Test method, device and computer program

Abstract

The invention relates to a test method for functional testing of an electrically controlled proportional valve (1) designed as a solenoid valve, which is used to meter a gaseous medium, such as hydrogen, wherein the proportional valve (1) comprises a closing element (2) which completely or partially releases an opening cross-section depending on its electrical control when the closing element (2) lifts off a valve seat (5), wherein a stroke of the closing element (2) is limited by a stroke stop (10) facing away from the valve seat (5). In order to simplify and / or improve the functional test of the electrically controlled proportional valve (1), an electrical functional test without flow through the proportional valve (1) is carried out instead of a conventional pneumatic functional test, whereby design parameters that can also be detected and checked with the conventional pneumatic functional test are detected and checked with the electrical functional test without flow through the proportional valve (1).

Description

[0001] The invention relates to a test method for functional testing of an electrically controlled proportional valve designed as a solenoid valve, which is used to meter a gaseous medium, such as hydrogen. The proportional valve comprises a closing element which completely or partially opens an opening cross-section depending on its electrical control when the closing element lifts off a valve seat, wherein a stroke of the closing element is limited by a stroke stop facing away from the valve seat. The invention further relates to a device designed to carry out all steps of such a method. The invention further relates to a computer program configured to carry out all steps of such a method. State of the art

[0002] The German patent application DE 10 2017 214 506 A1 discloses a proportional valve for controlling a gaseous medium, in particular hydrogen, with a valve housing in which a closing element arranged therein cooperates with a valve seat for opening and closing at least one passage opening, with a magnet armature device operatively connected to the closing element and with an electromagnet by means of which a magnetic force can be generated on the magnet armature device and the magnet armature device can be moved along a longitudinal axis of the proportional valve, wherein the electromagnet comprises an inner pole, an outer pole and a magnetic coil and the magnet armature device comprises a magnet armature, wherein the valve housing and the inner pole are magnetically connected to one another via a magnetic throttle point and the magnetic throttle point is formed in an axial extension region of the magnet armature.The function of such a proportional valve is tested, for example, by applying a gaseous test medium to the valve inlet under defined conditions, in particular at a defined pressure and temperature. A time-varying current is then applied to the electromagnet, and the flow through the valve is measured. The result of this measurement is the so-called valve characteristic curve. The valve's function is then evaluated using selected points located on this valve characteristic curve. Due to the gaseous medium, the test must be carried out comparatively slowly; otherwise, the test boundary conditions cannot be kept constant and the flow measurement would be distorted. Disclosure of the invention

[0003] The object of the invention is to simplify and / or improve the functional testing of an electrically controlled proportional valve designed as a solenoid valve, which serves for dosing a gaseous medium, such as hydrogen, wherein the proportional valve comprises a closing element which completely or partially releases an opening cross-section depending on its electrical control when the closing element lifts off a valve seat, wherein a stroke of the closing element is limited by a stroke stop facing away from the valve seat.

[0004] The object is achieved in a test method for functional testing of an electrically controlled proportional valve designed as a solenoid valve, which is used to meter a gaseous medium, such as hydrogen, wherein the proportional valve comprises a closing element which completely or partially releases an opening cross-section depending on its electrical control when the closing element lifts off a valve seat, wherein a stroke of the closing element is limited by a stroke stop facing away from the valve seat, in that instead of a conventional pneumatic functional test, an electrical functional test is carried out without flow through the proportional valve, wherein design parameters which can also be detected and checked with the conventional pneumatic functional test are detected and checked with the electrical functional test without flow through the proportional valve.It is consciously accepted that certain design parameters cannot be detected and verified using the electrical functional test without flow through the proportional valve in the claimed test method. Such parameters are then verified, for example, by a supplier who performs a complete test of the proportional valve, including a conventional pneumatic functional test with flow through the proportional valve. Particularly advantageous is the electrical functional test without flow through the proportional valve, which also detects and verifies other design parameters or layout parameters that cannot be detected and verified, or cannot be readily detected, using the conventional pneumatic functional test.

[0005] A preferred embodiment of the testing method is characterized in that a visual inspection is performed on the proportional valve, during which design parameters that cannot be detected and verified with the electrical functional test without flow through the proportional valve are identified and verified. The design parameters preferably include all parameters that influence the flow through the proportional valve. These include, for example, the diameter of a flow-through hole or chamfers on an inlet edge. The visual inspection preferably involves detecting chips and burrs that could clog a flow-through hole.

