DE102008063924A1 - Method for detecting erratic behavior of hydrostatic system with hydrostatic machine, involves producing control signals for controlling hydrostatic machine by controller - Google Patents

Abstract

The method involves producing control signals for controlling a hydrostatic machine by a controller (10). Multiple groups of causes are defined for the behavior of an erratic behavior of a hydrostatic system. A comparison variable is produced from the measured system parameters. An expectancy value is determined for the comparison variable. The comparison variable is compared with another expectancy value. An independent claim is included for a controller for a hydrostatic system.

Description

The The invention relates to a method for detecting errors in a hydrostatic system and the assignment of errors to cause groups as well as a control unit.

In hydrostatic systems electronic control units are often used to adjust, for example, a hydraulic pump in terms of their delivery volume. In such a hydraulic system, the control unit detects a part of the system parameters of the hydrostatic system and calculates on this basis setting values, for example for a control valve of an adjusting device for adjusting the delivery volume of the hydrostatic machine. The acquired measured values for the system parameters are used exclusively by the control unit to be able to adjust or regulate the hydrostatic machine. On the basis of the detected measured values, a control signal or a plurality of control signals is therefore generated by the control device, which are output, for example, to proportional solenoids with electro-proportional adjustments. Such a control unit is from the DE 195 38 649 A1 known.

Especially in hydrostatic systems of mobile machines such as excavators or wheel loaders must function even if an error occurs remain guaranteed. To shut down the system too It is necessary to avoid the cause of this Otherwise, for safety reasons the entire system must be completely switched off.

It is therefore the object of the invention, a method and a corresponding Control device to create a fault in operation a hydraulic system limited and a limited Error assigned emergency operation can be initiated.

The The object is achieved by the method according to the invention with the features of claim 1 and the inventive Control unit with the features of claim 10 solved.

According to the invention by a control unit control signals for controlling a generated hydrostatic machine of a hydraulic system. It Several causes groups are defined in which an occurring Error is classified. To do this, set several cause groups measured values of one or more system parameters or Measured variables of the hydraulic system detected. On the basis of these measured values becomes a comparison quantity generated. The comparison size can be the simplest Case be identical to a measured value. However, it is also possible that multiple readings to a comparison size of a comparison type. For example, a possible comparison size be the torque or the power of a hydraulic pump. In this Case becomes the set delivery volume and the pressure difference or also determines the speed of the hydraulic pump and to a Value for a comparison quantity type "Torque" or "performance". z. B. "power" or "torque" is through the controller determines an expected value. The expected value is the value that works when the hydraulic system is functioning correctly would have to be determined as a benchmark. Subsequently becomes the comparison quantity with the expected value compared and so a system error in detecting a deviation between the benchmark and the expected value recognized. The error that occurred then becomes one the previously specified single cause of error and / or cause groups assigned. This assignment allows judging, whether a serious mistake or just a little function influencing error is present.

The Control unit according to the invention has to Generating control signals for the hydrostatic machine a central control section. Furthermore, in the control unit a memory available and an interface unit for reading from Measured values of system parameters of the hydraulic system. By doing Storage is a set of causes for what to do Error saved. The cause groups can only be So an element contains an exactly defined single cause. In addition to detecting a fault, the control unit a comparison variable generator in which the measured value or the measured values a comparison variable is produced. The control unit also has an analysis device for generating an expected value as well as for comparing the comparison variables with the expected value generated. In an assignment section, which is connected to the analysis device, then the assignment takes place, provided that in the analysis device a deviation of the comparison of the expected value has been recognized.

The Cause groups can systematically add to an assembly summarize the machine belonging causes. Eg then form all causes of error that affect the adjustment (lower Valve lift, low control pressure, leakage in the feed system, ...) which lead to a mistake in the adjustment, a cause group. Alternatively, a grouping of the possible errors is after the severity of the error possible.

