Valve control for controlling a solenoid valve, valve arrangement and method for operating a solenoid valve

Abstract

Valve control (3) for controlling a solenoid valve (2), comprising a control circuit (38) having an input interface (30) for receiving a switching signal and an output interface (31) for coupling a solenoid valve (2), and configured for processing the switching signal and for providing a coil current dependent on the switching signal to the output interface (31), wherein the control circuit (38) is configured to regulate the coil current to a pull-in current during a first time period and to regulate the coil current to a holding current that is less than 70 percent of the pull-in current during a subsequent second time period, wherein the control circuit is configured to increase the holding current by at least 20 percent for a limited time during the second time period if a predetermined coil current threshold is exceeded.wherein the control circuit (38) comprises a microcontroller which is configured to control the coil current during the first time interval and during the second time interval, characterized in that the control circuit (38) is configured such that the percentage increase of the holding current provided for when a predetermined coil current threshold is exceeded is determined by parameterizing the control circuit in order to enable the at least one solenoid valve (2) controlled by the valve control (3) to be adapted to different operating conditions.

Description

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

[0002] WO 2017 / 045 701 A1 discloses a valve control for the electrical control of at least one valve actuator, comprising a control circuit designed to influence an electrical energy flow between an electrical source and the valve actuator, and comprising a bus interface for communication with a higher-level control arrangement and a sensor means designed to determine a physical quantity of the energy flow that changes through electrical control of the valve actuator and to provide a sensor signal to the control circuit that depends on the determined physical quantity.According to the invention, the control circuit is designed to determine a state value for the valve actuator based on the sensor signal and at least one characteristic value of a physical quantity from the group: energy flow duration, energy flow voltage, energy flow current, fluid pressure, and to provide the state value at the bus interface.

[0003] DE 197 42 037 B4 discloses a method for detecting the dropout of a magnetically driven device, wherein its winding is supplied with current by a switching regulator in two-point operation. A high current is passed through the winding during switch-on, and a reduced current during holding operation. The switching regulator is controlled by electronics. To detect a faulty dropout of the device's armature during holding operation caused by external mechanical vibrations, a prolonged period of the coil current occurring during the armature dropout is evaluated for fault detection.

[0004] From DE 10 2004 056 653 A1, a method for detecting the switching of a magnetic armature whose magnet coil is energized with an electrical voltage is known. For this purpose, the electric current flowing through the magnet coil is measured by a measuring circuit, and the current's behavior over time is evaluated. The magnetic armature is detected when the measured current drops by a predetermined value within a specified time period. Unwanted de-engagement of the magnetic armature is detected when the current rises by a predetermined value within a specified time period. Once the magnetic armature is detected, the circuit switches from a higher pull-in voltage to a lower holding voltage. If unwanted de-engagement of the magnetic armature is detected while the holding voltage is applied, a refresh pulse with a higher voltage is applied.

[0005] DE 10 2009 017 878 ​​A1 discloses a valve device for supplying fluidic consumers, with several valve modules arranged in a stacking direction; each comprising a plate-shaped channel body with a feed channel recess and / or a vent channel recess and four 2 / 2-way valves, wherein the four 2 / 2-way valves are interconnected in a full bridge arrangement and are designed as valve units in which the actuating means forms a compact unit with a valve section, which is mounted on a mounting surface of the channel body.

[0006] The object of the invention is to provide a valve control for controlling a solenoid valve, a valve arrangement and a method for operating a solenoid valve, with which a predetermined switching state of the solenoid valve can be maintained with high energy efficiency even when taking external disturbance factors into account.

[0007] This problem is solved for a valve control for controlling a solenoid valve with the features of claim 1. The valve control is provided to have a control circuit which has an input interface for receiving a switching signal and an output interface for coupling a solenoid valve, and which is configured to process the switching signal and to provide a coil current dependent on the switching signal to the output interface. The control circuit is configured to regulate the coil current to a pull-in current during a first time period and to regulate the coil current to a holding current, which is less than 70 percent of the pull-in current, during a subsequent second time period. The control circuit is further configured toDuring the second time period, if a predetermined coil current threshold is exceeded, the holding current is increased temporarily by at least 20 percent, preferably by at least 30 percent, and in particular by at least 40 percent.

