Hydraulic arrangement and leakage measurement method for a hydraulic arrangement

Abstract

Hydraulic arrangement with a hydraulic machine (2) and with an adjusting device (4) for adjusting a delivery volume of the hydraulic machine (2), wherein a blocking means (16) is provided downstream of the hydraulic machine, and wherein a pressure measuring device (10) is arranged on the outlet side of the hydraulic machine (2) and upstream of the blocking means (16), wherein a pressure regulator (6) is provided which regulates a pressure according to a setpoint by means of the adjusting device (4), and wherein a detection device (28) is arranged for detecting a control degree of the adjusting device (4) and / or a control signal supplied to the adjusting device (4), wherein a control unit (30) is provided which is configured to specify a setpoint pressure and which is configured to evaluate the control degree and / or the control signal to determine the leakage.

Description

Field of invention

[0001] The invention relates to a hydraulic arrangement comprising a hydraulic machine and an adjusting device for adjusting the delivery volume of the hydraulic machine. Furthermore, the invention relates to a method for leakage measurement for such a hydraulic arrangement. Background of the invention

[0002] Hydraulic machines, such as hydraulic pumps or hydraulic machines that can be operated as pumps, are subject to wear during operation. A worn condition of the seals and running surfaces of the hydraulic machine can be reliably detected by leakage or a deteriorating volumetric efficiency.

[0003] DE 10 2011 115 650 B4 discloses a method for diagnosing the condition of a hydrostatic displacement machine. According to the invention, the diagnosis is carried out as a function of a step response of a housing pressure, which results from an adjustment of a load on the hydrostatic displacement machine according to a step function. Disclosure of the invention

[0004] The object of the invention is solved with regard to the hydraulic arrangement according to the features of claim 1 and with regard to the method according to the features of claim 9.

[0005] Advantageous further developments of the invention are the subject of the dependent claims.

[0006] A hydraulic assembly or unit preferably comprises a hydraulic machine, a hydraulic pump, or a displacement device. An adjustment device allows the flow rate or displacement volume of the hydraulic machine to be adjusted. This adjustment device may be, for example, a variable-speed drive or an electric motor for driving the hydraulic machine, and / or a rotary angle adjuster, particularly for an axial piston machine, or an outer ring adjuster in the case of a vane pump. Furthermore, a blocking device may be provided to shut off a flow path emanating from the hydraulic machine on the outlet and / or high-pressure side. A pressure measuring device is provided to measure the pressure in the flow path between the hydraulic machine and the blocking device.This can be arranged on the outlet side, particularly on a high-pressure side of the hydraulic machine, and upstream of the sealing element (i.e., preferably in the flow path between the hydraulic machine and the sealing element). A pressure regulator allows the pressure to be controlled by the adjusting device according to a specified value. A detection device can be provided to record the degree of adjustment of the adjusting device and / or a control signal supplied to the adjusting device. A target pressure can be specified on the outlet side of the hydraulic machine by a control unit. Furthermore, the degree of adjustment and / or the control signal can be evaluated by the control unit. Advantageously, the leakage, particularly of the hydraulic machine, can be determined by this evaluation.

[0007] Advantageously, the following steps are to be carried out in the leakage measurement procedure for the hydraulic arrangement: - Closing the locking device or leaving the locking device in a closed position, - Adjusting the specified target pressure, thereby enabling a defined drive load or load on the arrangement, - Calculating the leakage from the control level and / or the control signal.

[0008] The solution offers the advantage that the hydraulic system or unit is equipped in such a way that leakage from the hydraulic machine can be tested by the control unit or electronics of the hydraulic system itself while installed. A defined drive load can then be generated using the hydraulic system, and the leakage can be calculated or determined based on the control signal and / or the degree of control. Therefore, only relatively simple sensors are required for leakage measurement, resulting in low costs. The determined leakage can advantageously be used to draw conclusions about the service life of the hydraulic machine. Furthermore, the hydraulic system allows for the timely detection of hydraulic machine failure (predictive maintenance) in a simple manner.

[0009] The described method allows the control loop of speed-controlled hydraulic drives to be used to calculate leakage under a defined condition, preferably during pressure maintenance operation, based on the rotational speed of the hydraulic machine. Thus, the hydraulic arrangement and the method enable extremely simple leakage detection. Furthermore, it is advantageous that this creates a cost-effective measurement concept, preferably using existing measurement parameters.

