WO2011144642A1

WO2011144642A1 - Piezo electric controlled high-pressure valve and method for controlling a high-pressure valve

Info

Publication number: WO2011144642A1
Application number: PCT/EP2011/058009
Authority: WO
Inventors: Göran Cewers
Original assignee: Mindray Medical Sweden Ab
Priority date: 2010-05-17
Filing date: 2011-05-17
Publication date: 2011-11-24
Also published as: EP2572129A1

Abstract

A system and a method are described for converting a small motion from a piezoelectric actuator to a larger motion in a valve mechanism (118). A piezoelectric actuator (113) is connected in series to a mechanical amplifier (119), a mechanical temperature compensation element (114), a mechanical fine tuning element (115), all acting in the same effective direction as the piezoelectric actuator.

Description

TITLE: PIEZO ELECTRIC CONTROLLED HIGH-PRESSURE VALVE AND METHOD FOR

CONTROLLING A HIGH-PRESSURE VALVE

Field of the Invention

The disclosure pertains in general to the filed of piezoelectrically controlled valves and a method of converting a small motion, preferably from a piezoelectric actuator, to a larger motion which may control a valve mechanism. Even more particularly the disclosure relates to the controlling of a high pressure valve device but could also be applied for a low pressure valve device.

Background of the Invention

As new technological advances are made, above all in the field of piezoelectric ceramics, piezo ceramics are being increasingly used in actuator applications where they are superseding electromagnetic solutions. The reason is that the force relative intrinsic mass is approximately ten times greater with piezoelectric ceramic techniques compared with electromagnetic techniques. One example where electromagnets have been replaced by piezoactuators are fuel injection valves in the car industry. This has led to a new generation of car engines with lower fuel consumption and emissions. The reason is that piezoactuator technology makes it possible to control fuel injection almost to the millisecond for each piston stroke.

Unfortunately replacing electromagnets with piezoactuators is not entirely straightforward, as extremely little amplitude of movement is generated by the latter, even if the force is great. Thus the motion generated by piezoactuators must be amplified. Moreover, piezoelectric actuators have extremely low thermal expansion coefficients, which at first sight may seem an advantage, but it is a problem as the surrounding material acting as mechanical reference point to the piezoelectric actuator must also have an extremely low thermal expansion coefficient. Very few materials possess this property, especially if there are also claims for processivity, corrosion, price, durability etc. Yet another issue with the piezo ceramic technology is that the tolerances of the parts are often several times larger than the motion amplitude they are able to create. This demands high requirements for mechanical fine tuning, i.e. trimming.

Even if extremely large forces are generated by piezoelectric actuators, it should be noted that the motion is extremely small. Any amplification of motion results in an equivalent reduction in force. For this reason, a high pressure valve should be designed so that the inlet pressure has as little impact as possible on the valve seat. In US patent 5,265,594 a high pressure valve is disclosed having a valve mechanism at the end of a tube with a spring tensioned soft seat pressing against the tube end. The cross-sectional area of the entire tube will contribute to a force caused by the inlet pressure, a force which the abovementioned spring must resist, and a force which the electromagnet must overcome. As a result a large, strong, expensive and energy-guzzling electromagnet is needed in this design.

One object of the invention is thus to provide an valve device and a method for controlling the valve device to eliminate the abovementioned technical issues related to tolerances of particular elements, differences in material properties (e.g. thermal expansion), amplification of a small movement. Particularly the invention provides a piezo-electrically controlled high pressure valve with a small dependency on the inlet pressure.

Summary of the Invention

These objectives are met by means of the device and the method in accordance with in the appended independent claims, while particular embodiments are dealt with in the dependent claims.

Accordingly, embodiments of the present invention seek primarily to mitigate, alleviate or eliminate one or more of the above-identified deficiencies or disadvantages in the art, singly or in any combination, and solve at least partly the abovementioned issues by providing a device and method according to the appended patent claims.

According to a first aspect of the invention, an actuator controlled high pressure valve is provided with a valve inlet and a valve outlet. The high pressure valve comprises a piezoelectric actuator, a mechanical amplification element and a valve mechanism acting on a valve seat. The actuator, the mechanical amplifier element and the valve mechanism are arranged along a common axis. The actuator is designed to generate a motion for controlling the valve mechanism and the mechanical amplifier element is arranged to amplify the motion of the actuator to the valve mechanism's closing or opening motion.

This high pressure valve design allows one to exploit the advantages of piezo technology as opposed to e.g. electromagnetic technology. But one also avoids the issues which are still associated with the small movements of piezoactuators and their low thermal expansion coefficients.

This solution is in one embodiment provided by connecting at least one actuator unit in series to at least one mechanical amplifier element which boosts the actuator unit's amplitude, which can then control a valve to open or close.

In yet another embodiment of the invention, the actuator controlled high pressure valve comprises a first flow resistance element which is positioned between the valve seat and the valve outlet. The flow resistance element is used here to equalize the pressure of the flow, among other things by helping to prevent turbulence and increasing the dynamic flow range. It can also be used together with a differential pressure gauge as a flow meter element.

In another embodiment of the actuator controlled high pressure valve, the differential pressure gauge is connected upstream and downstream of the flow resistance element respectively.

In this design, the differential pressure becomes a signal which can be linearized and compensated for pressure, fluid type and temperature to obtain a measure of fluid flow. Such extra parameters can be measured and the measurement data used to linearize the flow values.

In yet another embodiment of the actuator controlled high pressure valve, at least one other flow resistance element is placed downstream of the first flow resistance element.

This second flow resistance element has the same function as the first, i.e. to equalize the fluid pressure through the channel and prevent turbulence and increase the dynamic flow area, or be used as a flow measurement element. Here the flow resistance elements may take the shape of a cylindrical tube or a cone. The device may also be designed so that the flow channel downstream of the outside of the first flow resistance element decreases in width.

In another embodiment of the actuator controlled high pressure valve, at least one thermal expansion element 114 is connected in series to the actuator.

This additional unit is used to adjust the actuator in order to compensate for temperature dependent expansion of surrounding design elements.

In another embodiment of the actuator controlled high pressure valve, at least one mechanical fine tuning element 115 is connected in series to the actuator.

The mechanical fine tuning element is used to correctly adjust the stroke length of the actuator relative to the other units of the design. This is extremely important, since the tolerance of piezoactuators is often several times higher than the motion amplitude they can generate.

Another aspect of the invention comprises a method for controlling a high pressure valve where all included components are connected in series along a common axis. The method comprises the valve being controlled by a piezoelectric actuator with a stroke length which is amplified by a mechanical amplifier element to a valve mechanism acting on a valve seat. The method also comprises generating a motion with the actuator, transmitting the motion to the mechanical amplifier element and controlling the valve mechanism with the amplified motion to a closing or opening motion in the valve mechanism. If needed, the method may comprise fine tuning the valve with a mechanical fine tuning element and temperature compensating the motion with a thermal expansion element. The advantages of this method is, as for the equipment described above, that it is a simple and inexpensive way of exploiting, preferably, piezoactuators and their advantages in controlling a high pressure valve while at the same time solving issues associated with piezoactuators.

Further embodiments of the invention are defined in the dependent claims, wherein features for the second and subsequent aspects of the invention are as for the first aspect mutatis mutandis.

It should be emphasized that the term "comprises/comprising" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

Brief Description of the Drawings

These and other aspects, features and advantages of which the invention at least is capable of will be apparent and elucidated from the following description of embodiments of the present invention, reference being made to the accompanying:

Figure 1 , which in a schematic view is showing an exemplary embodiment of a piezoelectric valve;

Figure 2, which in a schematic view is showing an exemplary embodiment of a piezoelectric valve;

Figure 3, which in a schematic view is showing an exemplary embodiment of a temperature compensation means;

Figure 4, which in a schematic view is showing an exemplary embodiment of a temperature compensation means;

Figure 5, which in a schematic view is showing an exemplary embodiment of a trimming device;

Figure 6, which in a schematic view is showing an exemplary embodiment of a trimming device connected in series with a temperature compensation means;

Figure 7, which in a schematic view is showing an exemplary embodiment of a part of a mechanical motion amplifier and 4 mechanical motion amplifier parts connected in series;

Figure 8, which in a schematic view is showing an exemplary embodiment of a part of a mechanical motion amplifier and 6 mechanical motion amplifier parts connected in series;

Figure 9, which in a schematic view is showing two exemplary embodiment of driver circuits ;

Figure 10, which in a schematic view is showing an exemplary embodiment of a flow measuring device; Figure 11 which in a schematic view is showing an exemplary embodiment of a flow measuring device;

Figure 12, which in a schematic view is showing an exemplary embodiment of a flow restriction element; and

Figure 13 which in a schematic view is showing an exemplary embodiment of a flow restriction element.

