Method for obtaining the remaining operating time of an electromagnetic coil of an electromagnetic actuator

Abstract

The invention relates to a method for obtaining the remaining operating time (ΔR1, ΔR4) of an electromagnetic coil of an electromagnetic actuator, in particular of a valve, wherein in each actuation of the electromagnetic actuator by means of the electromagnetic coil, the operating time (Δt) is obtained as the duration of the actuation, and the temperature (T) of the electromagnetic coil (131) during or after the actuation is obtained, wherein the temperature (T) of the electromagnetic coil is assigned to one of a plurality of predefined temperature ranges (ΔT1-ΔT7), wherein in the actuation, the operating times (Δt) for the respective temperature ranges (ΔT1-ΔT7) are added up separately, wherein a step set (ΔH2) for the different temperature ranges (ΔT1-ΔT7) is formed by adding, for each temperature range (ΔT1-ΔT7), the operating times of all temperature ranges having a higher temperature value, and wherein the remaining operating time (ΔR1, ΔR4) of the electromagnetic coil is obtained for a specific temperature range (ΔT1, ΔT4).

Description

Field of the Invention

[0001] The present invention relates to a method for obtaining the remaining operating time of an electromagnetic coil of an electromagnetic actuator of a valve, in particular a hydraulic valve. Background Art

[0002] Valves, in particular hydraulic valves, are usually controlled in the presence of a computing unit or a corresponding control device. Such valves have an electromagnetic drive (or actuator) here, and in the case of a hydraulic valve, an associated hydraulic regulating unit, by means of which a desired parameter, such as volume flow or pressure, can be adjusted by presetting a specific current or a specific voltage. The current of the electromagnetic actuator can be preset here by supplying a voltage to the electromagnetic coil or the corresponding winding of the electromagnetic actuator also in pulse-width modulation form.

[0003] The electromagnetic coil is subject to aging based on continuous stress and therefore usually only has a limited operating time or service life. The failure of the electromagnetic coil and thus the valve is considered when the maximum operating time or service life is reached. Summary of the Invention

[0004] According to the present invention, there is provided a method for obtaining the remaining operating time of an electromagnetic coil of an electromagnetic actuator, a computing unit for performing the method, a computer program, and a machine-readable storage medium. Advantageous design solutions are the subject of the following description and at least include: the theoretically maximum operating time of the electromagnetic coil in the corresponding temperature range is obtained by means of a service life model of the electromagnetic coil; wherein the model according to Eyring is used as the service life model; wherein the remaining operating time of the electromagnetic coil is obtained as the quotient or difference of the so far operating time according to a set of steps and the theoretically maximum operating time of the electromagnetic coil in the relevant temperature range; wherein the temperature of the electromagnetic coil is obtained by means of the ohmic resistance of the electromagnetic coil; wherein the electromagnetic actuator is used to manipulate a valve, in particular a hydraulic valve.

[0005] The method according to the present invention is used to obtain the remaining operating time or remaining service life or remaining useful life of an electromagnetic coil of an electromagnetic actuator of a valve, in particular a hydraulic valve or a hydraulic valve. Here, in each manipulation of the electromagnetic actuator by means of the electromagnetic coil, the operating time is obtained as the duration of the manipulation, and the temperature of the electromagnetic coil during or, if necessary, after the manipulation is obtained. The temperature of the electromagnetic coil is obtained here in particular by means of the ohmic resistance of the electromagnetic coil or its winding. For this purpose, the winding temperature can be calculated, or appropriate tables etc. can be stored or used to assign a specific temperature to a specific resistance. Here, the resistance or temperature can in particular also be obtained as an average value over the duration of the manipulation.

[0006] The temperature of the electromagnetic coil is assigned to one of a plurality of predefined temperature ranges. The plurality of temperature ranges are in particular adjacent to one another here, i.e., the upper limit value of one temperature range simultaneously forms the lower limit value of the next temperature range. The temperature ranges should in general cover the entire range of temperatures that can occur during operation of the electromagnetic coil. Depending on the specific mode of operation, the electromagnetic coil can be heated to different degrees based on the current. The width of the temperature ranges can be selected according to the desired accuracy of the proposed method. The temperature ranges can for example all have the same width.

[0007] It is also conceivable that, for example, during a manipulation process with a temperature change (sharply) over a longer period of time, in the sense of the manipulation mentioned above, this manipulation process is divided into two or more individual manipulations or manipulation processes, and is accordingly assigned to different temperature ranges in order to obtain more accurate results.