[0010] If several hydraulic machines are provided, which are connected to a common tank or oil tank, for example, the hydraulic arrangement allows a defect in at least one of the displacers to be detected in time, which in turn enables an analysis and rectification of the cause, for example poor oil quality, thus preventing damage to the other hydraulic machine.

[0011] The adjustment device is preferably a variable-speed drive for powering the hydraulic machine. Its control degree and / or control signal can be detected very easily, with the control degree being, in particular, the actual speed of the drive. The control signal is then, for example, a target speed of the drive.

[0012] Alternatively, a swivel angle adjuster of the hydraulic machine, particularly in the form of an axial piston machine, could be used as the adjusting device. The adjustment value could then be the actual swivel angle of the swivel angle adjuster, and the control signal could be the target swivel angle for the swivel angle adjuster.

[0013] Furthermore, it is conceivable to provide an adjuster for an outer ring of a hydraulic machine designed as a vane-type machine. The control signal could then be a target displacement of the outer ring of the vane-type machine.

[0014] In a further embodiment of the invention, the pressure regulator can be a frequency converter. In a constant pressure system, the frequency converter can regulate the speed of the drive, for example the electric motor, according to the prevailing system pressure. By providing a demand-based flow rate, the pressure regulator can then keep the system pressure constant regardless of the number of consumers.

[0015] The locking device of the hydraulic arrangement is advantageously designed to achieve a defined state (pressure maintenance operation). For example, the locking device is a directional control valve, in particular a 2 / 2-way valve with an open and a closed position. Additionally or alternatively, it is conceivable to design the locking device as a poppet valve or directional poppet valve, which is preferably leak-free or substantially leak-free, so that the determination of leakage in the hydraulic arrangement is not, or substantially not, influenced by the leakage of the locking device. It is also conceivable to design the locking device as a cost-effective check valve, a spool valve, or a pilot-operated valve. In an advantageous embodiment of the locking device, a valve element can be acted upon in the direction of the open position by a spring force from a valve spring and in the direction of the closed position by an actuator force from an actuator.If the actuator is switched off, the valve element is advantageously arranged in the open position, meaning that no actuator control is necessary during normal operation of the hydraulic system. Thus, in a rest position of the locking mechanism, the unit can supply hydraulic power to a consumer.

[0016] In a further embodiment of the invention, a memory can be provided in which the determined control level and / or the determined control signal and / or the determined leakage and / or the target pressure (in particular on the outlet side of the hydraulic machine) and / or an actual pressure (in particular on the outlet side of the hydraulic machine) is stored. If a change is detected during the leakage measurement, a trend or development can be calculated from the stored values, particularly using a model.

[0017] It has proven advantageous if the target pressure for leakage measurement is lower than the operating pressure during normal operation of the system or lower than the system pressure. For example, if a check valve is used as a sealing device, it may be closed by the system pressure, and the leakage measurement can be performed using the lower target pressure. Advantageously, the target pressure for leakage measurement is less than 200 bar.

[0018] To easily identify the cause of an increased leakage, an oil level sensor can be used to determine the oil level, particularly the oil level in a tank, and / or a particle sensor can be used to determine the number of particles in the oil, and / or a temperature sensor can be used to determine the temperature. Alternatively or additionally, pressure spikes can be detected using a pressure measuring device and / or an additional pressure sensor. One application of the aforementioned sensors is explained in more detail below.

[0019] As explained above, a check valve can be provided as a blocking device. This is preferably arranged in a flow direction away from the hydraulic machine. In a further embodiment of the invention, a hydraulic accumulator is preferably arranged downstream of the check valve. This accumulator can provide a system pressure that is above the target pressure when measuring the leakage, thus ensuring that the check valve is reliably closed. A pressure sensor, in particular a gas pressure sensor for the hydraulic accumulator, especially its bladder, can be provided for easy monitoring of the check valve's closed state. Alternatively or additionally, a pressure sensor can be arranged downstream of the check valve. Furthermore, the check valve can prevent the hydraulic accumulator from being discharged via the hydraulic machine.The check valve is therefore preferably arranged in the flow path between the hydraulic accumulator and the hydraulic machine.

