fig1 a - 1 d illustrate the principle of a pneumatic pinch valve as known in the art . fig1 a - 1 b illustrate top and side views of the open configuration of the valve , while fig1 c - 1 d illustrate top and side view of the closed configuration . a cylindrical channel or tube 101 is surrounded by a chamber 102 with an injection port 105 , and in close connection to the channel 101 . when the chamber 102 is filled with air or some fluid under pressure 103 the cylindrical channel 101 will be pinched as shown schematically in fig1 c - 1 d and the valve is closed . however , if the channel 101 is a conventional more or less circular tube , the valve will have difficulties in closing completely as the tube will wrinkle in compression 104 in some undefined shape not known a priori . furthermore , this wrinkling 104 leads to severe wear and fatigue of the channel material even after a relatively few closing and opening operations of the valve . fig2 a - 2 d illustrate a pinch valve as used in a respiration valve according to the invention . as in the prior figures , fig2 a - 2 b illustrate top and side view of the open configuration of the valve , while fig2 c - 2 d illustrate a top and side view of the closed configuration . the channel 101 with the flow regulated by the valve is surrounded by a chamber 102 with an injection port 105 . the channel 101 is designed as a tube with a flexible wall 201 , comprising two opposing wall segments 202 connected angularly at interconnection points 203 . the two wall segments 202 are in this embodiment of the invention connected at an acute angle 205 . the cross sectional shape is furthermore symmetric and elongated such that the largest distance between the two opposing wall segments 202 is smaller than the distance between the interconnection points 203 . only the design of the part of the channel inside the chamber 102 is of importance . outside the chamber 102 the channel 101 could have any arbitrary shape or cross section . the two - sided channel is designed such , that the two wall segments 202 are pinched together and close the channel completely 204 when pressure is applied to the chamber 103 . this is illustrated in fig2 c - 2 d . the pressure needed to close the channel is minimal because of the cross sectional shape and the flexibility of the wall segments 202 . also , due to the well defined shape of the cross section of the channel at increasing pressure in the chamber 102 , the flow through the channel 101 can be controlled precisely by the pressure and regulated precisely from fully open to fully closed and all positions in - between . furthermore , the shape leads to only minimal stresses in the flexible channel wall 201 even in the fully closed and deformed position 204 as the problematic stresses occurring at the bending locations of a conventional tube are avoided by the angular interconnection 203 of the wall segments 202 . a further advantage of the valve is the absence of any parts protruding into the channel which would inevitably increase the flow resistance . it is also advantageous that the valve is without any mechanically moving parts . furthermore , it is possible to manufacture the valve as a one - piece in silicone , a thermoplastic elastomer or the like . the pinch valve can also be manufactured as a hybrid of different materials where for instance the wall segments of the channel are made in a flexible material like silicone and the chamber is made in a more rigid and inexpensive material like for instance a plastic . hereby , the wall thicknesses of the chamber can be made smaller and the weight minimized . another embodiment of a valve which advantageously can be used in a respiration valve according to the invention is shown in fig3 a - 3 d . here , the cross sectional shape of the channel 101 is formed in large as an elongated hexagon 301 . this design also allows the channel to close completely 304 when pressure is applied to the chamber 103 . the channel could also be shaped as an elongated hexagon with straight walls if more advantageous for example for production reasons . the part of the channel passing through the chamber 102 may also be of the shape as a rhomb or any convex multisided polygon as long as the shape is such , that the wall segments 202 will be pinched together in a controlled and well defined manner when the pressure is applied exterior to the channel . this controlled folding can be achieved if two interconnection points 203 on the periphery of the cross section are situated so , that the distance between them following the circumference of the channel the one way around or the other is just about the same . fig4 a - 4 d illustrate a respiration valve 401 for performing respiration tests on humans or animals . fig4 a - 4 b illustrate the respiration valve 401 in a top and side view with both pinching valves in open positions . fig4 c - 4 d illustrate the same respiration valve 401 from the top and the side , but with one of the pinching valves being closed . the respiration valve 401 contains three ports — one mouth port 402 , and two breathing ports 403 and 404 . the port 402 forms a mouthpiece or mouthpiece connection into which the patient inhales and exhales . the air that the patient breathes comes from either of the two ports 403 and 404 , where one of the ports 403 is normally connected to the atmospheric air , while the other port 404 is connected to a rebreathing bag ( not shown ) filled with a blood soluble , physiologically inert gas mixture . the two breathing ports 403 and 404 can also be used in the opposite configuration . according to the invention the two breathing ports 403 and 404 comprise a pneumatic pinch valve each . these pneumatic pinching valves can preferably be of the types and principle illustrated in the previous fig2 - 3 . as can be seen in the upper drawings in the figure , the channels 101 leading from the two ports 403 and 404 to the mouthpiece 402 are in this embodiment of the invention made of flexible wall segments 202 shaped in cross