WO2015082573A1

WO2015082573A1 - Oscillating valve and method of operating the same

Info

Publication number: WO2015082573A1
Application number: PCT/EP2014/076470
Authority: WO
Inventors: Yves Gamache
Original assignee: Fluid Automation Systems S.A.
Priority date: 2013-12-03
Filing date: 2014-12-03
Publication date: 2015-06-11
Also published as: DE112014005498T5

Abstract

An electromagnetic control valve (10) is provided, as well as a method of purging contaminants in the valve. The electromagnetic control valve (10) includes a housing assembly (12) including a chamber (20) for circulating fluid; at least first and second ports (30, 32) opening in the chamber (20) a solenoid assembly (22) including a solenoid (221). The valve (10) also includes a plunger assembly (24) disposed in the chamber (20). The plunger assembly (24) is magnetically coupled to the solenoid (221) and is movable to interrupt or restrict a flow of the fluid in the chamber (20) upon circulating a current within the solenoid (221). The method includes a step of injecting a fluid in the chamber (20) and of circulating the current in the solenoid (221) to oscillate the plunger assembly (24) within the chamber (20) and successively pressurize and depressurize fluid contained in the chamber (20), thus forcing contaminants to exit the chamber (20).

Description

OSCILLATING VALVE AND METHOD OF OPERATING THE SAME

TECHNICAL FIELD OF THE INVENTION

The technical field relates to proportional solenoid valves, and more specifically to proportional solenoid valves used in analytical systems.

BACKGROUND

A proportional solenoid valve allows controlling a flow of fluid (such as gas) within the valve proportionally to a current circulating in a magnetic coil. A controllable input signal allows closing, opening or varying the aperture of the valve and/or restricting the flow of fluid passing through the valve. Many types of solenoid valves exist for controlling the flow of fluids.

In some of the existing solenoid valves, a current signal is controllably circulated in a coil surrounding a magnet, inducing movement of a plunger toward or away from a valve seat, to close or open the valve. The flow of fluid is typically controlled proportionally to the input current circulated in the coil.

In other solenoid valves, the magnet is fixed and a seal is moved toward or away from the magnet, depending on the current circulating in the coil surrounding the magnet. A permeable membrane allows the seal to move from the closed to the open position. The current input to the solenoid may control the flow of fluid between the inlet and the outlet of the valve.

One of the main disadvantages of existing proportional solenoid valves used in analytical systems, including for example in gas chromatography, is the presence of "dead volumes", i.e. in regions in which fluids can be trapped, within the valves. Dead volumes are often difficult or impractical to purge and impurities may get trapped therein, which often leads to a contamination of the fluid to be analyzed. Such contamination may falsify or skew the results of the analysis. The prevalent method to purge proportional solenoid valves used in analytical systems is to send a continuous flow of gas in the valve. This method rarely allows efficient purging of contaminants trapped in "dead volumes".

Known to the Applicant are US 5,232,196 (HUTCHINGS et a/.); US 6,220,569 (KELLY); US 7,055,798 (OGAWA); and US 8,672,292 (LEISER et al.). Solenoid valves as described above are therefore still subject to several inefficiencies and various challenges still exist in the area of proportional solenoid valves, such as those used in analytical systems. SUMMARY OF THE INVENTION

According to an aspect of the invention, an electromagnetic control valve having a configuration that allows reducing or eliminating contamination problems related to dead volumes is provided.

According to a possible embodiment, the electromagnetic control valve is for analytical systems and, comprises a housing assembly including a chamber for circulating fluid therethrough. At least a first and a second port open in the chamber. A solenoid assembly including a solenoid is also provided. A plunger assembly is disposed in the chamber. The plunger assembly is magnetically coupled to the solenoid assembly and is movable to interrupt or restrict a flow of the fluid in the chamber upon circulating a current within the solenoid. A controlling unit is adapted to control the current in the solenoid to oscillate the plunger assembly within the chamber to successively pressurize and depressurize fluid contained in the chamber.

Preferably, the plunger assembly and the first and second ports are axially aligned.

Preferably, the chamber as a substantially cylindrical configuration. Preferably, the chamber (20) is sized, shaped and configured for limiting entrapment of contaminants in the chamber.

Preferably, the control valve further comprises sensing sections removably connectable to the housing assembly. The sensing sections can include thermal sensor section and/or a pressure sensor section.

In another embodiment, a method of purging contaminants in an electromagnetic control valve is provided. The method includes steps of providing a control valve as described above; of injecting a fluid in the chamber; and of circulating a current in the solenoid to oscillate the plunger assembly within the chamber and successively pressurize and depressurize fluid contained in the chamber, thus forcing contaminants to exit the chamber.

