Valve control and method for operating a valve control

Abstract

The invention relates to a valve control (2) for controlling a magnetic coil (12) of a solenoid valve (4), comprising a control device (7) which has a current measuring device for determining a coil current, wherein the control device (7) is designed to determine an electrical resistance of the magnetic coil (12) and, based on the determined resistance, to select at least one parameter from the group: starting current, starting time, holding current and holding time from a value table stored in the control device (7) for a subsequent control of the magnetic coil (12) and / or to determine a starting current as a parameter, wherein the control device (7) is designed to determine the starting current to provide a continuously increasing coil current (I1) to the magnetic coil (12) and to determine the starting current (Ia) by determining a first change in direction characterizing a valve movement, in particular a current drop,in the measured coil current (I2). Furthermore, the invention relates to a method for operating a valve control for controlling a solenoid coil of a solenoid valve.

Description

[0001] The invention relates to a valve control for controlling a solenoid coil of a solenoid valve and a method for operating a valve control.

[0002] From DE 10 2019 203 574 A1 a valve arrangement is known, comprising at least one connection section for connecting a valve unit which comprises a solenoid valve, wherein the valve arrangement is designed to recognize the type of the valve unit connected to the connection section on the basis of an electrical variable associated with the solenoid valve.

[0003] EP 1 571 679 A2 discloses a method for automating the calibration of the drive voltage waveform of a solenoid-operated valve. In the method, an initial estimate of the valve's electromagnetic parameters is used for initial operation of the valve. The estimate is subsequently adjusted based on feedback and used for subsequent operation.

[0004] DE 102 12 092 A1 shows a method for operating a valve connected to a direct current circuit and controlled to switch back and forth between two switching positions for actuating a closing body of a hydraulic valve, wherein by means of an electronic control device the coil winding of the electromagnet is supplied with an excitation current in the pull-in phase of the armature of the electromagnet and with a holding current which is lower than the excitation current in the holding phase of the armature, wherein the actual current in the coil winding is continuously measured after the electromagnet is actuated and evaluated to detect the movement of the armature.

[0005] DE 10 2006 059 624 A1 discloses a device for controlling an electromagnetic valve. Reading means of the device write a plurality of measured values ​​for the current and / or voltage into a first memory to represent a curve. Evaluation means perform a state analysis and / or a curve analysis. Based on the state analysis and / or the curve analysis, evaluation means correct at least one control variable that characterizes the control and writes this value into a second memory. Based on the control variables, control means control an output stage.

[0006] DE 10 2022 211 625 A1 discloses a method for switching an electromagnetically actuated hydraulic valve, wherein the hydraulic valve comprises a switching element and an electromagnet with a coil and an armature, the armature being connected to the switching element for joint movement. When the coil is energized with a current (I), the armature moves together with the switching element for a switching operation from an initial position (AP) to an end position (EP).

[0007] The object of the invention is to provide a valve control for controlling a solenoid coil and a method for operating a valve control for controlling a solenoid coil of a solenoid valve with improved control quality.

[0008] This object is achieved according to the invention by a valve control for controlling a magnetic coil of a solenoid valve, with a control device which has a current measuring device for determining a coil current, wherein the control device is designed to determine an electrical resistance of the magnetic coil and, based on the determined resistance, to select at least one parameter from the group: starting current, starting time, holding current and holding time from a value table stored in the control device for a subsequent control of the magnetic coil and / or wherein the control device is designed to determine a starting current as a parameter, wherein the control device for determining the starting current is designed to provide a continuously increasing coil current to the magnetic coil and to determine the starting current by determining a first change in direction characterizing a valve movement, in particular a current drop,in the measured coil current.

[0009] For effective control of the solenoid valve, it is necessary to take into account the parameters that characterize the solenoid coil in its interaction with other components of the solenoid valve. These include, in particular, parameters such as the pull-in current, pull-in time, holding current, and holding time. These parameters differ from solenoid valve to solenoid valve and can also change during operation of the solenoid valve. Since, for example, in a complex system with a large number of solenoid valves, it is considerably difficult for a user to clearly identify each of the solenoid valves used manually and to control them optimally, the valve controls used are often given parameters that work for a large number of solenoid valves, although this results in lower control quality.

