Valve device with a valve based on an electrodynamic actuator and method for controlling a valve with an electrodynamic actuator

Abstract

Valve device comprising a valve (10) with at least one valve seat (14a, 14b) and an electrodynamic actuator, which has an actuating element rotatably mounted about a rotary axis (D) with a coil (22) and a stationary magnet arrangement with permanent magnets (32, 34), wherein the rotary movement of the actuating element opens or closes the valve seat (14a, 14b) and wherein a driving force caused by energizing the coil (22) by means of a voltage source and transmitted to the actuating element is linearly dependent on the current strength, comprising a pre-connection electronics (38) connected to the coil (22), which has a capacitor (40) connected in parallel to the coil (22), wherein the pre-connection electronics (38) is arranged such that the coil (22) continues to be energized after the energizing by means of the voltage source is discontinued by a discharge of the capacitor (40).

Description

[0001] The invention relates to a valve device comprising a valve with an electrodynamic actuator. The invention further relates to a method for controlling a valve with an electrodynamic actuator.

[0002] As the demands on equipment manufacturing increase, so do the demands on the valves used within it. For example, in modern laboratories, and especially in clinical settings directly in the patient environment, avoiding or reducing noise pollution is becoming increasingly important. However, there are very few low-noise solutions available on the market, particularly for "media-separated" valves, such as those used in food processing, analytical, laboratory, and medical technology.

[0003] For many of the applications mentioned above, solenoid valves are the first choice from a technical perspective. They are designed for rapid switching and, with appropriate design, are suitable for aggressive or neutral liquid and gaseous media in various temperature and pressure ranges. A solenoid valve typically comprises a magnetic armature (core) that is movable in one direction by the force of an electromagnet and in the opposite direction by the force of a return spring. When the electromagnet is energized, the armature is accelerated from its initial state by the generated magnetic field until it reaches a predetermined end position defined by an end stop, usually a metal plug. During the switching stroke, the armature's speed increases steadily. The magnetic force becomes greater as the armature approaches the plug.At the end of the switching stroke, when the armature strikes the plug, a clearly audible clicking noise occurs, which is usually perceived as annoying, especially at high switching frequencies. Noise damping can be achieved by attaching an elastomer element to the plug or armature. However, this measure leads to a reduced armature stroke and a reduced driving force at the end of the stroke.

[0004] In the aforementioned area of ​​media-separated valves, a valve type is now becoming established, referred to here simply as the "Lorentz valve." This valve type, known, for example, from WO 2010 / 066459 A1, uses an electrodynamic actuator. A stationary magnetic assembly exerts a Lorentz force on a coil when energized, which is used to deflect a mechanically preloaded actuator. A prerequisite for this is that the coil is part of the movable actuator. Unlike a solenoid valve, the actuating force of a Lorentz valve is linearly dependent on the current; that is, the actuating force remains constant at a constant current. Such a valve is usually quieter because the actuator does not impact a metallic end stop. However, a noise may still be audible during switching if the actuator...a projection of the actuator meets a valve seat.

[0005] The object of the invention is to create a direct-acting valve with improved switching characteristics. In particular, effective end-position damping and / or accelerated switching should be achieved.

[0006] This problem is solved by a valve device with the features of claim 1 and by a valve control method with the features of claim 9. Advantageous and expedient embodiments of the device and method according to the invention are specified in the dependent claims.

[0007] The valve device according to the invention comprises a valve with an electrodynamic actuator, which has a movable actuating element with a coil and a magnet arrangement that is stationary relative to the coil, wherein a driving force generated by energizing the coil and transmitted to the actuating element is essentially linearly dependent on the current. According to the invention, a series of electronic components connected to the coil includes a capacitor connected in parallel to the coil.