[0008] The valve control unit can be configured to control a single solenoid valve or a group of solenoid valves and includes, in addition to the control circuitry, other electrical or electronic components. These components can, for example, appropriately influence and supply an electrical voltage provided at a supply interface of the valve control unit to power the control circuitry and the at least one solenoid valve that can be connected to the valve control unit. An example of such a component is an electrical output stage that can be controlled by the control circuitry with a control signal and that is configured to release electrical energy to the solenoid valve depending on a switching signal provided to the control circuitry via an input interface.Preferably, the input interface and the power supply interface are configured as a common interface to which a connector can be attached, which is part of a cable connection between the valve control and a higher-level control unit. Alternatively, the input interface and the power supply interface can be configured for an electrical plug connection with a base plate of a valve manifold, wherein this base plate can have multiple slots for connecting valve controls.

[0009] The control circuit can be implemented, for example, as a microcontroller or microprocessor and configured to execute a computer program. This computer program serves to evaluate incoming switching signals, to provide control signals to one or more output stages of the valve control, to process sensor signals, and to regulate a coil current supplied to the connected solenoid valve. Alternatively, the control circuit can be implemented as an analog circuit using discrete electronic components.

[0010] For current control, the control circuit is equipped with or electrically connected to a sensor or sensor array. For example, a current sensor is provided, which is arranged in a connecting line between the electrical output stage and the solenoid valve and is configured to provide a sensor signal proportional to the current flow between the output stage and the solenoid valve. This sensor signal is processed in the control circuit to perform the desired control of the coil current.

[0011] The control circuit is designed to provide a time-varying supply of electrical energy to the solenoid valve, enabling highly energy-efficient operation. To achieve this, the control circuit initially supplies a high coil current, known as the pull-in current, to transition a valve element of the solenoid valve from its first operating position to its second. Once the valve element, which is moved within a solenoid coil of the solenoid valve, has been transitioned from its first operating position (also known as the rest position) to its second operating position (also known as the active position), the coil current is reduced to a level known as the holding current.This holding current is less than 70 percent of the pull-in current and is selected to keep the valve element in the second operating position. The control circuit stores predefined current values ​​for both the pull-in and holding currents, which are used to regulate the coil current during the respective operating phases (pulling-in and holding).

[0012] However, situations may arise where external magnetic fields are coupled into the solenoid coil of the solenoid valve, or accelerations act on the valve element coupled to the solenoid coil, which can cause a change in the coil current flowing in the solenoid coil. For example, the coupling of an external magnetic field into the solenoid coil can increase the current flow in the coil, causing the control circuit to reduce the coil current as part of its regulation.This can lead to an undesired movement of the valve element from the second operating position to the first operating position, particularly during the holding phase. This can cause a malfunction of the solenoid valve because the holding current is insufficient to move the valve element back from the first to the second operating position, and the control circuit is unaware that the valve element has unexpectedly left the second operating position and moved back to the first. A similar situation can occur if an external acceleration acts on the solenoid valve, causing the valve element to move from the second to the first operating position, without the control circuit being able to prevent this undesired movement of the valve element by regulating the coil current to the holding current.

[0013] Accordingly, to prevent such undesirable changes in the operating state of the solenoid valve, the control circuit is designed to monitor the coil current for exceeding a predefined threshold during the second phase, also known as the holding phase, during which the coil current is regulated to the holding current level. If this threshold is exceeded, the control circuit is configured to increase the holding current by at least 20 percent for a limited time, thereby preventing an undesirable movement of the valve element from the second operating position to the first operating position.

[0014] The time limit for increasing the holding current stipulates that if the predefined coil current threshold is exceeded, the control circuit increases the holding current for a predetermined period. The coil current resulting from this increase of at least 20 percent is, for example, referred to as the safety current. After the predetermined period has elapsed, the control circuit restores the holding current to the solenoid. If, after the predetermined period has expired and the safety current has ceased to be supplied, the coil current again exceeds the threshold, the control circuit is designed to perform another time-limited increase of the holding current to the safety current.If, after the specified time period has elapsed, a coil current is established that is below the coil current threshold, the control circuit provides the holding current.