[0010] The solenoid valve to be controlled generally comprises a solenoid coil, a valve armature, and a sealing element coupled to the valve armature for movement. It can be designed, in particular, as a seat valve or a slide valve. The sealing element is designed to interact with a valve seat surrounding a valve opening of a fluid channel. The fluid channel extends in a valve housing of the solenoid valve between an inlet port and an outlet port.

[0011] The sealing element can be attached directly to the valve armature and, in this case, is surrounded by a pressurised fluid that is provided at the inlet connection and flows to the outlet connection, provided the valve seat is not blocked by the sealing element. Such a valve can be used, particularly in the field of automation technology, as a pilot valve for a downstream, compressed air-controlled main valve or directly for controlling compressed air consumers, with compressed air being used as the pressurised fluid. Alternatively, it can be provided that a diaphragm, in particular a rubber-elastic one, is mounted between the assembly comprising the solenoid coil and valve armature and the fluid channel with the valve seat. This diaphragm ensures hermetic separation between the fluid channel and the assembly comprising the solenoid coil and valve armature and is also referred to as a media-separated solenoid valve.Such solenoid valves are used in particular for controlling pressurised liquid flows, for example in the field of laboratory technology, especially for dosing liquids.

[0012] When the solenoid valve is deactivated, the valve armature is in a deactivated end position, which is designed, for example, as a closed position, in which the sealing element coupled to the valve armature seals against the valve seat, so that fluid flow through the valve opening is blocked. When the solenoid valve is activated, the valve armature is in an activated end position, which is referred to as the open position, wherein the sealing element is spaced from the valve seat and the valve opening is open for fluid flow. A solenoid valve designed in this way is also referred to as a “normally closed” valve or NC valve. Alternatively, it can be provided that the solenoid valve releases the valve seat in the deactivated state and closes the valve seat in the activated state; a solenoid valve designed in this way is also referred to as a “normally open” valve or NO valve.

[0013] To move the valve armature from the deactivated end position to the activated end position, the control device supplies a coil current to the solenoid coil, whereupon the solenoid coil generates an electromagnetic field that moves the valve armature to the activated end position. When the coil current is switched off, the valve armature should return to the deactivated end position. For this purpose, a valve spring can be provided in the solenoid valve for this purpose. This spring is deformed when the valve armature moves from the deactivated end position to the activated end position, thereby exerting a greater restoring force on the valve armature in the activated end position than is the case in the deactivated end position.

[0014] The control device can be configured as a microprocessor on which a program mapping the functions of the control device is executed. This program is stored in a memory connected to the microprocessor or integrated into the microprocessor.

[0015] To determine the coil current, the control unit has a current measuring device, which can be either a separate (discrete) current measuring sensor or directly integrated into the control unit. The current measuring device measures the current applied to the solenoid coil, converts this current into a measured value, and provides this measured value to the program running in the control unit for further processing.

[0016] The pull-in current is the current intensity required to move the valve armature from the deactivated end position to the activated end position using the electromagnetic field generated by the solenoid coil and thus, in the case of an NC valve, to enable fluid flow through the solenoid valve.

[0017] The pull-in current varies for differently designed solenoid valves, which in particular have differently designed components from the group: solenoid coils, valve armatures, and sealing elements. Furthermore, the pull-in current can change during solenoid valve operation due to heating of the solenoid coil. If the current supplied to the solenoid coil is too low, the solenoid valve will not open or will only open incompletely.

[0018] The pull-in time ta parameter is the time that elapses from the supply of the coil current until the valve armature reaches its end position, i.e. until the valve armature has moved from the deactivated end position to the activated end position. The movement of the valve armature requires that at least the pull-in current is applied and that the solenoid coil can generate a sufficiently strong electromagnetic field. Consequently, the pull-in time is the period of time between the time at which the coil current is supplied to the solenoid coil and the time at which the valve armature has reached the activated end position and the movement of the valve armature thus ends. To ensure that the solenoid valve opens completely, the pull-in current must be provided for at least a period of time when the solenoid coil is activated that corresponds to the pull-in time of the solenoid valve connected to the valve control.

