EP0202721A1 - Switch valve - Google Patents
Switch valve Download PDFInfo
- Publication number
- EP0202721A1 EP0202721A1 EP86200897A EP86200897A EP0202721A1 EP 0202721 A1 EP0202721 A1 EP 0202721A1 EP 86200897 A EP86200897 A EP 86200897A EP 86200897 A EP86200897 A EP 86200897A EP 0202721 A1 EP0202721 A1 EP 0202721A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- piston
- source
- main
- pressure
- auxiliary
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
-
- A—HUMAN NECESSITIES
- A62—LIFE-SAVING; FIRE-FIGHTING
- A62B—DEVICES, APPARATUS OR METHODS FOR LIFE-SAVING
- A62B9/00—Component parts for respiratory or breathing apparatus
- A62B9/02—Valves
Definitions
- the invention relates to a switch valve, in particular to a multiway valve for connecting an apparatus to different fluid supplies.
- auxiliary source such as an auxiliary supply carried in a tank by the user of a breathing apparatus.
- immediate switch to the auxiliary supply is necessary.
- a known automatically switching valve which functions this way is provided in the housing thereof with check valves in the respective connecting passages between the air inlet connections and the outlet connection to the breathing apparatus and as soon as the pressure in the main-source supply line drops below the pressure in the auxiliary-source supply line the valve in the auxiliary-source supply line opens and the valve in the main-source supply line closes.
- a problem with this known switch valve is that depending on the type, portable compressed air tanks used in practice are adjusted to different working pressures which may vary from 5-8 bar and it is therefore possible that the main-source pressure, at least the pressure of the air supplied from the source, is too low in relation to the auxiliary supply pressure, so that from the start, only air from the auxiliary tank is supplied to the breathing apparatus.
- the main-source pressure at least the pressure of the air supplied from the source
- the auxiliary supply pressure so that from the start, only air from the auxiliary tank is supplied to the breathing apparatus.
- the object of the invention is an automatically switching valve whereby this disadvantage is obviated.
- a switch valve comprising a housing having connection means for a main-source supply-line, for an auxiliary-source supply-line, and for a delivery line to a breathing apparatus as well as pressure responsive control means in connecting passages extending between the respective supply line connections with the delivery line connection
- said control means comprise a differential piston the smaller part of which is loadable by the auxiliary-source pressure and the larger part by the main-source pressure, and which piston in each of its end positions closes off one of the said connecting passages and clears the other passage.
- a relatively low main-source presure is sufficient to accomplish a piston displacement in the sense of interrupting the supply from the reserve tank. It is . for example possible to select the ratio of the piston diameters such that even a nine times higher auxiliary-source pressure than the main-source supply pressure acting on the larger piston end face will move the piston to the end position closing off the auxiliary-source supply line, so that it is guaranteed that irrespective of the adjusted working pressure of the reserve tank, the reserve supply is only tapped when the main-source pressure falls off entirely or substantially entirely.
- a venting bore can be provided in the end wall concerned, through which a rod connected to the piston extends so as to leave an annular passage, said rod carrying a valve which in the end position of the piston which is determined by the main-source pressure closes off said annular passage.
- a switch valve of the subject kind comprising a piston for selectively closing off mains air supply passages and emergency air supply passages towards a delivery line is known per se from GB-A-2,058,580.
- This known valve must be manually reset to switch back to the main supply after the auxiliary supply has been activated. The switching is not automatically back and forth between the auxiliary and main sources and the piston is neither of the differential type nor loadable by the main source pressure.
- US-A-4,499,914 discloses the use of a differential piston in a shuttle valve which is part of a complicated selector valve device for use in an aircraft on board oxygen generation system with high pressure oxygen backup, for blending several gaseous components to provide an optimized breathable air supply.
- the switching of the shuttle valve is not directly controlled by the presence of suffiecient mains air pressure, but by pressure supplied to the shuttle valve by the main blending valve.
- this known valve differs from the valve according to the subject invention in that the larger end of the differential piston is not exposed to the mains air pressure and the known piston is not directly loadable by the auxiliary pressure either, but by a spring.
- the switch valve comprises a housing 1 with a connection 2 for a reserve tank, a connection 3 for a remote main source, and a connection 4 for a breathing apparatus comprising a breathing mask.
- a differential piston 5 is displaceable between end positions depicted in Fig. 1 and Fig. 2.
- the differential piston 5 has a larger cylinder part 6 and a smaller cylinder part 7 and is movable within fitting cylinder spaces 8 and 9 respectively.
- the cylinder space 8 is positioned in the connecting path 10 between the main-source connection 3 and the outlet connection 4 to the breathing mask and the cylinder space 9 is situated in the connecting path 11 between reserve tank connection 2 and mask connection 4.