[0020] In a further preferred embodiment, at least one additional hydraulic machine is provided. This is preferably associated with a further adjustment device. An additional shut-off device allows this additional hydraulic machine to be shut off at its outlet, particularly on its high-pressure side. An additional pressure measuring device can be arranged upstream of the shut-off device in the flow path between the hydraulic machine and the shut-off device. The pressure regulator or an additional pressure regulator allows the pressure at the outlet of the additional hydraulic machine to be controlled according to a specified value via the adjustment device. The degree of adjustment of the adjustment device and / or the control signal supplied to the adjustment device can then be detected by the sensing device or an additional sensing device. The target pressure at the outlet of the hydraulic machine and the degree of adjustment and / or the control signal can be evaluated by the control unit or an additional control unit.Preferably, the hydraulic machines are fluidically connected to each other on the outlet side and downstream of their sealing means. With this arrangement, leakage from any one hydraulic machine can be easily detected when several hydraulic machines are involved.

[0021] Preferably, check valves are provided as a sealing device for the at least two hydraulic machines. These can be fluidically connected to each other downstream of the hydraulic machines, as already explained above. To detect a leak in one hydraulic machine, its outlet setpoint pressure is regulated below the operating pressure of the other hydraulic machine, thereby closing the sealing device of the hydraulic machine under test.

[0022] If a check valve is provided as a locking device, a further pressure sensor can be provided downstream of the check valve, starting from the hydraulic machine, to determine whether the check valve is open or closed.

[0023] In a further embodiment of the invention, the locking device, in the form of a directional control valve, serves to control a hydraulic actuator, in particular a hydraulic cylinder. A displacement measuring system for measuring the adjustment speed of a piston and / or piston rod of the hydraulic cylinder can be associated with this actuator. When the directional control valve is closed, the leakage can be determined as described, and when the directional control valve is open, the leakage can be determined additionally or alternatively by comparing the degree of control and / or the control signal with the piston rod speed or the adjustment speed of the piston.

[0024] In the leakage measurement method described above, it is advantageous that, when adjusting the specified target pressure by means of a control loop, the rotational speed of the drive, in particular the electric motor, can be reduced according to the leakage of the hydraulic machine. Before calculating the leakage, the control level and / or the control signal is preferably determined.

[0025] In a further embodiment of the invention, the closing state of the locking device is monitored in order to carry out a reliable measurement of the leakage.

[0026] Preferably, the leakage is measured during a standby or idle phase of the hydraulic system, thus allowing the leakage to be measured without disrupting the ongoing operation, for example, of a consumer driven by the hydraulic system. The standby phase is preferably a pressure maintenance mode for a consumer. It is conceivable that the standby phase is detected and / or communicated to the control system during the ongoing operation of the hydraulic system, particularly by the control unit.

[0027] To measure leakage as accurately as possible, factors can be incorporated to compensate for disturbances. For example, leakage from the sealing element can be considered when calculating the leakage. Alternatively or additionally, temperature can be factored into the leakage calculation, which in turn allows for consideration of viscosity at different temperatures or oil temperatures. For this purpose, a temperature sensor is preferably used, and a viscosity grade is also taken into account. Thus, the disturbance variable temperature and the resulting viscosity change can be considered in a single model. Alternatively or additionally, it is conceivable to consider slippage in adjustment devices such as asynchronous machines (electric motors) when calculating the leakage.Alternatively or additionally, when calculating the leakage, a leakage of one or more other components in the flow path between the output of the hydraulic machine and the sealing device can be taken into account, such as a throttle for setting a minimum speed or a pressure relief valve.

[0028] When the leakage changes, it is advantageous to calculate a course and / or trend using a model, preferably also using values ​​stored in memory.

[0029] Preferably, the measured leakage is compared with a limit value for maximum permissible leakage, allowing the time until the hydraulic unit needs to be replaced to be calculated and displayed. Preferably, several test cycles can be performed, in which the procedure is repeated and the results advantageously compared. It is advantageous to repeat the procedure periodically, particularly periodically (e.g., weekly) and / or during a standby phase. Alternatively or additionally, it is conceivable to perform the procedure after each start-up of the hydraulic system and / or before each shutdown.Alternatively or additionally, the process could be triggered when an oil temperature, determined in particular by a temperature sensor (for example, the oil temperature of oil in a tank), reaches a specific temperature value and / or is greater than or equal to that specific temperature value. Furthermore, the process could be triggered when requested by the control system, for example, via a signal. This would allow, for instance, a person operating the hydraulic system to instruct the process to be carried out.