[0015] Preferably, it is provided that the coil current is also regulated by the control circuit when the holding current is temporarily increased to the level of the safety current.

[0016] According to the invention, it is provided that the percentage increase of the holding current can be determined during parameterization of the control circuit, thus enabling adaptation to different operating conditions for the valve control and the at least one solenoid valve controlled by the valve control.

[0017] It is advantageous if the time-limited increase in holding current is carried out over a period of less than 0.5 seconds, preferably less than 0.3 seconds, and particularly less than 0.15 seconds. By limiting the increase in holding current to a period of less than 0.5 seconds, most disturbances that can act on a solenoid valve are controlled without causing an undesired movement of the valve element from the second operating position to the first operating position. Such disturbances can include, in particular, external magnetic fields or accelerations acting on the solenoid valve.

[0018] Furthermore, according to the invention, the control circuit includes a microcontroller which is configured to control the coil current during the first time period and during the second time period.

[0019] The object of the invention is achieved according to a second aspect of the invention by a valve arrangement according to claim 3. Here, the valve arrangement comprises at least two solenoid valves and at least one valve control according to the invention, wherein each solenoid valve has a valve housing through which a fluid channel extends between an inlet port and an outlet port and in which a valve element is arranged, which is movably received in the fluid channel between a first functional position and a second functional position, wherein a magnetic actuator is arranged in the valve housing, which is designed to initiate movement on the valve element and which is electrically connected to the valve control.

[0020] Preferably, the valve housing of the solenoid valve is designed for both fluid guidance and for accommodating the magnetic actuator. In this case, the valve housing, which is particularly made of plastic, has a fluid channel extending between an inlet port and an outlet port, in which a movably mounted valve element is arranged. Depending on the design of the valve seat and the valve element arranged in the fluid channel, it can be a poppet valve (sealing at least substantially axially), a spool valve (sealing at least substantially radially), or a combination of a poppet valve and a spool valve. If the valve element is designed as a spool valve, the valve housing can also have several fluid channels which are interconnected in different fluidic configurations depending on the positioning of the valve element along an axis of movement.can be separated from each other.

[0021] As an example, it is envisaged that the valve element can be moved from a first operating position to a second operating position by means of the magnetic actuator, against the restoring force of a return spring. For this movement of the valve element from the first to the second operating position, the supply of the actuation current to the magnetic actuator is necessary, since this movement must first overcome the static friction present between the valve element and the fluid channel when the valve element is at rest, as well as the inertia of the valve element. Furthermore, after the valve element has begun moving, the sliding friction between the valve element and the fluid channel must be overcome, and the deformation energy for the elastic deformation of the return spring must also be supplied.Once the valve element has reached the second operating position and has assumed a rest position there, the second time period begins, within which the control circuit can reduce the coil current of the magnetic drive to the holding current strength, since in the second operating position the restoring force of the restoring spring and, if necessary, flow forces exerted on the valve element by a fluid flowing through the fluid channel must be compensated by the magnetic drive.

[0022] The magnetic drive comprises at least one magnetic coil, but can also include an arrangement of several magnetic coils. By supplying a coil current to the at least one magnetic coil, a magnetic flux is provided, which can be used, for example, to move an armature made of a magnetically conductive material, such as iron, and which is coupled to the valve element. Depending on the design of the magnetic drive, the armature can perform a linear or a pivoting motion. By way of example, the magnetic coil is provided with a circular sleeve shape, and a first armature part is fixed in a central recess of the magnetic coil. A second armature part, axially adjacent to the first armature part, is movably received in the central recess and can be moved linearly along a coil axis depending on the coil current.The armature part can also be equipped with one or more permanent magnets, which also interact magnetically with the magnetic flux of the magnet coil.

[0023] If external disturbances cause a short-term increase in the coil current, which, due to the control circuit's intervention, could lead to a reduction in the coil current with the risk of an undesired movement of the valve element from the second operating position to the first operating position, the control circuit according to the invention can provide a counter-reaction by monitoring the coil current for exceeding the predetermined coil current threshold, thereby preventing this undesired movement of the valve element. Instead of the usual reduction of the coil current, which would otherwise be necessary to maintain the holding current due to the increased coil current from external sources such as magnetic field coupling or mechanical acceleration, the holding current is temporarily increased by at least 20 percent.This prevents the valve element from being moved from the second operating position to the first operating position, which could happen with coil current control without monitoring of the coil current threshold.

