GAS VALVE AND METHOD OF DELIVERING A GAS PULSE

Abstract: A gas valve comprisng a housing (13, 19) with a gas inlet (11) and a gas outlet (12), which housing (13, 19) comprises an annular valve seat (14) and a valve disc (15) disposed upstream thereof, which valve disc (15) can sealingly rest on said valve seat (14). The valve disc (15) is centrally provided in a membrane (16, 17), whilst the circumferential edge of the membrane (16) is fixed in the housing (13, 19). The side of the membrane (16) that faces towards the valve seat (14) is in direction communication with said gas inlet (11), and the side of the membrane (16, 17) that faces away from the valve seat (14) bounds a control chamber (31) which is in communication with the gas inlet (11) via a throttle opening. Means are present for allowing gas to flow from the control chamber (31) to the gas outlet (12) so as to open the gas valve.

Description: GAS VALVE AND METHOD OF DELIVERING A GAS PULSE The invention relates to a gas valve comprising a housing with a gas inlet and a gas outlet, which housing comprises an annular valve seat and a valve disc disposed upstream thereof, which valve disc can sealingly rest on said valve seat, and which is centrally provided in a membrane, whilst the circumferential edge of the membrane is fixed in the housing, wherein the side of the membrane that faces towards the valve seat is in direction communication with said gas inlet, and wherein the side of the membrane that faces away from the valve seat bounds a control chamber which is in communication with the gas inlet via a throttle opening, wherein means are present for allowing gas to flow out of said control chamber so as to reduce the pressure to such an extent that the valve disc is lifted from the valve seat. A valve of this kind is known from WO 96/27095. The valve disc of such a valve is preferably centrally disposed in the membrane. In another preferred embodiment, the membrane and the valve disc are integrally made of a material which is flexible to such an extent that on the one hand it is sufficiently rigid to form the valve disc whereas on the other hand it is sufficiently flexible to form the membrane. A valve of this kind can be used in particular for delivering a gas pulse, that is, a brief but intensive gas flow-through, for example for the purpose of cleaning a dust filter wherein an intensive gas flow is effected through the dust filter for a short period of time in a direction opposed to the direction of the gas flow during filtration. The gas valve comprises a membrane, one side of which is in direct communication with the gas inlet. This side of the membrane has a smaller surface area than the other side of the membrane, which other side forms the boundary of the control chamber. The former side has a smaller surface area because the valve disc is centrally disposed in the membrane on that side. The control chamber is in communication with the gas inlet via one or more throttle openings, so that the same pressure, that is, the supply pressure of the gas valve, prevails on either side of the membrane in the closed position of the valve . The gas valve is opened by suddenly reducing the gas pressure in the control chamber. This can be done by opening an electromagnetically controlled valve, so that the control chamber is placed into communication with the ambient atmosphere . One drawback of such a gas valve is the fact that relatively much noise is produced by the gas flowing out of the control chamber into the ambient atmosphere. Moreover, it may be undesirable to allow the gas to flow into the ambient atmosphere, in particular when said gas is a specific gas or a conditioned gas. The object of the invention is to provide a gas valve which can be opened quickly by discharging gas from a control chamber, wherein the noise production of the gas valve is limited and wherein no gas is released into the environment . In order to accomplish that objective, said means are so designed that they place the control chamber into communication with the gas outlet. At the point in time that the gas valve is to be opened, a relatively low gas pressure prevails in the gas outlet, so that the discharge of the gas from the control chamber to said . gas outlet can take place quickly. In practice, the fact that subsequently the gas pressure in the gas outlet will rise because the gas valve is open, does not appear to have an adverse effect as regards the opening of the valve, because the quick opening of the valve has already taken place before the gas pressure in the gas outlet increases. Preferably, the valve disc is provided with a passage for placing the control chamber into communication with the gas outlet. This arrangement