[0030] To determine the cause of the leak, further sensor values ​​can be queried in real time and / or from memory or data storage. For example, the sensor value of the oil level sensor, the sensor value of the pressure sensor, the sensor value of the pressure measuring device, the sensor value of the particle sensor, and / or the sensor value of the temperature sensor can be queried.

[0031] A sudden, abrupt, or rapid increase in the oil level sensor reading indicates that oil has been added, particularly by the control unit. If the hydraulic system's efficiency subsequently deteriorates and / or leakage increases, the control unit may conclude, for example, that the oil is of poor quality or contaminated. Conversely, a relatively slow increase in the oil level sensor reading may indicate water ingress into the oil. This water ingress could be caused, for instance, by high humidity in the environment or a defect in an oil-water heat exchanger.

[0032] The sensor reading from the pressure sensor and / or pressure measuring device can be used, in particular by the control system, to determine pressure peaks that indicate impermissibly high loads.

[0033] The sensor reading from the particle sensor can detect an increased number of particles in the oil, especially from the control unit, which may be the cause of an increase in leakage.

[0034] The sensor reading from the temperature sensor can indicate an increased oil temperature, which can lead to damage to plastic seals in the displacer.

[0035] After determining the cause, the identified cause can be displayed by the control system and / or measures, in particular by the control system, can be initiated after determining the cause and / or measures, in particular by the control system, can be initiated after determining the increase in leakage.

[0036] If the hydraulic arrangement includes the accumulator with the check valve, a gas pressure, particularly in a bladder of the accumulator, can be determined by means of the pressure sensor before or during the procedure, and / or a pressure downstream of the check valve can be determined by means of the pressure sensor. The target pressure to be regulated, which is, for example, 190 bar, is then preferably lower than an operating pressure, which can be, for example, 200 bar during normal operation of the unit, for measuring the leakage. Furthermore, the target pressure is preferably higher than the gas pressure or the pressure downstream of the check valve. This ensures that the check valve remains closed during the leakage measurement. A control loop can also be performed once or several times to determine whether the measured accumulator pressure is higher than the target pressure, thus ensuring that the check valve is closed.The hydraulic system can be used in normal operation both before and after the leakage measurement.

[0037] If two hydraulic machines with two check valves are provided, the leakage measurement method may involve an outlet pressure between the hydraulic machine under test and its check valve that is lower than the outlet pressure of the hydraulic machine not under test, thus closing the check valve associated with the hydraulic machine under test. In a control loop, which can be performed once or several times, the outlet pressures can then be checked to determine whether the check valve is closed. Preferably, the hydraulic system is operated in normal mode before and after the leakage measurement.

[0038] In a hydraulic arrangement comprising a hydraulic machine with a downstream check valve and a connected load, consumer, or consumer pressure, the check valve can advantageously be closed by the external load, consumer, or consumer pressure during leakage measurement. The external load can then be checked via the pressure sensor in a control loop, which can be performed once or several times.

[0039] As explained above, when measuring the leakage of a hydraulic cylinder connected to the hydraulic machine via the directional control valve, the measurement can be performed with the directional control valve closed, or alternatively, the measurement can be performed with the directional control valve open. In this case, the control degree and / or the control signal can be compared with the piston rod velocity to determine the leakage. For hydraulic cylinders with leakage, this leakage can be taken into account when measuring the leakage with the directional control valve open. Brief description of the drawings

[0040] Preferred embodiments of the invention are explained in more detail below with reference to schematic drawings. These show: Fig. 1 to Fig. 7 each in a simplified representation a hydraulic arrangement according to one embodiment and Fig. 8 in a flowchart a procedure for the hydraulic arrangement. Detailed description of preferred embodiments