[0019] If the valve armature is in the activated end position, a current lower than the pull-in current is sufficient to hold the valve armature in this position. For the purposes of this application, this current is referred to as the holding current. The holding current should not be exceeded for safe operation, preventing the solenoid valve from closing accidentally. The holding current is lower than the pull-in current, so that when the current applied to the solenoid coil is reduced from the pull-in current to the holding current, the solenoid coil of the solenoid valve heats up less, and electrical energy can be saved.

[0020] The holding time, as defined in this application, is the period of time during which the holding current is applied to the solenoid coil. More precisely, the holding time results from the difference between the time at which the current applied to the solenoid coil is reduced from the pull-in current to the holding current and the time at which the current applied to the solenoid coil is reduced to achieve movement of the valve armature from the activated end position to the deactivated end position and, if the solenoid valve is configured as an NC valve, to block the fluid flow.

[0021] The aforementioned parameters are valve-specific and / or specific to the solenoid coil used in the solenoid valve. For optimized solenoid valve control, these parameters should be selected according to the solenoid valve's characteristics and taken into account during control.

[0022] In order to enable optimized operation of various solenoid valves with the valve control, the invention provides that the valve control automatically recognizes the solenoid valve and in particular the solenoid coil of the connected solenoid valve and makes a parameter selection tailored to the recognized solenoid coil.

[0023] A characteristic feature of a solenoid coil is its electrical resistance, so determining this resistance allows the solenoid coil to be identified. Accordingly, the valve control system determines the electrical resistance of the solenoid coil during commissioning in order to identify the solenoid coil of the connected solenoid valve. After identifying the solenoid coil, the control unit selects at least one parameter from the group consisting of pull-in current, pull-in time, holding current, and holding time from a value table stored in the control unit's memory for the subsequent control of the solenoid coil. The value table can be stored as a file in the control unit's memory or, equivalently, in the control unit.

[0024] When using the valve control with a solenoid valve whose parameters from the group: pull-in current, pull-in time, holding current, and hold time are not stored in the value table and / or if the electrical resistance of the solenoid coil cannot be identified or is unknown to the valve control, the valve control according to the invention can determine a parameter from the group: pull-in current, pull-in time, holding current, and hold time. For example, it is possible for the valve control to be signal-connected to a flow meter that measures the flow through the solenoid valve connected to the valve control.If the measured flow rate in this measurement corresponds to the maximum flow rate of the connected solenoid valve, the valve armature is in the open position, so that the period between no flow rate and maximum flow rate represents a measure of the actuation time, whereby the period can be corrected by the control device for any delay time caused by an inertia of the fluidic system.

[0025] Advantageous further developments of the invention are the subject of the subclaims.

[0026] For determining the pull-in current, the control device is designed to provide a continuously increasing coil current to the solenoid coil and to determine the pull-in current by determining a first change in direction, in particular a current drop, in the measured coil current, which characterizes a valve movement.

[0027] For the purposes of the present application, a continuously increasing coil current is understood to mean a coil current that increases over an observation period, regardless of whether the increase occurs continuously or in a stepped manner, as is the case with a digital signal, for example. As already described, at a coil current that is at least equal to the pull-in current, the magnetic coil of the solenoid valve forms an electromagnetic field sufficient to cause the valve armature to move. When the valve armature moves from the deactivated end position to the activated end position, the measured coil current decreases as a result of the valve armature absorbing the movement, since the absorption of the movement results in a counter-induction in the magnetic coil that opposes the coil current.Accordingly, the movement of the valve armature, which can also be referred to as valve movement, causes a change in direction in a curve for the measured coil current, whereby the current intensity at which this change in direction begins corresponds to the pull-in current of the solenoid coil. Accordingly, by measuring the coil current, the pull-in current of the solenoid valve connected to the control device can be determined. This determined pull-in current can be stored in the control device for subsequent control processes, so that even if the solenoid valve cannot be identified based on the determined pull-in current, this pull-in current can be used to control the solenoid valve during a subsequent switching process.