obviates the necessity of making additional provisions in the housing, whilst in addition a passage through the valve disc forms a short connection between the control chamber and the outlet. In order to promote a quick discharge of the gas from the control chamber, this passage preferably has a diameter of more than 15% of the diameter of the valve seat, more preferably a diameter of more than 20% of the diameter of the valve seat. A passage having such a large cross-sectional area can easily be provided centrally, that is, axially, in the valve disc. In one preferred embodiment the valve disc and a membrane are integrally formed from a piece of a flexible material. Preferably, the valve disc extends substantially annularly around the central passage, and the membrane extends both outside the valve disc and within the valve disc, seen in axial direction relative to the annular form, and the part of the membrane that extends within the valve disc is fixed in the housing round the passage for discharging the gas from the control chamber to the gas outlet. As a result of this arrangement, at least part of the passage may be a stationary part of the housing, which stationary part can form a valve seat for a valve which controls the discharge of gas from the control chamber to the gas outlet . Preferably, the membrane extending within the valve disc is substantially tubular at the location where it is fixed in the housing, extending in axial direction at that location, whereby it surrounds the passage. In one preferred embodiment, the control chamber is annular and the wall of the control chamber disposed opposite said membrane comprises an annular protrusion extending into the control chamber, wherein, in the open position of the valve, the membrane is disposed on either side of said protrusion, that is, both within and outside the protrusion, seen in radial direction. In this manner the dead volume of the control chamber can be reduced and the protrusion can form a stop against which the valve disc can bear in the open position of the valve . In one preferred embodiment, the passage is connected to a second valve seat provided in the housing, which can be closed by a second valve disc for placing the central passage into communication with the control chamber or shutting if off therefrom. Preferably, the second valve disc is centrally provided in a second membrane, which second membrane on the one hand bounds the aforesaid control chamber and which on the other hand bounds a second control chamber, which second membrane comprises a central passage which is capable of placing the former control chamber into communication with the second control chamber, which passage is provided with a third valve seat, which mates with a closing member which forms part of the movable core of a controllable electromagnet. Preferably, an electromagnetically controlled valve is present for controlling the connection between the control chamber and the gas outlet. This makes it possible to effect a quick opening of the passage between the control chamber and the gas outlet . In one preferred embodiment, a stationary guide member is provided within the valve disc, which guide member is fixed in the housing together with the central portion of the membrane. The passage for placing the control chamber into communication with the gas outlet may be provided through said guide member. The presence of such a guide member disposed within the valve disc prevents the valve disc from being moved to an undesirable position (out of alignment) , whilst the guide means do not interfere with the gas flow round the valve disc. In addition, the guide member functions to support the membrane . Preferably, the membrane is sealingly enclosed at its circumferential edge between two annular surfaces of, respectively, two parts of the housing, wherein the two annular surfaces are substantially cylindrical surfaces, which surround one another. This makes it possible to accommodate the edge of the membrane in a satisfactory and reliable manner, also when the axial distance between the two parts of the housing slightly varies. In one preferred embodiment, the housing of the gas valve consists of at least two attached-together parts, between which a sealing ring is fitted, wherein each of said parts is provided with a cylindrically extending surface, an inwardly extending surface and an outwardly extending surface, respectively, between which surfaces the sealing ring is fitted. Also in this case, the distance between the parts of the housing may slightly vary in axial direction without this having an adverse effect on the correct sealing between the two housings. The above-described presence of two cylindrical