US 3707078 A
A fail-safe system for supplying oxygen to a breathing regulator operated upon demand by a recipient. A liquid oxygen storage vessel has an outlet port connected to its inlet port through a build-up circuit. As the liquid oxygen flows through the build-up circuit it is converted from a liquid to a gas through the effect of thermal energy. As a result of the liquid to gas conversion, a high internal pressure is created in the build-up circuit. A pressure responsive member placed in the build-up circuit will interrupt the flow when the pressure reaches a predetermined value during the active operation of the system. A supply circuit connected to the build-up circuit transmits the oxygen as a gas to operate the breathing regulator. A first solenoid in response to an electrical signal controls a flow control valve connected in the build-up circuit. An operational switch on the panel regulator supplies the electrical signal to the first solenoid, opening the control valve. As the valve opens, a latching shaft controlled by a second solenoid engages a notch on the plunger of the flow control valve to hold the valve open. The flow control valve will remain open until an operational closing signal is communicated to the second solenoid. Upon receiving the signal, the second solenoid moves the latching shaft away from the notch permitting a resilient member to close the fluid flow outlet port to the build-up circuit. To prevent excessive pressure in the build-up circuit when the first solenoid closes the flow control valve, a by-pass valve is utilized to provide an escape to the atmosphere.
Description (OCR text may contain errors)
United States Patent Cramer [151 3,707,078 [451 Dec.26, 1972  FAIL-SAFE LIQUID OXYGEN TO GASEOUS OXYGEN CONVERSION SYSTEM  Inventor:
 Assignee: The Bendix Corporation 22 Filed: Feb. 10, 1971  Appl. No.: 114,313
Robert L. Crlmer, Davenport, Iowa Primary Examiner-Meyer Perlin Assistant Examiner Ronald C. Capossela Attorney-William N. Antonis and Plante, Hartz, Smith & Thompson  I ABSTRACT A fail-safe system for supplying oxygen to a breathing regulator operated upon demand by a recipient. A liquid oxygen storage vessel has an outlet'port con.- nected to its inlet port through a build-up circuit. As the liquid oxygen flows through the build-up circuit it is converted from a liquid to a gas through the effect of thermal energy. As a result of the liquid to gas conversion, a high internal pressure is created in the build-up circuit. A pressure responsive member placed in the build-up circuit will interrupt the flow when the pressure reaches a predetermined value during the active operation of the system. A supply circuit connected to the build-up circuit transmits the oxygen as a gas to operate the breathing regulator. A first solenoid in response to an electrical signal controls a flow control valve connected in the build-up circuit. An operational switch on the panel regulator supplies the electrical signal to the first solenoid, opening the control valve. As the valve opens, a latching shaft controlled by a second solenoid engages a notch on the plunger of the flow control valve to hold the valve open. The flow control valve will remain open until an operational closing signal is communicated to the second solenoid. Upon receiving the signal, the second solenoid moves the latching shaft away from the notch permitting a resilient member to close the fluid flow outlet port to the build-up circuit. To prevent excessive pressure in the build-up circuit when the first solenoid closes the flow control valve, a by-pass valve is utilized to provide an escape to the atmosphere.
FAIL-SAFE LIQUID OXYGEN TO GASEOUS OXYGEN CONVERSION SYSTEM BACKGROUND OF THE INVENTION Presently known liquid oxygen. to gaseous oxygen systems have a pressure opening and closing valve whereby gas is drawn from the top of the storage container when the system pressure reaches a predetermined range of pressures. Pressure above this predetermined range is allowed to escape through a relief valve. Liquid oxygen trapped in the supply line during nonuse is prevented from returning to the storage chamber by a check valve located between the pressure opening valve and the pressure closing valve. However, as this trapped liquid is converted to gas due to the thermal energy resulting in an increase in pressure in the system, pressurized gas above a predetermined value is lost through a relief valve. As the pressure in the system drops the pressure opening valve, permits. fluid flow into the supply line to maintain an operating pressure at all times. Devices have been designed to prevent the pressure opening valve from operating, but require the operator to manually inactivate the pressure opening valve. If the operator inadvertently failed to engage this device, the oxygen supply would cycle to maintain the operating pressure with a resulting loss of oxygen as gas through the relief valve.
SUMMARY or THE INVENTION To reduce the loss of the oxygen during the stored or passive period, I have invented a liquid to gaseous oxygen conversion system having a flow control valve that is responsive to the ON-OFF toggle of a demand breathing regulator. The flow control valve is neither normally opened nor closed, but will remain in its intended position until an overt act on the part of the operator sends a signal indicating a desired change.
