fig1 shows a respiratory device 2 connected to a patient 4 , in the conventional , known fashion , by an inspiratory line 6 , a patient line 8 and an expiratory line 10 . the respiratory device 2 can e . g . be an anaesthetic machine , and the patient line 8 can be a tracheal tube and y - piece . a first directional valve 12 is arranged in the inspiratory line 6 ( or between the inspiratory line 12 and the patient line 8 ), and a second directional valve 14 is arranged in the expiratory line 10 ( or between the expiratory line 10 and the patient line 8 ). the function of the directional valves 12 , 14 is mainly to achieve one - way passage of gas through the lines 6 , 8 , 10 ; therefore they must not allow any retrograde leakage . at the same time , it is undesirable for the directional valves 12 , 14 to create any additional respiratory resistance for the patient 4 during inspiration and expiration . they must therefore open easily in the forward direction . fig2 shows a first embodiment of the first directional valve 12 ( the second has an identical construction ). in this instance , the inspiratory line 6 is connected to the inlet side of the first directional valve 12 , and the patient line 8 is connected to the outlet side of the first directional valve 12 . the first directional valve 12 has an essentially , horizontal valve seat 16 . a valve body 18 rests on the valve seat 16 . in this embodiment , the valve body 18 is disk - shaped , but other designs are possible . the surface of the valve body 18 in contact with the valve seat 16 is preferably made of a soft material . a hood 20 encircles the valve seat 16 and the valve body 18 . the hood 20 is preferably transparent to permit visual inspection by the operator . a coil 22 surrounds part of the first directional valve 12 for magnetic coupling to the valve body 18 that contains , or consists of , a permanently magnetized ferromagnetic material . when a current is applied to the coil 22 from a source of current 24 , the valve body 18 is either pressed against the valve seat 16 or lifted off the valve seat 16 , depending on the direction of current in the coil . the basic functions of the directional valve 12 accordingly can be maintained without loss in the event of a power failure . this is extremely important to patient safety . the source of current 24 is regulated by a control unit 26 on the basis of suitable control parameters . some of these control parameters can be obtained from changes in emf , induction etc . in the coil 22 occurring when the valve body 18 is affected by gases in the lines 6 , 8 . determination of these parameters can be performed by e . g . measuring voltage across the coil 22 with a voltmeter 28 and sending the measured value to the control unit 26 . ( alternatively or as a complement , current in the coil 22 can be measured inductively by sensor 48 and the measured value sent to the control unit 26 .) referring again to fig1 . the control unit 26 in the depicted embodiment is integrated into the respiratory device 2 and controls a first source of current 24 a for regulating the first directional valve 12 and a second source of current 24 b for regulating the second directional valve 14 . alternatively , a separate control unit ( in the form of a microchip or the equivalent ) can be integrated into the respective directional valves 12 , 14 . additional opportunities for obtaining control parameters are provided with a first flow meter 30 in the inspiratory line 6 , a second flow meter 32 in the expiratory line 10 , a first pressure gauge 34 in the inspiratory line 6 , a second pressure gauge 36 in the patient line 8 and a third pressure gauge 38 in the expiratory line 10 . flow through the respective directional valves 12 , 14 or the pressure gradient between the inlet and outlet sides of the respective directional valves 12 , 14 can be determined and used by the control unit 26 for regulating the directional valves 12 , 14 . the flow meters and pressure gauges 30 , 32 , 34 , 36 , 38 can be formed by components integrated into the directional valves 12 , 14 or of components in the respiratory device 2 ( or any combination thereof ). regulation is suitably performed in such a way that the control unit 26 , via the sources of current 24 a , 24 b and with the aid of the parameters , regulates the directional valves 12 , 14 by reinforcing their natural positions ( open - closed ) in every phase of the respiratory cycle . for many applications , the control unit 26 can suitably be supplied even with information from the respiratory device &# 39 ; s control system on the respiratory cycles etc . alternatively , the control unit 26 can even be an integral part of the control and regulatory system of the respiratory device 2 . fig3 shows a second embodiment of the directional valve 12 . as in the first embodiment , the inspiratory line 6 is connected to the inlet side of the directional valve 12 , and the patient line 8 is connected to the outlet side of the first directional valve 12 . the first directional valve 12 has a mainly horizontal valve seat 16 . a disk - shaped valve body 18 rests on the valve seat 16 . the valve body 18 preferably is made of a soft material at points at which it is in contact with the valve seat 16 . a hood 20 encircles the valve seat 16 and valve body 18 . the hood 20 is preferably transparent to permit visual inspection by the operator . in this second embodiment , the direction valve 12 contains a first coil 40 , arranged below the valve body 18 , and a second coil 42 , arranged above the valve body 18 . the valve body contains , or consists of , a ferromagnetic material . a current can be applied to the first coil 40 from a first source of current 44 , and a current can be applied to the second coil 42 from a second source of current 46 . the sources of current 44 , 46 are regulated by a control unit 26 on the basis of suitable control parameters in the same way as in the first embodiment . these parameters can be obtained from a voltmeter 28 , straight from the sources of current 44 , 46 or in some other way described above , such as with inductive sensors 48 . the sources of current 41 , 46 in this embodiment are regulated differently , since current is alternately applied to the first coil 40 and the second coil 42 respectively . other embodiments of the directional valves are possible . for example , the coil ( s ) can be located in other ways with retention of the same functions . although modifications and changes may be suggested by those skilled in the art , it is the intention of the inventor to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of his contribution to the art .
a directional valve for respiratory devices has a valve body and a valve seat whose contact surface with the valve body is primarily horizontal . in order to enhance and reinforce the directional valve &# 39 ; s operation , the valve body contains a ferromagnetic material , preferably permanently magnetized , a coil is magnetically couplable to the valve body , a source of current is connected to the coil , and a control unit controls the source of current in order to regulate current through the coil to magnetically couple the coil to the valve body , in one or both of the closing and opening directions .