The inventive method and the invention Control unit have the advantage that not only a deviation from the expected behavior is analyzed, but that an error identified by means of the analyzed deviation one of possibly several cause groups assigned and one of the initiated associated emergency group assigned emergency operation can be. For example, it is possible that although a mistake is recognized as such, but quite a Further operation of the hydrostatic machine is possible. For example, due to increasing leakage in a feed device of hydrostatic machine increasing the slew time in the adjustment of the delivery volume of a hydraulic pump be determined. This is basically an occurring Error, but the consequence is uncritical. An immediate shutdown of the Plant is therefore not required. Such a distinction however, can only be taken when the occurrence of the error classified in itself, that is in one of the groups of causes is classified.

In the dependent claims are advantageous developments of inventive method and the invention Controller executed.

In the control unit is preferably the analysis device connected to the control section, wherein the analysis device is set up so that it can be modeled on the basis of control signals generated by the control section at least one Expected value calculated. By the expectation calculation by means of a model of the hydraulic system can be in easier Way to the control signals generated by the control unit can be generated and output, different operating conditions be determined in a simple manner. The use of a model ensures that without much memory a variety of operating conditions can be covered.

alternative or in addition to this, the expected values or Part of it using a stored in the control unit Characteristic determined. Such a characteristic can, for example, in simple contexts are used. Especially This is a monitoring example of a proportional magnet of a Control device possible. Here is for several Temperature values each have a specific characteristic between current and stored voltage. The function of a proportional magnet is thus indirectly monitored.

Farther For example, it is preferable to have multiple expected values at a set of expected values summarize. This set of expected values will not then more with a single but with a plurality of comparison values compared. Such a procedure has the advantage that as well more complex scenarios can be covered. That's the way it is often not possible, from a single expectation value or the result of the comparison of the benchmark with the expected value to make a clear diagnosis. First against the background of the behavior of further comparative variables can be an assignment to a single cause and / or a single cause group. By using a plurality of expected values and a plurality of comparison values an accurate determination of causes possible. Preferably individual causes and / or individual groups of causes are determined and thus creating an accurate diagnosis.

there it is particularly advantageous if in the control unit a matrix is stored in memory, with the help of which a systematic Procedure for limiting the possible cause groups is stored for an error occurred. Such a matrix can progressively produce several expected values or sets of Expected values with the assigned comparison variables to compare. In this case, the order is determined by the matrix and in making the comparisons and / or the selection determined the comparative variables to be compared.

After this an error has occurred and assigned to one of the cause groups is, preferably based on this assignment the further course of action in the control of the hydrostatic machine or of the hydraulic system. This is in the central Control section next to the regular operating mode that uses if all parameters are proper Behavior show, at least another, safer mode of operation stored. This safe mode of operation is called to ensure a kind of emergency operation for the hydraulic system to be able to. It is particularly preferred if different Safe operating modes are available and depending from the assignment of the error to a cause group individually a safe operating mode can be selected.

The measurement of system parameters and thus the monitoring of the system is preferably clocked. However, in the presence of a particular control event, measurements taken within a certain time interval after the control event may be disregarded. Thus, for example, pivoting operations of the hydrostatic machine, which would generally lead to an implausible system parameter considered in isolation or a different comparison variable, from be blinded and thus the recognition of an actually yes not occurred error can be prevented. Such a control event can occur, for example, when reversing the direction of travel change in a hydrostatic drive and is generally defined by a specific sequence of control signals.

The temporal length of this interval, in which the measured values disregarded after the occurrence of a specific tax event stay, it can be preferably set, the setting also individually for each such interval by itself pulling the tax event is feasible.

Based The drawing will be a preferred in the following description Embodiment of the invention Method and the control device according to the invention shown in detail. Show it:

1 a schematic representation of an exemplary hydraulic system for carrying out the method according to the invention;

2 a representation for explaining the preferred arrangement of a control device according to the invention in the form of an OBE ("on-board unit") on an adjusting device of a hydraulic pump;

3 a block diagram of a control device according to the invention; and

4 a flowchart for explaining the method according to the invention.

