The invention concerns small and miniaturized valves for the active regulation of liquid streams or gas streams. Microvalves are valves with external dimensions preferably in the range from 0,1 mm to 10 mm and internal dimensions for example fluid passages preferably in the range of 10 Am to 500 AM.

Decisive factors of the valves of the invention are reliability, inertia and primarily the viability of the valves in a temperature range up to 200 °C and in a pressure range up to 20 bar.

In the field of hydraulics and pneumatics a plenty of valve principles are known. Mainly used are valve systems with pistons. This is mainly based on the possibility to connect these pistons directly to an electromagnetic actuator.

In such a manner by the design of the piston and the valve seat next to the function's opening and closing further criteria like pressure control or volume control can be performed. Due to the known advantages this functional principle is also used for small and miniaturized systems. It pushes in there however because of manufacturing uncertainties and high assembly efforts.

In the area of the miniaturized valves the alternative principles membrane valve or ball valve find as well application. As valves for high process pressures and high process temperatures, as they are necessary for example in the area of the gas chromatography, piston valves in the form of rotation pistons are however widespread prevalent. By way of grooves on the conical rotary piston surface more way valves can be realized relatively simply along with complex circuit possibilities.

The task of the invention exists therein to create a microvalve, along with that operating pressures up to 20 bar in operating temperatures up to 200 °C can be switched, wherein the microvalve shows high pressure tightness and in open position only a little pressure drop. This task will be fulfilled by a microvaive according to claims 1,6,12 and 17.

The microvalve is built up in the simplest case fundamentally from six single elements.

It is built up from the top to the bottom from a valve plate, described as the first plate which contains inlet and outlet passages for the fluid streams, of a second plate which is sandwiched between to membranes and is also named as the second plate and contains a hole as receptacle for a force transmission element as well as a control pressure plate or third plate.

In the further is to set apart in between the fluid stream and the control stream. As fluid stream a liquid or gaseous medium is marked whose flow can be actively stopped or released by the microvalve. As trigger or control stream a liquid or gaseous medium can be used, that is supplied to the invention with a specific pressure which can be essentially under the pressure of the fluid stream. Alternatively also the application of electromagnetic, piezo-electrical, mechanical or manual force transmission systems as trigger is possible.

In inactive status the microvalve is open that is called the fluid stream is released. At actuation the control pressure at the control pressure plate or the also called third plate is raised by a fluid pressure. The fluid activation passage in the third plate is open to a for instance cylindrical pressure chamber, which is closed at the upper end by an actuation membrane.

Inasmuch as the hole in the adjacent second plate corresponds with the pressure chamber an upward movement of the actuation membrane by raising the control pressure is possible. The diameters of the pressure chamber and the hole of the second plate have to be preferably of about the same size to get optimal excursion of the actuation membrane. The force transmission element, which is found in the hole in the second plate, is directly positioned on the actuation membrane and is moved by way of the bending membrane upwardly. Since the length of the force transmission element and the height of the second plate are identical, the sealing membrane is also moved upward by the force transmission element.

On the top side of the sealing membrane is found the first plate, which contains at the bottom side an annular valve seat. In the middle of the valve seat is a hole with a small preferably sub-millimeter diameter, which is connected to one of the two fluid passages. A annular groove, with an essentially bigger inner diameter than the diameter of the hole, surrounds the described hole at the bottom side radially, so that a protrusive ring remains, which directly puts on the sealing membrane in the assembled state. The annular groove is connected to the second fluid passage.

Due to the movement of the force transmission element respective the movement of the two membranes excited by increasing control pressure the upper elastic membrane is pressed along with a defined force of against the projecting ring.

By the abatement of the control pressure the dynamic pressure of the fluid stream is able to move the sealing membrane in the area of the valve seat downwards again, so that a flow cross section is opened. The microvalve is opened.

The switching statuses of the valve are reproducible, as long as the membranes are not plastically shaped by impact of the force.