Description of the Preferred Embodiments

These and other aspects, features and advantages of which the invention at least is capable of will be apparent and elucidated from the following description of embodiments of the present invention, reference being made to the accompanying drawings, in which:

Fig. 1 shows an exemplary embodiment of a piezoelectric controlled valve device.

From the outside, the valve comprises a tube 10 with an inlet channel 101 , outlet channel 102 and a fine tuning screw 50 which is part of a mechanical fine tuning element 115.

Inside tube 10, there is a mechanical fine tuning element, mechanical temperature compensation element 114, a piezoactuator 113 enclosed by pre-tension tube 112, buffer disc 123, mechanical motion amplifier 119, valve mechanism 118, valve seat 15 and a fluid permeable body 18 (e.g. a flow restrictor, such as a net) in series.

Additionally and/or alternatively, the fluid permeable body 18 may be positioned in a volume reducing tube 17, having narrowed down flow channel 122. The volume reducing tube 17 may in conjunction with the fluid permeable body provide a flow channel 122 with a relatively large surface of the flow restrictor, which at the same time has a small volume between the flow restrictor and the inner wall of the volume reducing tube 17, i.e. a decrease of the cross-section of the flow channel downstream of the volume reducing tube 17.

Mechanical fine tuning element 115 is fastened in tube 10 with spring ring 117 and is sealed from the surroundings with O-ring 116.

Buffer disc 123 acts as a sealing washer and as a moveable element between piezoactuator 113 and the high pressure cavity 100. The O-rings 110 and 111 act as seals against tube 10 and flexible elements for the motion of buffer disc 123. A ventilation channel 19 runs through tube 10 to the space between O-rings 110 and 111.

The mechanical amplifier 119 is exposed to a motion from buffer disc 123 which presses it against foundation disc 120. A compensation membrane 16 is trapped between foundation disc 120 and flow channel disc 14. The outer edge of the compensation membrane is fastened in valve mechanism 118.

Flow channel disc 14 has flow channels 13, 121 to the interior of the flow channel disc's outer part 12 which holds the soft valve seat 15. The flow channels 13, 121 are connecting the high pressure cavity 100 with the narrowed-down channel 122.

Parts 120, 12, 14, 15 and tube 10 are mechanically permanently connected with each other.

There is a gas permeable tube 18 trapped between flow channel disc 14 and end piece 11.

There is a volume reducing tube 17 with a conically shaped interior between the tube 10 and the gas permeable body 18. The volume reducing tube 17 may be an integral part of tube 10.

The function of ventilation channel 19 is that upon leakage from high pressure cavity 100 past O-ring 110, the gas should leak out through the ventilation hole 19. Thanks to ventilation hole 19, the O-ring 111 is not exposed to high pressures, thus leakage from the high pressure cavity is prevented up to piezoactuator 113. This may, for example, be advantageous in explosion-sensitive environments where it is important that the piezoactuator does not come in contact with the surroundings, or for preventing moist gas leaking into the actuator.

In operation the device functions as follows. A voltage applied to piezoactuator 113 causes it to expand and the actuator continues to move up to buffer disc 123, which then presses the mechanical amplifier 119 against the foundation disc 120. The valve mechanism 118 is then raised from valve seat 14 with the actuator motion multiplied by the amplification of mechanical amplifier 119. Gas then flows through the flow channels 13, 121 of flow channel disc 14 down into the narrowed- down channel 122 and then on through gas permeable body 18. A differential pressure gauge, not shown in the figure, is connected to channel 122 and under gas permeable body 18 respectively. The differential pressure is then converted to a signal which may be linearized and compensated for pressure, gas type and temperature to provide a measure of the gas flow.

In order to reduce the differential pressure during high flows, the inside of gas permeable body 18 may be lined with a foil with slit openings. This may reduce the flow resistance caused by turbulence in large flows, which will provide increased dynamic flow range.

Additionally and/or alternatively, the reduce flow resistance caused by turbulence in large flows will increase the dynamics of the flow measurements.

In the closed state, the inlet gas pressurises high pressure cavity 100 and also the top of compensation membrane 16. Since the connection between mechanical amplifier 119 and valve mechanism 118 comprises narrow linking elements. At high pressures in the closed position, the inlet gas endeavours to leak between valve mechanism 118 and valve seat 15. However, at the same time the pressure gives rise to a force above compensation membrane 16 which presses valve mechanism 118 harder against valve seat 15. This prevents leakage when inlet pressures are high. This allows the power, size and the price of the actuator to be reduced.

In yet another embodiment of the invention, the actuator controlled high pressure valve comprises a first flow resistance element which is placed between the valve seat and the valve outlet, such as flow measurement net 18.

The first flow resistance element is used here to equalize the pressure of the flow, among other things by assisting to prevent turbulence and increasing the dynamic flow range. It can also be used together with a differential pressure gauge as a flow meter element.

In yet another embodiment of the actuator controlled high pressure valve, at least one other flow resistance element (not shown) is placed downstream of the first flow resistance element.

This second flow resistance element has the same function as the first, i.e. to equalize the fluid pressure through the channel and prevent turbulence and increase the dynamic flow range, or to be used as a flow measurement element. Here the flow resistance element may take the shape of a cylindrical tube or a cone. The device may also be designed so that the flow channel downstream of the outside of the first flow resistance element decreases in width.

The principles described above are beneficial in combination with actuators with a small range of motion. Moreover in the case of piezoactuators, combinations may be made with other actuators such as electrostrictive, thermal or chemical ones.

Additionally and or alternatively, the actuator unit may be controlled by a driver circuit being a bucket-boost regulator (not shown). The actuator may be a capacitive element acting as a capacitor in the end stage of a boost regulator. By adding extra switch functions and by using an inductor with several windings the boost regulator can be combined with a buck regulator to provide charging of the capacitive element with energy recovery.

Additionally and/or alternatively, the driver circuit may be a bipolar buck-boost converter, whereby a capacitive element can be charged with both positive and negative voltages. The capacitive element is discharged with the abovementioned energy recovery and feedback to the device power supply

More detailed descriptions of the preferred mechanical trimming device, mechanical temperature compensation means, flow resistance element, flow meter element and driving circuit follows. Fig. 2 is an exemplary embodiment of a low pressure valve controlled by an actuator unit. In this example, piezo-actuator 90 is encapsulated in the actual flow channel by a valve body 82 being a housing. The movable disc 88 or ring is moved using the mechanical amplifier 91 connected to the movable disc 88 by an axis 84. The movement of the movable disc 88 may bring the valve to an open or closed state. The bellows 94 isolates the environment of the actuator 90 from the fluid channel.

Additionally the exemplary embodiment may also include a temperature compensation element 92 and a trimming device 93.

Fig. 3 is an example showing how an actuator portion may be connected to the valve portion. Here it is seen how a lever 348, which may be e.g. U or Y shaped, transmits the movement from actuator 406 via a mechanical motion amplifier 405, axis 404 and lower part of lever 403 to the movable guiding ring 343. This is done via an articulation 400, controlled via the pivoting point 401 , such as a hinge or a flexible pivot, and a second articulation 347. The friction may thereby be kept low.

Additionally, the actuator may be fine adjusted using trimming device 409. There may also be a temperature compensating unit 407 positioned in connections to the actuator. Holders or guiding means 345 and 346 are fastened to the chassis to snap onto the valve body. A fastening ring 344 holds the soft rubber in place and comes off with the valve unit when it is removed from the chassis. Inlet 340 and outlet 341 are connections to the valve unit e.g. for 22 mm conduits. 342 is an end adaptor to connect the flexible conduit to a less flexible tube.