To obtain low boil-off in the liquid to gaseous oxygen conversion system, the toggle of the regulator is placed in the OFF position. The toggle will remain in the OFF position until opened by the operator. A first solenoid of the flow control valve has an internal plunger resiliently biased toward an outlet port controlling flow through the build-up circuit. When the toggle is manually switched by an operator to the ON position, an electrical impulse is transmitted to energize the first solenoid. When the first solenoid is energized, the inner plunger will move away from the outlet port to permit fluid to flow through the build-up circuit. When the plunger of the first solenoid moves, a latching shaft of a second solenoid is engaged which holds the plunger in the opened position. When the toggle of the breathing rejector is switched to the OFF position, the second solenoid is energized pulling the shaft out of engagement and allowing the plunger to be seated, preventing fluid flow through the outlet port. Activation of the demand breathing regulator by an operator will insure operation conversion of the system until a subsequent deactivation of the breathing regulator, providing a fail-safe system uneffective by outside focus.
The flow control valve of the converter is provided with means for manual activation which will override the resiliently biased first solenoid, if power is not provided or unavailable. Thus, long standby or converter tcs t outside the aircraft is possible when electrical power is unavailable.
It is therefore the object of this invention to provide a fail-safe liquid oxygen conversion to gaseous oxygen system having an activation switch integrally tied to a breathing regulator device.
It is another object of this invention to provide a fluid flow control valve with means to maintain its intended position in a manner unaffected by outside energy sources uncontrolled by an operator.
It is still a further object of this invention to provide means to manually activate a flow control valve to operate a liquid to gaseous conversion system.
These and other objects will become apparent to those who read this specification and view the drawing.
BRIEF DESCRIPTION OF THE DRAWING The drawing shows a sectional view of a liquid oxygen to gaseous oxygen conversion system connected to a breathing regulator with an enlarged sectional view of a flow control valve operationally connected to the ON-OFF toggle of the regulator.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The liquid oxygen to gaseous oxygen conversion system 10 shown in the drawing includes a double walled storage vessel 12 having an inlet port 14 and an outlet port 16. The inlet port 14 is externally connected to the outlet port through a build-up circuit 20. The inlet port 14 is connected through a fill circuit 22 to a liquid oxygen supply adapter 24 and to connector means 26 in a supply circuit 28 going to a breathing regulator device 30. A pressure responsive interrupting valve 32 is located in the build-up circuit 20 downstream from a supply circuit connection 34. The interrupting valve 32 will open and close as the pressure in the build-up circuit 20 is reduced by withdrawal of gaseous oxygen through the breathing regulator 30. Opening and closing the interrupting valve will assure that the pressure of the gaseous oxygen transmitted to the regulator 30 will remain within a predetermined pressure range. Downstream from the interrupting valve 32 is a flow control valve means 36 having an operational signal transmitting line 38 connected to the ON-OFF toggle 40 of the breathing regulator 30. The flow control valve means 36, upon receiving an operational signal when the toggle 40 is moved to the ON position, will permit fluid to begin to flow as a liquid through port 14. As the liquid oxygen flows through the build-up circuit 20, thermal energy converts the liquid to a gas resulting in an increase in internal pressure. The pressure in the build-up circuit will increase until the interrupting valve 32 becomes operational. As long as the toggle 40 remains in the ON position, the fluid will flow through the control means 36 thereby providing the regulator 30 with pressurized gaseous oxygen.
Upon moving the toggle 40 to the OFF position, control means 36 will stop the flow in the build-up circuit 20. However, some fluid will remain in the build-up circuit 20 between the flow control valve means 36 and the gaseous outlet 16 of the storage vessel. This trapped liquid oxygen will continue to be converted to gaseous oxygen and build up a head within the build-up circuit 20 and the storage vessel 12. By-pass means 42, an integral part of the oxygen supply adapter 24, contains a pressure opening ball valve 44 which permits excessive pressure to escape harmlessly into the atmosphere. Since liquid oxygen will continue to .be converted to gaseous oxygenthrough the thermal energy penetrating the storage vessel 12, the ball valve 44 will be operational as long as the fail-safe system is on standby.
In more particular detail the individual elements of the system could be constructed as follows to provide a fail-safe operational liquid oxygen to gaseous oxygen conversion system.