[0006] Another preferred embodiment of the test method is characterized in that a short pneumatic test is performed with the proportional valve fully open, during which design parameters that cannot be detected and verified with the electrical functional test without flow through the proportional valve are detected and verified. The design parameters preferably include all parameters that influence the flow through the proportional valve. These include, for example, the diameter of a flow-through hole or chamfers on an inlet edge. The visual inspection preferably involves detecting chips and burrs that could clog a flow-through hole.

[0007] A further preferred embodiment of the test method is characterized in that the proportional valve is opened during the electrical functional test by actuating it with a current profile, without the gaseous medium flowing through the proportional valve.

[0008] A further preferred embodiment of the test method is characterized in that the pneumatic measurement is replaced by an electrical measurement of the current and voltage of the solenoid valve control. The proportional valve is opened by actuating it with a current profile without the gaseous medium flowing through the proportional valve. The stroke stop facing away from the valve seat is also referred to as the upper stroke stop. A lower stroke stop is defined by the closing element that closes the valve seat when this closes the valve seat. During the electrical measurement, the proportional valve is preferably controlled so that it opens completely and then closes completely again. By suitable filtering and processing of the current and voltage measurements, characteristic values can be determined for assessing and testing the function.

[0009] The measurement of the mass flow of the gaseous medium through the proportional valve is also referred to as pneumatic measurement. Unlike pneumatic measurement, electrical measurement does not allow for the assessment of all valve design parameters with regard to their influence on function. However, this can be compensated for, for example, by visually inspecting the flow-relevant cross-sections or by conducting an additional stationary pneumatic measurement with the proportional valve fully open.

[0010] Pneumatic measurement with a fully open proportional valve allows pneumatically effective design parameters to be verified. This checks, for example, whether the provided flow cross-section is sufficiently large. This can be caused by, for example, chips in a bore hole caused by manufacturing processes.

[0011] Pneumatic measurement can also be used to determine whether the stroke is sufficiently large when the valve is fully open. Other influencing variables, in particular all other influencing variables, on a proportional valve's valve characteristic curve are advantageously checked using electrical measurement. The other influencing variables relate, for example, to a magnetic circuit, a spring preload force or a c-value of a valve spring. The c-value is the spring constant of the valve spring. The claimed combination of pneumatic measurement with a fully open valve and electrical measurement can, for example, significantly reduce the time during which the proportional valve is held in a suitable holder with a nitrogen connection. Furthermore, the consumption of nitrogen used for the pneumatic measurement with the fully open valve can be reduced.The claimed test method is preferably carried out as part of a final test at the end of a production line. Among other advantages, the claimed test method eliminates the need for pneumatic measurement of the entire valve characteristic curve in both directions. This significantly reduces the time required for the final test.

[0012] A further advantage of the claimed test method is a significantly increased accuracy compared to pneumatic measurement, since apart from the highly accurate measurement of current and voltage, there are no other influencing factors on the measurement result.

[0013] Pneumatic measurement also requires voltage and current measurements. However, the pressure and temperature at the valve inlet, as well as the flow rate, must also be measured. Transient flow measurement, in particular, is subject to comparatively large uncertainties.

[0014] A further preferred embodiment of the test method is characterized in that the electrical measurement in the additional measurement step is performed for less than ten seconds. The duration of the electrical measurement is advantageously less than five seconds. A particularly relevant part of the electrical measurement, which is evaluated for the evaluation of the characteristic curve, advantageously lasts only less than one second. This allows the time required for the final test to be significantly reduced compared to conventional test methods.

[0015] A further preferred embodiment of the test method is characterized in that, in the additional measuring step, the proportional valve is subjected to a current profile which is triangular in shape over time such that an armature of the proportional valve with the closing element moves away from the valve seat towards its stroke stop facing away from the valve seat and back again. The armature is preferably a magnetic armature which is set in motion in a conventional manner via an electrical coil when energized. The current profile which is triangular in shape over time ensures that the armature of the proportional valve switches, i.e. the armature moves away from the valve seat to its upper stroke stop and back again. The proportional valve is energized, for example, via a suitable control and measuring device which is used for the final test of the proportional valve.The control and measuring device is a power output stage equipped with a microcontroller that monitors and regulates the current supply and also serves to evaluate the measured signals.

[0016] Another preferred embodiment of the test method is characterized in that the movements of the armature are recorded using current and voltage measurements. A movement, in particular an acceleration, of the armature in a magnetic field leads to a magnetic movement induction, the effect of which is recorded using current and voltage measurements. This advantageously allows important, meaningful insights into the functionality of the proportional valve to be obtained in a very short time, without any medium flowing through the proportional valve.