According to possible embodiments of the method, the current oscillating the plunger assembly can be a sinusoidal current or a pulsed DC current. Preferably, the method includes a step of monitoring the contaminants at an output of the outlet port of the control valve, and of oscillating the plunger assembly until a concentration of the contaminant in the fluid exiting said outltet port is below a predetermined threshold.

Other features and advantages of the present invention will be better understood upon reading of preferred implementations thereof, with reference to the appended drawings.

DESCRIPTION OF THE FIGURES

Figs. 1A, 1 B and 1 C are cross-section views of a schematic representation of the electromagnetic control valve, showing the plunger assembly of the valve in different positions, according to a possible embodiment of the valve. Fig. 1 D is an exploded view of some of the components of the electromagnetic control valve (10) of Figs. 1A-1 C.

Figs. 2A to 2E are different graphs of possible input signals circulating in the solenoid, as a function of time, for moving or positioning the plunger assembly in different positions.

Fig. 3 is a graph showing the pressure in the chamber of the valve, as a function of time, for an input signal having a duty cycle of 50%.

Fig. 4A is a schematic representation of an analytical system using a electromagnetic control valve according to a second possible embodiment, the valve in this case being a three-port valve used as a diverter. Fig. 4B is a cross- section of a schematic representation of a electromagnetic control valve, according to the second possible embodiment.

Fig. 5 is a cross-section of an electromagnetic control valve, according to another possible embodiment which, in this case, is configured as a flow controller.

Fig.6 is a cross-section of a schematic representation of an electromagnetic control valve, according to another possible embodiment, the valve being in this case a reluctance-based valve.

DETAILED DESCRIPTION

When used as part of an analytical system, it is important that control valves do not modify the nature of the fluids (typically gases) transiting through them, may it be carrier or sample fluids. Contamination of the analytical fluids passing through the valves may result from leaks, entrapment or retention zones in the valve, or from the inner surfaces of the components of the valve in contact with the fluids. The electromagnetic control valve of the present invention aims to reduce entrapment zones and possible sources of contamination.

Referring to Figs. 1A to 1 C, an electromagnetic control valve 10 is shown, in three different configurations. The control valve 10 comprises a housing assembly 12 including a chamber 20. The housing assembly includes components defining or enclosing, at least partially, the chamber 20. The housing assembly may also comprise seals, joints, nuts, collars, and the likes. In this embodiment, the housing assembly includes a housing having a lateral wall 14 defining the chamber 20. The control valve 10 also comprises a plunger assembly 24, which is controllably movable between two opposite ports 30, 32, to interrupt or restrict the flow of fluid in the chamber 20. The plunger assembly 24 can comprise a ferromagnetic core and any other components related to the core, such as coating layer, an encapsulating body and/or components used to suspend or center the plunger assembly relative to the housing 12.

In Fig. 1A, the first port 30 is closed, while the second port 32 is open; in Fig. 1 B, the plunger assembly 24 is centered in the chamber 20, and both ports 30, 32 are open; and in Fig. 1 C, the first port is open while the second port 32 is closed. In this embodiment, the control valve 10 is a solenoid valve, and the solenoid assembly 22 comprises a solenoid 221 surrounding the chamber 20. The plunger assembly 24 is magnetically coupled to the solenoid assembly 22. In the present embodiment, the plunger assembly 24 can also be referred to an armature.

The first port 30 and the second port 32 are preferably located at opposite ends of the chamber 20. The chamber 20 is sized and configured for limiting entrapment of contaminants in the chamber. In other words, the chamber 20 is preferably free from recesses or nooks in which fluid may be trapped or difficult to purge. The surface of the sidewall of the chamber is thus preferably smooth and regular. Preferably, the chamber 20 has a convex cross-section, and more preferably a circular cross-section. The plunger assembly 24 extends axially in the chamber 20, and can be controllably positioned between the first and second ports 30, 32 by circulating a current within the solenoid 221 . The plunger assembly 24 can also be referred to as a movable member or movable core, and comprises in this particular embodiment a magnet 25. The plunger assembly 24 is preferably axially aligned, or coaxial, with the first and second ports 30, 32. A controlling unit 60 is adapted to modulate and control the current in the solenoid 221 , so as to control movement of the plunger assembly 24 in the chamber 20. The controlling unit 60 is also adapted to oscillate the plunger assembly within the chamber 20, to successively pressurize and depressurize fluid contained in the chamber 20, as will be explained in greater detail below. The controlling unit can be a remote computer, or a device attachable to the housing assembly 12, and provided with a display screen, input means, a memory, a processor and circuitry configured to process the signals from/to the solenoid 221 , but also other information signals, as will be explained in more detail with reference to Fig 5. The controlling unit 60 can reside on a single device or its functions can be divided on more than one physical device.