surfaces between which the circumferential edge of the membrane and/or a sealing ring is present, may be considered to constitute a separate invention, and it can be used independently of the aforementioned aspects in a housing for a valve or for different hydraulic or pneumatic component when said housing consists of at least two parts which are sealingly connected with one another. The invention furthermore relates to a method of delivering a gas pulse, wherein an electromagnetically controlled gas valve is opened quickly by having gas flow from a control chamber bounded by a membrane into the gas outlet, as a result of which the membrane is moved by the gas pressure in the gas inlet of the gas valve, causing the gas valve to open, wherein the gas is led from the gas inlet to the gas outlet of the gas valve . Further aspects, which can be used independently and in combination with each other, will be disclosed by means of an embodiment and be defined in the claims. In order to explain the invention more fully, an embodiment of an electromagnetically operated gas valve will now be described with reference to the drawing. Figure 1 is a view of the gas valve ; Figure 2 is a sectional view along line II-II in Figure 1; Figure 3 is a sectional view corresponding to Figure 2, showing the valve in partially open position; Figure 4 shows a detail indicated by IV in Figure 2 ; and Figure 5 shows an enlarged portion of Figure 2. The gas valve is only schematically shown in the figures, and that in elevation in Figure 1. Figure 1 shows a gas inlet 11, to which a gas supply pipe can be attached by means of screw thread or other pipe connection. On its bottom side, the gas valve is provided with a gas outlet 12, to which a gas discharge pipe can be similarly connected. Both gas inlet 11 and gas outlet 12 are provided in the first housing part 13, in which also the annular valve seat 14 (Figure 2) is provided. The gas valve furthermore comprises a valve disc 15, which can rest sealingly on valve seat 14, as is shown in Figure 2. Valve disc 15 is integral with membrane 16, 17. Membrane 16, 17 extends radially outwards (indicated by numeral 16) and radially inwards (indicated by numeral 17) . The material of valve disc 15 and membrane 16, 17 is flexible to such an extent that on the one hand it is sufficiently rigid to form the valve disc whilst on the other hand it is sufficiently flexible to form membrane 16, 17. Membrane 16, 17 and valve disc 15 may also be made of different materials. The outwardly extending circumferential edge 18 of membrane 16 is accommodated in a recess between first housing part 13 and second housing part 19. Figure 4 shows in more detail the connection between first housing part 13 and second housing part 19. First housing part 13 is provided with a cylindrical, inwardly extending wall 21, and second housing part 19 is provided with a cylindrical, outwardly extending wall 22. Between said two walls 21, 22 a space is present, in which the circumferential edge 18 of membrane 16 is accommodated. In order to effect a proper gastight seal, circumferential 18 of membrane 16 is provided with an obliquely outwardly extending rib 23, which sealingly abuts against wall 21 of first housing part 13. Figure 4 also shows a sealing ring 24, which is likewise accommodated in the space between walls 21, 22 of, respectively, first and second housing part 13, 19. The sealing ring is an O-ring, which is slightly compressed between walls 21, 22. The distance between walls 21, 22 can be precisely determined in advance, and it does not depend on the relative positions in axial direction of first housing part 13 and second housing part 19. Flexible sealing ring 24 is thus compressed to a predetermined degree, which provides an optimum seal between first housing part 13 and second housing part 19. The same applies to circumferential edge 18 of membrane 17 and the rib 23 provided on said circumferential edge. First housing part 13 and second housing part 19 are attached together by means of a substantially circular clip 25, which is fitted in an outwardly extending gutter of the first housing part along part of its length (Figure 4) and which abuts against a radially extending stop surface on parts 26 of second housing part 19 along another part of its length (Figure 1) . A connection between the two housing parts 13, 19 of this kind is disclosed in the aforementioned publication WO96/27095 and also in publication WO96/27096. If this connection allows some play in axial direction between first housing part 13 and second housing part 19, an optimum seal between the two housing parts 13, 19 and a correct fixation of circumferential edge 18 of membrane 16 remains ensured, due to the use