[0017] A further preferred embodiment of the test method is characterized in that measured values recorded with the current and voltage measurement are recorded and filtered in order to calculate and evaluate a temporal profile of an electromagnetically induced voltage. In this way, the current at which the armature leaves the seat or the current at which the armature arrives back in the seat, as well as the current at which the upper stroke stop is reached or left behind, can advantageously be determined. Of course, other information available in a test system used for testing, such as the valve stroke, can be used to gain additional insights into the functionality of the proportional valve. The valve stroke, for example, has a major influence on the current difference between the armature running loose in the seat and the armature arriving at the upper stroke stop.Through appropriate evaluation, additional information regarding the magnetic circuit can also be obtained.

[0018] A further preferred embodiment of the test method is characterized in that overshoots in the time course of the electromagnetically induced voltage are interpreted as an indication of sticking of the closing element in the valve seat. This allows the testing of the proportional valve to be further improved during the final test.

[0019] A further preferred embodiment of the test method is characterized in that at least one, preferably each, of the following current values is determined: the current at which the valve seat is left; the current at which the stroke stop is reached; the current at which the stroke stop is left again; and the current at which the armature with the closing element hits the valve seat. Thus, with relatively little electrical measurement effort, a reliable statement about the functionality of the proportional valve can be made during the final test.

[0020] Another preferred embodiment of the test method is characterized in that the proportional valve is deemed to be OK if all four determined current values are within predetermined ranges. The predetermined ranges can be defined, for example, using conventionally tested proportional valves. This allows a significant reduction in the overall duration of the final test using simple means. This is particularly advantageous when the proportional valve to be tested is manufactured and installed in large quantities.

[0021] The invention further relates to a device designed to perform all steps of the method described above. The device advantageously comprises at least one computer and a known control and measuring device.

[0022] The invention further relates to a computer program configured to perform all steps of the method described above. Naturally, the invention also relates to a machine-readable storage medium having such a computer program stored thereon.

[0023] Further advantages, features and details of the invention will become apparent from the following description, in which various embodiments are described in detail with reference to the drawing. Short description of the drawing

[0024] They show: Fig. 1 a schematic longitudinal section of a proportional valve to be tested and the Fig. 2 to 6 Cartesian coordinate diagrams to illustrate a procedure for testing the functionality of the Fig. 1 shown proportional valve as part of a final test. Description of the embodiments

[0025] In Fig. 1, a proportional valve 1 with a valve housing is shown schematically in longitudinal section. In the valve housing, an armature 7 with a closing element 2 is arranged in the vertical direction, i.e. in Fig. 1 is movable upwards and downwards. The closing element 2 cooperates with a valve seat 5 to form a medium outlet opening 3 at a Fig. 1 lower end of the proportional valve 1 to be closed or released as required.

[0026] The armature 7 is designed as a magnetic armature and is moved by energizing an electrical coil 6 against the preload force of a valve spring 8 in Fig. 1 is moved upwards to fully or partially open the proportional valve 1 as needed. The preload force of the valve spring 8 can be adjusted using an adjusting screw 9.

[0027] A lower stroke stop is defined by the closing element 2 in the valve seat 5. A Fig. 1 upper stroke stop 10 limits the movement of the armature 7 during opening. When the armature 7 hits its upper stroke stop 10, the proportional valve 1 is fully open.

[0028] In the Fig. 2 to 6 show a total of six Cartesian coordinate diagrams, where Fig. 6 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 serve to illustrate a test procedure with which it is possible, among other things, to determine a pneumatic valve characteristic curve of the Fig. 1 using an electrical measurement without medium flow.

[0029] In the Fig. The proportional valve 1 shown in Figure 1 is a metering valve used to meter hydrogen into a fuel cell in a closed control loop. A fuel cell system with such a metering valve is described, for example, in the international patent application WO 2023 / 001498 A1. Fig. 3 and disclosed in the corresponding figure description.

[0030] As part of a conventional final inspection, a characteristic curve measurement is performed for each valve at the end of the production line. Measuring the entire valve characteristic curve in both directions takes several minutes. The claimed method replaces a pneumatic characteristic curve measurement with a stationary measurement of the flow through the proportional valve with the valve seat fully open and an additional electrical measurement of the proportional valve without any medium flow.

[0031] The pneumatic measurement with the proportional valve fully open verifies the pneumatically effective design parameters. All other variables influencing the valve characteristic, especially the magnetic circuit, the spring preload force, etc., are verified by electrical measurement. The duration of the electrical measurement is preferably less than five seconds. The relevant part of the electrical measurement, which is evaluated for the evaluation of the characteristic curve, lasts approximately one second.