In this embodiment, the electromagnetic control valve 10 is a two-port valve, the first port 30 being an inlet port, and the second port 32 being an outlet port. The electromagnetic control valve is typically a proportional control valve. The plunger assembly 24 preferably has a substantially cylindrical shape, with first and second opposite extremities 26a, 26b. One or both of the first and second opposite extremities of the plunger assembly 24 can be provided with plugs 43a, 43b respectively facing the seats 42a, 42b of the first and second ports 30, 32. The plugs 43a, 43b are sized, shaped and configured to close the corresponding first or second port 30, 32, depending on the position of the plunger assembly 24 in the chamber 20. The plugs 43a, 43b can be shaped as protrusions protruding from end surfaces of the plunger assembly 24. Of course, the plugs 43a, 43b can be part of an external capsule part of the plunger assembly 24, and enclosing the magnet 25, but other configurations can be considered.

The plugs 43a, 43b are preferably provided with respective soft cushions or pads 46a, 46b, devised to contact the seats 42a, 42b when closing the corresponding port. By "soft" cushion, it is meant that the material used for the cushion is made of a softer material than that of the seats 42a, 42b. The cushions 46a, 46b allow absorbing impact shocks upon closure on the seats 42a, 42b of the corresponding first or second ports 30 or 32. Of course, it is possible to provide the seats 42a, 42b with cushions made out of a softer material than the plugs 43a, 43b and/or extremities 26a, 26b of the plunger assembly 24. Cushions 46a, 46b prevent or limit wear of the port components, which in turn limit undesired leaks of fluid due to improper closure of the ports. The plunger assembly 24 is operatively suspended in the chamber, for example by at least one connector. In the present case, two connectors 34a, 34b are used. The connectors 34a, 34b are shaped and configured such as to allow the armature 24 to move longitudinally in the chamber 20 between the first and second ports 30, 32, without blocking the flow of fluid in the chamber 20. In the embodiment shown in Figs 1A-1 D, the connectors 34a, 34b are first and second permeable flexible connectors respectively connecting the first and second extremities 26a, 26b of the armature 24 to the lateral wall 14 of the housing 12. For this particular embodiment, and as best shown in Fig 1 D, each connector 34a, 34b consists of a flexible disk having a spiraled pattern perforated therein, allowing fluid to pass through it. The connectors 34a, 34b extend radially within the chamber 20, one (34a) being proximate to the inlet coupling 18, the other (34b) being proximate to the outlet coupling 19. Each of the first and second connector 34a, 34b has an outer periphery affixed to or near the lateral wall 14 of the valve and an inner periphery affixed to the extremities of the armature assembly 24, preferably using the plugs 43a and/or 43b. Other configurations and/or other types of connectors can be used, such as permeable membranes affixed at each end of the plunger assembly 24. The plunger assembly 24 can move axially between the inlet and the outlet ports 30, 32 to close, open or vary the distance between the valve seats 42a, 42b and the corresponding ports, so as to control the area available for the fluid to flow through, and therefore to control the flow of fluid passing through the valve. One or both connectors 34a, 34b can also have a resiliency or spring constant, allowing to force the plunger assembly 24 toward one of the ports 30, 32, transforming the port is either a normally-closed or a normally-opened port.

In order to limit dead volumes or entrapment zones in the valve, the chamber

20 has a configuration which avoids or limits entrapment of fluid or of contaminants in nooks or recesses. The solenoid control valve 10 of the present invention has a compact design, with small dimensions, the housing assembly 12 having for example an outer diameter which is less than 20 mm, and preferably less than 10mm. It will be appreciated that the configuration of the valve 10, which in this particular case as a substantially cylindrical configuration, limits possible fluid entrapment regions. The chamber 20 is the only space in which fluid can circulate, and this space can be effectively and rapidly purged between different fluid analyses. Effective purging in turn provides more accurate results than for existing valves, which are subject to trapped impurities.

In order to limit possible contamination of the fluid passing through the valve due to the contact of the fluid with the inner surfaces of the valve's components, the plunger assembly 24 preferably comprises an inert capsule 28, encapsulating the magnet 25, or in other embodiment a ferromagnetic core, such as magnetic iron or steel for example. Alternatively, the ferromagnetic core can be coated with an inert coating, such as with Diamond Light Carbon (DLC).