Further embodiments of actuator controlled valves can be is disclosed in the in PCT application PCT/EP2011/057810 and US patent applications 13/105,649 and 61/345,623, which are incorporated herein by reference in their entirety for all purposes. Further embodiments of actuator controlled valves can be is disclosed in the in US patent applications 13/106,654 and 61/345,628, which are incorporated herein by reference in their entirety for all purposes.

The valve devices disclosed above and the elements or means as described below may advantageously be used in medical device applications due to high requirements regarding reliability, energy efficiency, and patient safety.

Temperature Compensation Means

Preferred embodiments of the above-described temperature compensation means, method for assembly the means and method for mechanically temperature compensating may be found in US patent applications numbers US61/345.756 and US13/106,644 and PCT/EP2011/057965 of the same inventor, which is incorporated herein by reference in its entirety for all purposes. In US13/106,644 a mechanical temperature compensation means and method are disclosed for compensating for heat expansion effects in solid materials, and a method for manufacturing the device.

The mechanical temperature compensation means and methods are well suitable for the described valve devices, in accordance with the following reasoning. The temperature compensation is performed by mechanically working together with the device for which the temperature is to be compensated. The temperature compensation element comprising an enclosed disc, which via an inclined link device is connected to a housing whose heat expansion coefficient is different compared to the enclosed disc. Compensation for both negative and positive temperatures can be conducted. The manufacturing method comprising heating up or cooling down the components, achieving a pressure fit when the parts have been assembled and the temperature of the components has been controlled to the intended temperature compensation range.

In one aspect, the US61/345J56 disclosure includes a mechanical temperature

compensation element intended to be used as a compensation element for heat expansion. The element comprises a flat element with a first heat expansion coefficient, a housing with a second heat expansion coefficient different from the first heat expansion coefficient, a, in relation to the flat element, inclined linkage device which mechanically connecting the flat element and the housing; when the temperature changing the flat element expands radially and the linkage device is moved radially, wherein the radial expansion from the flat element is converted to an, relative to the flat element, orthogonal movement, which raises or lowers the housing depending on the temperature of the temperature compensation element.

This configuration provides a mechanical device which may be used to mechanically compensate for changes depending on temperature changes. The device may be used for temperature critical structures such as for micro-positioning, controlling of laser beams, microscope focusing - atomic, optical and ultrasound - semiconductor manufacturing, sensors for micro- positioning, spectroscopy and optical benches.

Additionally and/or alternatively, the device could also be used to compensate for the temperature dependent stroke length of a piezo element such as an actuator.

The temperature compensating is obtained by the flat material having a heat coefficient being higher or lower than an upper laying housing or a housing made of two opposed halves. When a temperature change occurs, the flat element is expanded radially, which results in, a to the housing connected, mechanical device executing a lever-like movement and raising and lowering the housing orthogonally relative to the flat element.

The flat element and the housing may have varying shapes in various embodiments. For example, they can either be circular shaped, polygonal shaped or ellipsoid shaped.

Additionally and/or alternatively, in one embodiment of the mechanical temperature compensation element, the link device comprising a disk element, such as a washer, with a rhomboidal cross-section, radial slits and/or separate segments with rhomboidal cross-section.

It is through this design, of the mechanically linked device between the flat element and the housing that results in the lever-like movement which is caused by the flat element's temperature dependent radial change.

Additionally and/or alternatively, in one embodiment of the mechanical temperature compensation element, the flat element has a heat expansion coefficient higher than that of the housing.

This provides positive temperature compensation, which provides a raising effect when the temperature increases. Examples of a material that may be used for the flat element is Zinc.

Additionally and/or alternatively, in one embodiment of the mechanical temperature compensation element, the flat element has a heat expansion coefficient lower than that of the housing.

This provides negative temperature compensation, which causes the mechanical temperature compensation element to lowers when the temperature increases.

Additionally and/or alternatively, in one embodiment of the mechanical temperature compensation element, it may be connected in series to a piezo element.

In a connection of this kind, the mechanical temperature compensation element is used to compensate for temperature dependent changes in the stroke length of the piezo element. But as already mentioned, the invention may be used to temperature compensate in other temperature critical structures.

Fig. 4 illustrates a device according to an embodiment of the invention. The device may be provided by a disc 210 having a relatively high thermal expansion coefficient. The disc 210 is enclosed by a housing 211 ,212. The housing 211 , 212 has two parts enclosing the disc 210.

In some embodiments, the housing 211 , 212 comprises two discs, each having a cavity.

Alternatively, only one of the housing parts 211 , 212 has a cavity.

The discs are mounted so that the cavities receive disc 210 inside the housing. Disc 210 is in tension with a link device 213, which may be a washer with rhomboidal cross-section, as shown in Fig. 4. The disc 210 has a high thermal expansion coefficient compared to the housing 211 , 212.

When the temperature increases disc 210 expands more radially than along the axis, since the diameter of the disc is greater than the thickness. Moreover, disc 210 expands more than the housing 211 , 212, whereupon the link device 213 exposes housing 211 , 212 to a radial pressure. In the exemplary embodiment, link device 213 comprising two rings with rhomboidal cross-section and exerts a radial pressure on housing 211 , 212. The rhomboidal cross-section of link device 213 is given a function of an inclined supporting element (e.g. a strut), with the diagonal lines in the cross-section of the link device 213. The radial movement caused by the heat expansion of disc 210 is converted in an axial movement having an amplification factor determined by the inclination of lines, i.e. the design of the link device 213 according to desired specifications and applications.

In Fig. 4 the device at the lowest working temperature is showed and in Fig. 5 at the highest working temperature. At typical working temperature parts 211 , 212 of the housing are separated by a distance of preferably half of what is illustrated in Fig. 5. At the same time, the linkage device 213 is only in contact with the disc 210 and housing 211 , 212 at the corner of the opposing diagonals.

Alternatively, by using a material having a high thermal expansion coefficient in the housing 211 ,212 and in the rest of the device using material having a low thermal expansion coefficient relative to it a negative thermal expansion coefficient may be obtained

In order for the device to withstand high axial counter forces, the radial surface of the disc 210 may be surrounded by a thin ring 214. The ring 214 is preferably made of a hard material. This prevents the shape of the disc 210 from being deformed, even if it consists of a material being softer than the housing.

Alternatively, for a negative thermal expansion coefficient, the ring 214 may be placed between the housing 211 ,212 and the linkage device 213.

Mechanical Trimming Device

Additionally and/or alternatively, in some embodiments of the valve, the valve device may comprise a mechanical trimming device.

Preferred embodiments of mechanical trimming device and trimming method for adjustment of dimensional tolerances can be found in US patent applications numbers US61/345J33 and US 13/106,461 and PCT/EP2011/057906 of the same inventor, which is incorporated herein by reference in its entirety for all purposes.

The mechanical trimming device and methods are well suitable for present disclosed embodiments of a valve device, according to the following reasoning. The mechanical trimming device is performed by mechanically working together with the device for which the dimension tolerances are to be compensated.

The mechanical trimming is performed by screwing a screw through a threaded hole. The ends of the screw pressing against a centre of a disk member or washer, which by deformation acts as a lever against an adjacent body. This reduces the effect of the lead of the screw to the transmission determined by the abovementioned lever and the adjacent body is moved a substantially shorter distance than the screw.

In one aspect of the US61/345J33 disclosure includes a mechanical trimming device comprising an adjustable; a first body having at least one threaded through hole that rotatable partly enclosing said adjustable screw; a movable second body, that is movable relative to the first body, and has a cavity into the second body. The cavity accommodates a proximal end of said screw. When the second body is laid against said first body; at least one disc member having a centre and an outer- edge and is positioned between the first and the second bodies. The cavity is facing the disc member and has an edge lying inside of the outer-edge of the disc member so that the outer edge of the disc member lies between the first and the second body.

The screw, when is adjusted, can raise the centre of the disc member in that the disc member works as a lever having a first distributed contact point against the cavity edge of the second body and a second distributed contact point along the outer-edge of the disc member against the surface of the first body, wherein the first body is moved in the axial direction of the screw with a substantially smaller motion than the screw.