[0041] According to Fig. Figure 1 shows a hydraulic arrangement 1 according to a first embodiment. This arrangement has a hydraulic machine in the form of a hydraulic pump 2, which is driven by a variable-speed drive as an adjustment device 4. The adjustment device 4 is, for example, an electric motor. Furthermore, a pressure regulator 6 is provided, which can be a frequency converter. This can regulate the pressure of a pressure line 8 connected to an output port P of the pump 2 by means of the adjustment device 4. The actual pressure 12 in the pressure line 8 is measured by a pressure sensor 10 and reported to the pressure regulator 6. The pressure regulator 6 also receives a setpoint pressure 14 as a reference. A blocking device in the form of a 2 / 2-way valve 16 is connected to the pressure line 8.This has an inlet port E, which is connected to the pressure line 8, and an outlet port A, which is connected to a working line 18 that is connected to a consumer. The directional control valve 16 can be designed as a poppet valve or a spool valve. A valve element is acted upon by a valve spring 20 in the direction of the opening position and can be actuated by an actuator 22 in the opposite direction of a closing position. During operation, the pump 2 delivers hydraulic fluid from a tank 24 via a suction line 26, which is connected to a tank port T of the pump 2, into the pressure line 8. Furthermore, the pump 2 is connected to the tank 24 via a leakage line 27.

[0042] A setting degree of the adjusting device 4, which in the embodiment is according to Fig. If the actual rotational speed is measured, it can be detected by an additional detection device, or the frequency converter designed as a pressure regulator 6 can be additionally used as a detection device 28. The actual rotational speed can then be read from the detection device 28 by a controller 30 and stored in a data memory 32.

[0043] To determine and calculate the leakage, the directional control valve 16 is closed and a predetermined target pressure 14 is regulated via the pressure regulator 6. The leakage can then be calculated using the following formula based on the actual rotational speed: Q_leck=V_th×n Q_leak = Leak oil volume flow rate V_th = Pump swallowing volume n = Actual pump speed

[0044] The procedure for measuring the leakage can be repeated periodically and / or while the hydraulic arrangement 1 is idling, and the results of the measurements can be compared.

[0045] Furthermore, an oil level sensor 33a, a particle sensor 33b and a temperature sensor 33c can be provided, which are schematically represented by a block in Fig. 1 are shown.

[0046] According to the second embodiment in Fig. 2 has the hydraulic arrangement 1 in contrast to the Fig. 1. A check valve 34 serves as a locking device. The valve body of the check valve 34 is acted upon by a valve spring 36 in the direction of a closed position. The check valve 34 opens in a pressure medium flow direction away from the pump 2. Downstream of the check valve 34, a hydraulic accumulator 38 is connected to the working line 18. The hydraulic accumulator 38 is a bladder accumulator, and the gas pressure in a bladder can be detected by the pressure sensor 40.

[0047] The method for measuring leakage in the hydraulic arrangement according to Fig. Procedure 2 can be performed during operation. In normal operation, the system pressure on the outlet side of pump 2, for example 200 bar, is regulated via the pressure regulator 6, the adjusting device 4, the pump 2, and the pressure sensor 10, which form a constant pressure control system. The hydraulic accumulator or the bladder of the accumulator, which is designed as a bladder accumulator, is pre-charged to, for example, 180 bar. This gas pressure of, for example, 180 bar is determined by the pressure sensor 40. Subsequently, the target pressure for the outlet side of pump 2 is reduced below the system pressure, while remaining above the gas pressure, and then, for example, reaching approximately 190 bar. It is ensured that the check valve 34 remains closed due to the gas pressure. One or more control loops are then used to check whether the measured accumulator pressure is greater than, for example, 190 bar, thus ensuring that the check valve 34 remains closed.With the set target pressure, it is then possible, as in the embodiment shown in . Fig. 1. The leakage is calculated from the control degree (actual rotational speed of the adjusting device 4), and the determined values ​​are stored. Subsequently, the hydraulic arrangement 1 is regulated back to the system pressure of 200 bar.

[0048] According to Fig. Figure 3 shows a hydraulic arrangement 1 which, unlike the embodiment in Fig. 2 does not have a hydraulic accumulator. A pressure sensor 42 is arranged downstream of the check valve 34 to determine the pressure in the working line 18. The leakage is measured according to the embodiment in Fig. 1, however, an external load, for example from a hydraulic cylinder connected to the hydraulic arrangement 1, is necessary to close the check valve 34 during the leakage measurement. To check whether the check valve 34 is closed, the pressure sensor 42 is provided, which, for example, during the leakage measurement in one or more control loops, measures the pressure in the pressure line 8.