The 1 shows a hydrostatic system according to the invention using the example of a traction drive. The traction drive 1 comprises a hydrostatic machine, which in the illustrated embodiment, a pump unit 2 is. With the pump unit 2 is a hydraulic motor in the closed hydraulic circuit 3 connected. Both the hydraulic pump unit 2 as well as the hydraulic motor 3 are adjustable in terms of their stroke volume. Both machines are preferably designed as axial piston machines in swash plate or Schrägachsenbauweise. In principle, the invention is also applicable to radial piston pumps, gear pumps or similar hydrostatic displacement units. The pump unit 2 includes a main pump 4 and a feed pump 4 ' , The main pump 4 is about a first line of work 6 and a second working line 7 in the closed hydraulic circuit with the hydraulic motor 3 connected. The main pump 4 and the feed pump 4 ' be via a common drive shaft 5 driven.

With the common drive shaft 5 is connected to a primary drive machine, not shown. The primary engine is usually designed as a diesel engine.

The hydraulic motor 3 has an output shaft 8th on, in a manner not shown with a driven axle of the vehicle, by the traction drive 1 is driven, is connected.

For adjusting the swivel angle of the pump unit 2 and thus for adjusting the delivery volume of the main pump 4 is an adjustment device 9 intended. The adjusting device 9 acts with an adjustment mechanism of the main pump 4 together. At the adjusting device 9 a so-called OBE is arranged directly. As indicated by the dash-dotted line representing the pump unit 2 indicates, is both the adjustment 9 as well as the arranged there OBE, which is a control unit 10 forms, in the pump unit 2 integrated. In addition to short cable runs, which reduce the likelihood of damage, this has the advantage that it also directly on a circuit board of the controller 10 a part of the relevant system parameters of the pump unit 2 can be detected. This will be explained below.

The control unit 10 is with a higher-level, central control unit 11 connected. Both the controller 10 as well as the higher-level control unit 11 are also with a bus system 12 connected. About the bus system 12 Not only can the individual control units present in the hydrostatic system communicate with each other. In addition, it is also possible to control signals that an operator, for example via an accelerator pedal 13 or a joystick 14 for the operation of a work hydraulics, not shown, are to supply the relevant control unit. An example is another operating lever 15 for controlling the traction drive 1 and another lever 16 for control z. B. provided a further working hydraulics.

In the schematic representation of 1 By way of example, some transducers for detecting different system parameters are shown. For example, the working pressure in the closed hydraulic circuit by means of a first pressure transducer 17 and a second pressure transducer 18 be recorded. The information obtained is not limited to the absolute pressures, but in the control unit 10 The pressure difference can also be determined. This can be used, for example, to determine a power consumption of a pump unit driven by a diesel internal combustion engine 2 to be required.

Furthermore, a third pressure transducer 19 provided by the in a feed system through the feed pump 4 ' measured pressure generated becomes. Another pressure whose measured values can be evaluated, to which in the 1 a corresponding pressure sensor is not shown, may be the suction pressure, the pressure of the pressure medium on the suction side of the feed pump 4 ' equivalent. Another pressure variable that can provide information about the operational behavior and the operating conditions of the hydraulic pump is the housing pressure, which is inside the housing of the pump unit 2 is measured. All the measured values determined by the pressure transducers are sent to the control unit 10 transmitted.

For detecting the speeds in a hydrostatic system such as the illustrated drive 1 of the 1 is a first speed sensor 20 on the drive shaft 5 the main pump 4 intended. In addition, the speed of the output shaft can also 8th through a second speed sensor 21 be recorded.

Furthermore, as described below with reference to the 2 will be explained, directly in the control unit 10 the set swivel angle of the main pump 4 detected. This can be done in a particularly advantageous manner when using an OBE by on the circuit board of the controller 10 an angle sensor is arranged. Because the OBE in the pump unit 2 is integrated and there preferably directly to the adjustment 9 is arranged, can thus be determined without the need for a cable guide the swivel angle and thus the set delivery volume or the volume flow resulting together with the speed. In the same way can directly on the circuit board of the controller 10 a temperature sensor may be arranged, by which the temperature of the pump unit 2 is determined.

