with reference to the drawings , wherein the same reference numbers indicate the same elements throughout , fig1 illustrates a schematic of a respiratory system 10 of the present invention . the respiratory system 10 provides ventilation and delivers oxygen to a user , such as an aircrew , at sufficient pressures and flow rates , so that the aircrew may perform their needed tasks during both ground and flight operations . more importantly , and as will be described , the respiratory system 10 provides fluid communications in the form of a flow of air , or in the form of a flow of oxygen , during failure mode conditions of the ventilation or oxygen systems supplying the respiratory system 10 . also , the respiratory system 10 provides a self contained and portable ventilator system . the respiratory system 10 comprises a ventilator system 12 that supplies a flow of air , an oxygen supply system 14 that supplies a flow of oxygen , a hood 16 that carries a transparent window 18 , a mask 20 , and a manifold 22 . the ventilator system 12 is self contained and portable , which is meant to mean that the system is man mounted , provides all necessary modes of operation without reconfiguration of the fluid couplings and does not require significant aircraft modifications . the ventilator system 12 comprises an electric cord 24 having a connector 26 at one of its ends which is mated to a battery 28 that may be either of the chargeable or non - chargeable type . the battery 28 provides the electrical power to excite a fan blower 30 that creates a flow of air 32 which is directed by a plenum 34 into a filtering canister 36 . a hose coupling adaptor 38 receives the flow of air 32 from the canister 36 and directs the flow of air 32 to the manifold 22 by way of fluid coupling means 40 which preferably is of a hose type coupling device that mates with complementary provisions of the device to which it is being connected . these hose type fluid coupling means are preferably used for all florid coupling means of fig1 to interconnect the separated elements shown therein . as seen in fig1 the flow of air 32 is directed from the manifold 22 to the mask 20 and a portion thereof , that is , flow of air 32a , is directed , relative to and into the hood 16 . the hood 16 and mask 20 have separate chambers with the mask 20 being sealed on the face and holding pressures that are higher than those of the hood . the oxygen supply system 14 comprises a regulator , sometimes referred to as an oxygen regulator , which is connected to a source of oxygen such as liquid oxygen , gaseous oxygen , or some other oxygen generation system commonly found aboard an aircraft . the oxygen regulator 14 supplies a flow of oxygen 42 that is routed to a filtering canister 44 , by means of fluid coupling means 46 . a hose coupling adaptor 48 , accepts the flow of oxygen 42 from the canister 44 and directs the flow of oxygen 42 to the manifold 22 by way of fluid coupling means 50 . as seen in fig1 the flow of oxygen 42 is directed from the manifold 22 into the mask 20 . the hood 16 comes into contact with a vest 52 worn by the user , or aircrew , and covers and isolates the entire head and neck of the user from external environments . the hood 16 carries the transparent window 18 , which is arranged in the general region of the eyes of the user , and preferably comprises a polycarbonate material . the hood 16 , as well as the other components exposed to the environment , such as the transparent window 18 , mask 20 , manifold 22 and vest 52 are preferably resistant to permeation by chemical and biological agents , fuels , oils , lubricants , or perspiration ; while at the same time , these materials are preferably compatible with 100 % oxygen . the mask 20 comprises a breathing compartment ( not shown but known in the art ) that includes separate ventilation / exhalation valves 54 and 56 . the mask 20 further comprises the necessary valves , hoses and interface devices to provide the user with fluid communications with the filtered - blown flow of air 32 from the ventilating system 12 and with the filtered - blown flow of oxygen 42 from the oxygen regulator 14 . the mask 20 has provisions , generally indicated by phantom line 58 , such as a microphone to establish voice communications with an intercom unit ( icu ) 60 which is preferably lightweight and battery powered . the mask 20 preferably further comprises an adaptor 62 , and fluid coupling means 64 having a connector 66 on one of its ends that is coupled to a drink facility 68 . the drink facility 68 provides hot and / or cold liquids that are delivered to the aircrew , via elements 62 , 64 and 66 . the mask 20 further comprises devices , such as hose