[0028] When the determined pull-in current is used for subsequent switching-on processes for the solenoid valve, this prevents the solenoid valve's solenoid coil from being subjected to an unnecessarily high coil current, which could lead to undesirable heating of the solenoid coil. To avoid errors in determining the pull-in current, appropriate signal filtering, for example of the measured coil current and / or the signal corresponding to the measured coil current, can preferably be carried out in the control device, in particular signal smoothing to reduce the influence of signal noise. The measured coil current is preferably converted into a digital signal by means of an analog / digital converter integrated in the control device or in the current sensor.

[0029] In a further development of the invention, the control device for determining the actuation time is designed to detect a further change in direction in the measured coil current, which indicates an end of the valve movement, and to determine the actuation time from the time difference between the provision of the coil current and the further change in direction of the measured coil current. If the movement of the valve armature ends upon reaching the activated end position, the measured coil current increases again until it reaches a predetermined maximum current strength. This is due to the fact that once the activated end position is reached, there is no further relative movement of the valve armature with respect to the solenoid coil and thus no further mutual induction.Thus, after the valve armature's movement has ended, there is another change in direction in the measured coil current, which marks the end of the valve armature's movement, i.e., the end of the valve movement. The pull-in time can thus be determined from the difference between the time at which the coil current is applied and the time at which the valve armature's movement ends.

[0030] Knowing the pull-in time can ensure that the current required for valve movement is supplied for a sufficiently long period of time, at least equal to the pull-in time, during subsequent solenoid valve switching operations to enable fault-free operation of the solenoid valve. At the same time, it can be ensured that the pull-in current is not supplied for an unnecessarily long period, thus wasting unnecessary energy and preventing the solenoid coil from heating up unnecessarily.

[0031] Further preferably, the control device for determining the holding current is designed to continuously reduce the coil current supplied to the solenoid coil and to determine the holding current by determining a change in direction characterizing a valve movement, in particular an increase, in the measured coil current. When the coil current supplied to the solenoid coil of the solenoid valve is continuously reduced, the magnetic forces acting on the valve armature from the solenoid coil are reduced, so that the valve armature is moved out of the activated end position, for example by the restoring force of the return spring. In other words, at a certain point in time, the holding current required to maintain the activated end position is undershot and a valve movement, i.e. a movement of the valve armature, occurs.As the valve armature moves through the electromagnetic field of the solenoid coil, the mutual induction associated with the movement causes an increase in the measured coil current. This change in direction in the measured coil current serves as an indicator of the valve movement. The measured coil current present when the valve armature begins to move corresponds to the holding current of the solenoid valve connected to the valve control. Accordingly, the valve control can determine the holding current required for the connected solenoid valve and take this into account in a subsequent switching operation for the solenoid valve. Preferably, the control device is configured to increase the determined holding current by a predetermined amount and to supply this increased holding current to the solenoid coil as soon as the valve armature has reached the activated end position.This ensures that a sufficiently high holding current is provided and enables safe operation of the valve, while at the same time avoiding the need to provide an unnecessarily high holding current.

[0032] Advantageously, the control device is designed to store a parameter from the group: pull-in current, pull-in time, holding current, and holding time in the value table in the control device and / or to update it in the value table stored in the control device. For example, the values ​​of an initially unknown solenoid valve can be stored in the control device to make them available for further operation without having to repeat the determination of the individual parameters before each switching operation. It is also possible to update parameters whose values ​​change as a result of the operation of the solenoid valve to make them available for further operation.

[0033] Preferably, the control device is configured to increase one of the determined parameters from the group: pull-in current, pull-in time, holding current, and holding time, by a suitable safety factor before storing and / or updating it in the value table. To further improve operational reliability and ensure correct functioning of the solenoid valve, the control device can increase the determined parameters, for example, by 10% or by another percentage, to counteract, for example, a change in the solenoid coil over its service life and / or heating of the solenoid coil and / or operational influences such as vibrations.