This device provides the possibility of using a screw to adjust the second, relative to the first body movable, body, e.g. orthogonally relative to the surface of the first body. The orthogonal adjustment of the second body, occurring when the screwing the screw, is due to the design of the device extremely small in relation to the motion of the screw. Preferably the adjustment is in the micrometre range. The adjustment using the abovementioned device may be performed either vertically or horizontally depending on the positioning of the device. When trimming, the second body is moved along the axial direction of the screw with a movement substantially less than the screw.

When the trimming has been completed the disc member locks the adjustment screw in its position provided there is a counter force through the second body keeping the disc member in a pre- stressed position. Thus the trimming cannot come undone.

This provides a cost effective and simple way to obtain a device usable for trimming by micro-positioning, such as controlling laser beams, microscope focusing; atomic, optical and ultrasound, semiconductor manufacturing, sensors for micro-positioning, spectroscopy and optical benches.

For example, the device may be used for mechanical trimming of the stroke length of a piezoelectric crystal stack, but also for other types of actuator unit.

Additionally and/or alternatively, in some embodiments, the mechanical trimming device has disc member slits running towards the centre. In some embodiments may the disc member also including towards the centre running sectioned elements. The disc member may be circular in shape but may also be polygonal. However, the geometry is not restrained to these shapes, but may also be ellipsoids or similar. The disc member may be designed in many ways as long as the general principles described here within are complied with. For example, the disc member may have a hole in the centre where the slits meet. It may also be large sections. The disc member may also be designed with a solid centre, where the screw presses, with outwards directing sections or arms.

Additionally and/or alternatively, in some embodiments of the mechanical trimming device, the mechanical trimming device is connected in series to a mechanical temperature compensation element.

This configuration of the device also provides, if required, compensation for changes in the ambient temperature, e.g. the stroke length of an actuator unit, preferably a piezoactuator.

Additionally and/or alternatively, in some embodiments, the mechanical trimming device may be connected in series to an actuator unit and to a mechanical temperature compensation element, if necessary.

Fig. 6 (upper drawing) shows a mechanical trimming device according to an embodiment of the invention. The device is obtained by a disc element 511 being installed between a chassis 510 and a movable circular body 513. The chassis 510 comprises an adjustment screw 512 positioned under the centre of disc member 511 , such as a washer. When the adjustment screw 512 is screwed into the chassis 510, the centre of disc member 511 is raised.

Segment may be formed by slits in disc member 511 , running towards the centre. These slits may then bend upwards when the adjustment screw 512 is screwed into the chassis 510. Thus each segment may be regarded as a lever acting on the outer edge of the disc member 511 against the chassis 10 and at the radius according to the arrow 515 on the movable body 513. The motion of the screw may then easily be reduced to less than 50 μιη per turn. The underside of the movable body 513 has a cavity to allow disc member 511 to be bent upwards underneath it.

Fig. 6 (lower drawing) shows an exemplary embodiment where a temperature compensation element 530 is positioned in series with the trimming device.

Mechanical Amplifier system

Additionally and/or alternatively, in some embodiments of the valve, the valve device may comprise a mechanical amplifier system.

Preferred embodiments of mechanical amplifier, system of said amplifiers and method for mechanically amplification of a motion can be found in US patent applications numbers US61/345,625 and US 13/105,661 and PCT/EP2011/057810 of the same inventor, which is incorporated herein by reference in its entirety for all purposes.

The mechanical motion amplifier and methods are well suitable for present disclosed embodiments of a valve device, according to the following reasoning. The mechanical motion amplifier is performed by mechanically working together with the device for amplification of a small motion from an actuator unit, such as a piezoactuator.

The mechanical motion amplifier uses thin beams made of foil and connected in series, wherein each beam acting as a lever has a motion amplification. Further each beam must manage forces with an amplification factor greater than for the following beam. These in series connected beams will transform the small but strong motion from an actuator unit to motion of a larger amplitude.

In one aspect of the US61/345,625 disclosure includes

a mechanical motion amplifier for amplification of an amplitude of a motion from an actuator unit. The motion amplifier comprises at least two beams connected in series at an angle, where the thickness of each beam is substantially less than its orthogonal extension, and wherein each beam has at least one supporting element about which the beam is pivotable. When the serial connection is exposed to a pushing or pulling motion having a first amplitude, from at least one actuator unit, amplifies and generates a second pushing or pulling motion, in parallel in the same plane, with a larger amplitude than the first amplitude. The amplified amplitude and its direction are determined by the gear provided by the design, which depends on how the beams, supporting elements and at least one actuator unit are positioned in relation to each other.

In one aspect, the disclosure includes a mechanical motion amplifier for amplification of an amplitude of a motion from an actuator unit. The motion amplifier may include at least two beams connected in a series at an angle, where the thickness of each beam is substantially less than its orthogonal extension, and wherein each beam has at least one supporting element about which the beam is pivotable. When the serial connection is exposed to a pushing or pulling motion having a first amplitude from at least one actuator unit, the amplifier amplifies and generates a second pushing or pulling motion, in parallel in the same plane, with a larger amplitude than the first amplitude. The amplified amplitude and its direction are determined by the gear provided by the design, which depends on how the beams, supporting elements, and at least one actuator unit are positioned in relation to each other.

The design combined with that the beams may be described as having properties which besides being thin comprise low torsional strength, low weight and small dimensions, leads important properties being obtained, such as the serial beam design having low inertia and thus a rapid amplification response.

Moreover, in some embodiments of the invention the gearing transmission is obtained by a pushing or pulling motion being applied to a first beam, either from one or a plurality of actuator units or from a second beam adjacent to the first beam, at a position a distance X1 from the supporting element of the first beam support, which in turn is positioned a distance X2 from where the first beam is touching a third beam or the last beam in the series where the final amplified motion is to be applied. Optionally, the device may be designed such that the distances are X1 <= X2 for each serially connected beam.

In order to archive an amplified amplitude of the final motion, the abovementioned relation must be complied with for each beam connected in the series.

In some embodiments of the mechanical motion amplifier, the position of each beam's supporting element is adapted to providing a transmitted amplified motion amplitude by the beam that is pushing or pulling.

By adjusting where the supporting element for each individual in series connected beam is positioned, the final amplified motion becomes pushing or pulling. For example, a pushing motion from an actuator unit may be an amplified pushing motion, but if one alters the position of the supporting elements, the same pushing motion may be converted to an amplified pulling motion.

In some embodiments the beams of the mechanical motion amplifier may be made of a foil. By making beams of foil they may be manufactured having properties such as being thin, have low torsional strength, low weight and small dimensions.

In yet another embodiment, the beams connected in series of the mechanical motion amplifier may be made as an integrally part of a continuous piece of foil.

In yet another embodiment of the mechanical motion amplifier, twisting motions and lateral motions that may occur against a first beam, caused by motions of a second adjacent beam, be absorbed by the first beam by means of lateral bending and torsion.

Twisting motions in the structure of beams connected in series are mainly absorbed, thanks to the angle between the beams, by the first beam by means of torsion.

In another aspect of the mechanical motion amplifier, a beam having no amplifying effect of the motion may connect two adjacent beams having amplifying effect of the motion.

In some embodiments of the mechanical motion amplifier, the actuator unit may be at least one piezoactuator. Moreover, the in series connected beams may form part of a system of a plurality of mechanical motion amplifiers, in which the design allows at least two units of in series connected beams to be linked together in order to, in a compact way, distribute the pushing and/or pulling motions from one or more actuator units, positioned vertically against the at least two units of in series connected beams, and generate in at least two zones parallel pushing and/or pulling motions with amplified amplitude.

This type of system having more than two units of beams connected in series, provides for effectively obtaining an amplified motion amplitude which may be either pushing or pulling to occur in parallel but at the same time almost simultaneously. From the same system a combination of pushing and pulling motion may be obtained.

Another aspect of the invention describes a mechanical motion amplification method. The method comprises using at least two in series connected beams, wherein each beam is designed to have low torsional strength, low weight and small dimensions. According to the method, the pushing or pulling motion from at least one actuator unit having a first amplitude, on one of the beams connected in series, is provided with an amplified amplitude as a result of cooperation between the beams connected in series so that the total amplification of the first pushing or pulling motion's amplitude is a product of the cooperating beams' amplifying effect on the motion amplitude. Thus, the final amplified pushing or pulling motion is parallel to the first pushing or pulling motion.