[0008] The invention is based on the understanding that the special design of a Lorentz valve enables a continuous switching movement controlled by the electric current. The capacitor connected in parallel to the coil is charged when the coil is energized and, after the current is switched off, acts as a buffer, preventing the coil from abruptly losing current and the actuator from returning to its initial state without damping. After the current is switched off, the capacitor continues to supply current to the coil until it is completely discharged. The exponential discharge curve of capacitors proves particularly advantageous in the damping achieved in this way, as the capacitor's discharge slows down precisely at the end of the switching path to its initial state. With a suitable design of the capacitor used, especially with regard to its capacitance, the switching noise is no longer perceptible.This makes the valve device according to the invention suitable for noise-sensitive environments, e.g., when handling patients.

[0009] A further advantage of the valve device according to the invention is that a valve damped by means of the capacitor generates virtually no pressure surge in the medium ("closing hammer") when returning to its initial state. Particularly in microfluidics, a high number of successive closing hammers from conventional valves can lead to disruptive pulses in the fluid flow in the connected fluidic line. These pulses are characterized by a short but significant increase in flow velocity or pressure acting on the fluid. The absence of these pressure disturbances, achieved with the invention, allows for better control of the flow processes. In certain microfluidic systems, such damped valves are even a necessary requirement, namely when stable droplets or multiphase systems are to be generated.In this context, too, the damping of the valve can be specifically adjusted to the application requirements by appropriately designing the capacitor's capacitance.

[0010] The invention is particularly suitable for valves in which the actuator of the electrodynamic actuator is mechanically biased into an initial state by means of a return element. Depending on which switching position corresponds to the initial state, such valves are referred to as "normally closed" (NC) or "normally open" (NO) valves. The return element is generally a spring element clamped between the housing and the actuator.

[0011] According to a first embodiment of the valve device, the upstream electronics provided for in the invention are a structurally separate unit from the valve. Separate upstream electronics have the advantage that they can be offered as an option to the actual valve. Furthermore, adaptation, maintenance, and replacement of the upstream electronics are simplified.

[0012] The upstream electronics can also be integrated into the electrodynamic actuator of the valve. This makes the device significantly more compact and easier to handle. Integrating the upstream electronics is generally straightforward, as only a few electrical components – in the simplest case, just a suitably sized capacitor – need to be housed within the actuator casing.

[0013] According to a first particular aspect of the invention, the upstream electronics include a switching device with which the voltage applied to the coil can be reversed. This switching device enables a faster return of the actuator to its initial state. Reversing the voltage causes the direction of the current flowing through the coil to abruptly reverse while the actuator is in the switching state, so that a force supporting the return element suddenly acts on the actuator. The Lorentz force provided in addition to the mechanical return force is particularly advantageous in non-pressure-balanced valve mechanisms, since closing the valve (initial state) requires working against the medium pressure.This leads, particularly with media-separated diaphragm valves, to an increased switching time compared to the short switching time when the valve opens (switching state), where the medium pressure provides support.

[0014] The upstream electronics preferably have at least one signal input. This allows the upstream electronics to be connected to a control unit, which can determine the processes in the upstream electronics via the signal line.

[0015] According to the invention, a diode can also be provided in the upstream electronics of the valve device instead of the capacitor.

[0016] In this case, the switching times can be specifically influenced by at least one resistor connected in series with the diode.

[0017] The invention also provides a method for controlling a valve with an electrodynamic actuator, which has a movable actuating element with a coil and a magnet arrangement that is stationary relative to the coil, wherein a driving force generated by energizing the coil and transmitted to the actuating element is essentially linearly dependent on the current. The method according to the invention provides that, during the control of the electrodynamic actuator, when the coil is energized by a voltage source, a capacitor connected in parallel to the coil is charged, and that after the energizing by the voltage source is discontinued, the capacitor continues to be energized by discharging.

[0018] For information on the damping effect and the other advantages of the valve control method according to the invention, reference is made to the above explanations regarding the valve device according to the invention.

[0019] As already indicated, the method according to the invention is particularly suitable for valves in which the actuator is preloaded to an initial state and the drive force acts against the preload (NC or NO valves).

[0020] According to the first particular aspect of the invention, the valve control method provides that, for an accelerated return of the actuator from a switching state to the initial state, the voltage applied to the coil is reversed. As already explained, this reverses the current flow through the coil, so that the Lorentz force acts in the opposite direction, i.e., in the direction of the initial state, and is added to the mechanical preload of the return element.

