Method for operating a storage device

Abstract

The invention describes a method for operating a bearing device (19) - in particular a rolling bearing or a plain bearing of a pump, which is particularly designed as a piston pump - wherein the bearing device (19) is lubricated and cooled by a liquid (43), wherein the liquid (43) acts on at least one sensor element (50, 59) and a property in the at least one sensor element (50, 59) is detected at different times (t, ....) and a property change value (DT / Dt) is determined.

Description

Prior ArtGerman patent specification DE 10 2013 008 743 B3 discloses a method for controlling a coolant flow in a motor vehicle. A coolant cooler and a control element are used to control a coolant flow between a component and the coolant. In the case where a temperature value of the coolant or a gradient of the temperature value exceeds a threshold value, a coolant flow is increased to improve cooling.Embodiments of the InventionAccording to a first aspect of the invention, a method for operating a bearing device is provided, which is in particular a rolling bearing or a sliding bearing of a pump, wherein the pump is very particularly designed as a piston pump. The bearing device is lubricated and cooled by a liquid. It is provided that the liquid acts on at least one sensor element and a property is detected in the at least one sensor element at different times and a property change value is determined. While it has been found in investigations of such an object that it is advantageous to detect a property of the liquid, such as its temperature, and its effect on a sensor element, it has also been found in the following of these studies that it is of greater advantage to determine a property change value of the property of the liquid. In the investigations it was found that by a detection or determination or determination of a property change value-and in particular its size determination or classification-which takes place continuously during operation of the storage device, a failure of the storage device can be predetermined in time.According to a further aspect of the invention, it is provided in a more specific manner that the property in the at least one sensor element correlates with a temperature and the property change value correlates with a change of a function, wherein the function is dependent on at least one temperature. It is thus very particularly provided that a temperature of the already mentioned liquid is determined by means of the at least one sensor element. Accordingly, it is also provided that the property change value is a change value of the temperature, i.e., the gradient thereof. The function mentioned is a description, here derivation, of a temperature profile of a temperature at one location or only the derivation of a profile of a temperature difference of two locations. It has been found that, for example, at an outlet of the storage device, i.e. at a location at which the mentioned liquid leaves or has left the storage device again, a temperature and a change in the temperature can be determined by means of the sensor element over time. Accordingly, in this case, the function would be dependent on a temperature which in this case is at the outlet of the storage device. If, for example, two sensor elements are used, each of which detects a property correlated with a temperature, then, for example, a property can be detected not only at the output of the storage device, but also, for example, at the input of the storage device. Accordingly, a property change value then correlates with a change in a function that is dependent on at least two temperatures. The function mentioned would be in this case, for example a derivation / gradient of a profile of a temperature difference of two locations, namely of the location of the coolant inflow to the storage device and of the location of the coolant outflow from the storage device. For example, the last-mentioned function could also describe a change over time, i.e. derivation or a gradient of a profile of an average value of the temperature at the inlet and of the temperature at the outlet of the storage device. The detection and evaluation of a temperature at the outlet of the storage device and thus of the outflow of the cooling liquid has the advantage that changes in the storage device and thus also changes in the liquid are detected very quickly. A corresponding evaluation of such a temperature thus leads to a sensitive method. If, on the other hand, the temperatures or the derivatives or gradients of a course of a temperature difference or a type of mean value, at least of a function which takes into account both temperatures, are evaluated, the method becomes more complex, since two temperatures have to be processed. With regard to the locations of the outlet of the bearing device and the inlet of the bearing device, it should be mentioned that the terms outlet and inlet relate in particular to the fact that the inlet represents an inflow of the cooling liquid to the bearing device. This inlet can be a location directly in front of the bearing device or else a location which is located at a mechanical interface at which the cooling liquid flows to the bearing device. This outlet can be a location directly after the bearing device, or else a location which lies at a mechanical interface at which the cooling