[0049] In Fig. 4 shows the hydraulic arrangement, which differs from the embodiment in Fig. 2 does not have a pressure sensor 4 for the hydraulic accumulator 38. Instead, a pressure sensor 44 is provided, which measures the pressure in the working line 18 and is therefore located downstream of the check valve 34. This pressure sensor 44 can be used to check whether the check valve 34 is closed.

[0050] According to Fig. In hydraulic arrangement 5, in addition to pump 2, there is another hydraulic machine in the form of pump 46. Downstream of pump 2, a check valve 34 is provided, and downstream of pump 46, another check valve 48 is provided. In the flow direction away from pumps 2 and 46, after check valves 34 and 48, the flow paths are interconnected. Thus, the working line 18 is connected to a pressure line 50 connected to the check valve 48. Pump 2 is connected according to the other embodiments described in the Fig. Pumps 2 and 46 are each assigned a pressure regulator 6, an adjustment device 4, and a pressure sensor 10. Similarly, pump 46 is also assigned an adjustment device 52, a pressure regulator 54, and a pressure sensor 56. Furthermore, pump 2 is assigned a sensing device 28, and pump 46 is assigned a sensing device 58. The control unit 30 with the data storage 32 can be shared by the components of both pumps 2 and 46. It would be conceivable to use a common directional control valve or a separate directional control valve for each pump instead of the check valves 34 and 48.

[0051] Under normal operating conditions, the system pressure at the outlet of pumps 2 and 46 is regulated to, for example, 200 bar. To measure a leak for pump 2, the target pressure at the outlet of pump 2 is regulated so that it is lower than the pressure at the outlet of pump 46, i.e., in this case, lower than the system pressure. This ensures that the check valve 34 is closed. In one or more control loops, the pressure sensors 10 and 56 can be used to determine that the target pressure at the outlet of pump 2 is indeed lower than the pressure at the outlet of pump 46. The degree of adjustment of the actuator 4, i.e., the rotational speed, can then be determined, and the leakage can be calculated from this according to the preceding embodiments. The determined values ​​can then be stored in the data memory 32. Subsequently, the system pressure at the outlet of pump 2 is readjusted.

[0052] The leakage of the other pump 46 is measured in the same way, whereby the target pressure on the outlet side of pump 46 is then smaller than the outlet pressure of pump 2, i.e. the system pressure.

[0053] According to Fig. Figure 6 shows a hydraulic arrangement which, unlike the embodiment in Fig. 1. A directional control valve 60 in the form of a 4 / 3-way valve. A consumer in the form of a hydraulic cylinder 62 is connected to this valve. The directional control valve 60 has a pressure port P, to which the pressure line 8 is connected. The directional control valve 60 is connected to a first working line 64 via a first outlet port A and to a second working line 66 via a second outlet port B. A tank line 68, which leads into the tank 24, is connected to a tank port T of the directional control valve 60.

[0054] The hydraulic cylinder 62 is designed as a differential cylinder and has a piston 70 that separates a cylinder chamber 72 from an annular chamber 76 through which a piston rod 74 passes. The working line 64 is connected to the cylinder chamber 72 and the working line 66 to the annular chamber 76. The displacement and displacement speed of the piston rod 74, and thus of the piston 70, can be detected by a displacement measuring system 78.

[0055] In the spring-centered home position of the valve spool of the directional control valve 60, ports A, B, P, and T are separated from each other. When the valve spool is moved from the home position towards a first switching position, the pressure port P is connected to the second outlet port B, thus connecting pump 2 to the annular chamber 76. Furthermore, outlet port A is connected to tank port T, and thus cylinder chamber 72 is connected to tank 24. When the valve spool is moved from the home position towards a second switching position, pressure port P is connected to working port A, and thus pump 2 is connected to cylinder chamber 72, and tank port T is connected to the second outlet port B, and thus annular chamber 76 is connected to tank 24.

[0056] In one possible method for measuring the leakage, the valve spool of the directional control valve 60 is in its home position, thus blocking the hydraulic fluid connection between the pump 2 and the hydraulic cylinder 62. The leakage is then measured, for example, according to the embodiment shown. Fig. 1 determined.

