Test method, device and computer program

Abstract

The invention relates to a test method for testing the function of an electrically operated proportional valve (1) designed as a magnetic valve for metering a gaseous medium, such as hydrogen, comprising a closing element (2) which closes the proportional valve (1) when the closing element (2) is lifted from a valve seat (5). The closing element completely or partially opens the opening cross section according to the electrical actuation of the closing element, and the stroke of the closing element (2) is limited by a stroke stop (10) away from the valve seat (5). In order to simplify and / or improve the functional test of an electrically actuated proportional valve (1), an electrical functional test is carried out instead of a conventional pneumatic functional test without flowing through the proportional valve (1), and some design parameters are identified and checked by the electrical functional test without flowing through the proportional valve (2), the design parameters can also be identified and checked using conventional pneumatic functional tests.

Description

Field of the Invention

[0001] The present invention relates to a test method for functionally testing an electrically controlled proportional valve embodied as a magnetic valve, which is used for metering a gaseous medium such as hydrogen. The proportional valve includes a closing element, and when the closing element is lifted from the valve seat, the closing element completely or partially opens the opening cross-section according to its electrical control. The stroke of the closing element is limited by a stroke stop facing away from the valve seat. The present invention also relates to a device configured to perform all steps of such a method. The present invention also relates to a computer program configured to perform all steps of such a method. Background Art

[0002] German Published Document DE 10 2017 214 506 A1 discloses a proportional valve for controlling a gaseous medium, in particular hydrogen. The proportional valve has a valve housing in which a closing element arranged to open and close at least one channel opening cooperates with a valve seat. The proportional valve has a magnetic armature device acting on the closing element and an electromagnet, and a magnetic force can be generated on the magnetic armature device by the electromagnet. The magnetic armature device can move along the longitudinal axis stroke of the proportional valve. The electromagnet includes an inner pole, an outer pole, and an electromagnetic coil, and the magnetic armature device includes a magnetic armature. The valve housing and the inner pole are magnetically connected to each other through a magnetic throttle point, and the magnetic throttle point is configured in the axial extension region of the magnetic armature. For example, the function of such a proportional valve is tested as follows: Under defined conditions, in particular conditions with a defined pressure and a defined temperature, a gaseous test medium is applied at the valve inlet. Then, a time-varying current is applied to the electromagnet, and the flow rate through the valve is measured. The result of this measurement is a so-called valve characteristic curve. Then, the function of the valve is evaluated by means of selected points on the valve characteristic curve. Due to the gaseous medium, the test must be carried out relatively slowly because otherwise the test boundary conditions cannot be kept constant and the flow rate measurement is also distorted. Summary of the Invention

[0003] The object of the present invention is to simplify and / or improve the functional test of an electrically controlled proportional valve embodied as a magnetic valve, which is used for metering a gaseous medium such as hydrogen. The proportional valve includes a closing element, and when the closing element is lifted from the valve seat, the closing element completely or partially opens the opening cross-section according to its electrical control. The stroke of the closing element is limited by a stroke stop away from the valve seat.

[0004] In a test method for functionally testing an electrically actuated proportional valve implemented as a magnetic valve, which is used for metering a gaseous medium such as hydrogen, the proportional valve includes a closing element that, when lifted from the valve seat, completely or partially opens the opening cross-section according to its electrical actuation, and the stroke of the closing element is delimited by a stroke stop facing away from the valve seat. The task is solved by performing an electrical function test instead of a conventional pneumatic function test without flowing through the proportional valve, and by identifying and checking the following design parameters by means of the electrical function test without flowing through the proportional valve, which can also be identified and checked by means of a conventional pneumatic function test. Here, it is deliberately accepted that in the required test method, certain design parameters cannot be identified and checked by means of the electrical function test without flowing through the proportional valve. Such parameters are, for example, checked at the supplier, who performs a complete test of the proportional valve, including a conventional pneumatic function test with the proportional valve being flowed through. Particularly advantageously, additional design parameters or layout parameters that cannot or cannot easily be identified and checked by means of a conventional pneumatic function test are also identified and checked by means of the electrical function test without flowing through the proportional valve.