Next to the possibility of the surface contact between the sealing membrane and the annular valve seat the possibility of a edge contact of the sealing membrane and the annular edge of the hole within the valve seat exists likewise. The realization of the edge or surface contact depends on the form of the force transmission element.

Inlet-and outlet passages for the fluid streams are arbitrarily interchangeable.

Control stream and fluid stream does not interact immediately with each other, but are connected via the force transmission element to each other, that takes up forces from both flows, which come into being by multiplication of the pressure loaded areas of the respective membranes. Thus it becomes possible through the design of the force transmission element and the hole in the second plate to switch high pressures of the fluid streams with considerably lower pressures of the control stream proportionate to the pressure loaded membrane areas. It is advantageous if the diameter of the hole in the second plate continuously or in levels rejuvenates from bottom to top onto a smaller diameter. The force transmission element has to be shaped respectively. Preferred relationships of the pressure loaded membrane areas lie in the area up to 1: 50.

In the described, simplest embodiment of the invention the sealing membrane adjoins immediately to the valve seat. The pressure tightness is only induced by the force-input in the switched status, whereas the sealing membrane in the open status is moved downwards by the pressure of the fluid stream, leading to a increase of the flow area. Out of that there could be a adverse valve characteristic with the disadvantage of high pressure drops of the fluid streams across the valve. To produce relief the valve seat should have a spacing to the sealing membrane. This can be realized most simply through the insertion of a further flat component between the sealing membrane and the valve plate. In the area of the valve seat this spacer component contains a sufficient large opening. It must be guaranteed that both membranes, the sealing and the actuation membrane, can be elastically bended by the amount of the height of the spacer component. Otherwise a sufficient large height of the spacer component is necessary, in order to minimize the pressure drop and to reproduce according to the setting of task. As a spacer component preferably a spacer membrane is intended. The spacer component guarantees in the opened status a sufficient large flow cross- section.

The microvalve for regulating a flow of fluid comprises: a first plate having an inlet passage, an outlet passage, a fluid transfer channel in a first face of said first plate extending between the inlet and outlet passages for fluid communication therebetween, the fluid transfer channel having a floor, and a valve seat extending outwardly from the fluid transfer channel toward the first face of the first plate ; a second plate in generally opposed relation with the first face of the first plate and having a piston receptacle opening from the second plate toward the first face of the first plate ; a sealing membrane located between the first face of the first plate and the second plate ; a piston at least partially disposed in the piston receptacle of the second plate and movable relative to the first plate between an open position in which the sealing membrane is spaced from the valve seat to permit fluid flow between the inlet passage and outlet passage through the fluid transfer channel, and a closed position in which the piston presses the sealing membrane against the valve seat to prevent fluid flow between the inlet passage and the outlet passage through the fluid transfer channel.

A spacer membrane is preferably located between the sealing membrane and the first face of the first plate for spacing the sealing membrane from the first face of the first plate. The spacer membrane has an opening therein generally aligned with the valve seat whereby the sealing membrane may be deformed through the opening by movement of the piston to said closed position into engagement with the valve seat.

The spacer membrane sealingly engages the first face of the first plate over the fluid transfer channel except at said opening of the spacer membrane.

The first face of the first plate preferably lies generally in a plane and the valve seat includes an engagement surface lying generally in the plate of the first face.

The valve seat is preferably associated with the inlet passage and therein the fluid transfer channel substantially surrounds the valve seat.

A microvalve for regulating a flow of fluid according to another embodiment comprises: a first plate having inlet passages, outlet passages, and fluid transfer channels in a first face, the fluid transfer channels extending between respective pairs of inlet and outlet passages to permit fluid communication between the pairs of inlet and outlet passages of said first plate extending between the inlet and outlet passages for fluid communication therebetween, the fluid transfer channel having a floor ; a second plate in generally opposed relation with the first face of the first plate and having piston receptacles toward the first face of the first plate ; a sealing membrane located between the first face of the first plate and the second plate ; a piston for each of said piston receptacles of the second plate, each piston being at least partially disposed in the piston receptacle and movable relative to the first plate between an open position in which the sealing membrane does not block fluid flow in a corresponding one of the fluid transfer channels between the inlet passage and outlet passage, and a closed position in which the piston deforms the sealing membrane to block fluid flow in said corresponding one of the fluid transfer channels between the inlet passage and outlet passage, at least some of the pistons being adapted for actuation independently of the other pistons.

