the volume flow sensor can be carried out in the electronic control device in a simple manner by means of appropriate calculations.

[0032] Significant or implausible deviations between the volume flow of the hydraulic pump specified by the control device when operating one or more consumers and the volume flow determined by the volume flow sensor can be recorded and used as indications for maintenance, so that repair is possible before the component causing the problem fails.

[0033] The change in the ratio between target and actual volume flows can be recorded and trends, for example regarding wear of the hydraulic pump, can be created, which can be used in the context of predictive maintenance.

[0034] Further advantages and details of the invention are explained in more detail with reference to the embodiment shown in the schematic figure.

[0035] The figure shows a circuit diagram of a hydraulic system 1 of a mobile work machine according to the invention, for example an industrial truck.

[0036] The hydraulic system 1 of the mobile work machine has a hydraulic steering device 2 and a working hydraulic system 3 as hydraulic consumers V.

[0037] To supply the hydraulic consumers V, a hydraulic pump 5 is provided, which is driven by a drive motor 6. In the illustrated embodiment, the drive motor 6 is designed as an electric motor.

[0038] The hydraulic pump 5 is operated in an open circuit and sucks hydraulic fluid from a container 7 and pumps it into a delivery line 8.

[0039] A priority valve 10 is arranged in the delivery line 8 for preferential supply to the steering system 2. The priority valve 10 is connected on the inlet side to the delivery line 8 of the hydraulic pump 5. On the outlet side, a supply line 12 leading to a steering valve 11 of the steering system 2 is connected to the priority valve 10 as a consumer primarily supplied with pressure medium. On the outlet side, a supply line 14 leading to a directional control valve block 13 of the working hydraulics 2 is also connected to the priority valve 8.

[0040] The steering valve 11 controls a hydraulic actuator 15 of the steering device 2, which in the illustrated embodiment is designed as a hydraulic steering cylinder 16 and is operatively connected to the at least one steered wheel 17a, 17b of the work machine for steering the same. The steering valve 11 can be actuated by means of an operating element 18, for example, a steering wheel.

[0041] The working hydraulics 3 of an industrial truck designed as a forklift truck comprise several hydraulic drives. In the illustrated embodiment, the working hydraulics 3 comprise a hydraulic lifting drive 20, with which a load-handling device 21 can be raised and lowered. In the illustrated embodiment, the working hydraulics 3 further comprise a hydraulic tilt drive 22, with which a lifting frame 23, on which the load-handling device 21 is arranged so that it can be raised and lowered by means of the lifting drive 20, can be tilted about a horizontal tilt axis 24.

[0042] In the illustrated embodiment, the lifting drive 20 comprises a lifting cylinder 25 which is connected to the directional control valve block 13 by means of a connecting line 26.

[0043] In the illustrated embodiment, the tilt drive 22 comprises a tilt cylinder 27 which is connected to the directional control valve block 13 by means of connecting lines 28a, 28b.

[0044] A volume flow sensor 30 is arranged in the delivery line 8 of the hydraulic pump 5 and is connected to an electronic control device 31. The electronic control device 31 is designed to determine the volume flow delivered by the hydraulic pump 5 based on the signal from the volume flow sensor 30. The volume flow sensor 30 is preferably designed as a measuring turbine with an impeller that is driven by the volume flow flowing in the delivery line 8.

[0045] The control device 31 is also connected to an operating element 32, for example a joystick, with which a driver of the work machine can execute corresponding instructions for actuating the lifting drive 20 and the tilting drive 22. For this purpose, the control device 31 controls control directional valves arranged in the directional valve block 13, with which the lifting drive 20 and the tilting drive 22 can be controlled.

[0046] The control device 31 is connected to the drive motor 6 of the hydraulic pump 5 for its control.

[0047] The control device 31 is further connected to a temperature sensor 35 which is designed to detect the current temperature of the hydraulic fluid.

[0048] In the illustrated embodiment, the control device 31 is further connected to a pressure sensor 36 which is designed to detect the delivery pressure of the hydraulic pump 5 in the delivery line 8.

[0049] The control device 31 is further connected to a sensor device 40 designed as a steering sensor, which is designed to detect the actuation, for example the actuation speed, of the steering cylinder 16.

[0050] The control device 31 is further connected to a sensor device 41 designed as a lifting height sensor, which is designed to detect the actuation, for example the actuation speed, for example the lifting speed, of the lifting cylinder 25 or the load-carrying means 21.

[0051] The control device 31 is further connected to a sensor device 42 designed as a tilt sensor, which is designed to detect the actuation, for example the actuation speed, of the tilt cylinder 27.