[0005] A preferred embodiment of the test method is characterized in that a visual inspection is performed on the proportional valve, in which the following design parameters are identified and checked: the design parameters that cannot be identified and checked by means of the electrical function test without flowing through the proportional valve. The design parameters preferably relate to all the following parameters: the parameters that have an impact on the flow through the proportional valve. For example, this relates to the diameter of the holes being flowed through or to the chamfer at the inlet edge. During the visual inspection, it is preferably about finding debris and burrs that block the holes being flowed through.

[0006] Another preferred embodiment of the test method is characterized in that a short pneumatic test is performed with the proportional valve fully open, in which the following design parameters are identified and checked: the design parameters that cannot be identified and checked by means of the electrical function test without flowing through the proportional valve. The design parameters preferably relate to all the following parameters: the parameters that have an impact on the flow through the proportional valve. For example, this relates to the diameter of the holes being flowed through or the chamfer at the inlet edge. During the visual inspection, it is preferably about finding debris and burrs that block the holes being flowed through.

[0007] Another preferred embodiment of the test method is characterized in that in the electrical function test, the proportional valve is opened by actuation with a current curve while the proportional valve is not flowed through by the gaseous medium.

[0008] Another preferred embodiment of the test method is characterized in that the pneumatic measurement is replaced by the electrical measurement of the current and voltage of the solenoid valve controlling the valve. Here, the proportional valve is opened by being controlled with a current curve, and the proportional valve is not flowed through by the gaseous medium here. The stroke stop deviating from the valve seat is also referred to as the upper stroke stop. The lower stroke stop is defined by the closing element closing the valve seat (when the closing element locks the valve seat). In the electrical measurement, it is preferred to control the proportional valve such that it is fully opened and then fully closed again. Here, by appropriately filtering and processing the current and voltage measurements, characteristic values for evaluating and checking the function can be obtained.

[0009] The measurement of the mass flow of the gaseous medium through the proportional valve is also referred to as pneumatic measurement. Compared with pneumatic measurement, in electrical measurement, not all design parameters of the valve can be evaluated in terms of their influence on the function. However, this can be compensated for by, for example, visually inspecting the cross-section relevant in terms of flow technology or performing an additional fixed pneumatic measurement with the proportional valve fully opened.

[0010] The pneumatically acting design parameters can be checked by performing a pneumatic measurement with the proportional valve fully opened. Here, for example, it is checked whether the provided flow cross-section is large enough. Here, for example, chips present in the drill hole due to manufacturing can cause damage. In pneumatic measurement, it can also be confirmed whether the stroke is large enough when the valve is fully opened. Advantageously, other influencing parameters on the valve characteristic curve of the proportional valve, especially all other influencing parameters, are checked by electrical measurement. Other influencing parameters relate, for example, to the magnetic circuit, the spring preload, or the c-value of the valve spring. The spring constant of the valve spring is referred to as the c-value. For example, the claimed combination of pneumatic measurement and electrical measurement with the valve fully opened can significantly reduce the following duration: during which the proportional valve is received in a suitable receptacle with a nitrogen connection. In addition, the consumption of nitrogen can be reduced, and with the nitrogen, the pneumatic measurement is performed when the valve is fully opened. The claimed test method is preferably carried out within the framework of the final test at the end of the production line. The claimed test method in particular offers the advantage that the pneumatic measurement of the entire valve characteristic curve in both directions can be dispensed with. This can significantly reduce the time required for the final test.

[0011] Another advantage of the claimed test method is the significantly increased accuracy compared to pneumatic measurement, because in addition to the highly accurate measurement of current and voltage, there are no other influencing parameters on the measurement result.

[0012] In pneumatic measurement, it is also necessary to measure voltage and current. However, additionally, the pressure, temperature and flow rate at the valve inlet must also be measured. In particular, the measurement of an unstable flow rate has a relatively large uncertainty.

[0013] Another preferred embodiment of the test method is characterized in that the electrical measurement is carried out in an additional measurement step for less than ten seconds. Advantageously, the duration of the electrical measurement is less than five seconds. A particularly relevant part of the electrical measurement evaluated for the evaluation of the characteristic curve advantageously has a duration of less than 1 second. Thus, compared with the conventional test method, the time required for the final test can be significantly reduced.