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

[0033] In Fig. 2 shows the mass flow or flow through the proportional valve in kilograms per hour. Fig. 2 shows a slowly measured valve characteristic curve in dashed lines and a valve characteristic curve measured at an accelerated rate in solid lines.

[0034] In Fig. 3, the current in amperes is plotted on the y-axis 14. During the electrical measurement, the proportional valve is supplied with a suitable current profile 15 by a power output stage. The current profile 15 ensures that the armature switches, i.e., the armature moves from the valve seat to the upper stroke stop and back again.

[0035] The acceleration of the armature in a magnetic field leads to magnetic induction, the effect of which can be determined by means of a Fig. 5 shown current and voltage measurement can be recorded. In Fig. 5 an induced voltage in volts is plotted on the y-axis 26. In Fig. 4 the voltage in volts is plotted on the y-axis 22. Fig. 4 shows the time course 23 of the voltage required to generate the current waveform in Fig. 3 was necessary.

[0036] If the power stage measures current and voltage very accurately and with sufficient sampling rate, as described in the Fig. 3 and Fig. 4, the current at which the armature leaves the seat, or the current at which the armature returns to the seat, as well as the current at which the upper stroke stop is reached or left, can be determined, as shown in Fig. 5 is shown.

[0037] In Fig. In Figure 5, arrows 27 and 28 indicate the time course of the induced voltage when opening and closing the proportional valve. Changing the valve spring preload via the adjusting screw affects the determination of the parameters from the induced voltage versus current curve.

[0038] When determining the parameters, a suitable filtering of the measured values of current and voltage is carried out and the induced voltage is calculated. Fig. Figure 5 shows the induced voltage plotted against the current. The corresponding current values can be seen with the naked eye in the noticeable variation ranges 31 to 34.

[0039] In Fig. 6, the armature stroke is plotted in micrometers on the y-axis 42. The induced voltage is plotted in volts on the y-axis 44. Fig. 6 shows the curve of the induced voltage above compared to the stroke measurement below. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2017 214 506 A1

[0002] WO 2023 / 001498 A1

[0029]

Claims

[1] Test method for functional testing of an electrically controlled proportional valve (1) designed as a solenoid valve, which serves for dosing a gaseous medium, such as hydrogen, wherein the proportional valve (1) comprises a closing element (2) which completely or partially releases an opening cross-section depending on its electrical control when the closing element (2) lifts off a valve seat (5), wherein a stroke of the closing element (2) is limited by a stroke stop (10) facing away from the valve seat (5), characterized by that instead of a conventional pneumatic functional test, an electrical functional test is carried out without flow through the proportional valve (1), whereby design parameters which can also be detected and checked with the conventional pneumatic functional test are detected and checked with the electrical functional test without flow through the proportional valve (1). [2] Test method according to claim 1, characterized by that a visual inspection is carried out on the proportional valve (1), during which design parameters which cannot be detected and checked with the electrical functional test without flow through the proportional valve (1) are detected and checked. [3] Test method according to one of the preceding claims, characterized by that a short pneumatic test is carried out with the proportional valve (1) fully open, during which design parameters which cannot be detected and checked with the electrical functional test without flow through the proportional valve (1) are detected and checked. [4] Test method according to one of the preceding claims, characterized by that the proportional valve (1) is opened during the electrical functional test by actuating it with a current profile (15) without the gaseous medium flowing through the proportional valve (1). [5] Test method according to one of the preceding claims, characterized by that the movements of the armature (7) are recorded by means of current and voltage measurements. [6] Test method according to claim 5, characterized by that measured values recorded with the current and voltage measurement are recorded and filtered in order to calculate and evaluate a time course (27,28) of an electromagnetically induced voltage. [7] Test method according to claim 5, characterized by that overshoots in the time course (27,28) of the electromagnetically induced voltage are considered as an indication of sticking of the closing element (2) in the valve seat (5). [8] Test method according to one of claims 5 to 7, characterized bythat at least one, preferably each, of the following current values is determined: the current at which the valve seat (5) is left; the current at which the stroke stop (10) is reached; the current at which the stroke stop (10) is left again; the current at which the armature (7) with the closing element (2) hits the valve seat (5). [9] Test method according to claim 8, characterized by that the proportional valve (1) is found to be OK if all four determined current values are within previously defined ranges. [10] Device designed to carry out all the steps of a method according to one of the preceding claims on a proportional valve (1).

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