The third plate preferably is in generally opposed relation with the second plate on the opposite side of the second plate from the first plate. The third plate has fluid activation passages therein opening from the third plate toward the second plate, at least some of said fluid activation passages are associated with a single piston receptacle whereby the pistons are capable of independent actuation.

An actuation membrane is preferably disposed between the third plate and the second plate and closing the fluid activation passage openings, the actuation membrane is deformable in a region of each fluid activation passage opening upon application of fluid pressure to said passage to engage one of the pistons for moving said one piston from its open position to its closed position.

Preferably the abutting face of the piston which is touching the sealing membrane is structured. Due to the structured contact area of the piston a higher pressing pressure with a in consequence higher pressure tightness is achieved. The structuring is preferably in such a manner formed that the abutting face of the piston does not press against the opening of the inlet passage.

In a further preferred embodiment of the invention the abutting face of the piston reveals a circular recess. In this embodiment there remains an annular edge of the piston which presses the sealing membrane against the valve seat surrounding the inlet passage.

In a further preferred embodiment of the invention the sealing membrane is positioned between the first plate and the spacer membrane. In this embodiment the sealing membrane is advantageously preshaped and shows a downward curvature in the area of the valve seat. This in relation to the afore described embodiment exchanged sequence of spacer and sealing membrane has the advantage that the strain on the sealing membrane in the closed position is less high and therefore a higher amount of life cycles of the membrane are reached.

The microvalve for regulating a flow of fluid according to another embodiment comprises: a first plate having an inlet passage, an outlet passage, a fluid transfer channel in a first face of said first plate extending between the inlet and outlet passages for fluid communication therebetween, the fluid transfer channel having a floor, and a valve seat extending outwardly from the fluid transfer channel toward the first face of the first plate ; a second plate in generally opposed relation with the first face of the first plate and having a ball receptacle opening from the second plate toward the first face of the first plate ; a sealing membrane located between the first face of the first plate and the second plate ; a ball at least partially disposed in the ball receptacle of the second plate and movable relative to the first plate between an open position in which the sealing membrane is spaced from the valve seat to permit fluid flow between the inlet passage and outlet passage through the fluid transfer channel, and a closed position in which the ball presses the sealing membrane against the valve seat to prevent fluid flow between the inlet passage and the outlet passage through the fluid transfer channel.

The advantage of the ball is that the sealing membrane is pressed against the edge of the inlet passage and therefore leading to a higher pressing pressure.

A spacer membrane is preferably located between the sealing membrane and the first face of the first plate for spacing the sealing membrane from the first face of the first plate. The spacer membrane has an opening therein generally aligned with the valve seat whereby the sealing membrane may be deformed through the opening by movement of the ball to said closed position into engagement with the valve seat.

The spacer membrane sealingly engages the first face of the first plate over the fluid transfer channel except at said opening of the spacer membrane.

The first face of the first plate preferably lies generally in a plane and wherein the valve seat includes an engagement surface lying generally in the plate of the first face.

The valve seat is preferably associated with the inlet passage and therein the fluid transfer channel substantially surrounds the valve seat.

