US2436853A - Respiration apparatus - Google Patents

Description

March 2, 1948.

E. D. COLEMAN RESPIRATION APPARATUS ts-Sheet lv Shec Filed April 10, 1944 which can be made at relatively small cost.

Patented Mar. 2, 1948 UNITED STATES PATENT OFFICE:

a mismtarron APPARATUS v Edwi 1). com Maywood; m. Application Api-il 1o. iaicseriai No. s so,2s7

This invention relatesto resuscitators and artificial respiration devices-and to devices for adigciaim (c1. res-29) ministering oxygen in high "altitude flying, and is adapted as wellfor the administration of anes- Another object of the invention is the provision of a respiration apparatus having a fluid control means suitable for control of the fiow of gas to either a mask for administration to the lungs of the patient, to a belt for applying and relieving pressure to the abdomen of the patient, and also suitable for the control of the flow of gas to both a mask and a belt to simultaneously control the fiow of gas to these instruments.

I of a respiration apparatus which may be so set by the operator that a new breathing cycle is automatically initiated when the lung pressure falls to a preselected lower positive pressure, or so that the cycle is not initiated until a slight negative pressure exists in the lungs so that the patient initiates the new cycle by a slight gasp.

A further object-of the inventionis the provision of a respiration apparatus which may be so set that the respiratory rate is under the control of the patient who initiates the cycle by slight gasp, and wherein means are provided to initiate a new respiratory cycle in the event that the patient falls within a reasonable time to initiate the cycle.

A still further object of the invention is the provision in a device of the character described wherein the inhalations and exhalations valves are so balanced with respect to each other that a minimum amount of force is requiredto operate the valves and to maintain the valves in inhalation and exhalation positions, and wherein tween their positions with a snap movement and for preventing the valves from coming to rest intermediate their fully open and fully closed positions.

Other objects and advantages will appear from the following description and the accompanying drawings, in which Figure 1 is a top view of a respiration apparatus embodying the invention;

' Fig. 2 is a fragmentary top view showing a position of the parts during the inhalation phase of the respiratory cycle;

Fig. 3 is a view similar to Fig. 2 showing the position of the parts at the instant of termination of the inhalation phase of the cycle;

Fig. 4 is a view on the line 4-4 of Fig. 2 showing the face of the exhalation valve;

Fig. 5 is a view on the line 5-5 of Fig. 2 showing the face of one of the snap mechanisms, and

Fig. 61s a greatly enlarged and exaggerated view of a fragment of the supply and inlet valves.

Another object of the invention is the provision of a respiration apparatus having a novel valve structure for controlling the flow of gas.

The invention contemplates a respiration apparatus of the type employing a conventional mask adapted to be placed over the face of the patient'ora belt adapted to be placed around the body of the patient arranged to be inflated and deflated for the purpose of producing proper exhalation from the lungs or in which both a belt and mask are employed operated in synchronism for the purpose of producing artificial respiration.

By artificial respiration as herein employed is and these devices are a common article of commerce, these devices are hereinafter referred to generally as an applicator. The mechanism is carried on a base board 9 to which most of the parts hereinafter described are directly mounted.

Connected to the applicator I I is an exhaust tube l2 which is preferably of relatively large diameter, the opposite end of the tube in this instance being connected to a fitting i3 which car-,

ries an exhaust valve designated generally by the means are provided for moving the valves be- 68) numeral H, the tube l2 and the valve 14 serving to discharge gas from the applicator. Also connected to the mask II or to the exhaust tube 12 adjacent the mask is a gas supply tube It adapted to supply gas to the mask. Where the device is used for resuscitation in oxygen therapy or high altitude flying, the gas will naturally be oxygen or mixtures of oxygen with other gas, and where the device is used for anesthesia, the selected gas used for this purpose will be supplied through the tube IS. The tube [5 is also connected to a supply valve l6 to which gas is supplied from a suitable source of gas supply, not shown, such for example as an oxygen cylinder through a pressure reducing and control valve designated generally by the numeral I1 and a tube l8 connected to the valve IS. The reducing and control valve I1 is of conventional design, and while the details thereof are not herein shown with particularity, it has the usual handle "a for adjusting the pressure delivered thereby to control the pressure of the gas in the tube 18. A pressure gauge I'Ib is provided on the outlet side of the valve, preferably calibrated in feet per minute of flow.