[0014] Another preferred embodiment of the test method is characterized in that, in an additional measurement step, the proportional valve is loaded with a current curve diagram that is triangular in time, such that the armature of the proportional valve moves towards its stroke stop away from the valve seat as the closing element moves away from the valve seat and then moves back again. The armature preferably relates to a magnetic armature which, when an electric current is applied to the magnetic armature, is moved in a known manner by an electric coil. The current curve diagram that is triangular in time ensures that the armature of the proportional valve switches, that is, the armature moves away from the valve seat towards its upper stroke stop and then moves back again. The proportional valve is energized, for example, by means of a suitable control and measuring instrument which is used for the final test of the proportional valve. The control and measuring instrument is a power output stage equipped with a microcontroller which monitors or regulates the energization and is also used for evaluating the measured signals.

[0015] Another preferred embodiment of the test method is characterized in that the movement of the armature is detected by means of current and voltage measurements. The movement of the armature in the magnetic field, in particular the acceleration, causes a magnetic motion induction, the effect of which is detected by means of current and voltage measurements. Thus, advantageously, without a medium flowing through the proportional valve, an effective understanding of the functional ability of the proportional valve can be obtained in a very short time.

[0016] Another preferred embodiment of the test method is characterized in that the measured values detected by means of current and voltage measurements are detected and filtered in order to calculate and evaluate the time curve of the voltage of the electromagnetic induction. Thus, advantageously, the current at which the armature leaves the seat can be determined; the current at which the armature reaches the seat again; and the current at which the upper stroke stop is reached or left. Naturally, additional information such as the valve stroke provided in the test system used for the test can be used in order to obtain additional understanding of the functional ability of the proportional valve. For example, the valve stroke has a large influence on the current difference between the start of the armature in the seat and the armature reaching the upper stroke stop. Additional information about the magnetic circuit can also be obtained by appropriate evaluation.

[0017] Another preferred embodiment of the test method is characterized in that an overshoot in the time profile of the electromagnetically induced voltage is evaluated as an indication for the closing element sticking in the valve seat. This allows the testing of proportional valves within the framework of the final test to be further improved.

[0018] Another preferred embodiment of the test method is characterized in that at least one current value, preferably each current value, of the following current values is determined: the current at which the valve seat is left; the current at which the travel limit is reached; the current at which the travel limit is left again; the current at which the armature and the closing element strike the valve seat. With relatively little electrical measurement effort, reliable statements about the functional capacity of the proportional valve can be made within the framework of the final test.

[0019] A further preferred embodiment of the test method is characterized in that the proportional valve is considered to be normal when all four determined current values are within a previously defined range. The previously defined range can be defined, for example, with conventionally tested proportional valves. Thus, a significant reduction in the total duration of the final test can be achieved with simple means. This is particularly advantageous when the proportional valves to be tested are manufactured and installed in large numbers.

[0020] The invention also relates to a device which is designed for all steps of the above-described method. Advantageously, the device comprises at least one computer and known control and measuring devices.

[0021] The invention also relates to a computer program, which is configured to execute all the steps of the method described above. Naturally, the invention also relates to a machine-readable storage medium having such a computer program stored thereon. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Further advantages, features and details of the invention emerge from the following description, in which various exemplary embodiments are described in detail with reference to the accompanying drawings. They show:

[0023] Figure 1 a schematic longitudinal section through the proportional valve to be tested, and

[0024] Figures 2 to 6 Cartesian coordinate diagram to visually illustrate the final test framework for testing Figure 1 The functional action method of the proportional valve is shown in FIG. DETAILED DESCRIPTION

[0025] exist Figure 1FIG. 0 schematically shows in a longitudinal section a proportional valve 1 with a valve housing. An armature 7 with a closing element 2 can move in the valve housing in the vertical direction (i.e., up and down in FIG. 0). The closing element 2 interacts with a valve seat 5 in order to lock or, as required, open a medium discharge opening 3 at the lower end of the proportional valve 1 in FIG. 0. Figure 1 In FIG. 0, it can move up and down. Figure 1 The closing element 2 interacts with the valve seat 5 in order to lock or, as required, open the medium discharge opening 3 at the lower end of the proportional valve 1.