A microvalve for regulating a flow of fluid according to another embodiment comprises : a first plate having inlet passages, outlet passages, and fluid transfer channels in a first face, the fluid transfer channels extending between respective pairs of inlet passages and outlet passages to permit fluid communication between the pairs of inlet and outlet passages of said first plate extending between the inlet and outlet passages for fluid communication therebetween, the fluid transfer channel having a floor ; a second plate in generally opposed relation with the first face of the first plate and having ball receptacles toward the first plate and the second plate ; a sealing membrane located between the first face of the first plate and the second plate ; a ball for each of said ball receptacles of the second plate, each ball being at least partially disposed in the ball receptacle and movable relative to the first plate between an open position in which the sealing membrane does not block fluid flow in a corresponding one of the fluid transfer channels between the inlet passage and outlet passage, and a closed position in which the ball deforms the sealing membrane to block fluid flow in said corresponding one of the fluid transfer channels between the inlet passage and outlet passage, at least some of the balls being adapted for actuation independently of the other balls.

The third plate is preferably in generally opposed relation with the second plate on the opposite side of the second plate from the first plate. The third plate has fluid activation passages therein opening from the third plate toward the second plate, at least some of said fluid activation passages are associated with a single ball receptacle whereby the balls are capable of independent actuation.

An actuation membrane is preferably disposed between the third plate and the second plate and closing the fluid activation passage openings. The actuation membrane is deformable in a region of each fluid activation passage opening upon application of fluid pressure to said passage to engage one of the balls for moving said one ball from its open position to its closed position.

Exemplary embodiments are described in the following on the basis the drawings.

Fig. 1A is a schematic vertical cross section of a first embodiment of the microvalve of the present invention showing the microvalve in a first, open position; Fig. 1B is a schematic vertical cross section similar to Fig. 1A but showing the microvalve in a second, closed position; Fig. 2A is a schematic vertical cross section similar to Fig. 1A except that the injection valve does not have a stopper in the third plate ; Fig. 2B is a schematic vertical cross section similar to Fig. 1 B except that the injection valve does not have a stopper in the third plate ; Fig. 3A is a schematic vertical cross section according to another embodiment showing the microvalve in an open position; Fig. 3B is a schematic vertical cross section similar to Fig. 3A but showing th microvalve in a closed position.

Fig. 4A is a schematic vertical cross section of another embodiment of the present invention, showing the microvalve in an open position; Fig. 4B is a schematic vertical cross section similar to Fig. 4A but showing the microvalve in a closed position.

Fig. 5 is a schematic vertical cross section of two combined valves.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Referring to Figs. 1A and 1B, microvalve 201 generally comprises a first plate 205 having an inlet passage 207, an outlet passage 209 and a fluid transfer channel 211. The inlet passage 207 and outlet passage 209 extend through the first plate 205 from a first face to a second face. The fluid transfer channel 211 formed in the first face of the first plate 205 has a floor 211 A and extends between the inlet passage 207 and outlet passage 209 of the first plate 205 for fluid communication there between.

The microvalve 201 further comprises a valve seat 213, a second plate 215, a sealing membrane 217, a spacer membrane 219 and a piston 221. In the illustrated embodiment, the second plate 215 includes two plate members 215A, 215B. The valve seat 213 extends outwardly from the floor 211A of the fluid transfer channel 211 toward the first face of the first plate 205. Second plate 215 is positioned in generally opposed relation with the first face of the first plate 205 and has a piston receptacle 223 opening from the second plate 215 toward the first face of the first plate 205. The sealing membrane 217 is located between the first face of the first plate 205 and the second plate 215.

Piston 221 is at least partially disposed in the piston receptacle 223 of the second plate 215.

Spacer membrane 219 is located between the sealing membrane 217 and the first face of the first plate 205 for spacing the sealing membrane from the first face of the first plate. The spacer membrane 219 has an opening 225 therein generally aligned with the valve seat 213 whereby the sealing membrane 217 may be deformed through the opening by movement of the piston 221 and into engagement with the valve seat to seal the inlet passage 207 from fluid communication with the fluid transfer channel 211. Preferably the spacer membrane 219 sealingly engages the first face of the first plate 205 over the fluid transfer channel 211 except at the opening 225 of the spacer membrane 219. Thus, fluid in the fluid transfer channel 211 can flow only between the inlet and outlet passages 207,209.