The electromagnetic control valve can include at least one spring, preferably located between one of the extremities 26a or 26b of the plunger assembly 24 and the corresponding first or second port 30, 32. The one or more spring 44a and/or 44b has a spring constant selected to form a normally closed or normally open port. By "springs", it is meant any spring or similar device having a resiliency or spring constant. For example, the springs can consist in Belleville washers. In the embodiment of Fig. 1A to 1 C, two springs 44a, 44b are used, at each end of the housing assembly 12, to damp movement of the plunger assembly 24 as it approaches the port 30 or 32. The springs can also be selected so as to assist the motion of the plunger assembly 24 in one direction. Depending on the type of springs and on their force constant, the springs 44a, 44b can force the valve 10 either in a "normally-closed" (NC) or "normally-opened" (NO) position when there is no current passing through the coil 22. The springs 44a, 44b allow reducing or eliminating shocks on the valve seats 42a, 42b, which in turn increases the operational life of the valve 10. The springs 44a, 44b also assist the oscillation of the plunger assembly 24 within the chamber 20, reducing the energy consumption of the valve 10.

The valve 10 preferably comprises first and second couplings 18, 19, which are preferably removably connected at each end of the housing assembly12. Each coupling 18 or 19 comprises a first side provided with a tube receiving end and a second side which can include the first or second port 30 or 32, or at least be in fluid communication with the ports 30, 32. In the embodiment shown in Figs. 1A- 1 C, the couplings 18, 19 are threadably connected to the lateral wall 14 of the housing assembly 12, but other types of connection can be considered, such as a snap-fit connection. The couplings may also be connected to the housing assembly 12 via other components, such as nuts or soldered joints. The couplings 18, 19 each have a tube receiving end, configured to threadably connect a tube (typically a capillary tube), and a port end, the port end interfacing with the chamber 20, directly or indirectly. In the present embodiment, the couplings 18, 19 comprise valve seat 42a or 42b. A channel connects the tube receiving end with the port end. It is possible for the first and second couplings 18, 19 to have different port diameters. Other types of couplings can also be connected to the housing assembly 12, in addition to or in replacement of the couplings 18, 19, as will be explained with reference to Fig 5.

Still referring to Figs. 1A-1 D, but also to Figs. 2A-2E, the valve 10 can be operated in different operating modes. In a first mode of operation, the input current in the coil has a fixed frequency, and the duty cycle D is modulated between 0 and 100%. The driving signal is in this case a Pulse-Width Modulation signal (PWM). Fig. 2A shows an example of a DC input signal with a 50% duty cycle, resulting in the armature oscillating between the first and the second ports 30, 32. When there is no current, as per Fig. 2B, the position of the plunger assembly 24 depends on whether or not springs are present in the valve 10, on their location (on one vs. on both sides of the valve) and on the type and force of the springs. Referring to Fig. 2C, a "closing signal" is circulated in the coil, resulting in the armature 24 closing the discharge port 32. If the port 32 is in the closed position when the duty cycle is 100% (D=100%), it will be in an open position at D=0%. In Fig. 2D, an "open signal" (inverted relative to the signal in Fig. 2C) is circulated in the coil, thereby maintaining the armature such that its plunger 43a closes port 30. In this mode of operation, a port in the open position at D=100% will be in a closed position at D=0%. With a control valve of the invention, for example configured such as shown in Figs 1A to 1 D, a pulsed signal can be circulated in the solenoid to drive the opening of the valve 10, while the action of the spring(s) 44a, 44b allows the closing of the valve 10. Advantageously, this variant of the valve 10, in which the springs assist in closing the ports, has low power consumption. The current signal pulsed in the solenoid 22 controls the time during which the plunger assembly 24 is moved, as well as the force (proportional to the intensity of the current) to move the plunger assembly 24. Extremities 26a, 26b of the plunger assembly 24 can thus be just slightly moved away from the seats 42a, 42b, or alternatively be moved at a greater distance from the valve seats 42a, 42b. In another mode of operation, a sinusoidal signal can be used instead of a DC signal. In some implementations, the wave amplitude can be fixed, while the frequency is variable. By varying the frequency, a variable restriction at the ports 30, 32 is obtained. The extremities 26a, 26b, which are preferably provided with soft cushions or pads 46a, 46b, do not necessarily need to touch/close the orifice of the ports 30, 32. By approaching or moving the plunger assembly 24 away from the corresponding ports 30, 32, the flow within the valve 10 is controlled. This operation mode is especially adapted for small diameter valve, i.e. with a chamber having a diameter of less than 10 mm.

Electromagnetic control valves used in analytical systems must often be purged of contaminants or impurities, such as between successive analyses of different gases. A common practice for purging proportional control valves is to have gas injected at a constant flow. However, it has been found that injecting a fluid in the chamber and successively pressurizing and depressurizing a volume of fluid in the valve forces contaminants to exit the chamber, resulting in an efficient method of purging a proportional valve. Efficient purging allows saving set-up time in between successive analyses, and allows reducing the presence of long "trails" of contaminants or impurities in the fluid to be sampled and/or analyzed.