[0026] The armature 7 is embodied as a magnetic armature and is moved upward against the preload of a valve spring 8 by passing a current through an energizing coil 6 in FIG. 0 in order to fully or partially open the proportional valve 1 as required. The preload of the valve spring 8 can be adjusted by an adjusting screw 9. Figure 1 In FIG. 0, it is moved upward against the preload of the valve spring 8 by passing a current through the energizing coil 6 in order to fully or partially open the proportional valve 1 as required. The preload of the valve spring 8 can be adjusted by the adjusting screw 9.

[0027] The lower travel stop is defined by the closing element 2 in the valve seat 5. The upper travel stop in FIG. 0 delimits the movement of the armature 7 during opening. When the armature 7 abuts against its upper travel stop 10, the proportional valve 1 is fully open. Figure 1 In FIG. 0, the upper travel stop delimits the movement of the armature 7 during opening. When the armature 7 abuts against its upper travel stop 10, the proportional valve 1 is fully open.

[0028] In FIG. 0 Figures 2 to 6 a total of six Cartesian coordinate diagrams are shown, where, in FIG. 0, two Cartesian coordinate diagrams are shown one above the other. The Cartesian coordinate diagrams each include an x-axis 11, 13, 21, 25, 41, 43 and a y-axis 12, 14, 22, 26, 42, 44. The total of six Cartesian coordinate diagrams are used to visually illustrate a test method by means of which it is possible, in particular, to predict the pneumatic valve characteristic curve of the proportional valve shown in FIG. 0 by means of an electrical measurement without medium flow-through. Figure 6 In FIG. 0, two Cartesian coordinate diagrams are shown one above the other. The Cartesian coordinate diagrams each include an x-axis 11, 13, 21, 25, 41, 43 and a y-axis 12, 14, 22, 26, 42, 44. The total of six Cartesian coordinate diagrams are used to visually illustrate a test method by means of which it is possible, in particular, to predict the pneumatic valve characteristic curve of the proportional valve shown in FIG. 0 by means of an electrical measurement without medium flow-through. Figure 1 In FIG. 0, the total of six Cartesian coordinate diagrams are used to visually illustrate a test method by means of which it is possible, in particular, to predict the pneumatic valve characteristic curve of the proportional valve shown in FIG. 0 by means of an electrical measurement without medium flow-through.

[0029] In FIG. 0 Figure 1 the proportional valve 1 shown in FIG. 0 relates to a metering valve by means of which hydrogen is distributed to a fuel cell in a closed control loop. For example, a fuel cell system with such a metering valve is shown in International Publication WO2023 / 001498 A1 in FIG. 0 and is disclosed in the associated figure description. Figure 3 In FIG. 0, it is shown and disclosed in the associated figure description.

[0030] In the framework of a conventional final test, characteristic curve measurements are carried out for each valve at the end of the production line. In order to measure the complete valve characteristic curve in both directions, it takes several minutes. By the required method, the pneumatic characteristic curve measurement is replaced by a fixed measurement of the flow-through of the proportional valve with the valve seat fully open and an additional electrical measurement of the proportional valve without medium flow-through.

[0031] The pneumatically acting design parameters are checked by means of a pneumatic measurement with the proportional valve fully open. The valve characteristic curve and all other influencing parameters of the magnetic circuit, in particular (spring pre-tension, etc.), are checked by means of an electrical measurement. Advantageously, the duration of the electrical measurement is less than 5 seconds. The relevant part of the electrical measurement that is evaluated for the purpose of evaluating the characteristic curve has a duration of approximately 1 second.

[0032] In Figure 2 , 5, 6, the current is plotted in amperes on the x-axes 11, 25, 41, 43 respectively. In Figure 3 , 4, the time is plotted in seconds on the x-axes 13, 21.

[0033] In Figure 2 the mass flow or the flow rate through the proportional valve is plotted in kilograms per hour. In Figure 2 the slowly measured valve characteristic curve is shown dashed and the accelerated measured valve characteristic curve is shown solid.