- a venting bore 13 is provided in the end wall 12 of the cylinder space 8 .
- a 'rod 14 extends through bore 13 leaving an annular channel 15.
- Rod 14 carries a valve 16 for closing annular channel 15 on the outside.
- Valve 16 may be arranged within an enclosure 17.
- a venting bore 18 for cylinder space 8 is provided on the other side of the larger piston part 6.
- the switch from the situation depicted in Fig. 1 to the situation according to Fig. 2 takes place when the main-source pressure Ps becomes so low that breathing becomes difficult. Depending on the specific apparatus and the adjustment thereof, this pressure will, in general, vary from at least 0.5 to 1 bar above atmosphere pressure. At such low source pressures, the piston 5 moves downwards, thereby allowing air and/or oxygen from the auxiliary tank to flow through connection 2 to the mask connection 4. Once the source pressure Ps increases again to a given minimum pressure, the piston will again move upwards, and operation of the device will return to the mode depicted in Fig. 1 wherein air and/or oxygen is fed from the source to the breathing apparatus.
- the pressure required to move the piston upwards be somewhat different from that at which the piston will fall downwards.
- the pressure required to move the piston from its down position upwards to its up position is 2.5 bars above atmospheric pressure. This difference in source pressures is created by the provision of bore 13.
- bore 13 is open and air and/or oxygen flowing through connection 3 is able to escape through the restricted opening 13 and through enclosure 17.
- the bore 13 is closed and all the air and/or oxygen flowing through connection 3 acts on the bottom surface of the larger piston part 6.
Landscapes
- Health & Medical Sciences (AREA)
- Pulmonology (AREA)
- General Health & Medical Sciences (AREA)
- Business, Economics & Management (AREA)
- Emergency Management (AREA)
- Respiratory Apparatuses And Protective Means (AREA)
Abstract
In a multiway valve having a housing (1) with connectors (2, 3, 4) for an auxiliary-source supply line, for a main-source supply line and for a delivery line to for example a breathing mask respectively, a differential piston (5) is movable between two end positions dependent on sufficient main source air pressure acting on the larger end part (6) of the piston (5), the smaller part (7) thereof being loaded by the auxiliary air pressure, said piston (5) when loaded by sufficient main source pressure automatically moves towards and remains in that end position in which the connecting passage (11) from the auxiliary supply line connector (2) to the delivery line connector (4) is closed off and said piston (5) automatically moves towards and remains in the other end position, in which the connecting passage (10) between the main supply line connector (3) and said delivery line connector (4) is closed off, as soon as the main supply pressure drops below a predetermined level.
Description
- The invention relates to a switch valve, in particular to a multiway valve for connecting an apparatus to different fluid supplies.
- For example, when the supply of air or oxygen to a breathing apparatus, as used by the fire department, or in cleaning operations within storage tanks and the like, through a supply hose from a remote main source, is interrupted, it must be possible to immediately switch over to an auxiliary source such as an auxiliary supply carried in a tank by the user of a breathing apparatus. Especially in the case of a sudden drop in supply pressure from the main source, for example because the supply hose is run over and damaged by a vehicle, immediate switch to the auxiliary supply is necessary.
- There is therefore a need for an automatic valve which switches to the auxiliary supply when the main-source pressure drops. A known automatically switching valve which functions this way is provided in the housing thereof with check valves in the respective connecting passages between the air inlet connections and the outlet connection to the breathing apparatus and as soon as the pressure in the main-source supply line drops below the pressure in the auxiliary-source supply line the valve in the auxiliary-source supply line opens and the valve in the main-source supply line closes.
- A problem with this known switch valve is that depending on the type, portable compressed air tanks used in practice are adjusted to different working pressures which may vary from 5-8 bar and it is therefore possible that the main-source pressure, at least the pressure of the air supplied from the source, is too low in relation to the auxiliary supply pressure, so that from the start, only air from the auxiliary tank is supplied to the breathing apparatus. In particular in the fire department there is no opportunity to perform pressure measurements beforehand in order to establish whether there is sufficient main-source pressure in relation to the pressure in the reserve tanks.
- The object of the invention is an automatically switching valve whereby this disadvantage is obviated.
- For this purpose, in a switch valve comprising a housing having connection means for a main-source supply-line, for an auxiliary-source supply-line, and for a delivery line to a breathing apparatus as well as pressure responsive control means in connecting passages extending between the respective supply line connections with the delivery line connection, according to the invention, said control means comprise a differential piston the smaller part of which is loadable by the auxiliary-source pressure and the larger part by the main-source pressure, and which piston in each of its end positions closes off one of the said connecting passages and clears the other passage.