The liquid storage vessel 12 includes an inner container 46 and an outer container 48 separated by an insulating member 50. A capacitance probe 52, of a type described in US. Pat. No. 2,848,666, is held against the interior wall of the inner container 46 by a resiliently biased cap 56 adjacent the inlet port 14. The electrical leads 58 of the capacitance probe 52 are carried through the gaseous port 16 and out of the storage vesse] 12 through a hermetic opening 60 in the build-up circuit to an electrical gauge (not shown) for indicating the amount of liquid in the storage vessel 12.
The supply adapter 24 includes a housing 62 having a supply chamber 64 with a spring controlled closure cap 66 overlying an opening 69 to the fill circuit 22. A shaft 68 retained in a bearing wall 71 of the housing 62 has a bevelled face 70 extending into a by-pass chamber 74. The bevelled face 70 is urged against an annular seat 76 surrounding an opening 78 to the atmosphere. An internal passage 80 from the opening 78 is connected to the by-pass valve 44.
The interrupting valve 32 includes a housing 82 having a control chamber 83 containing a stem 84 with a face 86 on one end and a bellows member 88 on the other end. A spring 90 is located inside the bellows member 88 and acts on the stem 84 in opposition to a closure spring 92. A wall 94'separates the inlet port 96 of the control chamber 83 from the outlet port 98. Without pressure in the control chamber 83, the bellows member 88 acts in conjunction'with spring 90 to unseat face 86 from the opening 100 in wall 94. As the pressure in the control chamber increases, the bellows member 88-will collapse and spring 92 will seat face 86 to close the flow between the inlet port 96 and the outlet port 98. As the pressure across face 86 drops due to a demand for gaseous oxygen through the breathing regulator device 30, spring 90, aided by the force created by thepressure drop, will overcome spring 92 to again permit fluid to flow.
The flow control valve means 36 includes a housing 102 having a flow chamber with an inlet port 104 and an outlet port 106. A wall 108 having a passage 111 is located adjacent the outlet port 106. A plunger 110 with a beveled end 112 having a shoulder 114 for retaining one end of a resilient member or spring 1 16 is located in an axial line with passage 111 and is retained in a bearing wall 118. The plunger 110 extends through the bearing wall 118 into a first solenoid 120. The end 122 of the plunger 110 extending into the solenoid 120 has an annular notch 124 which receives the end of a holding shaft 126 when the solenoid 120 is energized and moves the plunger 110 away from passage 111. A
second solenoid 128 surrounds shaft 126, with a resilient member 130 being caged between the end 132 of the solenoid and a shoulder 134 on the shaft to urge the shaft toward the notch 124. Centrally located on the end of the plunger 110 is a T-shaped cylindrical shaft 136 which is sealingly retained in wall 138 of the housing 102. A spring 140 rests against the-wall 138 and acts on top portion 142 of the T-shaped cylindrical shaft 136 to aid resilient member 116 in sealing bevelled end 112 against wall 108 surrounding passage 111 to prevent fluid flow therethrough. A projection solenoid 128 when the toggle 40 is in the OFF position 164 are not interchanged.
MODE OF OPERATION When it is desired to fill the storage vessel 12 with a liquid, usually oxygen, a supply source is mated with adapter 24. in connecting the supply source, the shaft 68 is pushed to the right compressing spring and thereby communicating outlet 16 with atmosphere via conduit 220, by-pass chamber 74 and opening 78. The supply liquid being under pressure unseats cap 66 and flows through fill circuit 22 into the fluid inlet 14. Connector means 26 includes a check valve (not shown) which prevents flow at this time to the regulator 30, in addition, since the toggle 40 is in the OFF position 164, flow through build-up circuit 20 is preventedby the plunger 110 being resiliently held against the housing surrounding passage 1 1 1. During the fill process liquid flows into inlet port 14 and displaces gas in the inner storage vessel 46. The displaced gas escapes through gaseous outlet 16, through conduit 220 of the build-up circuit and the by-pass chamber 74 to harmlessly escape to the atmosphere. The amount of liquid in the storage vessel is monitered by the capacitive probe 52 and when sufficiently full, the storage source is disconnected from the supply adapter 24. Upon disconnecting the supply source, resilient member 75 will seat bevelled face 70 against seat 76 and resilient member 67 will seat cap 66 on opening 69 to seal the liquid in the storage vessel 12.
During the passive or standby period, thermal energy will be transferred through wall 48, insulating member 50 and wall 46 to cause the liquid oxygen to boil and then be converted to gaseous oxygen. As the pressure in the chamber 13 builds up, this same pressure being present in conduit 220 will unseat resiliently held ball valve 44 of means and permit the gaseous oxygen to travel through passage and opening 78 to harmlessly escape to the atmosphere.