[0057] In a second method for measuring leakage, the directional control valve is in one of its switching positions, supplying hydraulic fluid to the hydraulic cylinder 62 and thus allowing the piston 70 to move. The displacement and displacement speed of the piston 70 are recorded by the displacement measuring system 78 and reported to the control unit 30. This compares the actuation degree of the adjusting device 4, i.e., the actual rotational speed of the electric motor, with the displacement speed of the piston 70. The leakage oil flow rate can then be determined using the following formula: Q_leak=V_th×n−v×A Q_leak = Leak oil volume flow rate V_th = Pump swallowing volume n = Actual speed of pump (measured via frequency converter) v = velocity of piston rod A = the surface of piston 70 bounding cylinder chamber 72, if cylinder chamber 72 is connected to pump 2, or the annular surface of piston 70 bounding annular chamber 76, if annular chamber 76 is connected to pump 2

[0058] According to Fig. 7 differs from the embodiments of Fig. In the hydraulic machine 1 to 6, an axial piston machine 80 with an adjustable swashplate or variable displacement pump is provided, driven by a constant-speed motor, e.g., an asynchronous motor on a three-phase network or a speed-controlled drive. With an asynchronous motor on a three-phase network, the speed of the hydraulic machine can be calculated if the frequency and slip are known. With a speed-controlled drive, the speed of the hydraulic machine can be read directly from the drive controller / frequency converter. Alternatively, a vane pump can be provided whose outer ring is movable to adjust the delivery volume. The axial piston machine 80 can be driven by a drive 82 in the form of an electric motor, the drive 82 being supplied by an electrical power supply 83. According to the embodiment in Fig. The directional control valve 16 and the pressure sensor 10 are provided.

[0059] To measure the leakage, in contrast to, for example, the embodiment in Fig. 1. After closing the directional control valve 16 and adjusting to a predetermined target pressure, the leakage is calculated using a different control factor. When the pump 80 is used as an axial piston pump, the control factor is the angle of the swashplate; when the pump 80 is used as a vane pump, it is the axial displacement of the outer ring. The leakage oil flow rate can be calculated using the following formula: Q_leck=V_th×n

[0060] The swallowing volume V_th depends on the adjustment angle of the swashplate or on the axial displacement of the outer ring.

[0061] Fig.Figure 8 shows the method for measuring leakage according to embodiments 1 to 7. In step 84, the sealing device associated with the hydraulic machine whose leakage is to be measured is closed. Alternatively, the hydraulic arrangement is operated in such a way that the sealing device is closed. In the subsequent step 86, the predetermined target pressure is then set. Subsequently, in step 88, the leakage can be calculated from the determined control degree and / or from the determined control signal.

[0062] Alternatively or additionally to the embodiments described above, the leakage can be measured using a flow meter located in a leakage line of the hydraulic machine. Alternatively or additionally, the leakage can be measured by measuring the oil temperature of the oil in the leakage line and / or the pressure line and / or the tank line connected to the hydraulic machine. Furthermore, a flow sensor can be additionally or alternatively provided in the outlet pressure line of the hydraulic machine to determine the volumetric displacement efficiency. From this, the leakage can then be calculated using the flow sensor in the pressure line or in the leakage line, taking into account the displacement speed and the displacement volume.

[0063] A hydraulic arrangement is disclosed, comprising a hydraulic machine to which a shut-off device is assigned on the output side to isolate the hydraulic machine. In the locked state, a predetermined pressure can be regulated, whereby a leakage is calculated from the degree of adjustment of a control device for the hydraulic machine. Reference symbol list 1 hydraulic arrangement 2 pumps 4 Adjustment device 6 pressure regulators 8 Pressure line 10 pressure sensor 12 Actual pressure 14 Target pressure 16-way valve 18 Work management 20 valve springs 22 Actuator 24 Tank 26 Suction line 27 Leakage pipe 28 Recording device 30 Control 32 data storage devices 33a Oil level sensor 33b Particle sensor 33°C temperature sensor 34 Check valve 36 Valve spring 38 hydraulic accumulators 40 pressure sensor 42 Pressure sensor 44 Pressure sensor 46 Pump 48 Check valve 50 Pressure line 52 Adjustment device 54 pressure regulators 56 Pressure sensor 58 Recording device 60-way valve 62 hydraulic cylinders 64 Work management 66 Work management 68 Tank line 70 pistons 72 cylinder space 74 Piston rod 76 Ring space 78 Distance measuring system 80 pump 82 Drive 83 Benefit provision 84 steps 86 steps 88 steps E input connector P pressure connection A Output port B Output port T tank connection