The purging method will be described in more detail with reference to Figs. 1 A-1 D and also Fig. 3. According to a possible implementation, the outlet port 32 is closed and the inlet port 30 is open, and a pressurized fluid is injected in the chamber 20 which is filled with the fluid. The inlet port 30 is then closed, thus opening the outlet port 32, and the fluid present in the chamber 20 is discharged out of the valve from the outlet port 32, the outlet port having a lower pressure than the fluid in the chamber 20. The process is successively repeated for at least a few oscillations of the plunger assembly. Oscillating the plunger assembly 24 in the chamber 20 provides an efficient means of purging the valve 10. The fluid to be purged, which may comprise contaminants such as air or other gases, is located in the chamber 20 and around the plunger assembly 24. This fluid is firstly diluted by closing the inlet port 30 and opening the outlet port 32, thereby depressurizing the chamber 20; and, secondly, by opening the inlet port 30 and closing the outlet port 32, thereby further pressurizing the chamber 20. These two steps are then performed repeatedly for effectively purging the valve 10. Fluids such as air and/or other contaminants likely to stagnate around the plunger assembly are thus evacuated by successive dilutions of the volume of fluid present in the chamber 20. Such method of varying the pressure within the valve 10 is more efficient to purge fluid than if a constant pressure was used. This possible mode of operation of the solenoid valve 10 offers many advantages, since the valve 10 is rapidly purged after being in contact with a contaminant and can be subsequently used again for fluid analysis or other purposes. When the valve 10 is purged by successive oscillations, a discrete fluid volume is transferred in and out of the chamber 20 at each cycle corresponding to the opening and closing of the inlet and outlet ports 30, 32. The flow of fluid may also be controlled with both inlet and outlet ports 30, 32 in an open position and by controlling the gap between extremities 26a, 26b of the plunger assembly 24 and the corresponding inlet or outlet ports 30, 32. In this variant of the purging process, the plunger assembly 24 is oscillated by successively approaching the plunger assembly near the first and second ports 30, 32 to restrict the flow of fluid, without closing the first and second ports. The current circulated in the solenoid by the controlling unit to oscillate the plunger assembly can be a DC or a sinusoidal current.

The purging process can further comprise a step of monitoring the presence of contaminant(s) or impurity(ies) at the output of the outlet port 32, while oscillating the plunger assembly 24 in the chamber 20, until the concentration of the contaminant(s) in the fluid exiting said outlet port 32 is below a predetermined threshold.

Referring to Figs. 4A and 4B, the present valve can optionally be used as a diverter or 3-way switching valve. In this embodiment of the control valve 10, a third port 33 opens in the chamber 20. This third port 33 is located between the first and second ports 30, 32, this embodiment of the electromagnetic control valve being a three-way valve. The third port 33 can thus be used as an inlet port and the first and second ports 30, 32 are used as outlet ports. The third port 33 is preferably part of a coupling 21 , similar in function to the couplings 18 and 19.

Such a diverter or 3-way switching valve is very useful in multidimensional chromatography (GCxGC), as it can switch at 1 kilocycle, i.e. close and open each of the valve outlets 30, 32 up to about 1000 times per second. This fast switching speed is attainable because of the small mass and small diameter of the valve, having an outer diameter which is typically less than 20mm. The diameter of a diverter or 3-way switching valve may be as small as an eighth of an inch or approximately 3.2mm. In some embodiments, the diverter or 3-way switching valve may also feature two separate coils 223, 224, each of the coils being controlled by either one current input or two separate current inputs, operatively linked to a controlling unit 60. It is also to be noted that such a valve typically has a very small internal volume, and there is very little space between the plunger assembly 24 and the lateral wall 14. In some embodiments, the radial distance between the plunger assembly 24 and the lateral wall 14 is of about 1 mm. This small space allows for very low flows with very little accumulation in the chamber 20.

Referring to Fig. 5, different types of functional sections 50 can be connected to the housing assembly 12 of the valve, allowing to configure the valve according to different application needs, without having to change the core of the valve. These functional sections comprise different types of sensors, such as pressure, temperature or flow sensors, operatively connectable to the control unit 60. The sections 50 preferably have an annular shape similar to that of the housing assembly 12, and are threadably connectable at each end of the assembly 12. The sections50 are also preferably connectable to other similar sections. The control valve 10 can thus optionally include flow sensors and proportional-integral- derivative (PID) loops. For example, a pressure sensor section 52, comprising a pressure sensor or temperature sensor 48 operatively connected to the controlling unit 60, can be removably connected at one end of the housing assembly 12, such as between the chamber 20 and an end coupling comprising a tube receiving end. Preferably, the pressure sensor section is shaped and configured as an annular coupling, threadably connectable to the housing 12 of the valve. Alternatively, nuts can be used to the connect the different sections. Alternatively, or in addition to the pressure sensor section 52, a thermal sensor section 56, comprising a temperature sensor 49, can be connected to the housing 12.