connectors , so as to accept one end of each of the fluid coupling means 70 and 72 that have their other end connected to the manifold 22 . in general , the manifold 22 has a first port 74 , a second port 76 , a third port 78 , and a fourth port 80 , with the first and third ports 74 and 78 , respectively , serving as input ports and the second and fourth ports 76 and 80 , respectively , serving as output ports . the first and second ports 74 and 76 , respectively , have a one - way flow valve . the manifold 22 further comprises a switch handle 82 , having means for carrying a duct that is selectable to establish fluid communications between the first and fourth ports 74 and 80 , respectively , and between the second and third ports 76 and 78 , respectively . the selectability allows for the respiratory system 10 , in particular manifold 22 , to allow the aircrew to transition between operational modes by a single motion of the selector switch so as to accommodate for failure conditions of the ventilator system 12 or of the oxygen regulator 14 in a manner to be described with reference to fig8 . the manifold 22 may be further described with reference to fig2 . fig2 illustrates the manifold 22 as preferably having an &# 34 ; h &# 34 ; shaped configuration and as being a four - port , crossover valve . the h - manifold 22 comprises a webbing 84 that carries a button - socket arrangement 86 which is used to mate with a complementary button - socket arrangement ( not shown ) carried by the vest 52 of fig1 . the complementary button arrangements are situated on the h - manifold 22 and the vest 52 so that the user , such as the aircrew , has easy and convenient access to the switch handle 82 to transition between ground and flight operational modes , and to respond to the failure conditions of the ventilator system 12 and the oxygen regulator 14 . as seen in fig2 the second port 76 has a pin 88 , whereas the fourth port 80 has a pin 90 . the h - manifold 22 further comprises a plurality of screws 92 that are used to join together various components thereof . a screw 94 is used to connect the switch handle 82 to the manifold 22 that may be further described with reference : to fig3 which is a view taken along line 3 -- 3 of fig2 . fig3 illustrates , in cross - section , a face seal o - ring 96 and two plungers 98 . the plungers 98 are inserted into a shaft 100 which also has to the switch handle 82 connected thereto via the screw 94 . the shaft 100 carries a duct 102 which is switchable between chambers 104 and 106 respectively related to and interposed between the first and second ports 74 and 76 , and between the third and fourth ports 78 and 80 . the duct 102 is switchable by the rotation of shaft 100 which , in turn , is preferably rotated by the clockwise movement of the switch handle 82 and provides a detent action when switched . the shaft preferably provides ease of motion , but should provide adequate resistance such that , in conjunction with the detent feature , inadvertent actuation of the valve is prevented . the duct 102 may be further described with reference to fig4 which is a view , in section , of the manifold 22 of fig2 . fig4 illustrates that the duct 102 comprises a first end 108 and a second end 110 which are preferably placed into chambers 106 and 104 by the clockwise rotation of the switch handle 82 of fig1 - 3 . fig4 further illustrates the first port 74 as having fastening means 112 and an o - ring 114 , whereas the second port 76 is further illustrated as having an o - ring 116 . the o - rings 114 and 116 mate with flapper - type , one - way flow valve 118 respectively situated in the first ( 74 ) and second ( 76 ) ports and each of which comprises a lower ( as viewed in fig4 ) valve seat 120 and an upper flapper valve 122 . the flapper - type , one - way flow valve 118 , in particular , the valve seat 120 may be further described with reference to fig5 which is a top view thereof . the valve seat 120 comprises three members , 124 , 126 and 128 , each preferably having a circular shape , and all arranged to have an abutting relationship as shown in fig5 . the circular member 128 is dimensioned and configured to provide a plurality of passageways 130 1 , 130 2 , 130 3 , 130 4 , 130 5 , and 130 6 , wherein the passageways 130 1 , 130 2 , 130 3 and 130 4 are near the outer edge of member 128 and the passageways 130 5 and 130 6 are near the inner edge of member 128 . the member 128 carries a flapper valve mounting stem 130 which may be further described with reference to fig6 which is a view taken along line 6 -- 6 of fig5 . as seen in fig6 the flapper valve mounting stem 132 is preferably t - shaped in cross - section and is situated at the central