[0024] In an advantageous embodiment of the invention, two or more than two solenoid valves are accommodated in a common valve housing, wherein the valve housing is provided with a number of inlet ports, outlet ports, fluid channels and valve elements corresponding to the number of solenoid valves.

[0025] Preferably, each solenoid valve is assigned a valve controller. By individually assigning a valve controller to each solenoid actuator of each solenoid valve, a particularly advantageous control of the respective actuator is enabled. This is especially true if individual adaptation of the valve controller to the respective solenoid actuator, for example through parameterization, is already planned.

[0026] In a further embodiment of the valve arrangement, the solenoid valves are arranged adjacent to one another, particularly with direct physical contact between the respective valve housings, along a common axis. Such an arrangement of solenoid valves, as used especially in valve manifolds for industrial or laboratory automation, enables a particularly compact arrangement of the solenoid valves. By way of example, the valve housings of the solenoid valves are cuboid in shape, with the largest surface area of ​​each valve housing adjacent to the largest surface area of ​​a neighboring valve housing. This results in a common axis for the solenoid valves, with the spatial extent of the valve housings in the direction of the common axis being considerably smaller than in the spatial direction perpendicular to this common axis.

[0027] Preferably, the solenoid valves of the valve arrangement are arranged on a common channel plate. By way of example, at least one supply channel for supplying a gaseous fluid, in particular compressed air, to the solenoid valve is provided in the channel plate, and each of the valve housings has an interface for a sealing connection to the supply channel.

[0028] Additionally, the duct plate may be designed to include an exhaust duct for the removal of gaseous fluid, particularly compressed air, from the respective solenoid valves. Furthermore, the duct plate may also be equipped with connectors for supplying electrical power to the control circuit and / or for providing control signals.

[0029] The object of the invention is achieved according to a third aspect of the invention by a method for operating a solenoid valve according to claim 7, comprising the following steps: parameterizing a control circuit to determine a percentage increase of a holding current which is supplied to at least one solenoid valve controlled by the valve control when a predetermined coil current threshold is exceeded; regulating a coil current for a solenoid coil during a first time interval to a first coil current level in order to supply a first magnetic flux to a valve element and thus move the valve element from a first operating position to a second operating position; regulating the coil current for the solenoid coil during a second time interval to a second coil current level which is a maximum of 70 percent of the first coil current level.to provide a second magnetic flux to the valve element and thus hold the valve element in the second operating position, monitoring the coil current supplied to the solenoid during the second time period for an exceedance of a predetermined coil current threshold, and implementing a temporary increase of the second coil current level by at least 20 percent, preferably by at least 30 percent, in particular by at least 40 percent, in order to achieve the specified percentage increase in the holding current strength when the predetermined coil current threshold is exceeded.

[0030] In a further development of the method, it is provided that the time-limited increase of the holding current is carried out during a period of time that is less than 0.5 seconds, preferably less than 0.3 seconds, in particular less than 0.15 seconds.

[0031] An advantageous embodiment of the invention is shown in the drawing. Here, the drawing shows: Fig. 1 a strictly schematic representation of a solenoid valve system with a solenoid valve designed as a diaphragm valve and an associated valve control, Fig. 2 a strictly schematic representation of the essential functional components of the valve control, Fig. 3 a strictly schematic representation of a current-time diagram, and Fig. 4 A strictly schematic representation of a valve arrangement with several solenoid valves, each having a valve control and arranged on a common channel plate along an array axis.

[0032] One in the Fig. The solenoid valve system 1 shown comprises a solenoid valve 2 and a valve control 3 electrically connected to the solenoid valve 2. By way of example only, the solenoid valve 2 is designed as a diaphragm valve in which a flexible, in particular rubber-elastic, diaphragm 20 is sealed between a first valve housing part 18 and a second valve housing part 19 of a valve housing 17.