- In the switch valve according to the invention a relatively low main-source presure is sufficient to accomplish a piston displacement in the sense of interrupting the supply from the reserve tank. It is . for example possible to select the ratio of the piston diameters such that even a nine times higher auxiliary-source pressure than the main-source supply pressure acting on the larger piston end face will move the piston to the end position closing off the auxiliary-source supply line, so that it is guaranteed that irrespective of the adjusted working pressure of the reserve tank, the reserve supply is only tapped when the main-source pressure falls off entirely or substantially entirely.
- In order to conserve the auxiliary source and to assure that sufficient flow is always provided to the delivery line it can be very important to be able to switch completely from one source to the other and back automatically, as is accomplished by the present valve.
- In order to avoid that during switching from main source to reserve tank, air entrapped in the cylinder space of the larger piston part prevents a complete piston stroke, according to the invention a venting bore can be provided in the end wall concerned, through which a rod connected to the piston extends so as to leave an annular passage, said rod carrying a valve which in the end position of the piston which is determined by the main-source pressure closes off said annular passage.
- It is to be noted that a switch valve of the subject kind, comprising a piston for selectively closing off mains air supply passages and emergency air supply passages towards a delivery line is known per se from GB-A-2,058,580. This known valve, however, must be manually reset to switch back to the main supply after the auxiliary supply has been activated. The switching is not automatically back and forth between the auxiliary and main sources and the piston is neither of the differential type nor loadable by the main source pressure.
- US-A-4,499,914 discloses the use of a differential piston in a shuttle valve which is part of a complicated selector valve device for use in an aircraft on board oxygen generation system with high pressure oxygen backup, for blending several gaseous components to provide an optimized breathable air supply. In this known device the switching of the shuttle valve is not directly controlled by the presence of suffiecient mains air pressure, but by pressure supplied to the shuttle valve by the main blending valve. Further this known valve differs from the valve according to the subject invention in that the larger end of the differential piston is not exposed to the mains air pressure and the known piston is not directly loadable by the auxiliary pressure either, but by a spring.
- For better understanding of the invention one embodiment of the switch valve will be described, by way of example, with reference to the accompanying drawings.
- Fig. 1 is a schematic sectional view of the switch valve during supply from the main source; and
- Fig. 2 is a view similar to Fig. 1 of the valve in the situation corresponding to supply from the auxiliary source.
- According to the drawings the switch valve comprises a housing 1 with a
connection 2 for a reserve tank, aconnection 3 for a remote main source, and a connection 4 for a breathing apparatus comprising a breathing mask. - In the housing 1 a
differential piston 5 is displaceable between end positions depicted in Fig. 1 and Fig. 2. Thedifferential piston 5 has alarger cylinder part 6 and asmaller cylinder part 7 and is movable withinfitting cylinder spaces cylinder space 8 is positioned in the connectingpath 10 between the main-source connection 3 and the outlet connection 4 to the breathing mask and thecylinder space 9 is situated in the connectingpath 11 betweenreserve tank connection 2 and mask connection 4. - In the
end wall 12 of the cylinder space 8 aventing bore 13 is provided. A 'rod 14 extends throughbore 13 leaving an annular channel 15.Rod 14 carries avalve 16 for closing annular channel 15 on the outside.Valve 16 may be arranged within anenclosure 17. Aventing bore 18 forcylinder space 8 is provided on the other side of thelarger piston part 6. - The operation of the switch valve is as follows: In the high position depicted in Fig. 1
differential piston 5 is under the influence of the main-source pressure supplied throughconnection 3. Valve 16 closes off annular channel 15. Thesmaller piston part 7 prevents air flow from the reserve tank throughconnection 2 and connectingpassage 11 to the mask connection 4. Breathing-air is supplied throughconnection 3 and connectingpassage 10 to mask connection 4. - In the case of interruption of the air supply through
connection 3 the pressure of the reserve tank on the end face of thesmaller piston part 7 prevails and thedifferential piston 5 is displaced to the low position depicted in Fig. 2. Air entrapped incylinder space 8 below thelarger piston part 6 can escape through annular passage 15 so that thedifferential piston 5 is able to move entirely to the low position depicted in Fig. 2. In this position the connectingpassage 10 is closed off by thelarger piston part 6 and the connectingpassage 11 betweenreserve tank connection 2 and mask connection 4 is opened. - The switch from the situation depicted in Fig. 1 to the situation according to Fig. 2 takes place when the main-source pressure Ps becomes so low that breathing becomes difficult. Depending on the specific apparatus and the adjustment thereof, this pressure will, in general, vary from at least 0.5 to 1 bar above atmosphere pressure. At such low source pressures, the
piston 5 moves downwards, thereby allowing air and/or oxygen from the auxiliary tank to flow throughconnection 2 to the mask connection 4. Once the source pressure Ps increases again to a given minimum pressure, the piston will again move upwards, and operation of the device will return to the mode depicted in Fig. 1 wherein air and/or oxygen is fed from the source to the breathing apparatus. - To prevent oscillation of the
piston 5 during operation it is desirable that the pressure required to move the piston upwards be somewhat different from that at which the piston will fall downwards. In general, the pressure required to move the piston from its down position upwards to its up position is 2.5 bars above atmospheric pressure. This difference in source pressures is created by the provision ofbore 13. In fact, when thepiston 5 is in the down position,bore 13 is open and air and/or oxygen flowing throughconnection 3 is able to escape through the restrictedopening 13 and throughenclosure 17. Alternatively, when the piston is in its up position, thebore 13 is closed and all the air and/or oxygen flowing throughconnection 3 acts on the bottom surface of thelarger piston part 6. - By providing the
larger piston part 6 on its end face withprojections 19 defining the lowest position of thedifferential piston 5 it is always ensured that pressure supplied throughsource connection 3 can act on the entire end face ofpiston part 6.