[0034] In an advantageous embodiment of the valve control, the control device has at least one controller, in particular a PID controller, wherein a control behavior of the controller is adapted depending on at least one parameter from the group: pull-in current, pull-in time, holding current and holding time and / or depending on the determined electrical resistance of the solenoid coil. The aforementioned parameters and / or the electrical resistance of the solenoid coil are used in particular for the selection of a P component, an I component, a D component, an integral action time and / or a derivative action time of the controller. This makes it possible, for example, for the coil current supplied to the solenoid coil to be kept constant by adapting the controller even if the solenoid coil heats up and the electrical resistance of the solenoid coil changes accordingly. The other parameters can also be used to adjust the controller.are available through the determination by the control device for the control even in the case of a previously unknown solenoid valve.

[0035] In a preferred embodiment of the valve control device, the control device is designed to determine the electrical resistance of the solenoid coil using a switching signal sent to the solenoid valve. For this purpose, the switching signal can trigger a resistance measurement, or a signal component of the switching signal itself can be used to determine the electrical resistance of the solenoid coil, whereby a temporal offset is created between the switching signal and the movement of the valve armature. Accordingly, the electrical resistance of the solenoid coil can be determined repeatedly over the service life of the solenoid valve, and a temporal change, particularly due to heating of the solenoid coil, can be taken into account for the control.

[0036] The previously defined task is also solved by a method for operating a valve control for controlling a solenoid coil of a solenoid valve.The method comprises the steps of: determining an electrical resistance of the magnetic coil of the magnetic valve connected to the valve control by means of a switching signal sent to the magnetic valve, selecting at least one parameter from the group: pull-in current, pull-in time, holding current and holding time based on the determined resistance from a value table stored in the control device for subsequent control of the magnetic valve and / or determining a pull-in current as a parameter, providing a continuously increasing coil current, measuring the continuously increasing coil current, determining the pull-in current by determining a change in direction of the measured coil current that characterizes a valve movement and / or providing a continuously decreasing coil current, measuring the decreasing coil current and determining a pull-in current by determining a change in direction of the decreasing coil current that characterizes a valve movement.

[0037] In a further embodiment, the method for operating a valve control for controlling a solenoid coil of a solenoid valve further comprises: determining a further change in direction of the measured coil current characterizing an end of the valve movement and determining a pickup time from the time difference between the provision of the first coil current and the further change in direction of the measured coil current.

[0038] Preferably, the method for operating a valve control for controlling a solenoid coil of a solenoid valve further comprises adapting a control behavior of a controller of the control as a function of a selected and / or specific parameter from the group: pull-in current, pull-in time, holding current and holding time.

[0039] The invention is explained in more detail below with reference to the accompanying drawing, which shows Fig. 1 a strictly schematic representation of a valve arrangement and a valve control connected to the valve arrangement, Fig. 2 a strictly schematic representation of a solenoid valve of the valve arrangement of Fig. 1, Fig. 3 a strictly schematic representation of a curve of a measured coil current and a switching signal during a switching operation of a solenoid valve, Fig. 4 a strictly schematic representation of a starting current and holding current determination and Fig. 5 a strictly schematic representation of a course of a determined electrical resistance, a switching signal and a movement of a valve armature.

[0040] In the Fig. 1 shows a valve arrangement 1 and a valve control 2 connected to the valve arrangement 1 for signaling purposes. The valve arrangement 1 has, purely by way of example, a total of four disc-shaped valve units 3, which are arranged in a row in such a way that one side of a valve unit 3 is in contact with at least one side of another valve unit 3. Each valve unit 3 expediently has at least one solenoid valve 4 and a main valve 5, which is expediently a fluidically actuated valve. The solenoid valve 4 serves to control the supply of a fluid, via which a valve member (not shown) of the main valve 5 is actuated. The solenoid valve 4 can accordingly also be referred to as a pilot valve.For coupling the valve units 3 to the valve arrangement 1, the valve arrangement 1 has a connection section 6 into which the valve units 3 can be plugged, for example, wherein it is provided in particular that individual valve units 3 can be exchanged for other valve units 3 for different configurations of the valve arrangement 1.