liquid flows out of the bearing device.According to a further aspect of the invention, it is provided that a threshold value is determined for the property change value. It has been found that a threshold is suitable for separating property change values in terms of their meaning. Property change values which are below a determined or determined threshold value are considered to be non-critical, while property change values which are above a determined threshold value are considered to be critical. If, for example, the temperature changes comparatively strongly over time, this can mean that the liquid flowing through the bearing device is exposed to comparatively high loads (compressive and / or shear forces or, for example, shear forces. Solid friction in the bearing device with heat development and heat transfer to the coolant) and as a result its temperature rises. Thus, for example, temperature gradients above a threshold value can mean that the bearing device is no longer lubricated by means of full lubrication, but instead, for example, boundary layer lubrication is present in the bearing device. Accordingly, it is provided that a property change value, in particular a current property change value, is compared with the threshold value.Such a comparison with the threshold value advantageously enables a property change value and its quality to be determined. If this is smaller than a threshold value, for example, it is determined therefrom, for example, that this does not indicate a defective bearing device. If the characteristic change value is greater than the threshold value, this characteristic change value may be classified as an indication of a change in the function and, as a result, it may be concluded that the durability of the bearing device changes. According to a further aspect of the invention, it is provided that it is determined how often in a time interval the just mentioned threshold value has been exceeded. Overrange events per unit time or time period can generally serve, for example, as a basis for durability.According to a further aspect, it is provided that a sensor element detects the property of the liquid after passage of the storage device. This has the advantage that the property of the liquid is detected by means of the sensor element directly or almost directly after the high load in the storage device. If only one temperature measurement point is evaluated and not two measurement points, susceptibility to errors is reduced, since only one sensor is to be evaluated. A further advantage is that only a so-called free temperature channel is taken into account or used in the control unit. The cost and expenditure are thus less.Furthermore, an embodiment of the method may be provided, according to which the property is detected with the at least one sensor element at specific time intervals. This can be done with one sensor element or with both or more sensor elements. In particular, the determined time intervals are regularly of the same length. In particular, the determination of the property at specific time intervals makes it possible in a particularly simple manner to determine whether or not a threshold value has been exceeded. According to a further embodiment of the invention, it can be provided that an average value is formed from a plurality of values of the property of at least one sensor element. This has the advantage that special individual events, i.e. particularly high or particularly low values of the property, are thereby averaged out. Accordingly, it is preferably provided that a respective property change value is determined from a plurality of mean values, whether it be one sensor element or whether it be a plurality of sensor elements. Here too, the advantage results that exceptionally high or exceptionally low values are averaged out. In particular, extreme values are relativeized by such averagings, so that corresponding values, which can arise, for example, as a result of any measurement errors, are significantly less important.According to a further aspect, it is provided that when a criterion determined on the basis of a property change value is fulfilled, an operator of the storage device-in particular a driver of a motor vehicle-is informed by a signal about the fulfilled criterion with respect to the storage device-which is in particular an expected failure. Corresponding information can be provided by the system integrator, for example by the system responsible for the internal combustion engine or the vehicle, for example by a simple red lamp on a so-called dashboard or another operating unit. Text information could likewise be output, which requests, for example, to shut down the storage device or to put the storage device or the device equipped therewith out of operation, such as a motor vehicle. In addition to the information of the driver by means of a lamp in the dashboard, a reaction for relieving the bearing-a so-called LimpTime function-can also be triggered in order to extend the time until the bearing device fails completely. In this case, for example, a load on the bearing device is reduced. In addition to a text output and lamp (both optical information communication), an acoustic information transmitter can be switched on in the event of a fault.Furthermore, a computer program is provided which is designed to execute all steps of one of the methods or