To check the operation of the storage vessel 12 prior to attaching the regulator device 30, T-shaped cylindrical shaft 136 is pushed manually until spring loaded shaft 126 engages notch 124. Fluid will now be permitted to flow in build-up circuit 20 until the pressure acting on bellows 88 causes it to collapse thereby permitting spring 92 to seat face 86 and close opening 100. As long as the pressure at the junction 34 in the buildup circuit remains constant the pressures across the interrupting valve 32 will prevent further flow in the build-up circuit 20. With any further pressure build-up in circuit 20 fluid is allowed to escape through by-pass valve means 42 to prevent damage to the system. To release the plunger 110 from its held open position, projection 144 is pulled to overcome resilient member 130 thereby disengaging the shaft 126 from notch 124. Upon disengaging the shaft from the notch, resilient members 116 and 140 will again seat plunger 110 on the housing around passage 111 to prevent fluid flow from the inlet port 104 to the outlet port 106.
Upon joining the regulators to the supply circuit 28 through connecting means 26,. the check valve contained therein is opened permitting liquid oxygen convertible to gaseous oxygen under pressure to be supplied to the breathing regulator device 30. The intensity of the pressure varies with the pressure in the buildup circuit created by thermal energy in the liquid to oxygen conversion. lf fluid flow in the build-up circuit has been interrupted or prevented prior to connecting the breathing regulator device 30, then the initial gaseous oxygen supplied will be at a minimal pressure.
When the operator desires to place the breathing regulator device in operation, toggle switch 40 is placed in the ON position 162. In the ON position 162 electrical energy is transmitted through leads 154 156 to the first solenoid 120. When the coil 121 is energized, the plunger 110 becomes magnetized and the mutual action of the field in the solenoid on the poles created of the ends 112 and 122 of the plunger 110 causethe plunger to move within the solenoid. This moving force becomes zero only when the magnetic centers of the plunger 110 and the solenoid 120 coincide. The maximum uniform pull to overcome the resiliently biasingclosing members 116 and 140 occurs when the end of the plunger 122 is located within the bore 123 of the solenoid 120. As the plunger 110 moves in the solenoid 120, the bevelled end 122 slides along the end of shaft 126 partially compressing spring 130. When the plunger 110 approaches the center of equilibrium with the solenoid 120, shaft 126 snaps into groove 124. This latching will occur almost instantaneously after the toggle 40 has been switched to the ON position 162. To prevent the solenoid from heating, a conventional timing device (not shown) will stop the flow of electrical energy to the coil after a predetermined period of time. With plunger. 110 locked open, fluid flow will be permitted from inlet port 104 to outlet port 106 without hinderance. As the flow of liquid oxygen progresses from the liquid port 14 to the gaseous port 16, heat will have converted all the liquid to a gas resulting in an increase in line pressure. When the pressure in the build-up circuit reaches a predetermined value, the interrupting valve means 32 will close. The pressure across the seat face 86 of the interrupting valve means 32 will prevent flow in the build-up line until the differential is sufficient to overcome the resilient members 92. Through this interrupting valve means, the pressure of the oxygen supplied to the breathing regulator device 30 will remain within a predetermined range.
If electrical power failure should occur, operation of the liquid oxygen to gaseous oxygen conversion system will be unaffected since the solenoid plunger 110 and shaft 126 could be mechanically positioned and remain so until an overt act on the part of the operator repositions them. During a power failure if it be desired to return the system to a passive stage, projection 144 could be pulled out to permit the resilient members, 1 16 and to seat plunger 110 and close passage 111 to thereby prevent fluid flow.
With electrical energy available, the operator switches toggle 40 to the OFF position 164 at the end of an active period to stop the flow of gaseous oxygen through the breathing regulator device 30. Simultaneously with the toggle 40 in the OFF position, electrical energy is transmitted through leads 158 and to the second solenoid 128 to energize the coil 133. When coil 133 is energized, a magnetic flux will occur pulling shaft 126 out of contact with the notch 124 thereby permitting the plunger to be resiliently closed and stop fluid flow in the build-up circuit 20. After a predetermined period of time, the electrical energy which is supplied the coil 133 of the second solenoid, is terminated and the flow control means inactivated.