[0041] The valve control 2 comprises a control device 7 with a regulator 8 and a current sensor 9 and is connected to each valve unit 3 via control lines 10. Purely as an example, Fig. 1, the control device 7 is housed in a separate housing, in particular a housing designed as a connector, and is designed as a microcontroller having a programmable memory 11. However, it is also conceivable that the control device 7 is integrated into a higher-level control system and then connected via signaling to the controller 8 and / or the current sensor 9, provided these are not also integrated into the higher-level control system.

[0042] In Fig. 2 is a strictly schematic representation of a solenoid valve 4 of any valve unit 3 from Fig. 1. Purely by way of example, the solenoid valve 4 is designed as a 2 / 2-way valve and has a solenoid coil 12, a valve armature 13, a valve member 14 which is motion-coupled to the valve armature 13, and a valve opening 16 surrounded by a valve seat 15, which fluidically connects a valve inlet 17 to a valve outlet 18. The solenoid valve 4 is shown in an activated state in which the valve armature 13 is in an open position in which the valve member 14 is lifted from the valve seat 15 and thus releases the valve opening 16 for fluid flow, so that fluid can flow from the valve inlet 17 to the valve outlet 18. In a deactivated state of the solenoid valve 4 (not shown), the valve armature 13 is in a closed position in which the valve member 14 rests against the valve seat 15 and thus blocks the valve opening 16 for fluid flow.In order to provide a sufficiently large sealing force and to move the valve armature 13 from the open position to the closed position, a valve spring 21 is arranged between a housing wall 19 of the solenoid valve housing 20 and the valve armature 13.

[0043] The one in the Fig. The activated state of the solenoid valve 4 shown in Figure 2, or the open position of the valve armature 13, is achieved from the deactivated state or the closed position when the solenoid coil 12 is supplied with a sufficiently high current, which can also be referred to as the pull-in current Ia, during a switching operation by the control device 7, and the solenoid coil 12 forms a corresponding electromagnetic field, so that the valve armature 13 is moved from the closed position to the open position. If the valve armature 13 is in the open position, the control device 7 can reduce the current supplied to the solenoid coil 12 to a current at which the strength of the electromagnetic field formed by the solenoid coil 4 is sufficient to hold the valve armature 13 in the open position against the spring action or restoring force of the valve spring 21. This current can also be referred to as the holding current Ih.A change from the deactivated state to the activated state and in the opposite direction, i.e. from the activated state to the deactivated state, can be referred to as a switching process.

[0044] Fig. 3 shows a strictly schematic representation of a curve of a measured coil current I2 and a switching signal U during an exemplary switching operation of the solenoid valve 4. The curves shown, in particular any ratios, are greatly exaggerated for better visibility. During commissioning, the control device 7 determines an electrical resistance W of the solenoid valve 4 in order to identify the solenoid valve 4 connected to the control device 7. If the solenoid valve 4 is identified as a solenoid valve known to the control device 7, the control device 7 retrieves the parameters pickup current Ia, pickup time ta, holding current Ih and holding time th from a value table stored in its memory 11 in order to take these into account when controlling the connected solenoid valve 4.At a time t1, the control device 7 receives the switching signal U, whereupon the control device 7 provides a coil current I1 to the magnetic coil 12 via the control line 10, wherein this is a maximum coil current Im which corresponds to the pull-in current Ia increased by a safety factor.

[0045] Between time t1 and time t2, the measured coil current I2 increases linearly until, at time t2, it reaches the current intensity corresponding to the pull-in current Ia. At this time t2, the strength of the resulting electromagnetic field is sufficient to initiate the movement of the valve armature 13 from the closed position against any adhesive forces between the valve member 13 and the valve seat 15, as well as a restoring force of the valve spring 21. The movement of the valve armature 13 in the solenoid coil 12 causes an induction in the solenoid coil 12, resulting in a current drop and thus in a first change in direction in the measured coil current I2. When the movement of the valve armature ends at time t3, the measured coil current I2 increases up to the maximum coil current Im provided by the control device 7.The maximum coil current Im corresponds to the pull-in current Ia, which has been increased by a safety factor by the control device 7. The further change in direction of the measured coil current I2 accordingly indicates the end of the movement of the valve armature 13. The movement of the valve armature 13 occurs between times t2 and t3. The difference between t1 and t3 corresponds to the pull-in time ta of the solenoid valve 4.