The pressure and/or flow sensors sections 52, 56 are used at the output of the valve, in conjunction with an electronic circuit part of the controlling unit 60, to transform the valve in a flow or pressure control module. A flow sensor can be, for example, a thermal conductivity mass flow sensor. Every section 50 of the valve 10 is preferably screwed together and sealed with a radial shaft seal (lip seal) or a metal seal. Similar annular sections can be connected at the input end of the valve as well. A flow section 54, or a discharge adapter, can be removably connected at the inlet and/or the outlet ports 30, 32 and are linked together by seals 58. By connecting an annular section having a pressure sensor 48 and a capillary orifice, the control valve 10 is transformed into a flow controller.

In other implementations, the electromagnetic control valve 10 can further comprise a position sensor 48 operatively connected to the control unit 60, to detect a position of the plunger assembly 24, the control unit 60 controlling the current in the solenoid based on the position of the assembly 24. The position of the armature 24 is monitored, for example with a position detector 48, so as to control its acceleration or deceleration when moving towards or away from one of the valve seats 42a, 42b. This configuration avoids repetitive shocks between the soft cushions or pads 46a, 46b and the valve seats 42a, 42b, and results in the valve seats 42a, 42b being less damaged overtime. With an appropriate electronic circuit, a control algorithm and a feedback loop for controlling the position of the moving core (such a Hall Effect sensor), movement of the armature assembly 24 is anticipated and its speed is lowered when the plungers 43a, 43b are close to the corresponding inlet or outlet seats 42a, 42b and/or inlet or outlet ports 30, 32, so as to avoid a potentially damaging collision. A valve with a longer operational life span is essential for use in applications such as capillary chromatography or multidimensional chromatography (GCxGC). In such applications, it is typical to operate with small volumes and/or low flows, and dead volume effects tend to broaden chromatography peaks, which is undesirable. By limiting damaging shocks and continually purging the chamber by repetitive pressurization/depressurization cycles, chromatography peaks are narrowed and the operational life span of the valve is increased. Such valves are also usable in analytical electronic pressure or flow regulator modules, as micro-valves for vials or pipette dispensers in life sciences or as general instrumentation.

As can be appreciated, different functional sections 50 can be connected to the housing assembly 22 of the control valve 10. In some implementations, an outlet volume buffer section is installed at the outlet port 32 and acts as a low pass filter. The size of the outlet port 32 may also be adjustable so as to obtain different valve flow capacity ratings (flow coefficient C_v). When the outlet volume buffer is installed in series with the outlet port, an RC-like filter is obtained. In other implementations, the valve 10 may have an inline configuration or a perpendicular/vertical valve configuration, depending on the manifold on which they are to be fitted. The mass of the plunger assembly 24 can be changed or adapted as needed. Depending on the mass of the plunger assembly 24, the input signal frequency will advantageously be chosen. For example, an armature with a higher mass will require an input signal of a lower frequency, whereas an armature with a lower mass will require an input signal of a higher frequency.

Referring now to Figure 6, another possible embodiment of the electromagnetic valve 10 is shown. In this case, the control valve is a reluctance- based valve. The housing assembly 12 includes a housing 225, having a lateral wall 14 defining, at least partially, the chamber 20. The housing 225 is preferably cylindrical and made of a ferromagnetic material, such as magnetic steel, and forms part of the magnetic circuit used to actuate the plunger assembly 24. First and second ports 30, 32 open in the chamber 20. The solenoid assembly 22 comprises a solenoid 221 and a fixed magnetic core 222. In this embodiment, the core 222 forms part of the inlet coupling 18, but other configuration can be considred. The solenoid 221 is operatively connected to a controlling unit 60, which controls the current circulating in the solenoid 221 , as previously described. The plunger assembly 24 is disposed in the chamber 20, and comprises a magnetic core 240 magnetically coupled to the solenoid assembly 22. A resilient connector 34b is used to center and suspend the plunger assembly 24 is the chamber 20. The resilient connector 34b can act as a spring to force either one of ports 30, 32 is a closed position. The core 240 is preferably shaped as a cylindrical disk. The plunger assembly has opposite extremities 26a, 26b facing the respective ports 30, 32. The plunger assembly 24 preferably includes soft cushions 46a, 46b. A plug 43b can be provided at the second extremity 26b of the assembly 24. While in this embodiment the plug 46b is a distinct component, it is possible to form plug 43b integrally in the core 240. The plunger assembly 24 is movable to interrupt or restrict a flow of the fluid in the chamber 20 upon circulating a current within the solenoid 221 . Similar to the other embodiment, a controlling unit 60 adapted to control the current in the solenoid 221 to oscillate the plunger assembly 24 within the chamber 20 to successively pressurize and depressurize fluid contained in the chamber 20. In the present embodiment, a coupling 18 is affixed at one end of the housing assembly 12. The coupling 18 can be soldered to the inner surface of the lateral wall 24; however, other types of connections are possible. The coupling 18 has a tube receiving end and a port end. A channel 180 connects the receiving end to the port end. In this embodiment, the coupling 18 has a body portion extending in the housing assembly 12, and is surrounded by the coil 221 . In other configuration, it is possible for the coupling to extend only partially in the housing assembly 12. In this case, the plunger assembly 24 would be longer and be partially surrounded by the coil 221 .