The microvalve 201 still further comprises a third plate 227 and an actuation membrane 229. Third plate 227 is in generally opposed relation with the second plate 215 on the opposite side of the second plate from the first plate 205. The third plate 227 has a fluid activation passage 231 therein opening from the third plate 227 toward the second plate 215 and associated with piston receptacle 223. Actuation membrane 229 is disposed between the third plate 227 and the second plate 215 and closes the fluid activation passage opening. The actuation membrane 229 is deformable in a region of the fluid activation passage opening upon application of fluid pressure to said passage to engage the piston 221 for moving the piston. Preferably third plate 227 additionally includes a stopper 233 positioned in the area of the fluid activation passage opening to restrict the range of movement of the piston for minimizing plastic deformation of the actuation membrane 229.

The microvalve 201 operates by moving the piston 221 relative to the first plate 205 between an open position (Fig. 1A) in which the sealing membrane 217 is spaced apart from the valve seat 213 to permit fluid flow between the inlet passage 207 and outlet passage 209 through the fluid transfer channel 211, and a closed position (Fig. 1B) in which the piston 221 presses the sealing membrane 217 against the valve seat 213 to prevent fluid flow between the inlet passage 207 and the outlet passage 209 through the fluid transfer channel 211.

The microvalve 201 is operated by an actuator (not shown) in fluid communication with fluid activation passage 231. The actuator supplies pressurized fluid, preferably a pressurized actuation gas, which acts on actuation membrane 229 via fluid activation passage 231. In the open position of the microvalve as described above, no pressurized fluid is supplied by the actuator and the actuation membrane 229 is in its relaxed position (Fig. 1A).

'6 close the microvalve as described above, pressurized fluid supplied by the actuator via fluid activation passage 231 acts to deform the actuation membrane 229 from its normal position to move the piston 221 into the closed position as described above and as shown in Fig. 1B.

The figures 2A and 2B correspond to the figures 1A and 1 B with the difference that no stoppers 233 are arranged underneath the actuation membrane.

In the figures 3A and 3B a further embodiment is represented, which differs from the embodiment of the figures 2A and 2B thereby, that the abutting face 222 of the piston 221, which contacts the sealing membrane 217, is structured. The structuring shown here consists of the fact that the abutting face 222 of the piston 221 has a recess 222A, so that an annular edge 222B is formed, which presses the sealing membrane 217 against the valve seat 213. The sequence of the sealing membrane 217 and the spacer membrane 219 is interchanged and the sealing membrane is preformed-and shows a downward curvature in the area of the valve seat. This formation has the advantage that the strain to the sealing membrane 217 in the closed position is less high and therefore a higher amount of life cycles of the membrane 217 are reached. In the open position the pre-formed sealing membrane 217 allows a fluid flow through the open fluid transfer channel 211 with only a little pressure drop in the area of the valve seat 213.

In the figures 4A and 4B a further embodiment is shown, which differs from the embodiments of figure 2A and 2B respective 3A and 3B in using a ball 121 instead a piston. This ball 121 is positioned on the actuation membrane 229 with metal ring 122, whereby the ring is attached to the actuation membrane 229. The ball 121 has for example a diameter of 1 mm. The second plate 215 shows a height of about 1 mm and is in this case monolithic. The diameter of the cylindrical pressure chamber amounts to 6 mm for example.

The metal ring 122 has preferably a height of 0,75 mm and hole (diameter 0,5 mm), whereby the ball is countersinked by the amount of the height of the metal ring. The pressure tightness in the closed position of the valve is achieved by the edge contact between the annular edge of the inlet passage 207 and the sealing membrane 217, which is drawn out by the ball 121 respectively, like it is shown in figure 4B.

As membrane material polyimide foils with an about 10 Nm strong PTFE layer were used. The valves showed in endurance test up to temperatures to 150 °C fauitless function and fulfilled the above mentioned requirements.

In the Fig. 5 a further embodiment is represented in which two microvalves 201 like the valves showed in Figs. 1A and 1B are combined to one device.