section as elongated hexagons as described in fig3 a - 3 d . both pinch valves are fully opened in fig4 a - 4 b . each of these valves is fully or partially closed independently by letting compressed air into the small closed chambers 102 surrounding each channel 101 . by default , the pinch valve above the breathing port 403 is open whereas the pinch valve above the breathing port 404 is closed ( pressurised ) by default . to initiate a rebreathing manoeuvre the two pinch valves are switched e . g . with a short delay between the operation of the individual pinch valves . the air pressure can for instance be controlled by a computer controlled solenoid valve in connection with a source of compressed gas ( not shown ), whereby the operation compared to the operation of a manually controlled valve is eased and simplified dramatically . in fig4 c - 4 d the pinch valve 405 is in its fully closed position , where the two opposing wall segments 202 are pinched together . as these chambers surrounding the channels are small in dimensions , the switching ( closing and opening ) can be performed very fast and with only the need for a low air pressure . a big advantage of the invention is the compactness of the pinch valves which together with the overall constructional design of the respiration valve makes the whole respiration valve compact and small and therefore lighter . furthermore , the compactness of the valves and the design and placing of the two breathing ports means that the dead space between the ports 403 and 404 is kept at a minimum which is of high importance to the quality of the measurements . the exact placing of the three ports in relation to each other in the respiration valve is not necessarily of special importance as long as both the overall size and the dead space are kept minimal . in other embodiments of the invention the ports are placed differently such as for instance with the port 403 lying opposite the port 404 or opposite port 402 forming or connecting to the mouthpiece . the respiration valve can in this embodiment shown in the figures be produced as one single unit out of for instance silicone or a thermoplastic elastomer with an appropriate flexibility . a possibility according to the invention is to further reduce the amount of the relatively expensive silicone rubber material used in the respiration valve and thereby also the weight by reducing the wall thicknesses of the pinch valve chambers . the stiffness of the chamber walls needed to keep down the pneumatic pressure closing the valves could then be obtained by embedding the respiration valve in a rigid housing made of a more inexpensive yet more rigid and lighter material like for instance a plastic . in yet another embodiment the pinch valve is manufactured as a hybrid of different materials , where for instance the wall segments of the channel are made in a flexible material like silicone and the chamber is made in a more rigid and inexpensive material like for instance a plastic . hereby , the wall thicknesses of the chamber can be made smaller and the weight minimized . a further advantage by the respiration valve shown in the figures is that the distances between the interconnection points in the pinch valves compared to the diameters of the ports are chosen such that the flow resistance everywhere in the respiration valve is basically the same . hereby , the breathing by the patient is obstructed as little as possible by the respiration valve , which is important in order not to affect the patient &# 39 ; s breathing . fig5 a - 5 b illustrate a design of the respiration valve 401 as it can be produced in one single piece . fig5 a illustrates the valve from the side and slightly below . here , the channel wall segments 202 in the two , in this case , open pneumatic pinch valves can be seen . the chambers 102 around the channels are open due to manufacturing reasons , but are to be closed and separated by a cover or a cork on each side of the respiration valve of a shape following the contour 502 . the cover can for instance be welded or glued onto the main piece . the air supplies controlling the air pressure in each chamber 102 independently are in this design led through small openings in the cover . fig5 b illustrates the respiration valve from the bottom with the two breathing ports 403 and 404 . it should be noted that the above - mentioned embodiments illustrate rather than limit the invention , and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims . in the claims , any reference signs placed between parentheses shall not be construed as limiting the claim . the word ‘ comprising ’ does not exclude the presence of other elements or steps than those listed in a claim . the invention can be implemented by means of hardware comprising several distinct elements , and by means of a suitably programmed computer . in a device claim enumerating several means , several of these means can be embodied by one and the same item of hardware . the mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage .
the present invention relates to a respiration valve for performing respiration tests on e . g . humans , consisting of at least three ports , a first mouth port and two breathing ports . the breathing ports comprise pneumatic pinch valves consisting of a channel with a flexible wall to be used for the flow of material and molded as an integrated part of a surrounding chamber . the flexible wall comprises two opposing angularly interconnected wall segments which are angularly connected at interconnection points and which flexible wall is pinched by a pressure from fluid , such as air , introduced into the chamber . the cross sectional shape corresponds in one embodiment approximately to a elongated hexagon . the construction of the respiration valve comprising these pneumatic pinch is valves enables a very small , light , hygienic , and safe yet inexpensive construction with a long life expectancy . the respiration valve is preferably completely or partially made of silicone rubber .