[0033] By way of example, a first fluid port 21, also referred to as the inlet port, and a second fluid port 22, also referred to as the outlet port, are formed on the valve housing 17. By way of example, the first fluid port 21 opens into a fluid channel 23, which is partially sleeve-shaped and has an outlet opening 24 that leads into a valve chamber 25. The outlet opening 24 is formed, by way of example, on an annular end face 26 of the fluid channel 23 and is also referred to as the valve seat. The valve chamber 25 extends coaxially to the fluid channel 23 and is fluidically connected to the second fluid port 22 via a fluid line 21.

[0034] The membrane 20, made of a rubber-elastic material, is positioned so close to the annular end face 26 of the fluid channel 23 that it can be pressed against the annular end face 26 by elastic deformation, creating a seal. To achieve this sealing effect, the solenoid valve 2 is equipped with a magnetic actuator 4. The magnetic actuator 4 comprises a solenoid coil 5, a magnetic core 6, a movably mounted armature 7, and a yoke 8, which is shown here as an example with a rectangular profile. The solenoid coil 5 is shown as an arrangement of multiple wire windings (not shown) that together form a circular cylindrical sleeve extending coaxially to a longitudinal axis 9. Furthermore, both the magnetic core 6 and the armature 7 are rotationally symmetrical about the longitudinal axis 9 and made of a magnetic flux-conducting material.

[0035] The magnetic core 6 is fixedly mounted in the magnetic coil 5, while the armature 7 is linearly movable along the longitudinal axis 9 in the magnetic coil 5.

[0036] A flat end face 10 of the magnetic core 6, facing away from the armature 7, is in planar contact with the yoke 8, which is made of a magnetic flux-conducting material. The yoke 8 surrounds the magnetic coil 5 and is shown in the plane of the Fig. 1 is formed with a rectangular profile and is provided with a recess 11 formed coaxially to the longitudinal axis 9, which is penetrated by the armature 7. In order to specify a preferred position for the armature 7, a spring device 12, in particular a helical spring, is arranged between the armature 7 and the magnetic core 6, which has an internal preload and which presses a valve element 14, which is rigidly connected to the armature 7 for illustrative purposes only, onto the diaphragm 20 when the solenoid coil 5 is de-energized, so that the diaphragm rests sealingly against the annular end face 26.

[0037] In this rest position of the solenoid valve 2, also referred to as the first functional position, which can thus be described as normally closed, a fluidically communicating connection between the first fluid port 21 and the second fluid port 22 is interrupted.

[0038] To allow fluid flow from the first fluid port 21 to the second fluid port 22 or in the reverse direction, it is necessary to eliminate the sealing effect between the diaphragm 20 and the annular end face 26 of the fluid channel 23, which serves as the valve seat. For this purpose, it is necessary to move the armature 7 from its first operating position as shown in the illustration. Fig. 1 to be converted into a second operating position (not shown) in which the distance between the armature 7 and the magnetic core 6 is reduced and the spring assembly 12 is compressed. To bring about this conversion of the armature 7, a coil current is supplied from the valve control 3 to the solenoid coil 5, thereby generating a magnetic flux in the magnetic core 6, the yoke 8, and the armature 7. Since the magnetic flux must overcome an air gap 15 between the armature 7 and the magnetic core 6, an attractive force arises between the armature 7 and the magnetic core 6. This attractive force causes an elastic deformation of the spring assembly 12, thus bringing the armature 7 closer to the magnetic core 6 and lifting the diaphragm 20 from the annular end face 26.

[0039] To carry out this approach process between the armature 7 and the magnetic core 6, the valve control 3 is configured to supply a coil current to the magnetic coil 5 via an output interface 31, to which connecting lines 28, 29 of the magnetic coil 5 are connected. The valve control 3 is supplied with power via an input interface 30, which is electrically connected to a higher-level control unit (not shown).