region of the member 128 . further , fig6 illustrates that the circular member 126 preferably has a cutout 133 formed therein . further still , the t - shaped stem 132 is interposed between the inner passageways 130 5 and 130 6 . the valve seat 120 of fig5 and 6 cooperates with the flapper valve 122 of fig7 during the operation of the flapper - type , one - way flow valve 118 . fig7 illustrates the flapper valve 122 , which is comprised of a resilient material , such as rubber , and has a plurality of step portions 134 1 and 134 2 . the flapper valve 122 of fig7 is further arranged relative to the valve seat 120 so that its dome portion 136 , in particular a slot portion 138 carried by the dome portion 136 , is in correspondence with the stem 132 of the valve seat 120 . the slot 138 is dimensioned so as to allow the insertion of stem 132 therein and free movement of the stem 132 within slot 138 . the slot 138 is further preferably dimensioned so as to not allow the stem 132 , except for its base , to come into direct contact with the slot 138 . the operation of the flapper - type , one - way flow valve 118 comprising the valve seat and flapper valve 120 and 122 , respectively , of fig4 - 7 may be further described with reference to fig8 . fig8 is composed of fig8 ( a ), 8 ( b ), and 8 ( c ) each of which schematically illustrates the location of one flapper - type , one - way flow valve 118 arranged at the first port 74 so as to serve as an input port one - way flow valve , and the other flapper - type , one - way flow valve 118 arranged at the output port 76 so as to serve the output port one - way flow valve . fig8 ( a ) also illustrates the location of the duct 102 , controlled by the switch handle 82 ( not shown ), and the flapper - type , one - way flow valves 118 during the flight , non - failure , mode of operation of an aircraft and the respiratory system 10 . fig8 ( b ) illustrates the location of the duct 102 and the flapper - type , one - way flow valves 118 during the ground mode of operation of the aircraft and respiratory system 10 and also during the failure mode of the oxygen regulator 14 . fig8 ( c ), illustrates the location of the duct 102 and the flapper - type , one - way flow valves 118 during the failure mode of the ventilator system 12 . as seen in fig8 ( a ), each of the first , second , third and fourth ports 74 , 76 , 78 and 80 define a region and the duct 102 is located in the central region of the manifold 22 so as not to interfere with the flow of air 32 supplied by the ventilator system 12 nor with the flow of oxygen 42 supplied by the oxygen regulator 14 . as further seen in fig8 ( a ), the flow of air 32 passes through the manifold 22 in straight - like manner and , similarly , the flow of oxygen 42 also passes through manifold 22 in a straight - like manner . further , this passage of oxygen 42 and the means which provide this passage should be preferably dimensioned to prevent the cross - flow dilution of the pure oxygen supply . this non - disruptive passage is accomplished by the operation of each of the flapper - type , one - way flow valves 118 that responds to a pressure differential to provide for an open position to establish fluid communications between the first port 74 and the second port 76 . more particularly , the flapper - type , one - way flow valve 118 , arranged in the first inlet port 74 , provides an open position when the pressure of the fluid entering the region of the first port 74 is greater than the pressure of the fluid exiting the region of the first port 74 . in other words , if the flow of air 32 is flowing into the input port 74 , the flapper valve 122 ( see fig7 ) lifts away from the valve seat 120 ( see fig5 ) to allow the flow of air 32 to flow through passageways 130 1 . . . 136 6 so as to provide for the open position . similarly , the flapper - type , one - way flow valve 118 , arranged in the output the port 76 , provides an open position when the pressure of the fluid ( flow of air 32 ) entering the second port region is greater than the pressure of the same fluid ( flow of air 32 ) exiting its second port region . again , the flapper valve 122 lifts away from the valve seat 120 to provide the open position . the input and output one - way flow valves 118 operate in unison to provide a flow of air 32 to the mask 20 of fig1 . further , as seen in fig8 ( a ), the manifold 22 does not interfere with the flow of oxygen 42 so that it passes with minimal drop in pressure during typical flow conditions to the mask 20 . the operation of the manifold 22 in response to an oxygen regulator 14 failure may be further described with reference to fig8 ( b ). as seen in fig8 ( b ), the duct 102 is positioned