[0021] Since the capacitor connected in parallel to the coil interferes with the voltage reversal, it should be removed from the control circuit of the electrodynamic actuator during the accelerated reset of the actuator. This means that the capacitor is deactivated, at least for the period during which the reversed voltage is applied to the coil, by a switch or similar device.

[0022] According to a first particular aspect of the invention, the valve control method provides that, for accelerated switching of the actuator from the initial state to a switching state, the voltage applied to the coil is briefly increased above a nominal coil voltage. (The nominal coil voltage is the value of the electrical voltage specified by the manufacturer or supplier for normal operation. The same applies to the nominal current.) Such overexcitation is harmless to the coil if it is not continuously exposed to the increased voltage. For the switching process, however, it is sufficient to apply only a short voltage pulse to the coil.

[0023] In general, accelerated switching to the switching state (by overexcitation) or the previously described accelerated return to the initial state (by reversing polarity) are particularly advantageous in applications where high switching speeds are required, e.g. in industrial printing or dispensing.

[0024] The capacitor connected in parallel to the coil can be used to temporarily increase the voltage.

[0025] In principle, the first and second special aspects of the invention (accelerated switching to the switching state or returning to the initial state) can also be realized independently of the presence of a capacitor connected in parallel to the coil.

[0026] Further features and advantages of the invention will become apparent from the following description and from the accompanying drawings, to which reference is made. The drawings show:

[0027] Fig. 1 a sectional view of a valve device according to the invention in a first embodiment.

[0028] Fig. 2 a circuit diagram of a valve device according to the invention in a second embodiment;

[0029] Fig. 3 a circuit diagram of a valve device according to the invention in the first embodiment;

[0030] Fig. 4 Two switching cycles of a valve of a valve device according to the invention and a valve device according to the prior art in a current-time diagram; and

[0031] Fig. 5 Two supported switching changes of a valve of a valve device according to the invention in a voltage-time diagram.

[0032] In Fig. Figure 1 is an example of an embodiment of a media-separated valve. 10Here, a microvalve is shown with an electrodynamic actuator. The electrodynamic actuator is mounted on a two-part fluid housing. 12a , 12b mounted in which two adjacent valve seats 14a , 14b are formed. The valve seats 14a , 14b can be from one between the housing halves 12a , 12b clamped membrane 16 or are alternately opened or closed by means of stamps or other sealing elements inserted therein.

[0033] The electrodynamic actuator includes an actuator housing. 18 , in which a movable actuator and a stationary magnet assembly are housed. The actuator essentially consists of a coil carrier. 20 made of a non-magnetic material and mounted on the coil carrier 20 coil wound or otherwise firmly connected to it 22formed from a copper wire, i.e. the coil carrier 20 and the coil 22 They always move together.

[0034] The coil 22 comprises a multitude of windings around a non-soft magnetic core 24 (Air or another non-magnetic material) with a central axis extending in the z direction. The embodiment described here is therefore an air coil.

[0035] The longitudinal axis of the coil, which is in the form of two spaced-apart complementary semicircles with a linear central piece connecting the semicircles 22 extends in a direction y perpendicular to the z-direction. The winding ends 26a , 26b the coil 22 are through the coil carrier 20 guided through and via electrical conductors with two electrical connections designed as pins 28a , 28b on the upper front face of the actuator housing18 connected. The electrical connections 28a , 28b In this embodiment, they are directly connected to a control device for actuating the electrodynamic actuator, which will be discussed in more detail later.

[0036] The coil carrier 20 is in turn firmly attached to a seesaw. 30 connected or fits into a seesaw in one piece 30 about which is rotatably mounted about a rotational axis D, which is oriented parallel to the z-direction. The rocker 30 is designed as a two-armed actuating lever that connects to the diaphragm 16 or interacts with the stamps.