Once the operator shows a need for oxygen the system is not subject to power failure in the electrical system since the flow of liquid oxygen in the build-up circuit is controlled by the latched solenoid control valve 36 tied to the toggle 40 of the breathing regulator device 30. Through the manual override devices 142, for the first solenoid, and 144, for the second solenoid, a means is provided to shut the system down after a power failure, to activate the system without power and to perform a test on the connector prior to installation in the system without the regulator. ln addition, the number of breathing regulator devices 30 and 31 can be varied to meet the requirement of the number of breathing systems required for the occupants of an airplane, but the operation of the liquid oxygen connection to gaseous oxygen is controlled by the master breathing regulator 30 connected to the flow control valve of the liquid oxygen to gaseous oxygen conversion system. I claim: 1. A fail-safe system for supplying a gas to a regulator in a breathing system in response to a breathing de mand of an operator, said system comprising:
a liquid storage vessel having a liquid port and a gaseous port; a
a pressure build-up circuit connecting said liquid port to said gaseous port, the liquid in said storage vessel being converted from a liquid to a gas by thermal energy upon flowing from said liquid port to said gaseous port through said build-up circuit;
a supply circuit with a connection connected to said build-up circuit and said regulator, said supply circuit converting said liquid to a gas, said supply circuit delivering said gas to said regulator at a rate necessary to maintain a physiological level for said operatori pressure responsive means located in said build-up circuit downstream from said supply circuit connection for interrupting the flow of said liquid in said build-up circuit when the fluid pressure therein caused by the liquid to gas conversion reaches a predetermined value, said pressure responsive means thereby correspondingly limiting the pressure of the gas transmitted to said regulator through said supply circuit;
by-pass means located in said build-up circuit for venting excessive fluid pressure in said liquid storage vessel to atmosphere; and
control means located in said build-up circuit downstream from said pressure responsive means, said control means being latched to an opened position for permitting fluid flow in said build-up circuit to create a fluid pressure therein in response to an electrical operational signal being communicated from said regulator.
2. The fail-safe system, as'recited in claim 1, wherein said control means includes:
a housing having a chamber located therein with an inlet port connected to said pressure responsive means and an outlet port connected to said pressure build-up circuit leading to said gaseous port of the storage vessel;
a plunger retained in a bearing wall in said chamber, said plunger having a valve face on'one end and a notch on the other end; first resilient means secured to said plunger for urging said valve face into sealing engagement with a seat of said housing to prevent fluid flow from the inlet port to the outlet port; and
first solenoid means surrounding said plunger having an electrical circuit connected to an activation section of an operational switching means for said regulator, said first solenoid moving said face away from said seat upon energization by said electrical operational signal.
3. The fail-safe system, as recited in claim 2, wherein said control means further includes:
a shaft retained in a bearing wall adjacent the other end of said plunger; and
second resilient means secured to said shaft for urging one end of said shaft toward said plunger, said one end of the shaft engaging the notch end of said plunger to hold the valve face away from the seat upon deactivation of said first solenoid means.
4. The fail-safe system, as recited in claim 3, wherein said control means further includes:
second solenoid means surrounding said shaft having an electrical circuit connected to a deactivation portion of the switching means of said regulator, said second solenoid means receiving an electrical signal from a deactivation section of said switch member being operated upon by an operator, said electrical signal causing said second solenoid means to move said shaft away from said plunger permitting said first resilient means to position said valve face against said seat. 5. The fail-safe system, as recited in claim 4, wherein said switching means of said regulator includes:
an interconnected circuit between the activation and deactivation sections for transmitting an electrical signal to said control means corresponding to an operational signal from an operator to said regulator. v6. The fail-safe system, as recited in claim 5, wherein said control means further includes:
override means secured to said plunger for permitting manual movement of said valve face away from said seat causing said shaft to engage said notch and thereby allow fluid to flow from the inlet rt to the outlet port in said build-up circuit. 7. e fail-safe system, as recited in claim 6, wherein said control means further includes:
release means secured to said shaft for permitting manual disengagement of said shaft with said notch to allow the valve face of the plunger to seat and prevent fluid flow in said build-up circuit through said chamber.
8. The fail-safe system, as recited in claim 7, wherein the electrical circuits for the first and second solenoid includes:
plug-in means for connecting the regulator with the control means having a lock pin which snaps into a slot to assure proper alignment of the circuits and the corresponding solenoids.
9. The fail-safe system, as recited in claim 8, wherein said supply circuit includes:
connector means for opening a check valve upon joining said supply circuit with said build-up circuit to permit said gas to freely flow to the regulator.