of the axially extending walls 21, 22. Second housing part 19 and membrane 16, 17 together enclose a control chamber 31. The gas pressure in control chamber 31 exerts a downward force on membrane 16, 17, and thus on valve disc 15, whilst the gas pressure in gas inlet 11 exerts an upward force on membrane 16 an thus on valve disc 15. Control chamber 31 is connected to gas inlet 11 via throttle opening 32, so that the gas pressure that prevails in control chamber 31, which is closed for that matter, is the same as the gas pressure in gas inlet 11 in the closed position of the gas valve. Since the surface area of membrane 16, 17 on which the control chamber exerts the downward force is larger than the surface area of membrane 16 on which the same gas pressure exerts the upward force in the gas supply pipe, valve disc 15 will rest on valve seat 14, thus closing the gas valve. It should be considered thereby that the gas pressure in gas outlet 13 will be lower than the gas pressure in gas inlet 11 at all times. The radially inwardly extending portion of membrane 17 tapers off tubularly in upward direction, and it is clamped down between second housing part 19 and a guide member 33 fitted in said housing part, with an O-ring 34 providing a proper seal. Guide member 33 is disposed within valve disc 15 and forms a guide to ensure correct movement in vertical direction of valve disc 15. Said guide member may extend further downwards than is shown in Figure 2. Valve disc 15 is provided with a central passage 35, which connects to a central passage 36 within guide member 33. Second housing part 19 comprises a second valve seat 41, which is capable of sealing cooperation with a second membrane 42 (Figure 5) . As long as membrane 42 closes valve seat 41, the gas valve remains closed, due to the resulting downward force on valve disc 15, as described above. The gas valve is opened in that membrane 45 is lifted from valve seat 41, as a result of which control chamber 31 is connected, via passage 36 in the guide member 33 disposed in passage 33, to gas outlet 13, where a lower gas pressure prevails . The gas pressure fall-out in control chamber 31 causes membrane 16, 17, and thus valve disc 15, to move in upward direction, as a result of which the gas valve is opened. This at least partially open position of the gas valve is shown in Figure 3, which figure shows fewer parts of the gas valve than Figure 2 for that matter, in particular first and second housing part 13, 19 and the parts present therein. The second membrane 42 as shown in Figure 5, which can rest sealingly on valve seat 41, is clamped down at its circumferential edge between second housing part 19 and a third housing part 43, and it is provided with a central opening, in which a control element 44 is mounted. Control element 44 is provided with a central passage 45 and with a third valve seat 46, which supports a closing member 47 of a flexible material, which is fitted in the movable core 48 of an electromagnet 49. Present on the upper side of second membrane 42 is a second control chamber 52, which is in communication with control chamber 31 via a throttle opening (not shown) in membrane 42. Consequently, the same gas pressure as in gas inlet 11 prevails in second control chamber 52 in the closed position of the gas valve. When the movable core 48 is moved in upward direction against the force of spring 54 as a result of electromagnet 49 being energized, the gas pressure in the second control chamber 52 will fall out, because an open communication to the gas outlet is created via open valve 46, 47, passage 45 in control element 44, passage 36 in guide member 33 and passage 35 in valve disc 15. As a consequence, second membrane 42 will move in upward direction, so that control chamber 31 is placed into open communication with the gas outlet via valve 41, 42, passage 36 and passage 35. As already described before, this will cause valve member 15 to move in upward direction, as a result of which the gas valve is opened. In practice it has become apparent that when the gas valve is opened in this manner, wherein in fact three valves are opened in succession, said opening can take place very quickly. The electromagnetic valve is controlled via a control unit 51. The valve may also be operated by remote control, via a gas pipe which is connected with the second control chamber 52. Gas is discharged from second control chamber 52 via said gas pipe in that case so as to open the valve . To that end the gas pipe may be connected to an electromagnetically controlled gas valve, which is disposed at some distance from the valve. The above-described embodiment only serves to explain the invention, may variations to it are possible.