which is programmed in such a way that it executes a method according to one of the steps when it is executed on a computer. In addition, a machine-readable storage medium is provided on which the computer program is stored. In addition, a control device is intended to be designed which is capable of executing all steps of one of the methods or is programmed for use in a method as disclosed here in this description.The invention is explained in more detail with reference to the figures listed below: FIG. 1 shows a storage device in its environment, which is designed, for example, as a motor vehicle, FIG. 2 shows a curve of a property, here the temperature, over time. In addition, this schematic diagram shows the course of a property change value, here the change of the temperature over time,FIG. 3 shows two different temperature curves on two different sensor elements at different positions of the bearing device, and also a differential temperature curve and a curve of a property change value,FIG. 4 illustrates how a mean value is formed in sections from a series of properties determined (temperature T 1), FIG. 5 shows a characteristic change value characteristic which is significantly more rough in comparison with the characteristic change value characteristics illustrated above.FIG. 1 shows a machine 10 in an abstract manner, which can be embodied as a motor vehicle, for example. This machine 10 has a device 13 which has preferably rotating parts, which are not designated in more detail here. This device 13 can be an internal combustion engine, for example. Fastened to this device 13 is, for example, a unit 16 which is, for example, a pump, in particular a piston pump. This unit 16 has a bearing device 19. A first rolling element 25 is driven by means of a shaft 22. In this exemplary embodiment, this first rolling element has two cams 28 arranged opposite one another. A second rolling element 31 rolls on the first rolling element 25. The bearing device 19 accordingly has the first rolling element 25 and the second rolling element 31. A piston 34, which is schematically illustrated here, is driven by means of the second rolling element 31. The second rolling element 31 accordingly drives, in general form, an output element which is designed here as a piston 34. This piston 34 slides back and forth in a cylinder, not shown here, corresponding to the double arrow. The bearing device 19 can accordingly be part of a piston pump, in particular a high-pressure pump of a fuel supply system for internal combustion engines, in particular of a so-called high-pressure accumulator system (common rail). The unit 16 has both an inlet 36 (inlet) and an outlet 38 (outlet). From a liquid container 40, which is a fuel tank, for example, in an embodiment of the machine 10 as a motor vehicle, but can also be a lubricant container, liquid 43 is guided from the liquid container 40 by means of a pump, not shown here, through a line system, only outlined here, to the inlet 36. The line system is shown symbolically here, in particular in the inlet 36 by means of a liquid flow 46. Furthermore, a further liquid stream 48 is returned from the outlet 38 back into the liquid container 40. If the unit 16 is a high-pressure delivery pump for the aforementioned common rail fuel supply system of a motor vehicle, there is, for example, a further liquid flow by means of which a rail is filled with liquid which is a fuel. A sensor element 50 is arranged at the outlet 38 of the unit 16. This sensor element 50 is in indirect or direct contact with the liquid 43 flowing out of the unit 16. In this example, a sensor element 59 is likewise arranged at the inlet 36, which sensor element is likewise in direct or indirect contact with the liquid 43. The sensor element 59 is connected to the evaluation unit 56 via a data line 62. The evaluation unit 56 is connected to an information output unit 65. A further data line 68 is used to transmit information from the evaluation unit 56 to the information output unit 65.As already mentioned at the outset, either a) an embodiment of the unit 16 with a sensor element 50 at the outlet 38 of the unit or b) an embodiment of the unit 16 with a sensor element 50 at the outlet 38 and a sensor element 59 at the inlet 36 can be used by the method.A method for operating a bearing device 19 is provided, which is in particular a rolling bearing or a sliding bearing of a pump, which is very particularly designed as a piston pump. A liquid 43 flows through the bearing device 19, i.e. in particular lubricated and cooled. The liquid 43 acts on at least one sensor element 50, 59. a property in the at least one sensor element 50, 59 is detected at different times t and a property change value is determined.By way of example, FIG. 1 shows a control device 70 which is designed to carry out all the steps of one of the methods mentioned here in this description or to be programmed for use in one of the methods mentioned here in this description. FIG. 1 also shows a machine-readable storage medium 73 on which a computer program 76 is stored or on which the computer program 76 is stored for application in one of the methods mentioned here in this description. The computer program 76 is designed to execute all steps of one of the methods mentioned here in this description or to execute all steps of one of the methods mentioned here in this description