As another temperature, the temperature of the leakage oil in the housing of the pump unit 2 be recorded. This is in turn a in the 1 also not shown additional temperature sensor required. In addition to the pressures in the first working line 6 and the second working line 7 it is preferred that the temperature of the pressure medium in the closed circuit is detected. For this purpose, the temperature is detected on the high pressure side, which can change in the illustrated embodiment of a traction drive, however. For both directions of travel and thus conveying directions of the main pump 4 To detect the temperature on the high pressure side, two temperature sensors are preferably again provided, which in the first working line 6 or the second working management 7 are arranged. By means of other sensors, other variables that are critical for the system can also be detected. Thus, a sensor may be provided to monitor the contamination present in the pressure medium. This can be used to determine the oil quality in the hydrostatic system. The specified system parameters are not exhaustive but merely exemplary.

In the 2 is a section through a part of the adjustment 9 the pump unit 2 shown the arrangement of the control unit 10 as OBE clarify. The entire controller 10 is in through a first housing part 20 and a lid 21 trained housing room. arranged. The first housing part 20 is directly on the adjusting device 9 arranged so that via a return lever 22 the position of the adjusting device 9 and thus information about the set displacement volume of the main pump 4 on a wave 23 can be transferred. The control unit 10 includes a printed circuit board 24 in the first housing part 20 is arranged. Among other things is on this circuit board 24 a sensor 25 arranged by the rotation of the shaft 23 can be detected. The sensor may be formed, for example, as a Hall sensor and the rotation of a in a groove of the shaft 23 inserted magnets 26 capture and so the set delivery volume of the main pump 4 determine. On the circuit board 24 are other electronic components 27 arranged, whose individual functions or sections below with reference to the 3 be explained. Furthermore, with the circuit board 24 a connector assembly connected, which pins 28 having. These pins 28 serve the electrical contacting of the control unit 10 with a bus system 12 or even with other transducers that are not directly in the control unit 10 can be integrated. Examples of such additional transducers have already been described with reference to 1 explained.

The 3 shows a block diagram of the control device according to the invention 10 , The control device according to the invention 10 is with a number of transducers, as they are already referring to the 1 have been explained and as it is indicated schematically by the arrows 33 in the 3 is shown connected. The measurement signals detected by the transducers, for example pressure sensors or speed sensors, become an interface unit 30 fed. Also with the interface unit 30 are internal transducers 25 and 32 connected. 25 refers to the already with reference to 2 explained angle sensor while with 32 a temperature sensor is designated. With the help of such, directly on the circuit board 23 an OBE arranged temperature sensor 32 , the temperature of a hydrostatic piston machine can be determined in a simple manner. In the illustrated preferred embodiment, therefore, all the sensors, the measured values for the control unit 10 deliver, with the interface Ness 30 connected.

The interface unit 30 is also with the central control section 31 connected. In the central control section are those via the interface unit 30 supplied measured values control signals generated. The generated control signals become a signal output 39 fed. The signal output 39 is how it is in the 3 is shown only schematically, connected to the components to be controlled of the hydraulic system. In the case of an OBE as a control unit 10 this is primarily the adjusting device for adjusting a delivery volume of the main pump 4 ,

In addition to the regular control algorithm 42 for generating the control signals by the central control section 31 serves, through the central control section 31 two more safe modes of operation 42 ' and 42 '' be called. The function and the call of these additional, safe operating modes will be discussed below.

With the interface unit 30 is next to the central control section 31 also a comparison quantity generator 34 connected. In the comparison variable generator 34 is made up of one or more of the available and via the interface unit 30 read measured values for the various system parameters one or more comparison variables. Such comparison variables can be generated either by equating with a measured value of a system parameter or by calculating a variable that can not be measured directly. For example, in the simplest case, the temperature, which by the temperature sensor 35 is used as a reference. On the other hand, it is also possible, for example, to determine a comparison variable of the "performance" type, as has already been explained.