Claims: CLAIMS 1. A gas valve comprising a housing with a gas inlet (11) and a gas outlet (12), which housing (13, 19) comprises an annular valve seat (14) and a valve disc (15) disposed upstream thereof, which valve disc (15) can sealingly rest on said valve seat (14) , and which is centrally provided in a membrane (16, 17) , whilst the circumferential edge of the membrane (16) is fixed in the housing (13, 19), wherein the side of the membrane (16) that faces towards the valve seat (14) is in direction communication with said gas inlet (11) , and wherein the side of the membrane (16, 17) that faces away from the valve seat (14) bounds a control chamber (31) which is in communication with the gas inlet (11) via a throttle opening, wherein means (35, 36) are present for allowing gas to flow out of said control chamber (31) so as to reduce the pressure to such an extent that the valve disc (15) is lifted from the valve seat (14) , characterized in that said means (35, 36) place said control chamber (31) in communication with said gas outlet (12) . 2. A gas valve according to claim 1, characterized in that said means comprises a central passage (35) through the valve disc (15) and a stationary passage (36) connecting to said central passage, which stationary passage (36) is fixedly disposed in the housing (19) . 3. A gas valve according to any one of the preceding claims, characterized in that the valve disc (15) and the membrane (16, 17) are integrally formed from a piece of a flexible material. 4. A gas valve according to any one of the preceding claims, characterized in that the valve disc (15) . is substantially annular, and the membrane (16, 17) extends both outside the valve disc (15) and within the valve disc (15) , seen in axial direction relative to the annular form, and the part of the membrane (17) that extends within the valve disc (15) is fixed in the housing (19) round a passage (36) for discharging the gas from the control chamber (31) to the gas outlet (12) . 5. A gas valve according to claim 4, characterized in that the membrane (17) extending within the valve disc (15) is substantially tubular at the location where it is fixed in the housing (19) , extending in axial direction thereby. 6. A gas valve according to claim 4 or 5, characterized in that the control chamber (31) is annular, that the wall of the control chamber (31) disposed opposite said membrane (16, 17) comprises an annular protrusion (40) extending into the control chamber (31) , and that the membrane (16, 17) is disposed on either side of said protrusion (40) in the open position of the valve. 7. A gas valve according to any one of the claims 4 - 6, characterized in that said passage (36) is connected to a second valve seat (41) provided in the housing (19) , which can be closed by a second valve disc (42) for placing said passage (36) into communication with the control chamber (31) or shutting if off therefrom. 8. A gas valve according to claim 7, characterized in that the second valve disc (42) is centrally provided in a second membrane (42) , which second membrane (42) on the one hand bounds said control chamber (31) and which on the other hand bounds a second control chamber (52), which second membrane (42) comprises a central passage (35, 36) which is capable of placing the second control chamber (52) into communication with the central passage of the valve, which passage (45) is provided with a third valve seat (46) , which mates with a closing member (47) which forms part of the movable core (48) of a controllable electromagnet (49) . 9. A gas valve according to any one of the preceding claims, characterized in that an electromagnetically controlled valve (41, 42; 46, 47) is present for controlling the connection between the control chamber (31) and the gas outlet (12) . 10. A gas valve according to any one of the preceding claims, characterized in that a stationary guide member (33) is provided within the valve disc (15) . 11. A gas valve according to claim 10, characterized in that said guide member (33) is fixed in the housing (19) together with the central portion of the membrane (17) . 12. A gas valve according to claim 11, characterized in that said guide member (33) comprises a passage (36) for placing the control chamber (31) into communication with the gas outlet (12) . 13. A gas valve according to any one of the preceding claims or other hydraulic or pneumatic component, comprising a housing (13, 19) which consists of at least two attached-together parts, between which a sealing ring and/or the circumferential edge (18) of a membrane (16, 17) is fitted, characterized in that each of said parts (13; 19) is provided with a cylindrically extending surface (21, 22) , an inwardly extending surface (21) and an outwardly extending surface (22) , respectively, between which surfaces (21, 22) the sealing ring and/or the circumferential edge (18) of said membrane (16, 17) is (are) fitted. 14. A method of delivering a gas pulse, wherein an electromagnetically controlled gas valve is opened quickly by having gas flow from a control chamber (31) bounded by a membrane (16, 17) into the gas outlet (12) , as a result of which the membrane (16, 17) is moved by the gas pressure in the gas inlet (11) of the gas valve, causing the gas valve to open, characterized in that the gas is led from the control chamber (31) to the gas outlet (12) of the gas valve.

Inventors: OOMEN TJERK, VAN DER ZEE JAN, OOMEN, TJERK, VAN DER ZEE, JAN
Applicants: ASCO CONTROLS BV, OOMEN TJERK, ZEE JAN V D, ASCO CONTROLS B.V., OOMEN, TJERK, VAN DER ZEE, JAN
Application year: 1999
Main classification: F16K31
IPC codes: F16K31