[0034] In Figure 3 the current is plotted in amperes on the y-axis 14. In the electrical measurement, the proportional valve is loaded by a power output stage with a suitable current curve diagram 15. The current curve diagram 15 ensures that the armature is switched on, that is, the armature moves from the valve seat to the upper stroke stop and back again.

[0035] The acceleration of the armature in the magnetic field leads to a magnetic induction, the influence of which can be detected by means of the current and voltage measurements shown in Figure 5 . In Figure 5 the induced voltage is plotted in volts on the y-axis 26. In Figure 4 the voltage is plotted in volts on the y-axis 22. Figure 4 Shows the time curve 23 of the voltage required for the generation of the current curve in Figure 3 .

[0036] If the power stage detects the current and voltage very accurately and with a sufficient sampling rate (as shown in Figure 3 and 4 ), then the following current is determined: in which the armature reaches the seat again; or the following current: in which it reaches or leaves the upper stroke stop, as shown in Figure 5 .

[0037] In Figure 5 the time curves of the induced voltage when the proportional valve is opened and closed are indicated by the arrows 27 and 28. If the spring pre-tension of the valve spring is changed by means of an adjusting screw, the determination of the characteristic parameters is influenced by the curve of the induced voltage with respect to the current.

[0038] When obtaining the characteristic parameters, appropriate filtering of the measured values of the current and voltage is performed, and the induced voltage is calculated. In Figure 5 , the induced voltage is plotted with respect to the current. The corresponding current values can already be seen with the naked eye in the clearly changing regions 31 to 34.

[0039] In Figure 6 , the stroke of the armature is plotted in micrometers on the y-axis 42. The induced voltage is plotted in volts on the y-axis 44. Figure 6 The curve of the change in the induced voltage is shown above in comparison with the stroke measurement below.

Claims

1. A test method for functionally testing an electrically controlled proportional valve (1) implemented as a magnetic valve, which is used for metering a gaseous medium such as hydrogen, wherein, The proportional valve (1) includes a closing element (2) which, when lifted from the valve seat (5), fully or partially opens the opening cross-section according to its electrical control. The stroke of the closing element (2) is delimited by a stroke stop (10) facing away from the valve seat (5). It is characterized in that an electrical function test is performed without flowing through the proportional valve (1) to replace the conventional pneumatic function test, and design parameters that can also be identified and checked by the conventional pneumatic function test are identified and checked by means of the electrical function test performed without flowing through the proportional valve (1).

2. The test method according to claim 1, characterized in that, A visual inspection is performed on the proportional valve (1), in which design parameters that cannot be identified and checked by the electrical function test without flowing through the proportional valve (1) are identified and checked.

3. The test method according to any one of the above claims, characterized in that A short pneumatic test is performed with the proportional valve (1) fully open, in which design parameters that cannot be identified and checked by the electrical function test without flowing through the proportional valve (1) are identified and checked.

4. The test method according to any one of the above claims, characterized in that, During the electrical function test, the proportional valve (1) is opened by controlling it with the aid of a current curve graph (15), and the proportional valve (1) is not flowed through by the gaseous medium at this time.

5. The test method according to any one of the above claims, characterized in that, The movement of the armature (7) is detected by means of the current and voltage measurements.

6. The test method according to claim 5, wherein The measured values detected by the current and voltage measurements are detected and filtered to calculate and evaluate the time variation curves (27, 28) of the voltage of electromagnetic induction.

7. The test method according to claim 5, wherein Overshoot in the time variation curves (27, 28) of the voltage of electromagnetic induction is evaluated as an indication that the closing element (2) is stuck to the valve seat (5).

8. The test method according to any one of claims 5 to 7, characterized in that At least one current value, preferably each current value, of the following current values is determined: the current leaving the valve seat (5) in the current; the current reaching the stroke stop (10) in the current; the current when the armature touches the closing element (2) in the valve seat (5) in the current.

9. The test method according to claim 8, characterized in that, When all four determined current values are within the previously specified range, the proportional valve (1) is considered normal.

10. A device configured to perform all steps of the method according to any one of the above claims on a proportional valve (1).

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