The comparison variable generator 34 is with an analysis device 35 connected and gives the determined comparison variables to the analysis device 35 further. The analysis device 35 is also with the central control section 31 connected. Because of this connection, the analyzer has 35 about information about that from the central control section 31 output control signals. Based on the output control signals, the analyzer forms 35 at least an expected value. This expected value is formed for each comparison quantity type. If, for example, the torque or the power is used as a comparison variable, then the recorded torque or the absorbed power of the hydrostatic machine, ie the main pump in the embodiment shown, becomes the control signals which cause a specific reaction of the hydrostatic system in the case of an intact system 4 determined. Thus, a deviation of the hydrostatic system from error-free behavior is possible by comparing the expected value with the associated comparison variable. Such a deviation is thus directly equivalent to the occurrence of a fault in the entire system. For detecting the error, preferably the same system parameters are used, which are also provided for control.

The analysis device 35 is further provided with an allocation section 38 connected. In the assignment section 38 the error cause is limited on the basis of the determined measured values. The delimitation is done systematically, for example, after an exclusion process. In a store 36 Several causes groups are stored. After the cause of the error, which is responsible for the deviation of the comparison quantity from an expected value, has been limited, an assignment is made to one of the groups of causes that are in the memory 36 are stored.

The assignment to one of the cause groups can be done, for example, in the exclusion process. For this is a matrix 41 in the store 36 stored. The matrix 41 contains a selection of expectation values that may occur simultaneously, for example. If a deviation from these expected values is detected, the matrix specifies which combinations of expected values as a set of expected values must be compared with the assigned comparison variables in order to rule out at least a portion of possible causes of the errors. In this way, when an error which can not initially be assigned occurs, a limitation of the possible cause of the error can be carried out step by step. This stepwise delimitation can also be carried out in several steps, whereby a selection from the expected values to be checked is determined in each case in a predefined sequence. It may also be that in one step, no further limitation is possible. In this case, the matrix will give a different selection to Reviewer, which may then allow the delimitation. Besides the selection of a part of the total available expectation values, the further order of the comparisons still to be carried out can also be determined on the basis of the knowledge recently obtained from the comparisons. The matrix 41 thus forms a system with a tree-like structure, whereby each branch determines a certain test sequence and scope of testing. This leads to the branch tip to a clear assignment of the error occurred on the assignment section 28 ,

For controlling the hydraulic system be by the control device according to the invention 10 both a measured value or a comparison variable of a measured variable and / or a plurality of measured values or comparative variables of different measured variables (ie in each case a measured value combination or comparison variable combination to a measured variable combination) are read to determine a present operating state ( 33 ) as well as control signals for effecting a desired operating condition ( 39 ). Since comparison variables are determined from measured values, they are referred to below as measured values for the sake of simplicity. The desired operating state is assigned a specific expected value as a desired measured value of a measured variable and / or a plurality of specific expected values as desired measured values of the various measured variables. Each operating state is associated with a specific measured value combination and a specific expected value combination, which in particular in the memory 36 is stored. During operation of the hydraulic system, a read-in measured value combination, which corresponds to the present operating state, is compared with an expected value combination, which corresponds to the operating state in the case of a fault-free function. The comparison leads either to no or to a deviation of the determined measured value combination with respect to the expected value combination. Each deviation is first assigned a group of error causes (cause group). The mappings are in memory 36 saved.

in the Further, within the cause group, a further reduction respectively. For this purpose, subgroups of the cause group are used in the exclusion process educated. The exclusion process can be so long with subgroups continue until the last subgroup has only one more exactly contains certain errors. This is then a specific one Emergency operation assigned. Is a resolution of the cause group towards a single error not possible, it is like already explained the selection of the assigned emergency operation based on the determined cause group.