[0040] A schematic diagram for the valve control 3 is the Fig. As can be seen in Figure 2. It should be noted that an electrical supply voltage Uv is provided to the valve control 3 between an input terminal 33 and a ground terminal 34 only when the solenoid valve 2 is actually being actuated, with the input terminal 33 and the ground terminal 34 forming the input interface 30. At all other times, it is not necessary to provide a supply voltage Uv to the valve control 3. In this respect, the supply voltage Uv provided at the input interface 30 also serves simultaneously as a switching signal for actuating the solenoid valve system 1. In an embodiment of the valve control not shown, a continuous supply voltage and a separate switching signal are provided to the valve control.

[0041] As the depiction of the Fig. Downstream of input terminal 33, an input filter 35 is provided, the function of which is to attenuate or preferably completely eliminate interference that can affect the valve control 3 from the outside, as well as interference that can be caused by the valve control 3. Downstream of the input filter 35, a branch is provided to a power stage 36 and a power supply module 37, wherein the power stage 36 can have one or more electrically controllable switches and wherein the power supply module 37 is configured to provide a stable supply voltage to a downstream microcontroller 38.The microcontroller 38 is electrically connected to the output stage 36 and provides control signals, in particular pulse width modulated control signals, to the output stage 36 in order to initiate a current flow from the input terminal 33 to the solenoid coil 5 coupled to the output stage 36 in the . Fig. to enable the operation of the solenoid valve 2 (not shown in detail). The solenoid coil 5 is connected on one side to the output stage 36 and on the other side to the ground terminal 34 via a measuring resistor 40. This allows current to flow from the input terminal 33 through the output stage 36, the solenoid coil 5 and the measuring resistor 40 to the output terminal 34 when a suitable control signal, provided by the microcontroller 38, is present.

[0042] A freewheeling diode 41 is arranged in parallel to the series connection of the magnetic coil 5 and the measuring resistor 40, which can dissipate the current that occurs due to the back-induction of the magnetic coil 2 when the power supply to the magnetic coil 5 is switched off.

[0043] The measuring resistor 40 is electrically connected to the microcontroller 38 via measuring lines 42, 43 and serves to detect a current-dependent voltage drop, whereby this voltage drop is determined by the microcontroller 38 and can be used as a measure of the current flow through the magnetic coil 5.

[0044] According to the presentation of Fig. Figure 3, which shows a current-time diagram in which the course of the supply voltage Uv is also shown, shows that the supply voltage Uv is provided at time t0 and switched off again at time t7.

[0045] Shortly after the supply voltage Uv is provided, a control signal is sent from the microcontroller 38 to the output stage 36 following initialization of the microcontroller 38. As a result, at time t1, the output stage 36 releases a coil current, which is then supplied to the magnetic coil 5. Thus, time t1 represents the beginning of a first time interval. Since the magnetic coil 5 opposes an externally applied current flow with its self-inductance, the following occurs in the schematic and idealized representation of the Fig. 3 to a linear increase in the coil current between time t1 and time t2. At time t2, the magnetic flux in the air gap 15, as described in the Fig. 1 shown, has grown to such an extent that the armature 7 overcomes the static friction against the yoke 8 and the magnet coil 5 as well as the restoring force of the spring device 12 and begins to move in the direction of the magnetic core 6.

[0046] This movement of the armature 7 in the magnetic coil 5 causes an additional induction in the magnetic coil 5, which manifests itself as a current that opposes the current applied to the magnetic coil 5. Accordingly, as shown in the illustration of the Fig. From time t2 onwards, the coil current temporarily reduces, which is also reflected in a decreasing voltage drop across the measuring resistor 40. This voltage drop is detected in the microcontroller 38 by comparing the currently measured voltage with previously measured voltages. Based on the voltage drop determined across the measuring resistor 40, the current curve for the solenoid 5, calculated accordingly, shows a change in sign for the slope of the current curve at time t2. This change in sign can be used as a trigger signal for the microcontroller 38 to initiate current control for the solenoid valve 2 from time t5 onwards, which is also referred to as the end of the first time interval and the beginning of a second time interval.

[0047] As shown in the schematic representation of the Fig. 3, the coil current initially drops from time t2 due to the relative movement of the armature 7 with respect to the magnet coil 5, until the armature 7 reaches the second functional position at time t3, in which, deviating from the purely exemplary representation of the Fig. 1. A minimum air gap 15 exists between the armature 7 and the magnetic core 6. From time t3, the coil current in the magnetic coil 5 increases again due to the armature 7 now coming to a standstill, until at time t4 a maximum value I1max for the coil current I1, regulated by the microcontroller 38 serving as the control circuit, is reached.