The first plate 205 has an inlet passage 207 and two outlet passages 209 and a fluid transfer channel 211 extending between the inlet and outlet passages to permit fluid communication between the passages. The second plate 215 has two piston receptacles 223 with two pistons 221.

The third plate 227 has two fluid activation passages 231 therein opening from the third plate 222 toward the second plate 215 with the two fluid activation passages 231 associated to the respective piston receptacles 223 whereby the pistons 221 are capable of independent actuation.

An actuation membrane 229 is disposed between the third plate 227 and the second plate 215 and closing the fluid activation passages 231 openings.

In the shown status the left valve is in open position in which the sealing membrane 217 does not block fluid flow in the corresponding fluid transfer channel between the inlet passage 207 and outlet passage 209 on the right side. The right valve is in closed position in which the piston deforms the sealing membrane to block fluid flow between the inlet passage 207 and right outlet passage 209.

The pistons are adapted for independently actuation.

A combination of more than two microvalves in one device is also possible. In corresponding devices balls instead of pistons can also be used.

The microvalve of the present invention may be constructed in any geometrical arrangement, for example, curved, circular or linear, with linear arrangements being generally more preferred to achieve greater spatial density Preferably each microvalve has a rectangular outer profile in plan to facilitate closely packing the valves together. However the arrangement, the first face of the first plate 205 preferably lies generally in a plane and the valve seat 213 includes an engagement surface (contacted by the sealing membrane 217 in the closed position) lying generally in the plane of the first face.

The microvalve was tested at 20°C, 100°C, 200°C and the components were inspected after 15.000 life cycles.

The design was as follows : - Piston (OD: 4 mm, ID : 0,8 mm, L: 5,8 mm) - Pure Kapton Membranes (All Foils thickness 50 microns) -Polished valve seat (OD: 2 mm, ID : 1 mm, HOLE: 0,4 mm) No preformed membranes, no O-Rings Results ofestseries : At upper membrane no plastic deformations or imprints are observed.

At lower membrane small plastic deformation is visible after 15.000 cycles + leak rate to outlet < 1 E-5 SCCM + leak rate to environment < 1 E-5SCCM + pressure drop < 1 MBAR/CCM Microvalves can be fabricated by methods known in the art. See, for example, Rich et al.,"An 8-bit Microflow Controller Using Pneumatically-Actuated Valves", pp. 130-134, IEEE (1999); Wang et al.,"A Parylene Micro Check \blve", pp. 177-182, IEEE (1999); Xdeblick et al.,"Thermpneumatically Actuated Microvalves and Integrated Electro-Fluidic Circuits", 251-255, TRF Solid State Sensor and Actuator Workshop, Hilton Head, South Carolina, June 13-16 (1994); and Grosjean et al.,"A Practical Thermpneumatic \hive", 147-152, IEEE (1999). As will be apparent to one skilled in the art, injection valves of the present invention may be constructed of any materials that are capable of being precision machined or micro-fabricated. Suitable materials include, for example, metal, glass, silicon, ceramic or quartz. In a preferred embodiment, the microvalve comprises precision-machined stainless steel. Membranes suitable for use in the invention may generally include polymer or metal films selected so as to minimize plastic deformation. Particularly preferred membranes include polyimide polymer films such as Kaptons commercially available from DuPont High Performance Films, Circleville, OH; teflon-coated polyimide polymer films ; and fluoropolymer films such as Kalrez'D commercially available form DuPont Dow Elastomers, Wilmington, DE.

Reference symbol list 201 microvalve 205 first plate 207 inlet passage 209 outlet passage 211 third transfer passage 211A floor 213 valve seat 215 second plate 215A plate member 215B plate member 217 sealing membrane 219 spacer membrane 221 piston 222 abutting face 222a recess 222b annular edge 223 piston receptacle 225 opening 227 third plate 229 actuation membrane 231 fluid actuation passage 233 stopper 121 ball 122 metal ring 123 ball receptacle