in such a way as to program them when it is executed on a computer.FIG. 2 shows a detail of a profile of a temperature T 1. This temperature T 1 is determined according to the illustration at a total of six different times (t 0... t 5). The corresponding temperatures assigned to the respective time are therefore given a corresponding index and are designated accordingly (T 10... T 15). In this example, the temperature T 1 is associated with the property that is detected in the sensor element 50 at the outlet 38 of the unit 16. Accordingly, at a total of six different times t 0... t 5 a property, here the temperature T 1, is detected. In this example, a property change value is determined from two properties detected immediately one after the other and the respective time of detection of the property. As can be seen from FIG. 2, the property change value between the points in time t 0 and t 1 is zero, i.e. the property associated with the temperature has not changed between these two points in time (T 10= T 11). At time t 2, a property associated with temperature T 12 is detected via sensor element 50. As can already be readily seen from the diagram, a property change value DT / Dt=(T 12- T 11) / ( t 2- t 1), which assumes a value not specified in detail here, is thus obtained. As can be seen from the graph of FIG. 2, the change in characteristic increases with each measurement at the following points in time t 3, t 4 and t 5. Between the timings t 4 and t 5 the characteristic change value DT 45 / Dt 45 takes a value that is noticeably larger than a threshold value SW. By definition, exceeding this threshold value SW determined for the property change value DT / Dt indicates that the property now increases at a speed that has exceeded a defined critical measure (threshold value SW). In the aforementioned method, the sensor element 50 is arranged at an outlet 38 of the unit 16.FIG. 3 shows a diagram in which a temperature profile T 1 of a sensor 50 at an outlet 38 shows and a temperature profile of the temperature T 2 of a sensor element 59 at an inlet 36. This is not very surprising in view of the described unit 16, since the sensor element 50 is arranged much closer to the bearing device 19 than the sensor element 59-or in other words-the distance between the bearing device 19 and the sensor element 50 is much shorter than the path to the sensor element 59 when viewed in the flow direction (downstream). The liquid 43 accordingly has a relatively long time (and has contact with more surface) in order to achieve a lower temperature level. FIG. 3 furthermore shows the temperature difference DT between the times t 0 and t 5. In an alternative method step, it is provided that in this case a property change value DT / Dt is determined, which is initially attributable to the difference between the two temperatures T 1 and T 2, DT. The characteristic change value is accordingly a change value that represents the change in the temperature difference between the sensor element 59 and the sensor element 50. The property change value may also be referred to herein as D(DT / Dt) and is also illustrated in FIG. 3. A threshold value SW is also represented or determined for this property change value. In this example, a critical state of the storage device 19 is then determined when the property change value exceeds the threshold value SW.FIG. 4 shows an exemplary temperature profile (property profile) of a sensor element 50. In this example, a temperature T 1 is determined at regular intervals (dt). A mean value is formed from a plurality of temperatures. This formation of an average value has the advantage that individual extreme values of temperatures which possibly exceed a threshold value are averaged out and the system thus reacts somewhat more gently overall. Accordingly, a mean value TM is formed from a plurality of values of the property T 1, T 2 of at least one sensor element 50, 59. As in the examples above, a property change value DTM / Dt is also determined. If the threshold value SW is exceeded, it is assumed that the storage device 19 has reached a critical state. According to the above, a property change value DTM / Dt is determined from a plurality of mean values TM 1, TM 2 over the course of the temperature or the property of a sensor element 50, 59.FIG. 5 shows, in comparison with the aforementioned representations, a curve of a property change value over time, which is significantly less idealised. In a sensor element 50, 59, a property is detected at different points in time t and a property change value is determined. Accordingly, as a characteristic, for example, a temperature is determined and a temperature change value is obtained. Such a property detection (temperature measurement) can be carried out, for example, with a frequency of 2 Hz.The property (temperature) detected in the at least one sensor element 50, 59 at different times is determined, for example, over a period of several times-for example. 