[0052] When the operating element 32 and / or the operating element 18 is actuated, the control device 31 determines a volume flow requirement of the controlled consumers of the working hydraulics 3 and / or the steering device 2 in accordance with the actuation of the operating element 32 or 18 and controls the speed of the drive motor 6 such that the hydraulic pump 5 delivers the determined volume flow requirement. Using the signal from the volume flow sensor 30, the control device 31 determines the volume flow delivered by the hydraulic pump 5 in the delivery line 8. The control device 31 uses the volume flow of the hydraulic pump 5 determined by the volume flow sensor 30 as a parameter to regulate the speed of the drive motor 6 of the hydraulic pump 5, so that the hydraulic pump 5 delivers the volume flow requirement of the controlled consumers into the delivery line 8.

[0053] The control device 31 further detects the current temperature of the hydraulic fluid with the temperature sensor 35 and corrects the signal of the volume flow sensor 30 designed as a measuring turbine by means of a correction factor stored in the control device 31 in order to reduce the effects of the viscosity of the hydraulic fluid on the measurement result of the volume flow sensor 30 designed as a measuring turbine.

[0054] During use of the work machine, the temperature-viscosity behavior of the hydraulic fluid may change due to aging of the hydraulic fluid or due to mixing with other hydraulic fluids after repair or maintenance, with the result that the correction factor stored in the electronic control device 31 is no longer correct. This leads to the volume flow of the hydraulic pump 5 determined by the volume flow sensor 30 in the control device 31 deviating from the actual volume flow actually delivered by the hydraulic pump 5 in the delivery line 8.

[0055] To compensate for this effect, the control device 31 is configured to calibrate the volume flow sensor 30 installed in the work machine. The control device 31 thus performs an internal calibration of the volume flow sensor 30 at regular or irregular intervals during use of the work machine in order to minimize the deviations between the volume flow of the hydraulic pump 5 determined by means of the signal of the volume flow sensor 30 and the actual volume flow actually delivered by the hydraulic pump 5.

[0056] For this purpose, the control device 31 is designed, during the calibration of the volume flow sensor 30, to compare the volume flow determined by means of the volume flow sensor 30 with an actuation of the consumer V detected by means of the sensor device 40, 41, 42, preferably an actuation speed of the consumer V detected by means of the sensor device 40, 41, 42.

[0057] For this purpose, the control device 31 is designed, during the calibration of the volume flow sensor 30, to determine the actual volume flow delivered by the hydraulic pump 5 from the actuation of the consumer V detected by means of the sensor device 40, 41, 42, preferably the actuation speed of the consumer V detected by means of the sensor device 40, 41, 42, and to compare the volume flow determined by means of the volume flow sensor 30 with the actual volume flow determined by means of the sensor device 40, 41, 42.

[0058] If a deviation is detected between the volume flow determined by the volume flow sensor 30 and the actual volume flow of the hydraulic pump 5 determined by the sensor device 40, 41, 42, the control device 31 adjusts the correction factor for the calibration of the volume flow sensor 30. Using the correction factor adjusted by the calibration, the control device 31 can thus calculate a volume flow as the measurement result of the volume flow sensor 30 with the signal from the volume flow sensor 30 designed as a measuring turbine, which corresponds to the actual volume flow of the hydraulic pump 5 actually delivered in the delivery line 8.

[0059] The calibration of the volume flow sensor 30 can occur, for example, when the steering cylinder 16 of the steering device 2 is actuated. When the driver steers the work machine, the volume flow determined by the volume flow sensor 30 can be compared in the control device 31 with the resulting steering movement detected by the sensor device 40. In conjunction with the temperature of the hydraulic fluid detected by the temperature sensor 35, the corresponding correction factor can be adjusted in the electronic control device 31.

[0060] Calibration of the volume flow sensor 30 can alternatively or additionally occur when the lifting cylinder 25 of the lifting drive 20 is actuated. When the driver of the work machine actuates the lifting cylinder 25, the volume flow determined by the volume flow sensor 30 can be compared in the control device 31 with the resulting actuation speed, for example, the lifting speed, of the lifting cylinder 25 detected by the sensor device 41. In conjunction with the temperature of the hydraulic fluid detected by the temperature sensor 35, the corresponding correction factor can be adjusted in the electronic control device 31.

[0061] Calibration of the volume flow sensor 30 can be performed alternatively or additionally upon actuation of the tilt cylinder 27 of the tilt drive 22. If the driver of the work machine actuates the tilt cylinder 27, the volume flow determined by the volume flow sensor 30 can be compared in the control device 31 with the resulting actuation speed, for example, the tilt speed, of the tilt cylinder 27 detected by the sensor device 42. In conjunction with the temperature of the hydraulic fluid detected by the temperature sensor 35, the corresponding correction factor can be adjusted in the electronic control device 31.