[0008] Furthermore, in several manipulations, i.e., from one manipulation to the next, the operating times for the respective temperature ranges are added up separately. In other words, the operating time of the current manipulation is added to the operating time already present in the temperature range in which the current temperature falls during the current manipulation. Thereby, a so-called step collective (Stufenkollektiv) for the different temperature ranges is formed, in that for each temperature range the operating times of all temperature ranges with higher temperature values are added separately. Thus, for each temperature range, a so-called cumulative frequency of the operating times is obtained, which includes the operating times of the higher temperature ranges. Thus, for the highest temperature range, only the sum of the operating times in this temperature range is obtained. For the second-highest temperature range, the sum of the operating times within the highest temperature range plus the sum of the operating times in this second-highest temperature range is obtained in total. This principle is also known under the term linear damage accumulation, in which it is obtained that different intensities of action (here different temperature ranges) lead to different intensities of damage. In this case, reference is also made to the attached drawings and the accompanying description for an intuitive illustration.

[0009] As a simple example, it can be mentioned that the electromagnetic coil is damaged more in a higher temperature during a specific operating time than in a lower temperature. Accordingly, a smaller maximum operating time or service life is expected during operation at a higher temperature than during operation at a lower temperature.

[0010] Obtain the remaining operating time of the electromagnetic coil for a specific temperature range. To this end, in particular for a specific temperature range and all temperature ranges with lower temperature values, the remaining operating time in the respective temperature range is obtained by means of the theoretically maximum operating time of the electromagnetic coil in the respective temperature range (i.e., for the specific temperature range and all temperature ranges with lower temperature values) and the so far operating time according to the step set in the respective temperature range.

[0011] The theoretically maximum operating time of the electromagnetic coil in the respective temperature range is obtained here in particular by means of the service life model of the electromagnetic coil. Based on the assumption that different stresses of the electromagnetic coil are realized at different temperatures, which results in different maximum operating times or service lives depending on the temperature. Such a model usually produces a smooth curve of change, which has a higher maximum operating time with decreasing temperature. Now, in order to assign this theoretically maximum operating time of the electromagnetic coil to the temperature range, an average temperature value can be selected from this temperature range, for which the theoretically maximum operating time is obtained from the model. For the constants or parameters of the service life model, in order to be able to obtain the theoretically maximum operating time for different temperatures, they are usually obtained for a specific type of electromagnetic coil or electromagnetic actuator, for example, by simulation and / or test measurement.

[0012] It should also be considered that although the remaining operating time or remaining service life is thus obtained for a specific temperature range, which can be directly obtained from the model by means of the attached maximum operating time, there may also be an even shorter remaining operating time in the lower temperature ranges. Based on the method for obtaining the step set described above, the shortest remaining service life is therefore selected from the obtained remaining service lives, i.e., the remaining operating time with the smallest value in the temperature range is used as the remaining operating time of the electromagnetic coil.

[0013] The remaining operating time of the electromagnetic coil (for a specific temperature range) can preferably be obtained here as the quotient or difference between the so far operating time according to the step set and the theoretically maximum operating time of the electromagnetic coil in the relevant temperature range. In other words, the remaining operating time is stated as a part of the theoretically maximum operating time, or as the absolute value of the remaining operating hours for a specific temperature range, for example, as a number.

[0014] In the practical application of the proposed method, the value of the remaining operating time of the electromagnetic coil obtained in this way can be shown, for example, on a suitable display, so that the user can estimate when to replace the electromagnetic coil or electromagnetic actuator or the component containing the actuator or the component of the actuator.

[0015] Here, the temperature region that appears last during operation or the current temperature region can, for example, be used as a specific temperature region. It is also conceivable to obtain the remaining service life in the manner described for multiple or even all preset temperature regions and, if necessary, also to display it graphically, for example.

[0016] The proposed method can thus in particular enable the reading of the (hitherto) stress of the electromagnetic coil and the prediction of the remaining service life. In addition, condition monitoring is possible without changing the control of the electromagnetic actuator, and it is also possible to implement the method in a superior, for example also remote, computing unit (such as the cloud) or in the firmware of the corresponding control device of the electromagnetic actuator. It is also conceivable to have a warning function and / or an indication of an upcoming replacement of the electromagnetic coil or the electromagnetic actuator. Implementation in models of other damage mechanisms (such as cut-off voltage peaks) is also conceivable. Thus, overall, the use area of the electromagnetic actuator or the components containing the actuator or the components of the actuator can also be extended, because the user can, for example, use a higher ambient temperature, but for this purpose, the components containing the electromagnetic actuator, such as valves, must be replaced more frequently.

[0017] The computing unit according to the invention, for example a control device for an electromagnetic actuator or a component containing the actuator, is in particular programmed technically to execute the method according to the invention.