Some important mechanical conditions were accounted for when developing the invention and are mentioned below. Thus the embodiments of the invention have advantages and particularly positive effects in addition to those mentioned above.

The rigidity of a beam having square cross section is increased by the cube of the beam's cross sectional width in the working direction of leverage. Thus the cross sectional width of the beam has been made greater compared to the orthogonal width in the working direction. This also decreases the mass and provides a high resonance frequency.

Metal with a low surface roughness has greater resistance to exhaustion than a processed surface. Therefore, the design complies with this in some of the embodiments of the invention. For example, a cross section of the foil is not bent but only the actual foil orthogonally to it.

A thin beam has low torsional strength. This may be exploited to absorb motions in the device. The thickness of the foil is in the range of 0.1-1 mm; preferably is the thickness approximately

0.5 mm. Motions of two beams in a row which in an undesirable manner are working against each other in a plane, may by bending one of the beams in an angle relative the other be absorbed, so that the motions may be converted to a twisting of the first beam.

By making the beams thin they may be manufactured from foil, and with a design according to the invention it is easy to produce three dimensional structures by bending the foil to the desired structure.

To work with large forces, structures may be provided that comprise several parallel beam systems.

An example of a mechanical motion amplifier is shown in Fig. 7 (upper). Fig 7 shows, a first beam 610 which at an angle 612 is lying against a base 619 orthogonally in line with the lever.

Force FO holds the beam pressed against the base 619. By means of a, in relation to the beam orthogonal, foil 613 the beam is exposed to a downward motion d. The extension X1 +X2 of beam 10 thus forms a lever with amplification X1 +X2/X1 .

The motion d of the first beam 610 is then directly transferred as incoming motion to a second beam 611. Under load, this beam 611 will be pivoted longitudinally about supporting element 614. Due to the angle between the two levers, this pivoting motion is advantageously absorbed by the first beam 610 by means of torsion. The area of transverse lines on the first beam 610 indicates this. The amplification of the second beam is -Y2/Y1 , and the amplification D/d of the entire device is the product of the levers' amplification.

All parts included in Fig. 7 (upper) may be made in a continuous piece of foil.

By bending the abovementioned pieces of foil at suitable positions, a structure according to Fig. 7 (lower) may be produced using four identical pieces of foil. The forces are then distributed into four groups, whilst the motions are parallel. Force F0 is in this case passed on from beam 621. The links 624 transmitting the initial motion are provided at an angle in order to absorb shear motions.

This structure provides for manufacturing of a motion amplification element providing approximately 50 times amplification, a volume of less than 0.5 cm³, a weight of less than one gram and handling of actuator forces in the range of 200 N. Higher amplification may be obtained by adding a third beam to each of the four beam devices involved. The low weight and the small dimensions result in low inertia of the system, and thus a rapid response to an amplified actuator motion.

Since a beam acting as a lever has a motion amplification, the first beam must manage forces with an amplification factor greater than for the following beam. This may be managed by making the beam higher in the direction of the load. An example for the first beam 610 is shown in Fig. 7 (upper), which increases in height towards the actuator point at foil 613. However, this is only possible to a limited extent, as the beam geometry may be jeopardized. Instead it is better to increase the beam thickness orthogonally towards the direction of the load, as a completion. However, a design of this kind may be less advantageous under some circumstances. For example, it could result in variations of the foil thickness in a design having more than one beam in the same piece of foil.

Moreover, a thicker foil may result in difficulties in bending it to the desired structures.

For this reason it may be more advantageous to double the first beam in the device.

Therefore, in some embodiments, the first beam may be doubled in the device. Fig. 8 (upper) is showing an example of such a design. Fig. 8 (upper) is showing one of six segments from Fig. 8 (lower). The first beam 641 has two beams merging into one crossbeam 648. This crossbeam 648 extends via a flexible part (the flexible areas are marked as transverse lines in the Figure) down to the next beam 642. This connection 644 is preferably rigid to avoid wear in the connection.

It may be advantageous to make this connection with a snap-connection included in the foil structure (not shown in the Figure).

The input motion to the first beam 641 occurs via segment 645 from the actuator (not shown in the Figure). The segment 645 has flexible areas to absorb motions generated by the beam pivoting about base 619. The folded-out angle from the first beams 641 serves as flexible support element against base 619. The angles 647 do not necessarily need to be fixed to the base 619. Instead it may be able to ride on the edge of the angle against the base. The angle does not need to flex in this case. The second beam 642, which is single, is pushed down by the first beam 641. The angle 643 folded out from the second beam 642 serves as flexible point of support against the base 619. The folded out angle 46 transmits the structure's initial motion via a flexible link marked as an area with lines. The structure's amplification D/d is then [(Χ1 +Χ2)/Χ1]*[(Υ1 +Υ2)Λ ].

The device shown in Fig. 8 (upper) may be regarded as a segment of the structure shown in Fig. 8 (lower).

The parts 647, 41 and 648 shown in Fig. 8 (upper) are six folded to a continuous foil which is folded and closed at the ends and obtains a structural shape 651 as shown in Figure 5. Parts 643,642 and 646 are six-folded in the same way to obtain a structural shape 652 as shown in Fig. 8 (lower). Actuator linkage 647 is also six-folded and obtains the structural shape 653 as shown in Fig. 8 (lower). This method results in a mechanical amplifier as shown in Fig. 8 (upper) and Fig. 8 (lower) with a force distribution from the actuator to twelve adjacent points and an exchanged motion from six linkages. The principles described above are advantageous in combination with actuators with small motion, and besides piezoactuators, combinations may be made with other actuators such as electrostrictive, thermal or chemical ones.

As is shown in the Figures, it is possible to generate both pushing and pulling amplified motions.

Driver Circuit For Controlling A Capacitive Element

Additionally and/or alternatively, in some embodiments of the valve, the actuator unit of the valve device may be controlled by a driver circuit being a bucket-boost regulator.

Preferred embodiments of driver circuit and method for controlling a capacitive element, such as a piezo actuator unit, can be found in US patent applications numbers US61/345J64 and US 13/108,308 and PCT/EP2011/057811 of the same inventor, which is incorporated herein by reference in its entirety for all purposes.

The driver circuit and method for controlling a capacitive element are well suitable for the present disclosed embodiments of a valve device and for controlling the actuator unit of such valves.

According to aspects of the US61/345J64, a device and a method are disclosed. This is achieved by means of a capacitive element acting as a capacitor in the end stage of a boost regulator. By adding extra switch functions and by using an inductor with several windings the boost regulator can be combined with a buck regulator to provide charging of the capacitive element with energy recovery. Embodiments comprise a method of charging or discharging a capacitive element, preferably a piezoelectric crystal. A device charges a capacitive element according to this method.

According to the various embodiments, the device comprises a bipolar buck-boost converter, whereby a capacitive element can be charged with both positive and negative voltages. The capacitive element is discharged with the abovementioned energy recovery and feedback to the device power supply according to certain embodiments.

In the first aspect of the invention, a drive circuit is provided which is configured to control a capacitive element. The drive circuit comprises a combined switched boost regulator circuit and a switched buck regulator circuit, as well as a plurality of change-over switches. The drive circuit has two operative states which are selectable using the abovementioned change-over switches, wherein one operative state is a boost regulator and the other operative state is a buck regulator.

According to various embodiments, the abovementioned change-over switches comprises at least four switches, of which a first primary switch S1 and a second primary switch S2 are arranged on a primary side and a first secondary switch S3 and a second secondary switch S4 are arranged on a secondary side.

In some embodiments, the drive circuit comprises at least one inductor which on the primary side preferably has at least two windings L1 and L2.

The operative states may be obtained as follows:

by opening the second primary switch S2 and the first secondary switch S3 as well as connecting the second secondary switch S4, thus providing a positive boost converter which is controlled by the first primary switch S1 for positive charging of the capacitive element X;

by opening the first primary switch S1 and the second secondary switch S4 and connecting the first secondary switch S3, thus providing a negative boost converter which is controlled by the second primary switch S2 for negative charging of capacitive element X;

by opening the first primary switch S1 and the second primary switch S2 and connecting the second secondary switch S4, thus providing a positive buck converter which is controlled by the first secondary S3 for discharging of the capacitive element X and feedback to a tank capacitor C.