A coupling 19 is also provided at the other end of the housing assembly 12.

The coupling 19 is affixed to component 225 via a nut 190. Advantageously, the coupling 19 is removably connected to the housing assembly 12, and can be replaced with another similar coupling 19 having an opening of a different diameter. In this embodiment, the valve 10 includes an interfacing component 121 , disposed in the housing assembly 12 between plunger assembly 24 and the second coupling 19. Component 121 has first and second opposite sides. The first side has an orifice facing the second extremity 26a of the plunger assembly 24. The second side has a nozzle facing the port end of the coupling 19. Interfacing component 121 is preferably made of stainless steel. The orifice and the nozzle are connected by a channel extending axially in component 121 . Of course, seals are preferably provided at the interface of the main components forming the valve, such as seal 192 provided between coupling 19 and component 121 . The present embodiment of the valve advantageously allows reducing the size and weight of the movable assembly 24, and is thus particularly adapted for low-energy consumption and/or low-flow applications. This configuration of the valve can be used with the different sections 50 described in relation with Fig. 5.

The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.

Claims

1 . A method of purging contaminants in an electromagnetic control valve (10) part of an analytical system, the method comprising the steps of:

a) providing the electromagnetic control valve (10) including:

- a housing assembly (12) comprising:

- a chamber (20) for circulating fluid therethrough,

- at least first and second ports (30, 32) opening in the chamber (20); and

- a solenoid assembly (22) comprising a solenoid (221 ) ;

- a plunger assembly (24) disposed in the chamber (20), the plunger assembly (24) being magnetically coupled to the solenoid assembly (22) and being movable to interrupt or restrict a flow of the fluid in the chamber (20) upon circulating a current within the solenoid (221 ); b) injecting a fluid in the chamber (20); and

c) circulating the current in the solenoid (221 ) to oscillate the plunger assembly (24) within the chamber (20) and successively pressurize and depressurize fluid contained in the chamber (20), thus forcing contaminants to exit the chamber.

2. The method according to claim 1 , wherein in step a), the chamber (20) is sized, shaped and configured for limiting entrapment of contaminants in the chamber (20).

3. The method according to claim 1 or 2, wherein in step a), the first and second ports (30, 32) are located at opposite ends (16a, 16b) of the chamber (20), the plunger assembly (24) extending in the chamber (20) and having first and second extremities (26a, 26b) respectively facing the first and second ports (30, 32).

4. The method according to any one of claims 1 to 3, wherein in step a), the chamber (20) is substantially cylindrical and the plunger assembly (24) extends axially in the chamber (20).

5. The method according to any one of claims 1 to 4, wherein in step a), the electromagnetic control valve (10) comprises a spring (44a or 44b) assisting oscillation of the plunger assembly in one direction.

6. The method according to any one of claims 1 to 5, wherein in step c) the current is a sinusoidal current.

7. The method according to any one of claims 1 to 6, wherein in step c) the current is a pulsed DC current.

8. The method according to any one of claims 1 to 7, wherein in step c), the plunger assembly (24) is oscillated by successively approaching the respective first and second extremities 26a, 26b near the first and second ports (30, 32) to restrict the flow of fluid, without closing the first and second ports (30, 32).

9. The method according to any one of claims 1 to 8, further comprising a step of monitoring the contaminants at an output of one of said at least first and second ports (30 or 32), and conducting step c) until a concentration of the contaminant in the fluid exiting said one port (30 or 32) is below a predetermined threshold.