[0046] At time t5, the control device 7 reduces the current supplied to the solenoid coil 12 to the holding current Ih selected for the solenoid valve 4, wherein the time difference between time t1 and time t5 corresponds to the pull-in time ta increased by a safety factor s. Fig. The holding current Ih shown in Figure 3 also corresponds to a holding current increased by a safety factor. With the end of the switching signal U at time t6, the control device 7 no longer supplies the solenoid coil 12 with coil current I, and the measured coil current I2 decreases. The difference between times t5 and t6 corresponds to the previously selected holding time th. The coil current I2 falls below the required holding current Ih at time t7, whereupon the movement of the valve armature 13 from the open position to the closed position begins. The movement of the valve armature 13 between the solenoid coil 12 again causes induction in the solenoid coil 12, resulting in an increase in the measured coil current I2.If the movement of the valve armature 13 ends after reaching the closed position at time t8, the measured coil current I2 continues to decrease until finally at time t9 no coil current is applied to the solenoid coil 12 and the switching process is completely terminated.

[0047] In the Fig. 4 shows, in a strictly schematic manner, curves of a provided coil current I1 and a measured coil current I2 for determining the parameters pickup current Ia, pickup time ta, and holding current Ih. The curves shown, in particular any ratios, are greatly exaggerated and smoothed for better visibility, and the provided coil current I1 and measured coil current I2 are scaled accordingly. The method is preferably carried out by the valve controller 2 when the solenoid valve 4 cannot be identified when determining the electrical resistance W of the solenoid valve 4 connected to the valve controller 2. This is particularly the case when the valve controller 2 is connected to the solenoid valve 4 for the first time, or when its resistance has changed significantly as a result of prolonged operation or heating.To determine the aforementioned parameters, the control device 7 supplies a continuously increasing coil current I1 to the solenoid coil 12. The measured coil current I2 then increases until a time t2, at which the valve armature 13 begins to move from the closed position to the open position. The coil current I2 measured at this time t2 corresponds to the pull-in current Ia of the solenoid valve 4 connected to the valve control 2. The value of the pull-in current Ia is received by the control device 7 and stored for this solenoid valve 4 in the memory 11 of the control device 7.

[0048] If the movement of the valve armature 13 ends at time t3, the measured coil current I2 increases again to follow the provided coil current I1. From the difference between times t1 and t3, the control device 7 determines the pull-in time ta and also stores this for later use in the memory 11. After the pull-in current Ia and the pull-in time ta have been determined, the control device 7 continuously reduces the provided coil current I1, whereupon the measured coil current I2 also decreases. At time t7, the measured coil current I2 falls below the holding current Ih characteristic of the solenoid valve 4 connected to the valve control 2, whereupon the movement of the valve armature 13 from the open position back to the closed position begins and the measured coil current I2 increases. The increase in the coil current I2 ends at time t8, at which time the valve armature 13 has reached the closed position and thus its movement has ended.The holding current Ih is also stored in memory 11 for later use. The method just described is preferably repeated several times, for example, five times, in order to eliminate any interference in the determined parameters by averaging or to reduce their influence.

[0049] In the Fig.Figure 5 shows, strictly schematically, a profile of a determined electrical resistance W of the solenoid coil 12, a switching signal U1 sent to the control device 7, and the movement U2 of the valve armature 13. The control device 7 first determines the electrical resistance W of the solenoid coil 12 at time t0 in order to identify the solenoid valve 4. Subsequently, a switching signal U1 is provided at each of the times tn, tn+1, and tn+2, with a first signal component being used to determine the electrical resistance of the solenoid coil 12, as can be seen from the illustrated peaks in the profile of the electrical resistance W.Only after this determination of the resistance does the movement of the valve armature begin at the times tn+tw, tn+1+tw, and tn+2+tw, where tw represents the time delay between the provision of the switching signal U1 and the onset of movement of the valve armature 13 and thus indicates the duration of the determination of the electrical resistance W of the solenoid coil 12. Accordingly, the electrical resistance W of the solenoid coil 12 can be determined during operation of the valve control 2 without having to interrupt operation or send a separate signal to the control device 7.