In another embodiment, the capacitive element X is earthed on one side, both the secondary switches S3 and S4 are placed on one side of the inductor's secondary winding L3, and a diode D2 is arranged between the second primary switch S2 and the primary inductor winding L2.

Clamping effects are avoided upon negative boosting by means of adding an extra diode D2, which results in that high negative voltages can be generated.

The circuit is built to drive capacitive elements, such as an actuator element, preferably a piezoactuator. The circuit is built with a boost regulator combined with a buck regulator by using an inductance/coil with more windings on the primary side and extra switches. Thanks to this structure, the drive circuit can control the capacitive element by charging with either positive or negative voltages by switching the circuit to either a positive boost converter or a negative boost converter.

The capacitive element can also be discharged by switching the circuit to a positive buck converter, which discharges with energy recovery and feedback to the device power supply. This means that the energy accumulated in the actuator that would otherwise be lost as heat when an actuator is controlled to a lower deflection is not lost.

Using this drive circuit structure, the negative control range to the actuator is also restricted. This means that when the drive circuit is used to control the actuator with a negative voltage, so as not to lose movement due to mechanical hysteresis, it is not possible to control the circuit at such high negative voltages that the actuator is destroyed. This limit on actuator capacity is in the range of 20% of the maximum permitted positive voltage.

The switches should preferably be MOS transistors, but are not limited to this.

In a second aspect, the invention comprises a method for driving and controlling capacitive elements. The method comprises providing a combined switched boost regulator circuit and a switched buck regulator circuit as well as a number of change-over switches, and providing two optional operative states by controlling these change-over switches, wherein one operative state is a boost regulator and the other a buck regulator.

In embodiments the boost regulator is used at negative and positive voltages to charge the capacitive element, such as an actuator element, preferably a piezoactuator, and the buck regulator is used to discharge the capacitive element by energy recovery and feedback to the drive circuit power supply.

In some embodiments a negative control range for the actuator is limited, such as limited to a range of 20% of the maximum permitted positive voltage.

Fig.9 (upper drawing) shows a schematic view of an exemplary embodiment of an electrical circuit.

The inductor has a winding ratio N1 and N2 on the primary side, and N3 on the secondary side. Description of Positive Boost

This process is active when a voltage Vcc is to be converted from a limited negative voltage to a high positive voltage across the crystal X. S2 and S3 are open, and S4 is closed in this operational state. The functional parts of the circuit in this operational state are described in Fig. 9 (upper drawing).

1. When S1 is closed, the current is ramped up in L1. The field in the transformer core builds up to a positive field value. During this time the voltage towards the diode D4 is Vcc*N3/N1 and there is no current flowing through D4 or X.

2. S1 opens and the field in the transformer core drops towards zero. The voltage over D4 drops immediately until it starts to conduct, approx. -0.6V and a current flows through D4, L3 and X so that the voltage across X in a number of cycles is gradually ramped up to a high voltage of e.g. 120V. The voltage across D1 will rise across Vcc at each cycle, and no current flows through L1.

3. S1 is connected again, and so on. Description of Negative Boost

This process is active when a voltage Vcc is to be converted from zero to a limited negative voltage across the crystal X. S1 and S4 are open, and S3 is closed in this operational state. The functional parts of the circuit in this operational state are described in Fig. 9 (upper drawing).

1. When S2 is closed, the current is ramped up in L2. The field in the transformer core builds up to a negative field value. During this time the voltage towards diode D1 is Vcc and there is no current flowing through D1. The voltage to diode D5 also becomes positive and no current flows through L3, D5 or X.

2. S2 opens and the field in the transformer core rises towards zero. There are then two competing processes:

A boost via L3 generates a negative voltage across X, or a boost across L1 which ramps energy stored in the transformer back to C and supply voltage Vcc. The active boost process is determined by the voltage across the capacitive element (the piezo crystal) X, Vcc and the transformer ratio N3:N1. In practice this means that the negative boost is limited to

-Vcc*N3/N1. If Vcc=12V and N3:N1 is 5:3, the maximum voltage across X is -20V.

3. S2 is closed again, and so on.

Description of Positive Buck

This process is active when crystal X is to be discharged, i.e. the voltage drops towards zero. S1 and S2 are open, S4 is closed in this operational state. The functional parts of the circuit in this operational state are described in Fig. 9 (upper drawing).

1. When S3 is closed, the current is ramped from X up in L3. The field in the transformer core builds up to a negative field value. During this time the voltage towards diode D1 is positive and there is no current flowing through D1. The crystal X is gradually discharged in this phase.

2. S3 opens and the field in the transformer core drops towards zero. The voltage across D1 immediately drops until it starts to conduct, approx. -0.6V and a current flows through D1 , L1 and C so that energy from crystal X is fed back to C and Vcc.

3. S3 is connected again, and so on. ln case the capacitive element is a piezoactuator, it may very advantageously be controlled by the circuit of embodiments. The Bipolar Buck-Boost Regulator may be used for driving at least one piezoactuator.

The piezoactuator may be an actuator in a valve. Thus, the valve has considerably faster response times and considerably lower energy consumption than conventional valves in this field.

Fig. 9 (lower drawing) shows a schematic view of another exemplary embodiment of an electrical circuit according to a principle of the invention. In this exemplary embodiment, the capacitive element X is earthed on one side, and the switches S3 and S4 are arranged on one side of the inductor's secondary winding L3. Furthermore, a diode D2 is added. D2 prevents clamping effect upon negative boost, which means that high negative voltages can be generated when D2 is included in the circuit.

Coaxial Means For Measuring A Flow And A Method Of Measuring A Flow

Additionally and/or alternatively, some embodiments of the valve, includes a flow restrictor and coaxial means for measuring a flow and a method of measuring a flow.

Preferred embodiments of the flow restrictor and the coaxial means for measuring a flow and a method of measuring a flow, can be found in US patent applications numbers US61/345J88 and US 13/108,769 regarding the flow restrictor, the US61/345J71 US13/108,779 for the flow measurement and further in PCT/EP2011/058008 of the same inventor, which is incorporated herein by reference in its entirety for all purposes.

The disclosed flow restrictor and the coaxial means for measuring a flow and a method of measuring a flow are well suitable for the present disclosed embodiments of a valve device.

In and aspect of PCT/EP2011/058008, a method is described for measuring a flow of gas passing a flow meter device. The device causes a pressure drop when a gas flows through it. The pressure drop across the device is a measure of the gas flow. The device is designed as a gas permeable tube which has a flow channel on the upstream side along the tube designed so as to decrease the cross-sectional area of the channel downstream of the gas permeable tube. A small volume is produced by adapting the device flow channel and flow restriction to the geometry of the flow profile of the gas flowing out from the flow valve. This provides for a minimum volume in the channel upstream of the device's pressure-drop-generating component. ln some embodiments the outlet from a gas valve is centred, and the outlet flow profile has the appearance of a jointed cone. In other cases the outlet is coaxial with a flow profile which may be described as a tube.

By designing the geometry of the device according to the embodiments of the invention for the abovementioned flow profiles, it is possible to make a flow restrictor for each of the mentioned valve types.

According to a first aspect of the invention, a flow meter element is provided comprising a tube element and a flow restrictor arranged inside the latter.

The tube element may comprise a connection interface to a flow valve. The flow restrictor comprises a closed fluid permeable body so as to form a fluid permeable tube which on the upstream side along the tube has a flow channel designed to decrease the cross-section of the flow channel downstream of the tube.

In an embodiment, the tube element is an outer tube. The outer tube and the fluid permeable body are arranged relative to each other at a distance which decreases along the direction of the flow meter element between the inner side of the outer tube and the fluid permeable body.

By adapting the flow meter element's flow channel and the flow restrictor to the geometry of the flow profile from a fluid flowing out from a flow valve it is possible to obtain a relatively large surface in the flow restrictor and at the same time a small volume between the flow restrictor and the interface (outer tube) to a valve. An increased pressure is generated upstream before the flow restrictor, e.g. by compressing a gas when flow resistance increases, and a pressure drop downstream of the flow restrictor. The pressure differential is proportional to the flow in the channel, allowing the flow to be measured.

In a particular embodiment of the flow meter element, the closed fluid permeable body is a cone.

A way of creating the abovementioned design is for the fluid permeable body to be conical in shape turned either upstream or downstream.