[0037] In the illustrated embodiment, the magnet arrangement consists of four cuboid permanent magnets, of which the sectional view shows the Fig. 1 only two permanent magnets 32 , 34 can be seen. The two permanent magnets 32are arranged side by side on one side of a longitudinal slit in which the actuator is located, in a direction x perpendicular to directions y and z. On the in Fig. On the opposite side of the longitudinal gap (not visible), two further permanent magnets are provided in the same arrangement. The permanent magnets are oriented such that their longitudinal axes are parallel to the longitudinal axis y of the coil. 22 The lines run and that opposite poles (north, south) are always opposite each other in the x and z directions.

[0038] With respect to direction x, two adjacent magnetic fields with opposite orientations (opposite principal directions) are formed, whose field lines traverse the longitudinal slit largely in the direction z parallel to the axis of rotation D. For the sake of simplicity, the following directional terms (left, right, etc.) will refer to the representation of the Fig. 1. Reference is made to this. Accordingly, the left magnetic field of the permanent magnets opposite each other on the left side penetrates the left half. 22a the coil 22 , while the right magnetic field of the permanent magnets opposite each other on the right side occupies the right half 22b the coil 22 penetrates.

[0039] In the current-free initial state of the electrodynamic actuator, a restoring element is tensioned. 36 in the form of a space between the actuator housing 18 and the coil carrier 20 clamped coil spring the rocker 30 mechanically into a valve position in which, according to Fig. 1 the right valve seat 14b is closed, while at the same time the left valve seat 14a is released. This valve position represents the valve's initial state. 10 dar.

[0040] When the coil is actuated 22 via the electrical connections28a , 28b With direct current, the current flow directions are in the left and right halves. 22a , 22b the coil 22 The directions of the left and right magnetic fields are exactly the same as those of the left and right magnetic fields. With the "correct" polarity of the applied voltage, it acts on both halves of the coil. 22a , 22b A left-directed Lorentz force. This causes the actuator to move against the mechanical preload of the return element. 36 The valve is pivoted counterclockwise around the axis of rotation D into a switching state. In this switching state, the right valve seat is located here. 14b opened and the left valve seat 14a closed. As soon as the power is switched off, the Lorentz force disappears, and the restoring element... 36 pushes the actuator back to its initial state.

[0041] The total force acting on the actuator depends on the strength of the magnetic fields and the total length of the current-carrying windings of the coil that can be used to generate the force. 22 in the magnetic fields, from the current strength and from the size of the longitudinal gap between the opposing permanent magnets.

[0042] The electrical control of the valve is described below. 10 described, whereby this does not refer to the embodiment of the valve described above. 10 It is not limited to this specific application, but is generally applicable to valves with an electrodynamic actuator. In particular, the valve control is also suitable for valves with only one valve seat, which can be selectively opened or closed.

[0043] Fig. 2 shows a circuit diagram with a valve 10 , which features an electrodynamic actuator and a pre-electronics unit 38, which is an essential component of the valve control. The upstream electronics 38 It has three inputs, two of which are for power supply, provided by an external power source (not shown). The third input is a signal input connected to a control unit (not shown) for controlling the processes in the upstream electronics. 38 .

[0044] The pre-electronics 38 is connected to the electrodynamic actuator, more precisely to the electrical connections 28a , 28b or the winding ends 26a , 26b the coil 22 connected. The pre-electronics 38 Among other things, it enables the following three switching variants, which differ from conventional switching operations without upstream electronics. 38Distinguish between: 1) Damped switching operations, 2) Accelerated return to the initial state and 3) Accelerated switching from the initial state.

[0045] With regard to the damping of switching processes, the upstream electronics 38 a parallel to the coil 22 switched capacitor 40 provided. In the simplest case, this results in a circuit as described in Fig. 3 is shown.

[0046] The pre-electronics 38 can, as in Fig. 2 indicated, a separate unit. Alternatively, the upstream electronics can be 38 but also in the electrodynamic actuator of the valve 10 be integrated. Fig. Figure 1 shows an example of a simple design in which the integrated ballast electronics 38 essentially only from the capacitor 40 consists of the two electrical connections. 28a , 28bis connected.

[0047] Regarding any other components of the ballast electronics 38 This will not be discussed in more detail here.