[0048] In the event that the microcontroller 38 cannot determine the voltage drop across the measuring resistor 40, or at least not reliably, a switch occurs from the first coil current I1 to a reduced and constant coil current I2, also referred to as the holding current, at a time t6, which in this case defines the end of the first time interval and the beginning of the second time interval. This time t6 can be permanently programmed into the microcontroller 38 and is chosen such that the armature 7 has reached the second operating position with a high degree of reliability.

[0049] If, however, the microcontroller 38 can reliably determine the voltage drop across the measuring resistor 40 and thus the current flow through the solenoid coil 5, a switch occurs from the first coil current I1 to the reduced and constant second coil current I2 at time t5, which is significantly before time t6. For example, a fixed time interval Δt (=t5-t2) is stored in the microcontroller 38 between time t2 and time t5. It is particularly advantageous if different time intervals Δt are stored in the microcontroller 38 for different solenoid valve types.

[0050] In the second time interval, which either begins at time t5, provided the microcontroller 38 can reliably determine the voltage drop across the measuring resistor 40 and thus the current flow through the magnetic coil 5, or begins at time t6, provided the microcontroller 38 cannot reliably determine the voltage drop across the measuring resistor 40 and thus the current flow through the magnetic coil 5, the microcontroller 38, serving as the control circuit, provides pulse-width modulated control signals to the output stage 36. This regulates the coil current to the holding current I2, which is a maximum of 70 percent of the maximum coil current I1max, also known as the pull-in current.

[0051] During normal use of the solenoid valve 2, the coil current in the solenoid coil 5 can increase due to external influences during the second time period, which begins at the latest at the lapse of time t6. Such external influences include, for example, a mechanical acceleration of the solenoid valve 2, in which the valve element 14 is displaced relative to the solenoid coil 5 due to its inertia, or an electrical activation of a neighboring solenoid valve 2, as described in the Fig. 4 is shown purely schematically, whereby a magnetic flux is coupled from the solenoid coil of the adjacently arranged solenoid valve 2 into the solenoid coil 5.

[0052] Such an increase in the coil current in the magnetic coil 5 causes a control intervention by the microcontroller 38, since the microcontroller 38 is configured to regulate the coil current to the specified holding current I2.

[0053] According to the invention, the microcontroller 38 is configured to perform this control intervention, which causes a brief reduction in the coil current, only if the preceding increase in the coil current caused by the external influence has not led to an exceedance of a predetermined coil current threshold Ia, as specified in the Fig. 3 is marked.

[0054] If the increase in coil current caused by the external influence leads to the coil current exceeding the specified coil current threshold Ia, the microcontroller 38 is configured to perform a short-term increase of the coil current to a safety current Is to ensure that the valve element 14 remains in the second operating position.

[0055] Purely as an example, in the Fig. Figure 3 shows that the coil current I increases abruptly at time ts0 due to an external disturbance and shortly thereafter exceeds the coil current threshold Ia. This is detected by the microcontroller 38 and leads to an additional increase of the coil current to the safety current level Is at time ts1. At time ts2, the increase phase for the coil current ends, which is thereby reduced back to the previous holding current level I2 and held there until time t7.