Referring now to the valve system comprising the exhaust valve l4, suppl valve 13, and driving means therefor, the supply control valve l8, best shown in Figs. 2 and 3, comprises a body portion l8 having a threaded opening at 2| for attachmentof the supply tube l8, a bore 22 and a counterbore 23 on the end thereof opposite the opening 2|. The tube also has a threaded bore 24 intersecting the bore 22 coming in from the side or the body with which the supply tube I5 i connected. The opening 2| and the bore 22 are interconnected by a small channel 25 which terminates in the bore 22 at the apex of the somewhat conical end 28 or the bore 22, this conical end serving as a seat for the somewhat conical end 21 of a valve stem designated generally by the numeral 28. The conical end 21 is substantially sharper than the conical seat 28 and the apex is rounded as shown at 214: to seat in a rounded recess 26a in the conical end 28 to prevent communication between the channel 25 and the bore 22. The bore 22 is of relatively great "diameter with respect to the stem 28 so as to leave a wide clearance space between the stem and the walls 01' the bore as shown at 29. Positioned across the otherwise open end or the counterbore 23 is a diaphragm 3| attached to the stem 28 and to the body I9 in a gas tight manner, thi diaphragm being formed of impregnated silk or other highly flexible gas-tight material so as to prevent the escape of gas from the valve and so as to transmit pressure 01' the gas within the counterbore 23 to the stem for a purpose presently to be described.

The exhaust valve l4 in this instance comprises a body 32 having a plate 33 provided with a plurality or openings 34 and a plate 35 superimposed thereon likewise having openings 38 so arranged that by rotation of the plate 35 with respect to the plate 33 the openings 34 and 36 may be brought into and out of registration to a greater or lesser degree, thereby controlling the rate oisfiow through the valve. To this end the plate 33 is fixed in the body 32, whereas the plate 35 has an annular flange 31 retained for rotation by a ring 38. and also has a lever 33 for manual rotation of the plate 35. The outer surface of the plate 35 extends beyond the plane of the ring 38 so that a valve disk 4| may seat thereagainst to prevent the passage of gas through the openings 34 and 36,;or in other words, to valve" the openings. Thevalve disk 4| is in this instance supported on the end oi the stem 28 by means of a ball and socket Joint 4la permitting free relative movement therebetween within a limited deree so that the disk is self-aligning with respect to the plate 35. Thus the same stem functions in the supply valve I8 and the exhaust valve l4, the two valves being positioned in alignment as shown for the purpose of permitting this arrangement. While this specific arrangement is convenient, it should be understood that it is not essential to the valve system.