by the clockwise rotation of the switch handle 82 ( not shown ) so that end 110 of duct 102 is interposed so as to intercept the flow of air 32 and to direct a portion of such flow of air 32 to the second end 108 of duct 102 so that there is a fluid communication path provided between the first port 74 and the fourth port 80 as shown in fig8 ( b ). it should be noted that the non - diverted portion of the flow of air 32 not intercepted by duct 102 passes to the output port 76 . accordingly , even though an oxygen regulator 14 failure may have occurred , the present invention provides for the switching of the duct 102 to allow the ventilated flow of air 32 to be delivered to both the hood 16 and mask 20 , thereby , temporarily providing the aircrew with uncontaminated breathable air in spite of the failed oxygen supply . the response provided by the manifold 22 , in particular the switchable duct 102 , to a ventilator system 12 failure may be further described with reference to fig8 ( c ). as seen in fig8 ( c ), the duct 102 is positioned by the clockwise rotation of switch handle 82 ( not shown ) so as to intercept the flow of oxygen 42 that enters the third port 78 and providing fluid communication between the third port 78 and the second port 76 . for such positioning , the hood 16 and the mask 18 is provided with a flow of oxygen 42 for both its air and oxygen fluid communication paths . for the operation shown in fig8 ( c ), the flapper - type , one - way flow valve 118 , located in the first input port 74 is in a closed condition , thereby , preventing any of the oxygen that is entering the third port 78 from flowing into the failed ventilator system 12 of fig1 by way of the input port 74 . such prevention is accomplished by the valve seat 120 and the flapper valve 122 ( see fig4 - 7 ) mating with each other and closing off the passageways 130 1 . . . 130 6 due to the interaction of the step portions 134 1 and 134 2 . this mating is accomplished because the pressure of the fluid entering into the first port 74 is less than the pressure existing in the remainder of the first port 74 . more particularly , because of the presence of the flow the oxygen 42 in the confines of the manifold 22 that includes the region on top ( as viewed in fig8 ( c )) of the flapper valve 122 of the flapper - type , one - way flow valve arranged in port 74 , the pressure on top of the flapper valve 122 exceeds that of the pressure being sensed by the valve seat 120 , so as to provide a downward force onto the valve seat 120 , thereby , causing a merger or closure between the valve seat and flapper valve 120 and 122 , respectively . it should be noted that the switch handle 82 ( not shown ) need only be rotated in one direction , preferably clockwise , to accommodate for both of the failures shown in fig8 ( a ) and 8 ( b ). this one - switch , one - position advantageously reduces the amount of effort required by the aircrew to respond to a fault condition and reduces the possibility of error . it should now be appreciated that the practice of the present invention provides for a respiratory system 10 having a manifold 22 that includes a single switch handle that is operated so as to respond to the failure conditions of the ventilator system 12 or to the oxygen regulator 14 so as to provide a user with either a flow of uncontaminated air or a flow of oxygen both of the fluid communication paths related to the ventilator and oxygen supply systems . although the hereinbefore given description of the respiratory system 10 was primarily directed to its use during ground and flight operations for the aircrew , it should be appreciated that the principles of the present invention are equally applicable to other commercial applications that require a respiratory system to provide a flow of either a current of air or a current of oxygen to individuals during the failure conditions related to ventilator or oxygen supply systems . many modifications or variations of the present invention are possible in view of the above disclosure . it is , therefore , to be understood , that within the scope of the appended claims , the invention may be practiced otherwise as specifically described .
a respiratory system that is particularly suited to provide uncontaminatedentilation and oxygen needs of an aircrew during the ground and flight operations is disclosed . the respiratory system has provisions to provide for a continuous flow of air or oxygen during the failure mode conditions of the ventilator and oxygen generating systems supplying the respiratory system so that the aircrew is always provided with at least a flow of uncontaminated breathing fluid under all such failure mode conditions .