[0048] The dashed curve in Fig. Figure 4 shows two typical, consecutive switching operations of the valve. 10 in a diagram showing the current flow I through the coil 22 is plotted over time. At time t1, an external voltage source is used to supply power to the coil. 22 specified nominal voltage U nenn to the actuator, more precisely to the one with the winding ends. 26a , 26b the coil 22 connected electrical connections 28a , 28b installed. The valve 10 The system then switches, as described above, overcoming the mechanical preload of the return element. 36 from the initial state to the switching state.

[0049] As shown in the diagram Fig. As can be seen in section 4, the voltage increases after applying the nominal voltage U. nenn the current does not directly affect the nominal value I Nenn on. This is because the one parallel to the coil 22 switched capacitor 40 is being charged, which leads to a short delay. As long as the nominal voltage U nenn when the valve is engaged, it remains closed. 10 in the switching state.

[0050] If the voltage from the external voltage source is switched off at time t2, the valve switches. 10 back to the initial state. However, the charged capacitor causes 40 , that the voltage U across the coil 22 and the current I does not drop abruptly to zero. Rather, the capacitor supplies 40 the coil 22 even after switching off, it continues to receive power until the capacitor 40 is completely discharged. During the discharge of the capacitor 40The voltage U – and therefore also the current I – decreases exponentially. This exponential discharge is described in... Fig. 4 is represented by the solid line, while the dashed line at t2 represents an abrupt shutdown process without a capacitor for comparison.

[0051] The controlled, "gentle" decrease in current results in a damped switching process; that is, the movement of the actuator is deliberately slowed down just before reaching the initial state. Thanks to this damping, virtually no switching noise is audible. In practice, the switching time is delayed by the damping to, for example, 15 milliseconds, when the typical switching time without damping is approximately 1 to 5 milliseconds. A similar switching characteristic, but in reverse, and a comparable delay occur earlier when switching to the initial state.

[0052] If there is no dampened, but rather an accelerated return to the valve's initial state 10 If desired, the pre-electronics can 38 carry out another measure. The nominal voltage U nenn , which are attached to the coil 22 applies to the actuator against the preload force of the return element. 36 To hold the device in the switching position, the polarity is reversed for a short time. At the desired switch-back time t2, the electrical connection is therefore switched to the desired position. 28a or 28b , which was connected to the positive terminal of the voltage source, is connected to the negative terminal or ground, and vice versa. This scenario is shown in the right part of the diagram. Fig. 5 shown.

[0053] Reversing the polarity changes the current flow through the coil. 22 Conversely, this generates a Lorentz force that acts in the opposite direction, thus counteracting the restoring element. 36This is supported. The increased restoring force accelerates the return of the actuator to its initial state. For optimal use of this effect, the reverse of the nominal voltage –U – should be applied. nenn at least as long as it's on the coil 22 the actuator remains in place until it has safely returned to its initial state.

[0054] The polarity reversal is handled by the upstream electronics. 38 A switching device is provided, for example in the form of a bridge circuit. The switching device only works without the capacitor. 40 , i.e., it will be removed from the control circuit for the coil by suitable measures as long as necessary. 22 eliminated ("switched off"). This is the case with the variant according to the Fig. 1 with the capacitor hardwired in the electrodynamic actuator 40 However, this is not possible.

[0055] An accelerated switching of the valve 10The transition from the initial state to the switching state can also be achieved using the upstream electronics. 38 This can be achieved by applying a voltage significantly higher than the nominal voltage U at switching time t1. nenn voltage applied to the coil 22 This process is established (overexcitation). This process is shown in the left half of the diagram. Fig. 5 is shown. The increased voltage results in a higher current flow through the coil. 22 and thus for an increased driving force on the actuator. The coil 22 However, the higher voltage should only be applied briefly (in pulses) to avoid overloading or damaging the coil. 22 to avoid (burning out).

[0056] The capacitor can be used to provide the additional voltage. 40 can be used. However, it is also possible to increase the voltage of the external voltage source or to otherwise increase the voltage at the coil. 22to increase temporarily.