10. An electromagnetic control valve (10) for analytical systems, comprising:

- a housing assembly (12) comprising:

- a chamber (20) for circulating fluid therethrough,

- at least first and second ports (30, 32) opening in the chamber (20); and

- a solenoid assembly (22) comprising a solenoid (221 ) ;

- a plunger assembly (24) disposed in the chamber (20) the plunger assembly (24) being magnetically coupled to the solenoid assembly (22) and being movable to interrupt or restrict a flow of the fluid in the chamber (20) upon circulating a current within the solenoid (221 ); and

- a controlling unit (60) adapted to control the current in the solenoid (221 ) to oscillate the plunger assembly (24) within the chamber (20) to successively pressurize and depressurize fluid contained in the chamber (20).

1 1 . The electromagnetic control valve (10) according to claim 10, wherein the chamber (20) is sized and configured for limiting entrapment of contaminants in the chamber (20).

12. The electromagnetic control valve (10) according to claim 10 or 1 1 , wherein the housing assembly (12) comprises opposite first and second ends, the valve (10) comprising first and second couplings (18, 19), each of said couplings (18, 19) comprising a first side provided with a tube receiving end and a second side comprising or being in fluid communication with one of the first and second ports (30, 32).

13. The electromagnetic control valve (10) according to claim 12, wherein at least one of the first and second couplings (18, 19) is removably connected to the housing assembly (12).

14. The electromagnetic control valve (10) according to claim 12 or 13, comprising an interfacing component (121 ) disposed in the housing assembly (12) between plunger assembly 24 and the second coupling (19), said interfacing component comprising first and second opposite sides, the first side comprising an orifice facing the second extremity (26a) of the plunger assembly (24) and the second side comprising a nozzle facing the coupling (19), the orifice and the nozzle being connected by a channel extending axially in the interfacing component (121 ).

15. The electromagnetic control valve (10) according to any one of claim 12 to

14, further comprising a thermal sensor section (49) removably connected at one of said first and second end of the housing assembly (24), between the chamber (20) and the corresponding first or second coupling (18 or 19).

16. The electromagnetic control valve (10) according to any one of claims 12 to

15, further comprising a pressure sensor section (48) removably connected at one of said first and second end of the housing assembly (24), between the chamber (20) and the corresponding first or second coupling (18, 19).

17. The electromagnetic control valve (10) according to any one of claims 10 to 16, wherein the first port (30) is an inlet port and the second port (32) is an outlet port.

18. The electromagnetic control valve (10) according to any one of claims 10 to

17, further comprising a third port (33) opening in the chamber (20), located between the first and second port (30, 32), electromagnetic control valve (10) being a three-way valve, said third port (33) being an inlet port and said first and second ports (30, 32) being outlet ports.

19. The electromagnetic control valve (10) according to any one of claims 10 to

18, further comprising a plunger assembly position sensor operatively connected to the controlling unit (60), to detect a position of the plunger assembly (24), the controlling unit (60) controlling the current in the solenoid (221 ) based on the position of the plunger assembly (24).

20. The electromagnetic control valve (10) according to any one of claims 10 to

19, wherein the plunger assembly (24) has first and second opposite extremities, and the first and second ports have first and second valve seats (42a, 42b), respectively, the plunger assembly (24) comprising at least one plug (43b) facing the second valve seats (42a, 42b), the at least one plug (43b) being configured to close the corresponding first or second ports (30 or 32).

21 . The electromagnetic control valve (10) according to any one of claims 10 to 20, wherein the plunger assembly (24) comprises soft cushions (46a, 46b) absorbing impact shocks upon closure of the corresponding first or second port (30, 32).

22. The electromagnetic control valve (10) according to any one of claim 10 to 21 , comprising at least one flexible connector (34b) operatively connecting the plunger assembly to the housing, said at least one connector (34b) being shaped and configured to allow the plunger assembly to move axially in the chamber (20) between the first and second ports (30, 32).

23. The electromagnetic control valve (10) according to any one of claims 10 to

22, wherein the plunger assembly (24) comprises a core made of a ferromagnetic material.

24. The electromagnetic control valve (10) according to any one of claims 10 to

23, wherein the plunger assembly (24) comprises a magnet (25) and an inert capsule (28) or an inter coating surrounding the magnet (25).

25. The electromagnetic control valve (10) according to any one of claims 10 to 24, wherein the solenoid assembly (22) comprises a fixed ferromagnetic core (222).

26. The electromagnetic control valve (10) according to any one of claims 10 to 25, comprising at least one spring (44a) disposed between one of the extremities of the plunger assembly (24) and the corresponding first or second port (30, 32), said at least one spring (44a) having a spring constant selected to form a normally closed or normally open port.