Claims (2)
1. Switch valve comprising a housing (1) having connection means (3) for a main-source supply line (2), for an auxiliary-source supply line, and (4) for a delivery line to a breathing apparatus, as well as pressure-responsive control means (5) in connecting passages (10, 11) extending between the respective supply-line connections (2, 3) with the delivery-line connection (4), characterized in that said control means comprise a differential piston - (5) the smaller part (7) of which is loadable by the auxiliary-source pressure and the larger part (6) thereof by the main-source pressure, and which piston (5) in each of its end positions closes off one of said connecting passages (10, 11) and clears the other passage (11, 10).
2. Switch valve according to claim 1, characterized in that a venting bore (13) is provided in at least the wall (12) bounding the cylinder space (8) opposite to the larger end face of the piston (5), a rod (14) connected to the piston (5) extending through said venting bore (13) leaving an annular passage, said rod (14) carrying a valve (16) which in the end position of the piston determined by the main-source pressure, closes off said annular passage - (13).
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL8501474 | 1985-05-23 | ||
NL8501474A NL8501474A (en) | 1985-05-23 | 1985-05-23 | DIVERSION VALVE. |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0202721A1 true EP0202721A1 (en) | 1986-11-26 |
Family
ID=19846027
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP86200897A Withdrawn EP0202721A1 (en) | 1985-05-23 | 1986-05-22 | Switch valve |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0202721A1 (en) |
NL (1) | NL8501474A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20150367150A1 (en) * | 2013-02-08 | 2015-12-24 | Honeywell International Inc. | Automatic Switching Device for a Breathing Apparatus with an Alarm-Relief Function and Automatic Reset |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3618636A (en) * | 1969-03-26 | 1971-11-09 | Dynamco Inc | Pneumatic logic valve |
FR2232715A1 (en) * | 1973-06-08 | 1975-01-03 | Zahnradfabrik Friedrichshafen | |
US4499914A (en) * | 1983-04-14 | 1985-02-19 | Litton Systems, Inc. | Selector valve for an aircraft on board oxygen generation system with high pressure oxygen backup |
-
1985
- 1985-05-23 NL NL8501474A patent/NL8501474A/en not_active Application Discontinuation
-
1986
- 1986-05-22 EP EP86200897A patent/EP0202721A1/en not_active Withdrawn
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3618636A (en) * | 1969-03-26 | 1971-11-09 | Dynamco Inc | Pneumatic logic valve |
FR2232715A1 (en) * | 1973-06-08 | 1975-01-03 | Zahnradfabrik Friedrichshafen | |
US4499914A (en) * | 1983-04-14 | 1985-02-19 | Litton Systems, Inc. | Selector valve for an aircraft on board oxygen generation system with high pressure oxygen backup |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20150367150A1 (en) * | 2013-02-08 | 2015-12-24 | Honeywell International Inc. | Automatic Switching Device for a Breathing Apparatus with an Alarm-Relief Function and Automatic Reset |
US10086219B2 (en) * | 2013-02-08 | 2018-10-02 | Honeywell International Inc. | Automatic switching device for a breathing apparatus with an alarm-relief function and automatic reset |
Also Published As
Publication number | Publication date |
---|---|
NL8501474A (en) | 1986-12-16 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): DE FR GB NL SE |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
18D | Application deemed to be withdrawn |
Effective date: 19870527 |
|
RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: KORSTANJE, MARINUS Inventor name: LAARHOVEN, JOHANNES PETRUS MARIA Inventor name: BAREMAN, JACOBUS |