Claims

[1] Hydraulic arrangement with a hydraulic machine (2) and with an adjusting device (4) for adjusting a delivery volume of the hydraulic machine (2), wherein a blocking means (16) is provided downstream of the hydraulic machine, and wherein a pressure measuring device (10) is arranged on the outlet side of the hydraulic machine (2) and upstream of the blocking means (16), wherein a pressure regulator (6) is provided which regulates a pressure according to a setpoint by means of the adjusting device (4), and wherein a detection device (28) is arranged for detecting a control degree of the adjusting device (4) and / or a control signal supplied to the adjusting device (4), wherein a control (30) is provided which is configured to specify a setpoint pressure and which is configured to evaluate the control degree and / or the control signal to determine the leakage. [2] Hydraulic arrangement according to claim 1, wherein the adjusting device (4) is a variable speed drive for the hydraulic machine (2) or a swivel angle adjuster for the hydraulic machine (2). [3] Hydraulic arrangement according to claim 1 or 2, wherein the control signal is an actual speed of the drive (4) and / or an actual swivel angle of the swivel angle adjuster, and / or wherein the control signal is a target speed for the drive and / or a target swivel angle for the swivel angle adjuster. [4] Hydraulic arrangement according to one of claims 1 to 3, wherein a data storage device (32) is provided which is configured in such a way that the determined actuation degree and / or the determined actuation signal and / or the determined leakage can be stored therein. [5] Hydraulic arrangement according to any one of claims 1 to 4, wherein the target pressure when measuring the leakage is less than a system pressure. [6] Hydraulic arrangement according to one of the preceding claims, wherein an oil level sensor (33a) is provided for determining an oil level and / or a particle sensor (33b) for determining a particle number in the oil and / or a temperature sensor (33c) for determining a temperature, and / or wherein pressure peaks are determined with the pressure measuring device (10) and / or an additional pressure sensor. [7] Hydraulic arrangement according to one of the preceding claims, wherein a check valve (34) is provided as a locking means which opens in the direction of flow away from the hydraulic machine (2), or wherein a directional control valve (60) is provided as a locking means for controlling a hydraulic consumer (62) whose valve spool can be brought into a closed position and at least one open position. [8] Hydraulic arrangement according to one of the preceding claims, wherein a hydraulic accumulator (38) is arranged downstream of the locking means (34). [9] A method for leakage measurement for a hydraulic arrangement according to one of the preceding claims comprising the steps: - Closing the locking device (16), - Setting a predetermined target pressure on the outlet side of the hydraulic machine (2), - Calculation of leakage from the control level and / or from the control signal. [10] Method according to claim 9, wherein a closed state of the locking means (16) is monitored. [11] Method according to claim 9 or 10, wherein the measurement of the leakage is carried out in a standby phase of the hydraulic arrangement (1). [12] Method according to any one of claims 9 to 11, wherein in the calculation of the leakage a leakage of the sealing means (16) is taken into account, and / or wherein in the calculation of the leakage a temperature is taken into account, and / or wherein in the calculation of the leakage a slip in adjusting devices in the form of asynchronous machines is taken into account, and / or wherein a leakage of further components in the flow path between the outlet of the hydraulic machine (2) and the sealing means (16) is taken into account. [13] Method according to any one of claims 9 to 12, wherein the method is repeated and the results obtained are compared by the control (30). [14] Method according to any one of claims 9 to 13, wherein, in order to determine a cause that leads to an increase in leakage, the sensor value of the oil level sensor (33a) and / or the sensor value of the pressure sensor (10) and / or the sensor value of the pressure measuring device (10) and / or the sensor value of the particle sensor (33b) and / or the sensor value of the temperature sensor (33c) is queried. [15] Method according to any one of claims 9 to 14, wherein the hydraulic accumulator (38) is arranged downstream of the blocking means designed as a check valve (34) and / or wherein the hydraulic accumulator is connected to the working line (18) which ensures that a system pressure is greater than the set pressure when the leak is detected.

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