In this way, a comparison leads to a determined individual error cause and / or cause group. On the basis of the determined individual cause of the fault and / or cause group, a fault-specific and / or cause-group-specific emergency operation can be determined. The emergency services are also in the store 36 saved. The stored emergency operations are in the store 36 associated with specific control signals and / or specific sequences of control signals (Ansteuersignalmuster), which can be used by the control unit to bring about an optimal behavior of the hydraulic system.

to Determination of a single cause of error and / or a cause group a measurement variable selection is examined. It can a complete range of measurements, which does not consider all measurands, or a reduced measurement variable selection, which is not all measured variables are considered. With the complete selection of measured variables becomes the entire measured value combination with the total expected value combination compared. This results in a complete comparison. By contrast, with the reduced measurement variable selection becomes only a part of a specific measurement combination with a corresponding part of a specific expected value combination compared. This results in a reduced comparison. On the basis of a deviation determined by (complete or reduced) comparison are individual causes of error which lead to the determined deviation, determined. Does such a procedure, eg. B. at a reduced comparison, not a clear result, d. H. a single cause of failure, the procedure is based on a new range of choice repeated, which Although it can also be reduced, it does not have to be. Instead of a reduced measurement variable selection for one Reduced comparison can also be a full range of measurements be considered for a complete comparison. The procedure is ideally repeated until a single one Error cause is found. The number for reduced comparisons considered measured variables can be gradual increase.

Furthermore, in the memory 36 to determine the expected values also characteristics 40 be stored. Such a storage of characteristic curves is useful, for example, when an insulated component has an exactly describable behavior. This can for example be the case when controlling a proportional magnet. A suitable characteristic 40 this would be a temperature-specific current / voltage characteristic. By measuring the voltage applied to the proportional magnet and simultaneously knowing the control current and the temperature, the resistance of the proportional magnet can thus be determined as a comparison variable.

Another way to determine the expected values in the analysis facility 35 is the use of a model of the hydrostatic system. Using such a model, different operating states of the hydrostatic system can be analyzed, with the control signals of the central control section being used as input variables for calculating the system parameters to be measured as expected values 31 be used.

The assignment section 38 is also with the central control section 31 connected. On Basis of certain assignments can thus by the assignment section 38 a classified, occurred error to the central control section 31 be transmitted. The central control section 31 changes to a selected safe operating mode depending on which cause group the error occurred belongs to. It is preferred if in the central control section 31 several safe operating modes 42 ' . 42 '' are present, so that depending on the cause of the error an adapted safe operating mode can be used. For example, certain errors occurring can only lead to a reduction of the maximum allowable delivery volume, while for other errors occurring a reduction of the maximum allowable speed is required. In this way, ie the selection of a safe operating mode taking into account the respective assignment of an error occurred to a cause group 37 , an adapted emergency program can be called up.

Basically, the check of the measured values is clocked. However, the situation may arise that certain measured values can only be measured if the system is in a defined operating state. For example, in the case of a pressure transducer, it is advantageous to check whether, when the pressure actually disappears, the measuring signal "0" is sent to the control unit 10 is transmitted. Such static measurements can be determined prior to system startup. During normal operation, however, static as well as dynamic processes can be monitored, for which purpose the measured values can be recorded in time and processed in the manner described above for comparison variables and compared with the associated expected values.

Each present operating state has a measured value for each measured variable. Each desired operating state has an expected value for each measured variable. Thus, each sequence of present operating states for each measured variable has a sequence of measured values (measured value pattern) and each sequence of desired operating states for each measured variable has a sequence of expected values (expected value pattern). As a result, measured value patterns with expected value patterns can also be compared on the basis of comparisons described above. Just as deviations of measured values in relation to expected values are attributed to individual causes of error and / or cause groups or by memory 36 In one exemplary embodiment, deviations from measured value patterns with respect to expected value patterns are likewise assigned individual error causes and / or cause groups or in the memory 36 saved. Also in this case, emergency operations are assigned to the individual error causes and / or the groups of causes. The comparison of measured value patterns and expected value patterns can be carried out on the basis of complete comparisons as well as on the basis of reduced comparisons. In this way, emergency operations can be initiated in a more differentiated manner (measured value patterns contain more information than measured values), since error causes can also be recognized in a differentiated manner. Depending on the particular operating situation of the hydrostatic drive, however, it may also be necessary to reject part of the measured values recorded over a specific period of time. This may be necessary during the so-called debounce time, for example. The debounce time is the time it takes for the system to return to the expected behavior after a certain control event, for example when reversing in a hydrostatic travel drive. The length of the interval in which the measured values are ignored can be defined. It is particularly preferred if different intervals are defined for different control events, of which reversing is just one example. The length of the interval preferably depends on one or the respectively present control signal and / or on the measured value of at least one measured variable, in particular the temperature.