[0018] Implementation of the method according to the invention in the form of a computer program having program code for executing all method steps is also advantageous, because this results in particularly low costs, especially when the implemented control device is also used for other tasks and thus already exists. Suitable data carriers for providing the computer program are in particular magnetic, optical and electrical memories, such as hard disks, flash memories, EEPROMs, DVDs, etc. Downloading the program via a computer network (Internet, intranet, etc.) is also possible.

[0019] Further advantages and refinements of the invention result from the description and the drawings.

[0020] It is to be understood that the features mentioned above and those to be explained later can be used not only in the respectively stated combinations, but also in other combinations or individually, without departing from the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The invention is schematically illustrated in the drawings by way of examples and is described in detail below with reference to the drawings. Among them:

[0022] Figure 1 A valve having an electromagnetic coil is schematically shown, in which the method according to the invention can be carried out;

[0023] Figure 2A diagram with a set of steps and a service life model is schematically shown in order to explain the method according to the invention in a preferred embodiment. DETAILED DESCRIPTION

[0024] Figure 1 A valve 100 is schematically shown as a component containing an electromagnetic actuator in which the method according to the invention can be performed. The valve 100 is designed as a hydraulic directional valve by way of example and has a slide 110 that can be moved in a housing in order to suitably connect the pressure connection P for the pump, T for the tank and the working connections A and B to one another.

[0025] The slide 110 is acted upon with a restoring force at one housing end by means of a spring 120 and with an adjusting force at the other housing end by means of an electromagnet 130 which in turn has a magnetic coil 131. The slide 110 and the electromagnet 130 form an electromagnetic actuator.

[0026] A voltage U is applied to the electromagnet 130 or the electromagnetic coil 131 in order to move the slide 110 depending on the value of the voltage. Furthermore, a computing unit 150 designed as a control device is provided in order to apply a voltage to the electromagnetic coil 131 and thus control the valve.

[0027] Furthermore, the current I flowing through the electromagnetic coil 131 can thus be detected in order to determine the current ohmic resistance of the electromagnetic coil from the quotient of the voltage U and the current I. The temperature of the electromagnetic coil can thus be detected.

[0028] Figure 2 A diagram with a set of steps and a service life model is schematically shown for explaining the method according to the invention in a preferred embodiment. For this purpose, the temperature T is recorded over the time t.

[0029] As already mentioned, the so-called linear damage accumulation is used to predict the remaining operating time or service life of mechanical components that are subjected to vibration stress. This can currently also be used for solenoid coils.

[0030] The basic concept of damage accumulation is that each vibration amplitude leads to partial damage to the component. Individual and repeated stresses eventually lead to the failure of the component as a whole. Therefore, it is applicable to valves or hydraulic valves that as soon as the valve or hydraulic valve is electrically actuated, current flows through the solenoid coil, which leads to heating due to the ohmic resistance of the solenoid coil or its winding. Temperature changes in turn lead to expansion and tension, which in turn lead to mechanical stresses and ultimately to failures, for example, due to cable breaks, insulation damage, etc.

[0031] For each actuation, the duration of the actuation and thus the operating time as well as the temperature of the magnetic coil are now acquired during the actuation. As already mentioned, the temperature can be obtained by acquiring the ohmic resistance.

[0032] In Figure 2 each of the durations or run times represented by Δt in is assigned to one of a plurality of preset temperature zones. In Figure 2 seven temperature zones ΔT1 to ΔT7 are exemplarily shown as temperature zones, where ΔT1 corresponds to the temperature zone with the highest temperature value. Depending on the operation, other temperatures can be formed, which in turn results in the run time being assigned to another temperature zone.

[0033] The individual run times Δt in the respective temperature zones are summed separately for the respective temperature zones. The run times for the summation for the respective temperature zones are shown here by Δt1 to Δt6, where it should be noted that in the example shown, there is no run time assigned to the temperature zone ΔT7. The following applies here:

[0034] Δt i = ∑Δt(ΔT i ),

[0035] where i is the index for the respective temperature zone and is from 1 to 7 in the example shown. It should be noted that the individual run times Δt do not of course have to be the same size, but for simplicity there are no significant differences.

[0036] Now the mentioned set of steps is obtained by adding for each temperature zone the run times of all temperature zones with a higher temperature value. Thus, the run time H i for a specific temperature zone T i according to the set of steps is obtained according to the following formula:

[0037]

[0038] where Δt0 = H0 = 0. The run time H2 according to the set of steps for the temperature zone T2 is exemplarily shown in this figure. Now, if one intuitively says with reference to the set of steps shown in this diagram that a run time is added within a specific temperature zone, then the set of steps for the specific temperature zone and all lower temperature zones is shifted to the right by this run time.