In a particular embodiment of the flow meter element the closed fluid permeable body is a partial cone.

A way of creating the abovementioned design is for the fluid permeable body to be partly conical in shape turned either upstream or downstream.

The cross-section of the tube geometry of the outer tube and the fluid permeable tube may either be of circular shape or polygonal shape or ellipsoid shape. ln some embodiments of the invention the flow meter element comprises a differential pressure meter which is connected to each side of the fluid permeable body. The differential pressure meter measures the differential pressure on both sides of the fluid permeable body, which is then used to calculate the flow

Some embodiments of the invention comprise the flow meter element having a flow valve which is connected to a first connection interface to the flow meter element.

Some embodiments of the invention comprise the flow meter element having a second connection interface identical to the flow valve's connection interface.

By the flow meter element having a mechanical connection interface adapted after a closed flow valve and a flow meter element having a second connection interface identical to that of the flow valve, the device can be coupled into a link with an already existing design.

Another aspect of the invention comprises a flow measurement method comprising a flow restrictor with a relatively large surface and a relatively small volume between the fluid permeable body placed in the flow channel of the flow restrictor and the outer tube of the connection interface; wherein the relatively small volume is provided by the outer tube and the fluid permeable body being arranged at a relative distance from one another which decreases along the longitudinal direction of the flow meter element between the inside of the outer tube and the fluid permeable body thus boosting the pressure upstream (P1) and producing a pressure drop downstream (P2) of the fluid permeable body, the difference between which is proportional to the flow.

Yet another aspect of the invention provides a method for measuring a flow which comprises measuring a flow of a fluid passing a flow meter device, wherein the device causes a pressure drop in the fluid flowing through it, and where the pressure drop across the device is a measure of the fluid flow. The method comprises providing a device which is designed as a fluid permeable tube which on the upstream side along the tube has a flow channel which is designed so that the cross-sectional area of the channel decreases downstream of the fluid permeable tube, whereby this method comprises providing a minimal volume in the channel upstream of the device's pressure-drop-generating part.

The advantages of this method are, as for the above described equipment, that the flow in a flow channel or out of a valve may be measured easily without the occurrence of false flows which might affect flow measurement.

According to yet another aspect of the invention a variable flow restrictor is provided. The variable flow restrictor comprises a flexible foil with movable parts such as flaps, and a fluid permeable body. The flexible foil is arranged immediately next to the fluid permeable body where the movable parts are pre-tensioned against the fluid permeable body resulting in a variable fluid flow through the flow restrictor as by increased displacement of the flexible parts with increased flow through the fluid permeable body and the flexible foil.

In order to reduce the flow resistance during increased flows, a thin flexible foil with flaps is placed close to the fluid permeable body. Thanks to the flaps being in tension, the flow resistance is high in small flows, which is then reduced when the flow increases. The flexible foil should preferably be placed adjoining the fluid permeable body by bending it and placing it with its convex side against the fluid permeable body. The flexible foil may be shaped as e.g. a cone, partial cone or as a cylinder. The tube geometry of the entire design may have a cross-section that may be circular and/or ellipsoid or and/or polygonal.

This may be obtained according to an embodiment where a foil with flaps downstream is placed next to a fixed flow restrictor in the form of a net or some other fluid permeable material.

One advantageous embodiment of the invention is to place the abovementioned flaps pre- tensioned against the fixed flow restrictor. This method ensures that the flow resistance is maximized at low flows. An advantageous way of pre-tensioning the flaps is to bend the foil with flaps and allow the convex side to lie against the flow restrictor, which has a matching shape. The flaps will in this case lie pre-tensioned against the flow restrictor. The curvature of the foil may be arbitrary in shape, such as a cone, sphere or cylinder.

Yet another advantageous embodiment of the invention is to provide the flow restrictor with holes or thin material where it is covered by the abovementioned flaps.

In some embodiments of the variable flow restrictor, the fluid permeable body has openings which allow the fluid to flow under the flaps.

Adding these openings or holes, which may also be thinner parts in the material, increases the effect of the variable flow restrictor by reducing the flow resistance more during flows.

In some embodiments of the variable flow restrictor, a differential pressure gauge is connected upstream of the fluid permeable body and downstream of the flexible foil.

Another aspect of the invention comprises a method for reducing the flow resistance in a flow restrictor at an elevated flow rate. The method comprises pre-tensioning moveable parts, such as flexible flaps, on a flexible foil by placing the flexible foil next to a fluid permeable body, thus creating a variable flow restrictor in that the moveable parts are moved more and more as the flow increases, thus providing a variable fluid flow through the flow restrictor. The advantages of this method are the same as for the equipment described above, i.e. providing a flow restrictor which reduces flow resistance as flow increases. This is important in removing increased flow resistance caused by turbulence and in increasing the dynamic flow range.

The term flow resistance refers to actual flow resistance as distinct from pressure drop. A gas permeable element is an element through which gas can flow. For instance, gas can flow through an outer to an inner side of a cylindrical or conical gas permeable element. Its flow resistance will differ for different gas flows there through (across it). An example for such an element is for instance a sintered metal having a defined pore size. Such sintered elements are commercially available as "Sica Fil". A gas permeable element has a defined permeability for both fluids and gases. For example, a fixed gas permeable element may be provided in the form of a net, sintered metal or ceramics of a particular pore size or cell size, or some other fluid permeable material. For example, gas permeable elements in the form of flow restrictors are used in flow meters to create pressure drops with a desired profile. Differential pressure across a gas permeable element may be measured and provides a measure of the

An exemplary embodiment of a device according to the invention may be obtained as shown in Fig. 10 by a gas flow from a flow valve flowing in the inside of a tube 710 and passing downstream through a gas permeable partial cone 711. Thanks to the shape of cone 711 the cross-sectional area of the flow channel gradually decreases downstream of cone 711. In this manner turbulence minimizes as well as the volume between cone 711 and inlet upstream of tube 710. A pressure P1 builds up upstream the cone depending on the flow. Pressure P2 is measured downstream the cone. The difference between P2 and P1 (P2-P1) is a measure of the flow.

Advantageous flow measurement is possible thanks to minimum turbulence and the minimal volume between cone 11 and the inlet upstream of tube 710. Thus flow measurement is largely independent of pressure variations in the flow channel. The signal from the differential pressure P2-P1 provides rapid and reliable gas flow control with a flow valve.

The device shown in Figure 10 is suitable for a flow valve with upstream peripheral circular outlet. For example, the flow valve can be fastened to the flow meter using a suitable flange (not shown) or using grooves which close on seals, see, for example, Fig. 12.

In some embodiments of the flow meter system, besides the differential pressure P2-P1 , other parameters such as gas temperature, outlet pressure P2, gas viscosity and gas density are measured. These parameters may be linearized. This allows flow to be calculated with extreme accuracy. Fig. 11 shows a schematic view of yet another exemplary embodiment suitable for a flow valve with peripheral circular outlet upstream. In this embodiment, gas permeable element 721 is cylindrical in shape with a closed end upstream. The cross-section of the flow channel gradually decreases downstream thanks to insert 722 gradually decreasing the cross-sectional area of the flow channel up to the fastening point of the cylindrical gas permeable element 721.

In other embodiments, a conical gas permeable element may be combined with a conical insert.

Fig. 12 shows the bent foil 821 and flow restrictor 820 with a shape matching the contour of foil 821 assembled. Here the flaps 832 are shown in contact to flow restrictor 820 in the tensioned condition. A gas permeable elements in form of a flow restrictor has a defined permeability for both fluids and gases. For example, a fixed flow restrictor may be provided in the form of a net, sintered metal or ceramics of a particular pore size or cell size, or some other fluid permeable material. For example, flow restrictors are used in flow meters to create pressure drops with a desired profile. Differential pressure across a flow restrictor may be measured and provides a measure of the flow Figure 13 shows the bent foil 821 and flow restrictor 820 with a shape matching the contour of foil 821 when a flow illustrated by the arrows in Fig. 13 passes through flow restrictor 820 and foil 821 installed downstream. Here it is shown how the now radially inwardly bent flaps 842 are bent by a larger flow, shown by the arrows.