Goes to the central control section due to the assignment of an error to a cause group 31 in a secure mode of operation 42 ' . 42 '' This is also the case with the analysis device 35 transmitted. The analysis device 35 now determines expected values taking into account the changed operating mode. In this way, it is possible to prevent, for example, maximum pressures which would be permissible in normal operation, but which are already outside the permissible pressure range in safe mode, to be able to occur at all.

The 4 again shows an overview of the sequence of the method according to the invention. First, control signals are in step 50 through the central control section 31 generated. Furthermore, cause groups are determined (step 51 ) and in the memory 36 stored. During operation or at the beginning during a static condition, measured values of system parameters in step 52 determined. These measured values are determined by the comparison quantity generator 34 processed to at least one comparison size (step 53 ). An expected value in step is added to this comparison variable 54 determined. When determining the expected value, those are calculated by the central control section 31 taken into account.

The comparison size and the associated expected value are then in step 55 compared to each other. Several comparison variables can also be compared with a set of expected values. In step 56 the determination is made as to whether there is a deviation between the expected value and the comparison value. If such a deviation is not present, the process is started again without changing the operating mode, as indicated by the arrow 57 is specified. As long as an error does not occur, the procedure described above is repeated cyclically.

However, if a deviation is detected by the comparison of the comparison variable with the expected value, then, as indicated by the arrow 58 then an assignment to a cause group in step 59 carried out. This assignment can, as it has already been described, z. By executing an instruction in matrix form in the memory 36 is stored. After the assignment of an occurred error to a cause group becomes in step 60 a safe operating mode 42 ' . 42 '' called. According to this safe operating mode 42 ' or 42 '' Then the control signals are generated and then a set of new expected values in step 62 determined. The new expected values take into account the changed possible settings or the expected system reaction. As it is in step 63 is specified, measured values are still recorded and determined from these measured values as before comparison variables. Between these new benchmarks and the new expected values is then in step 64 again a query regarding the match performed. If there is a match between the comparison quantity and the expected value, then a measured value acquisition and calculation of the comparison variables with subsequent comparison is also carried out cyclically. Conversely, it turns out that even in safe mode 42 ' or 42 '' If an error still occurs, an assignment to one of the cause groups is performed again. The assignment runs basically the same as in step 59 ,

Under Consideration of the additional renewables Assignment of an occurred error to a cause group becomes again selected an operating mode. This newly selected operating mode may be a recent limitation, for example include the adjustment ranges.

The Invention is not on the illustrated embodiment limited. Rather, individual features are also more advantageous Way combined with each other.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 19538649 A1 [0002]

Claims (19)