[0039] To calculate the theoretically maximum run time or service life, a service life model, for example the model according to Eyring, can now be considered. The theoretically maximum run time τ or at least one measure thereof can be obtained according to this model using the following formula:

[0040]

[0041] Here, A and B are constants that are related to a specific valve or a specific electromagnetic coil and can be obtained or determined, for example, by simulation and / or experimentation for a specific type of valve. The same applies to the stress factor S. E a / kT represents the so-called Arrhenius exponent, in which the temperature T is discussed, and the Arrhenius exponent can also be specifically used for a specific type of valve. Therefore, for each temperature, the theoretically maximum operating time of the electromagnetic coil can be obtained, which is recorded by curve M in Figure 2 the figure.

[0042] Now, furthermore, according to Figure 2 it can be well seen that when it comes to the set of steps, as mentioned, the set of steps moves to the right with each newly added operating time, and the maximum operating time of the electromagnetic coil is reached using curve M.

[0043] Correspondingly, however, for each temperature range, the remaining operating time can also be obtained in the set of steps, which is obtained from the difference between the theoretically maximum operating time in this temperature range and the sum of the operating times according to the set of steps in this temperature range. This is shown exemplarily for the temperature ranges ΔT1 and ΔT4 with the remaining operating times ΔR1 and ΔR4.

[0044] As already described, the remaining operating time of the valve can now be obtained for a specific temperature range, so that the remaining operating time of the specific temperature range and the remaining operating times with the minimum values of all temperature ranges with lower temperature values are used.

[0045] Although the valve 100 is also shown and described in the drawings as a component including an electromagnetic actuator, it should be understood that the present invention is advantageous for electromagnetic actuators in any component.

Claims

1. A method for obtaining the remaining operating time (ΔR1, ΔR4) of an electromagnetic coil (131) of an electromagnetic actuator, wherein in each actuation of the electromagnetic actuator by means of the electromagnetic coil (131), the operating time (Δt) is obtained as the duration of the actuation, and the temperature (T) of the electromagnetic coil (131) during or after the actuation is obtained, wherein the temperature (T) of the electromagnetic coil is assigned to one of a plurality of preset temperature regions (ΔT1 - ΔT7), wherein in the actuation, the operating times (Δt) for the respective temperature regions (ΔT1 - ΔT7) are added up separately, wherein a step set (ΔH2) for different temperature regions (ΔT1 - ΔT7) is formed by adding, for each temperature region (ΔT1 - ΔT7), the operating times of all temperature regions with higher temperature values, and wherein the remaining operating time (ΔR1, ΔR4) of the electromagnetic coil (131) is obtained for specific temperature regions (ΔT1, ΔT4), wherein the remaining operating time (ΔR1, ΔR4) of the electromagnetic coil is obtained for specific temperature regions (ΔT1, ΔT4) by, for the specific temperature regions (ΔT1, ΔT4) and all temperature regions with lower temperature values, respectively, using the theoretically maximum operating time of the electromagnetic coil (131) in the respective temperature regions (ΔT1, ΔT4) and the so - far operating time according to the step set (ΔH2) in the respective temperature regions (ΔT1, ΔT4) to obtain the remaining operating time (ΔR1, ΔR4) in the respective temperature regions, and wherein the remaining operating time with the smallest value of the temperature regions is used as the remaining operating time (ΔR1, ΔR4) of the electromagnetic coil (131).

2. The method according to claim 1, wherein the theoretically maximum operating time of the electromagnetic coil in the respective temperature regions (ΔT1, ΔT4) is obtained by means of a service life model (M) of the electromagnetic coil.

3. The method according to claim 2, wherein the model according to Eyring is used as the service life model (M).

4. The method according to any one of the preceding claims 1 to 3, wherein the remaining operating time (ΔR1, ΔR4) of the electromagnetic coil (131) is obtained as the quotient or difference between the so - far operating time according to the step set (ΔH2) and the theoretically maximum operating time of the electromagnetic coil (131) in the relevant temperature regions (ΔT1, ΔT4).

5. The method according to any one of the preceding claims 1 to 3, wherein the temperature (T) of the electromagnetic coil (131) is obtained by means of the ohmic resistance of the electromagnetic coil (131).

6. The method according to any one of the preceding claims 1 to 3, wherein the electromagnetic actuator is used to actuate a valve (100).

7. The method according to claim 6, wherein the valve (100) is a hydraulic valve.

8. A computing unit (150) configured to execute the method according to any one of the preceding claims.

9. A computer program product having a computer program which, when implemented on a computing unit (150), causes the computing unit (150) to perform the method according to any one of claims 1 to 7.

10. A machine-readable storage medium having a computer program stored thereon which, when implemented on a computing unit (150), causes the computing unit (150) to perform the method according to any one of claims 1 to 7.

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