[0062] The control device 31 is preferably designed to carry out the calibration of the volume flow sensor 30 in operating states in which a clear singular actuation of a single consumer V occurs.Given such a clear and singular actuation of a consumer V, for example lifting by means of the lifting cylinder 25 at maximum speed, the control device 31 can determine the actuation speed of the corresponding consumer V from the signal of the sensor device 40, 41, 42 via a suitable time and distance measurement and, if the geometric dimensions of the consumer V are known, for example the pressurized area of the corresponding hydraulic cylinder 16, 25, 27, the actual volume flow delivered by the hydraulic pump 5 can be calculated by conversion therefrom, which is compared and adjusted with the volume flow determined by means of the volume flow sensor 30 for the calibration of the volume flow sensor 30.

[0063] During the calibration of the volume flow sensor 30, the electronic control device 31 adjusts the correction factor that the control device 31 uses to calculate the volume flow of the hydraulic pump 5 for pump control. The correction factor is corrected by the control device 31 by comparing the two measured values of the volume flow sensor 30 and the sensor device 40, 41, 42. For the calibration of the volume flow sensor 30, it is expedient and advantageous if the movement of the consumer V is constant during the comparative measurement, so that the actuation speed of the consumer V determined by the sensor device 40, 41, 42 and the volume flow calculated therefrom are also constant.

[0064] If the calibration of the volume flow sensor 30 is carried out with several consumers V actuated at the same time, all associated movements of the corresponding consumers V must be recorded and all movements must be constant.

Claims

1. Mobile work machine (1), in particular an industrial truck, having at least one hydraulic consumer (V), wherein a hydraulic pump (5) is provided and supplies the consumer (V) with hydraulic fluid, wherein an electronic control device (31) is provided and is connected to a volumetric flow sensor (30) arranged in a conveying line (8) of the hydraulic pump (5), wherein the electronic control device (31) is configured to determine the volumetric flow conveyed by the hydraulic pump (5) based on the signal from the volumetric flow sensor (30), characterized in that the control device (31) is configured to calibrate the volumetric flow sensor (30) installed in the work machine (1), wherein the control device (31) is configured, during the calibration of the volumetric flow sensor (30), to compare the volumetric flow determined by means of the volumetric flow sensor (30) with actuation of the consumer (V) detected by means of a sensor device (40; 41; 42), in particular with an actuation speed of the consumer (V) detected by means of a sensor device (40; 41; 42).

2. Mobile work machine according to Claim 1, characterized in that the control device (31) is connected to a temperature sensor (35) detecting the temperature of the hydraulic fluid, wherein the control device (31) is configured to correct the signal supplied by the volumetric flow sensor (30) by means of a correction factor.

3. Mobile work machine according to Claim 1 or 2, characterized in that the control device (31) is configured, during the calibration of the volumetric flow sensor (30), to determine the actual volumetric flow conveyed by the hydraulic pump (5) from the actuation of the consumer (V) detected by means of the sensor device (40; 41; 42), in particular from the actuation speed of the consumer (V) detected by means of a sensor device (40; 41; 42), and to compare the volumetric flow determined by means of the volumetric flow sensor (30) with the actual volumetric flow determined by means of the sensor device (40; 41; 42).

4. Mobile work machine according to Claim 2 or 3, if Claim 3 refers back to Claim 2, characterized in that the control device (31) is configured to adapt the correction factor during the calibration of the volumetric flow sensor (30).

5. Mobile work machine according to one of Claims 1 to 4, characterized in that the consumer (V) is in the form of a hydraulic steering device (2) and the sensor device (40) is in the form of a steering sensor, in particular a steering angle sensor.

6. Mobile work machine according to one of Claims 1 to 5, characterized in that the consumer (V) is in the form of a hydraulic lifting drive (20) of a load-bearing means (21) and the sensor device (41) is in the form of a lifting height sensor.

7. Mobile work machine according to one of Claims 1 to 6, characterized in that the consumer (V) is in the form of a hydraulic tilt drive (22) of a lifting frame (23) and the sensor device (42) is in the form of a tilt sensor, in particular a tilt angle sensor.

8. Mobile work machine according to one of Claims 1 to 7, characterized in that the control device (31) is configured to calibrate the volumetric flow sensor (30) in operating states in which a single consumer (V) is singularly actuated.

9. Mobile work machine according to one of Claims 1 to 7, characterized in that the control device (31) is configured to calibrate the volumetric flow sensor (30) in operating states in which a plurality of consumers (V) are actuated at the same time.

10. Mobile work machine according to one of Claims 1 to 9, characterized in that the volumetric flow sensor (30) is in the form of a measuring turbine with an impeller driven by the volumetric flow.

11. Mobile work machine according to one of Claims 1 to 10, characterized in that the control device (31) is configured to use the volumetric flow of the hydraulic pump (5) determined by means of the volumetric flow sensor (30) as a characteristic variable for controlling the conveying volume of the hydraulic pump (5).