Method for detecting malfunction of a hydrostatic system with at least one hydrostatic machine, comprising the following method steps: - generating control signals ( 50 ) for controlling the hydrostatic machine ( 2 ) by a control device ( 10 ), - defining multiple cause groups ( 51 ) for the occurrence of a malfunction of the hydrostatic system ( 1 ), - measuring one or more system parameters ( 52 ) of the hydrostatic system ( 1 ), - generating at least one comparison variable ( 53 ) from the measured system parameter (s), - determining at least one expected value ( 54 ) for the comparison variable, - comparing at least one comparison variable with at least one expectation value ( 55 ) and - assign a detected deviation to a cause group ( 59 ). Method according to claim 1, characterized in that for determining the expected value ( 54 ) a model of the hydraulic system is calculated. Method according to claim 1, characterized in that for determining an expected value ( 54 ) one in the control unit ( 10 ) stored characteristic curve ( 40 ) is read out. Method according to Claim 1, characterized in that several expected values are combined into one set of expected values and this set is compared with a plurality of comparative values ( 55 ). Method according to one of claims 1 to 4, characterized in that a plurality of comparisons between at least one comparison value and an expected value is carried out successively ( 55 ), wherein a selection and / or the order of the comparisons to be carried out in each case depends on the result of the previously performed comparisons. Method according to claim 5, characterized in that that gradually a resolution of the cause group too a single mistake. Method according to one of Claims 1 to 6, characterized in that, on the basis of the assignment made for a detected incorrect behavior, a safe operating mode ( 42 ' . 42 '' ) from a plurality of possible operating modes ( 42 ' . 42 '' ) and the determination of the control signals by means of the selected operating mode ( 42 ' . 42 '' ) he follows. Method according to claim 7, characterized in that during operation in the safe operating mode ( 42 ' . 42 '' ), for the secure operating mode ( 42 ' . 42 '' ) are determined ( 62 ). Method according to one of claims 1 to 8, characterized in that the measurement of the system parameters ( 52 ) is timed, whereby measured values within an interval after a certain control event are disregarded. Method according to claim 9, characterized that the temporal length of the interval of the respective Control event and / or from a measured value of a measured variable depends. Control unit for a hydrostatic system ( 1 ) with a central control section ( 31 ) for generating control signals, a memory ( 36 ) and an interface unit ( 30 ) for reading measured values of system parameters of the hydrostatic system ( 1 ), characterized in that in the memory ( 36 ) several cause groups ( 37 ) are stored for faults in the hydrostatic system and that the control unit ( 10 ) a comparison quantity generator ( 34 ) for generating at least one comparison variable from the measured values and an analysis device ( 35 ) for generating an expected value as well as for comparing the comparison variables with the expected values and an assignment section ( 38 ), which is set up so that, when a deviation occurs, an assignment of the error that has occurred to one of the groups of causes ( 37 ) he follows. Control unit according to Claim 11, characterized in that the analysis device ( 34 ) with the control section ( 31 ) and is arranged to be modeled on the basis of 31 ) generates at least one expected value. Control unit according to claim 10, characterized in that the analysis device ( 34 ) with the memory ( 36 ) and in the memory at least one characteristic ( 40 ) is stored for determining an expected value. Control unit according to claim 10, characterized in that the analysis device ( 34 ) is arranged to combine a plurality of expected values into a set of expected values and to compare them to a plurality of comparison values. Control device according to one of Claims 10 to 13, characterized in that the analysis device ( 34 ) with the memory ( 36 ) and in the memory ( 36 ) a matrix ( 41 ) by the analysis facility ( 34 ) a selection and / or an order for performing the comparisons can be specified. Control unit according to one of claims 10 to 14, characterized in that by the control section ( 31 ) a control algorithm for a regular operating mode ( 42 ) and at least two other safe operating modes ( 42 ' . 42 '' ) are executable for determining the control signals, wherein the control section ( 31 ) is set up in such a way that it depends on the information provided by the allocation section ( 38 ) a secure operating mode ( 42 ' . 42 '' ) and that the control section ( 31 ) using the selected safe operating mode ( 42 ' . 42 '' ) corresponding control algorithm determines the control signals. Control unit according to Claim 15, characterized in that the analysis device ( 34 ) with the control section ( 31 ), the analysis device ( 34 ) is set up to be dependent on the selected safe operating mode ( 42 ' . 42 '' ) changed expected values. Control unit according to one of Claims 10 to 16, characterized in that the control section ( 31 ) with the analysis device ( 34 ) and the analysis device ( 34 ) is set up so that, depending on a sequence of control signals within a time interval, a comparison of expected values and comparison variables is suppressed. Control unit according to one of Claims 10 to 17, characterized in that the control unit ( 10 ) one in the pump unit ( 2 ) onboard unit is integrated.