[0057] For the two switching processes described last, 2) accelerated return to the initial state and 3) accelerated switching from the initial state, the capacitor 40 not (absolutely) required. The pre-electronics 38 In the simplest case, these two functions are limited to a switching device or an adjustable voltage source.

[0058] Basically, instead of the capacitor 40 A diode can also be used to achieve the switching characteristics described above. In this case, the switching times can be adjusted by connecting one or more resistors in series with the diode.

[0059] In general, valve control with the upstream electronics is suitable 38The invention is particularly applicable to media-separated valves, especially switching valves, with electrodynamic actuators, such as those used in food processing, analytical, laboratory, or medical technology. However, the invention can also be applied to valves without a separating diaphragm. Reference symbol list 10 valve 12a, 12b Fluid housing halves 14a, 14b Valve seats 16 Membran 18 actuator housings 20 coil carriers 22 coil 22a, 22b Coil halves 24 core 26a, 26b winding ends 28a, 28b electrical connections 30 rocker 32 permanent magnets 34 permanent magnet 36 Return element 38 Upstream electronics 40 Capacitor QUOTES INCLUDED IN THE DESCRIPTION

[0060] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0061] WO 2010 / 066459 A1

[0004]

Claims

[1] Valve device comprising a valve ( 10 ) with an electrodynamic actuator, which has a movable actuating element with a coil ( 22 ) and one relative to the coil ( 22 ) has a stationary magnet arrangement, wherein a current is applied to the coil ( 22 ) the driving force generated and transmitted to the actuator is essentially linearly dependent on the current, characterized by a connection with the coil ( 22 ) connected pre-electronics ( 38 ), which is parallel to the coil ( 22 ) switched capacitor ( 40 ) exhibits. [2] Valve device according to claim 1, characterized by that the actuating element of the electrodynamic actuator is powered by a return element ( 36 ) is mechanically pre-tensioned to an initial state. [3] Valve device according to claim 1 or 2, characterized by that the upstream electronics ( 38 ) a structurally separate valve ( 10) separate unit. [4] Valve device according to claim 1 or 2, characterized by that the upstream electronics ( 38 ) into the electrodynamic actuator of the valve ( 10 ) is integrated. [5] Valve device according to one of the preceding claims, characterized in that the upstream electronics ( 38 ) has a switching device with which the voltage on the coil ( 22 ) applied voltage can be reversed. [6] Valve device according to one of the preceding claims, characterized by that the upstream electronics ( 38 ) has at least one signal input. [7] Valve device according to one of the preceding claims, characterized by that instead of the capacitor ( 40 ) a diode is provided. [8] Valve device according to claim 7, characterized by that at least one resistor is connected in series with the diode. [9] Method for controlling a valve ( 10 ) with an electrodynamic actuator, which has a movable actuating element with a coil ( 22 ) and one relative to the coil ( 22 ) has a stationary magnet arrangement, wherein a current is applied to the coil ( 22 ) the driving force generated and transmitted to the actuator is essentially linearly dependent on the current intensity, characterized by that during the control of the electrodynamic actuator when the coil is energized ( 22 ) by means of a voltage source parallel to the coil ( 22 ) switched capacitor ( 40 ) is charged and that the capacitor ( 40 ) after the current is supplied by the voltage source, by a discharge of the capacitor ( 40 ) continues to be powered. [10] Method according to claim 9, characterized bythat the actuator is preloaded to an initial state and the driving force acts against the preload. [11] Method according to claim 9 or 10, characterized by that for an accelerated return of the actuator from a switching state to the initial state, the coil ( 22 ) the applied voltage is reversed. [12] Method according to claim 11, characterized by that for the reversal of the voltage parallel to the coil ( 22 ) switched capacitor ( 40 ) is eliminated from the control of the electrodynamic actuator. [13] Method according to any one of claims 9 to 12, characterized by that for an accelerated switching of the actuator from the initial state to a switching state, the voltage at the coil ( 22 ) applied voltage briefly exceeds a nominal voltage of the coil ( 22 ) is raised. [14] Method according to claim 13, characterized bythat for increasing the voltage of the coil parallel to the coil ( 22 ) switched capacitor ( 40 ) is used.

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