Additionally and/or alternatively the flow restrictor may be provided with holes in the area below flaps 842 according to a principle of the invention. The flaps 842 will then be bent by a major flow, passing the holes in the flow restrictor 820

As an alternative to or in combination with holes, the flow restrictor may be designed of thinned down material or large pore sizes or cell sizes or filter density where it is covered by the abovementioned flaps.

By combining a gas permeable element (flow restrictor) as described in the embodiments of figs. 12 to 13 with a flow meter element as described above with reference to Figs. 10-11 , an advantageous synergy is obtained. A flow meter with fast response times, and a high flow range is provided.

By combining a gas permeable element (flow restrictor) as described in the embodiments of figs. 12 to 13 with a flow meter element as described above with reference to Figs. 10-11 , an advantageous synergy is obtained. A flow meter with fast response times, and a high flow range is provided. ln the present exemplary embodiment the parts used are circular. However, the geometry of the device is not restricted to these shapes, but the circular shape can be replaced by polygons, ellipses or combinations thereof.

A actuator controlled high pressure valve as described above, may advantageously be used in medical device applications due to high requirements regarding reliability, energy efficiency, and patient safety.

A actuator controlled high pressure valve as described above, may advantageously be used in a valve of a medical ventilator, such as described in US61/345J97, which is incorporated herein by reference in its entirety.

The present invention has been described above with reference to specific embodiments. However, other embodiments than the above described are equally possible within the scope of the invention. Different method steps than those described above, performing the method by hardware or software, may be provided within the scope of the invention. The different features and steps of the invention may be combined in other combinations than those described. The scope of the invention is only limited by the appended patent claims.

Claims

An actuator controlled high pressure valve having a valve inlet and a valve outlet, comprising

- a piezoelectric actuator (113);

- a mechanical amplification element (119);

- a valve mechanism acting on a valve seat (118);

- wherein the actuator, the mechanical amplifier element and the valve mechanism are arranged along a common axis, wherein the actuator is arranged to generate a motion for controlling the valve mechanism and the mechanical amplifier element is arranged to amplify the motion of the actuator to the valve mechanism's closing or opening motion.

The high pressure valve of claim 1 , wherein the device is arranged in a tube with a valve inlet and a valve outlet.

The high pressure valve of claim 1 or 2, wherein a first flow resistance element is arranged between the valve seat and the valve outlet.

The high pressure valve of claim 3, wherein a differential pressure gauge is connected upstream and downstream of the flow resistance element respectively.

The high pressure valve of claim 4, wherein the flow resistance element comprises a closed fluid permeable body so as to form a fluid permeable tube which on the upstream side along the tube has a flow channel designed to decrease the cross-section of the flow channel downstream of said tube, wherein a differential pressure meter is connected to each side of the fluid permeable body, and is arranged to measure a differential pressure upon a flow across the fluid permeable body.

The high pressure valve of any of claims 3-5, wherein a second flow resistance element is arranged downstream of the first flow resistance element.

The high pressure valve of any of claims 3-5, wherein the first flow resistance element has the shape of a cylindrical tube or a cone.

The high pressure valve of any of claims 3-6, wherein a flow channel downstream of the outside of the first flow resistance element decreases in width.

9. The high pressure valve of any of claims 3-8, wherein said flow restrictor is a variable flow restrictor, comprising a flexible foil with movable parts, such as flaps; and a fluid permeable body; wherein the flexible foil is arranged adjoining the fluid permeable body).

10. The high pressure valve of claim 9, wherein said flexible foil is bent and has a convex side, and wherein the flexible foil is with its convex side positioned against said fluid permeable body, wherein the movable parts are tensioned against the fluid permeable body resulting in a variable fluid flow through the flow restrictor by increased

displacement of the movable parts with increased flow through the fluid permeable body and the flexible foil.

11. The high pressure valve of any of claims 1-10, wherein a thermal expansion element

(114) is connected in series to the actuator.

12. The high pressure valve of claim 11 , wherein said thermal expansion element (114) is a mechanical temperature compensation element for compensation of heat expansion, comprising:

- a flat element having a first thermal expansion coefficient;

- a housing having a second thermal expansion coefficient different from said first thermal expansion coefficient;

- a, in relation to said flat element, inclined linkage device which mechanically connecting said flat element and said housing;

- wherein at temperature changes said flat element expands radially and said linkage device is moved radially, wherein said radial expansion from said flat element is converted to an, relative to said flat element, orthogonal movement, which raises or lowers said housing depending on the temperature of the temperature compensation element.

13. The high pressure valve of any of claims 1-12, wherein at least one mechanical fine tuning element (115) is connected in series to the actuator.

14. The high pressure valve of claim 13, wherein said mechanical fine tuning element

(115) is comprising: an adjustable screw;

a first body that has at least one threaded through hole at least partly enclosing said adjustable screw for rotatable motion therein; a movable second body, that is movable relative to said first body, and has a cavity into said second body, wherein said cavity accommodates a proximal end of said screw, when said second body is laid against said first body;

at least one disc member that has a centre and an outer-edge and is positioned between said first and said second bodies, wherein said cavity is facing said disc member and has an edge lying inside of said outer-edge of said disc member so that said outer edge of said disc member lies between said first and said second body; and wherein said screw, when adjusted, is arranged to raise said centre of said disc member in such a manner that said disc member works as a lever having a first distributed contact point against said cavity edge of said second body and a second distributed contact point along said outer-edge of said disc member against said surface of said first body, whereby said first body is movable in an axial direction of said screw with a substantially smaller motion than said screw for said trimming.

5. The high pressure valve of any of claims 1-14, wherein two seals (110, 111) are arranged between the actuator (113) and the mechanical amplification element (119), and wherein a ventilation channel (19) is arranged between the two seals (110, 111).

6. The high pressure valve of any of claims 1-15, wherein said mechanical amplification element (119) is mechanical motion amplifier, for amplification of an amplitude of a motion from an actuator unit, comprising:

at least two beams connected in series at an angle, each beam having a thickness substantially smaller than its orthogonal expansion;

wherein each beam in turn comprising at least one supporting element about which said beam is pivotable;

wherein, when said serial connection is exposed to a pushing or pulling motion having a first amplitude from at least one actuator unit, the motion is amplified and a second, substantially parallel motion is generated having a second amplitude larger than said first amplitude; and

wherein said amplified second amplitude and its direction is obtained from a

transmission of a construction dependent on how said beams, said supporting elements, and said at least one actuator unit are positioned in relation to each other.

7. The high pressure valve of claim 16, wherein said transmission is provided by means of a pushing or pulling motion applied on said first beam, either from one or a plurality of actuator units or from a second beam bearing on said first beam at a position at a distance X1 from said supporting element of said first beam which in turn is positioned at a distance X2 from where said first beam is touching a third beam or the last beam in the series where the final amplified motion is to be applied.

18. The high pressure valve of claims 1-17 , wherein said actuator is controlled by a drive circuit configured to control a capacitive element (X), comprising in combination a switched boost regulator circuit and a switched buck regulator circuit, as well as a plurality of change-over switches, wherein the drive circuit has two operative states which are selectable by means of said change-over switches, wherein the first operative state is a boost regulator and the second operative state is a buck regulator, and wherein said change-over switches comprise at least four switches, of which a first primary switch (S1) and a second primary switch (S2) are arranged on a primary side and a first secondary switch (S3) and a second secondary switch (S4) are arranged on a secondary side; wherein the drive circuit comprises at least one inductor which on the primary side has at least two windings (L1 and L2); and wherein said operative states are obtained by opening or closing said first primary switch (S1) and said second primary switch (S2) as well as said first secondary switch (S3) and said second secondary switch (S4) in different constellations.

19. A method for controlling a high pressure valve where all included components are

connected in series along a common axis, said method comprising the valve being controlled by a piezoelectric actuator with a stroke length which is amplified by a mechanical amplifier element to a valve mechanism acting on a valve seat, and wherein said method comprises generating a motion with the actuator, transmitting the motion to the mechanical amplifier element and controlling the valve mechanism with the amplified motion to a closing or opening motion in the valve mechanism, and wherein, if needed, the method may comprise fine tuning the valve with a mechanical fine tuning element and temperature compensating the motion with a thermal expansion element.

20. The method of claim 19, comprising the high pressure valve of any of claims 1-18.