Claims

[1] Valve control (2) for controlling a magnetic coil (12) of a solenoid valve (4), with a control device (7) which has a current measuring device for determining a coil current, wherein the control device is designed to determine an electrical resistance of the magnetic coil (12) and, based on the determined resistance, to select at least one parameter from the group: starting current, starting time, holding current and holding time from a value table stored in the control device for a subsequent control of the magnetic coil (12) and / or wherein the control device (7) is designed to determine a starting current as a parameter, wherein the control device (7) is designed to determine the starting current to provide a continuously increasing coil current (I1) to the magnetic coil (12) and to determine the starting current (Ia) by determining a first change in direction characterizing a valve movement, in particular a current drop,in the measured coil current (I2). [2] Valve control according to claim 1, characterized by in that the control device (7) for determining a pickup time (ta) is designed to determine a further change in direction, which characterizes an end of the valve movement, in the measured coil current (I2) and to determine the pickup time (ta) from the time difference between the provision of the coil current (I1) and a further change in direction of the measured coil current (I2). [3] Valve control according to one of the preceding claims, characterized by in that the control device (7) for determining the holding current is designed to continuously reduce the coil current (I1) provided to the magnetic coil (12) and to determine the holding current (Ih) by determining a change in direction, in particular an increase, in the measured coil current (I2) which characterizes a valve movement. [4] Valve control according to one of the preceding claims, characterized by that the control device (7) is designed to store a parameter from the group: starting current, starting time, holding current and holding time in the value table in the control device and / or to update it in the value table stored in the control device. [5] Valve control according to claim 4, characterized by that the control device (7) is designed to increase one of the determined parameters from the group: starting current, starting time, holding current and holding time, by a suitable safety factor before storing and / or updating in the value table. [6] Valve control according to one of the preceding claims, characterized bythat the control device (7) has at least one controller, in particular a PID controller, wherein a control behavior of the controller is adapted as a function of at least one parameter from the group: starting current, starting time, holding current and holding time and / or as a function of the determined electrical resistance of the magnetic coil. [7] Valve control according to one of the preceding claims, characterized by that the control device (7) is designed to determine the electrical resistance of the magnetic coil (12) by means of a switching signal sent to the magnetic valve (4). [8] A method for operating a valve control for controlling a solenoid coil of a solenoid valve, comprising the steps of: determining an electrical resistance of the solenoid coil (12) of the solenoid valve (4) connected to the valve control (2) by means of a switching signal sent to the solenoid valve (4) and selecting at least one parameter from the group: pull-in current, pull-in time, holding current and holding time based on the determined resistance from a value table stored in the control device (7) for a subsequent control of the solenoid valve (4) and / or determining a pull-in current as a parameter, providing a continuously increasing coil current (I1), measuring the continuously increasing coil current (I2), determining the pull-in current (Ia) by determining a change in direction of the measured coil current (I2) characterizing a valve movement and / or providing a continuously decreasing coil current (I1),Measuring the falling coil current (I2) and determining a starting current (Ia) by determining a change in the direction of the falling coil current (I2) that characterizes a valve movement. [9] Method for operating a valve control for controlling a solenoid coil of a solenoid valve according to claim 8, further comprising: determining a further change in direction of the measured coil current (I2) characterizing an end of the valve movement and determining a pickup time (ta) from the time difference between provision of the first coil current (I1) and further change in direction of the measured coil current (I2). [10] Method for operating a valve control for controlling a solenoid coil of a solenoid valve according to one of claims 8 or 9, further comprising: adapting a control behavior of a controller (8) of the control device (7) as a function of a selected and / or determined parameter from the group: pull-in current, pull-in time, holding current and holding time.

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