[0056] According to the presentation of Fig. In a valve arrangement 51, several solenoid valve systems 1 are arranged along an axis 52 on a channel plate 53. The solenoid valve systems 1 are arranged with their largest possible surface areas 56 adjacent to one another, and an interface (not shown) is provided on the channel plate 53 for each solenoid valve system 1. This interface provides both electrical signals and a gaseous fluid, in particular compressed air, to the solenoid valve systems 1. As shown in the schematic representation of the Fig. As can be seen from Figure 4, each of the solenoid valve systems 1 comprises a solenoid valve 2 and, purely by way of example, a valve control 3 mounted on top of the valve housing 17. A fluid connection 54 for supplying a gaseous fluid, in particular compressed air, to the solenoid valve systems 1 and an electrical connector 55 for supplying electrical signals to the solenoid valve systems 1 are provided on the channel plate 53. By way of example, it is provided that a first solenoid valve system 1 is supplied with electrical energy at a first time, thereby activating the Fig. The sequence shown in Figure 3 is initiated for this first solenoid valve system. If, at a later time, a second solenoid valve system 1, in particular a second solenoid valve system 1 located directly adjacent to the first solenoid valve system 1, is supplied with electrical energy, the electrical activation of the second solenoid valve system 1 and the resulting change in magnetic flux for the second solenoid valve system 1 can influence the first solenoid valve system 1. If this influence on the first solenoid valve system 1 occurs at a time when the first time interval, which extends at most to time t6, has elapsed, this can cause an undesirable increase in the coil current in the first solenoid valve system 1. In order to prevent a displacement of the valve element 14 of the first solenoid valve system 1, the following can be used in connection with the Fig.The measures described in section 3 are taken by the valve control 3 of the first solenoid valve system 1.

Claims

[1] Valve control (3) for controlling a solenoid valve (2), comprising a control circuit (38) having an input interface (30) for receiving a switching signal and an output interface (31) for coupling a solenoid valve (2), and configured for processing the switching signal and for providing a coil current dependent on the switching signal to the output interface (31), wherein the control circuit (38) is configured to regulate the coil current to a pull-in current during a first time period and to regulate the coil current to a holding current that is less than 70 percent of the pull-in current during a subsequent second time period, wherein the control circuit is configured to increase the holding current by at least 20 percent for a limited time during the second time period if a predetermined coil current threshold is exceeded.wherein the control circuit (38) comprises a microcontroller configured to control the coil current during the first time period and during the second time period, characterized by , that the control circuit (38) is set up in such a way that the percentage increase of the holding current provided for when a predetermined coil current threshold is exceeded is determined in the course of parameterizing the control circuit in order to enable the at least one solenoid valve (2) controlled by the valve control (3) to be adapted to different operating conditions. [2] Valve control (3) according to claim 1, characterized by , that the temporary increase in holding current is carried out during a period of time that is less than 0.5 seconds. [3] Valve arrangement (51) with at least two solenoid valves (2) and with at least one valve control (3) according to one of claims 1 or 2, wherein each solenoid valve (2) has a valve housing (17) through which is penetrated by a fluid channel (23) extending between an inlet port (21) and an outlet port (22) and in which a valve element (14) is arranged which is movably received in the fluid channel (23) between a first operating position and a second operating position, wherein a magnetic actuator (4) is arranged in the valve housing (17) which is designed to initiate movement on the valve element (14) and which is electrically connected to the valve control (3). [4] Valve arrangement (51) according to claim 3, characterized by , that each of the solenoid valves (2) is assigned a valve control (3). [5] Valve arrangement (51) according to claim 3 or 4, characterized by, that the solenoid valves (2) are arranged adjacent to each other, in particular with direct physical contact of the respective valve housings (17), along a row axis (). [6] Valve arrangement (51) according to one of claims 3 to 5, characterized by that the solenoid valves (2) are arranged on a common channel plate (53). [7] Method for operating a solenoid valve (2) comprising the steps of: parameterizing a control circuit (38) to determine a percentage increase of a holding current which is supplied to at least one solenoid valve (2) controlled by the valve control (3) when a predetermined coil current threshold is exceeded; controlling a coil current for a solenoid coil (5) during a first time interval to a first coil current level in order to provide a first magnetic flux to a valve element (14) and thus move the valve element (14) from a first operating position to a second operating position; controlling the coil current for the solenoid coil (5) during a second time interval to a second coil current level which is at most 70 percent of the first coil current level in order to provide a second magnetic flux to the valve element (14) and thus hold the valve element (14) in the second operating position.Monitoring the coil current supplied to the magnetic coil (5) during the second time period for an exceedance of the specified coil current threshold, and carrying out a temporary increase of the second coil current level by at least 20 percent in order to achieve the specified percentage increase of the holding current strength in the event of an exceedance of the specified coil current threshold. [8] Method according to claim 7, characterized by , that the temporary increase in holding current is carried out during a period of time that is less than 0.5 seconds.

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