10 seconds averaged. Thus, for example, 20 determined values for the property are averaged. As can be seen very particularly in connection with FIG. 5, this has a certain advantage, in particular in connection with the number of limit value crossings (crossings of a threshold value) which may be determined. The averaged characteristic or mean temperature or averaged temperature is derived and a characteristic change value (change in the temperature) is thus determined. In the next step, it is queried whether or not the ascertained and averaged property change value has exceeded the set threshold value. Within the scope of the evaluation, a frequency of exceeding a limit value can be carried out very differently. Thus, for example, in the context of the method, it could be queried for each property determined and each property change determined whether or not a limit value, a threshold value, has been exceeded. If this is carried out, for example, at a relatively high frequency, i.e., for example, 2 Hz, then, for example, in a time period between t 3 and t 4, in the region of the first relative maximum there, for example 20 times, an exceeding n of the threshold value can be determined. Such a burst and thus also such a frequency in the determination of exceedances of threshold values can be too high. It can be advantageous, for example in a time period which is, for example, 10 seconds and here, for example, describes the time period between t3 and t4, to determine a trend by the mentioned averaging and thereby to make a more reliable decision about further steps. Accordingly, it is provided to count up a counter in order to determine how often a property change value has exceeded a threshold value in a specific length of the past (time interval).Consequently, a method sequence is provided in which, if a criterion (counter, threshold value) determined on the basis of a property change value is fulfilled, an operator of the storage device 19, in particular a driver of a motor vehicle, is informed of a fault event, in particular an expected failure, of the storage device 19 by a signal. This procedure can be planned and implemented, for example, by the manufacturer of the internal combustion engine or the vehicle manufacturer. Such information can consist, for example, in the illumination of a red lamp, which the driver of the motor vehicle or operator of the storage device must understand as a notice, which can preferably be unambiguously interpreted. The indication can also consist of text information.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2013 008 743 B3

[0001]

Claims

Method for operating a bearing device (19) - in particular a rolling bearing or a sliding bearing of a pump, which is very particularly designed as a piston pump - wherein the bearing device (19) is lubricated and cooled by a liquid (43), characterized in that the liquid (43) acts on at least one sensor element (50, 59) and a property in the at least one sensor element (50, 59) is detected at different times (t,...) and a property change value (DT / Dt) is determined.Method according to claim 1, characterised in that the property in the at least one sensor element (50, 59) correlates with a temperature (T 1, T 2) and the property change value (DT / Dt) correlates with a change in a function, wherein the function is dependent on at least one temperature (T 1, T 2).Method according to either of Claims 1 and 2, characterized in that a threshold value (SW) is determined for the property change value (DT / Dt).Method according to Claim 3, characterized in that a property change value (DT / Dt), in particular current property change value (DT / Dt), is compared with the threshold value (SW)Method according to Claim 4, characterized in that it is determined how often the threshold value (SW) has been exceeded in a time interval (dt).Method according to Claim 4 or 5, characterized in that a number (n) of permissible exceedivities of the threshold value (SW) is determined.Method according to one of the preceding claims, characterized in that a sensor element (50, 59) detects the property of the liquid (43) after passage of the storage device (19).Method according to one of the preceding claims, characterized in that a sensor element (50, 59) detects the property of the liquid (43) before a passage of the storage device (19).Method according to one of the preceding claims, characterized in that the property is detected in the at least one sensor element (50, 59) at specific time intervals (dt).Method according to one of the preceding claims, characterized in that a mean value (DTM) is formed from a plurality of values of the property of at least one sensor element (50, 59).Method according to Claim, characterized in that a property change value (DT / Dt) is determined from a plurality of mean values (DTM).Method according to one of the preceding claims, characterized in that, if a criterion determined on the basis of a property change value (DT / Dt) is fulfilled, an operator of the storage device (19) - in particular a driver of a machine (10), preferably of a motor vehicle - is informed by a signal about a fulfilled criterion - in particular an expected failure - of the storage device (19).A computer program (76) configured to perform all the steps of any of the methods of any of claims 1 to 12, or programmed to perform a method of any of claims 1 to 12 when executed on a computer.Machine-readable storage medium (73) on which the computer program (76) according to Claim 13 is stored or on which the computer program (76) according to Claim 13 is stored for application in a method of Claims 1 to 12.A controller (70) configured to perform all the steps of any of the methods of any of claims 1 to 12 or programmed for use in a method of any of claims 1 to 12.

Images