Positioned adjacent the stem 28 intermediate the valves l4 and I6 is an overcenter toggle spring snap mechanism designated generally by the numeral 42. While the specific structure of this overcenter mechanism may vary considerably, as will be understood by those skilled in the art from the description herein given and the function to be performed thereby, I have herein shown a unitary one-piece spring mechanism such as that shown in U. S. Patent No. 1,960,020 to Phillip K. McGall. The spring mechanism 42 comprises a central tension member 42a (see Fig. 5) and spaced compression members 421), the tension and compression members being interconnected at one end by an end portion 420. The tension member 42a is attached to a fixed support at 42d and the free ends of the compression members 421) are pivotally supported on anchors 42a for rocking movement with respect thereto. It will be seen that as the end 420 of the spring is moved in a. clockwise direction facing Figs. 2 and 3, the spring approaches a central position of unstable equilibrium and when moved beyond this position, the entire system will continue, the movement spontaneously with a snap movement, better described in the above-mentioned McGall patent. This action is repeated when the end 42c is thereafter moved back in a counter-clockwise direction. The spring 42 is so mounted as to have only two stable positions represented by the two positions of the valves and has sufilcient strength to drive the valves to one or the other of these positions and to retain the valves in these positions except for the action of driving spring 43. The driving spring system 43 is constructed in like manner witha tension member'43a, spaced compression members 43b, a movable end 430. a fixed support 4311 and an anchor 43c, and functions in like manner, the arrangement being such that the spring system 43 is stronger than the spring system 42. The stem 28 passes through an opening 42 in the ends 420 of the spring 42 (see Fig. 5), and the spring 42 is positioned in driving relation to the stem by pins projecting from the stem on opposite sides of the end as shown at 44 to impart longitudinal movement to the stem 'in response to snap movement of the spring. The opening 42) has a width only sufficient to permit free movement between the stem and the spring and a height only suflicient to accommodate for the change in angularity between the spring and the stem as the parts move between the seated positions of the valves. The spring 43 has an opening similar to 42f but substantially larger so that the spring 43 is capable of moving freely with respect to the stem 28. The stem has spaced collars 45 and 46 adapted to be engaged by the spring 43 for the purpose of driving the stem longitudinally in opposite directions, as will presently be more fully described. It will be seen that with this arrangement when the end 430 of spring 43 is moved in a clockwise direction from the position of Fig. 2 to a position beyond its position of unstable equilibrium, lost 2,4ee,ess

I thereafter moves with a snap movement eventually engaging the collar 45 and driving the stem 28 to the right facing Figs. 2 and 3 into the position shown in Fig. 3, thereby bringing the disk 4| out of contact with the plate 35 and opening the exhaust valve |4. Simultaneously the movement of the stem 28 brings the conical end 21 into the conical seat 26 closing the supply valve and stopping the flow of gas from the tube l6 into the supply tube 5, thereby terminating supplyof gas to the mask. During the initial movement of the stem 26, the spring 42 is being brought to and past its position of unstable equilibrium and this spring thereafter moves with a snap movement to assist the spring 43 in moving the valves to the opposite position in holding the stem in a position to maintain the supply valve closed. When the end 43c is moved in the opposite direction, the stem 28 is moved to the right through a. similar succession of operations, closing the exhaust valve and opening the supply valve.

A tube 41 leads from the exhaust tube |2 to a.

pressure responsive member indicated generally by the numeral 46 of the type commonly called a "puff which includes a gas-tight body 49 having a chamber one side of-which is closed by a highly flexible diaphragm 52, such, for example, as a diaphragm formed of silk impregnated to make the fabric gas-tight. The tube 41 is so connected as to transmit the pressure in the exhaust tube l2 and consequently the pressure in the applicator II to the diaphragm 52 so as to cause this diaphragm to move in response to changes of pressure in the applicator. The diaphragm 52 is connected by a rod 53 to a lever 54,

6 II to be open. when a mask is employed the mask II is, in accordance with the usual practice, tightly attached to the mouth and nose of the patient so that the gas pressure introduced into the mask through the supply pipe I5 is communicated directly to the lungs of the patient and tends to cause them to expand. Since the exhaust valve H is closed when the supply valve the two being pivotally interconnected as shown I at 55. The lever 54 is pivotally supported at 66.

and has arms 51 and 56 projecting laterally therefrom substantially at right angles. the arm 58 is a coil spring 56, the Opposite end Attached to of the spring being attached to an adjusting lever 6| which is pivoted at 62 and has a locating pin 63 for the purpose of securing the adjusting lever in desired adjusted positions to thereby regulate the force which the spring 59 imparts to the lever 54, the spring normally acting to rotate the lever 54,- in a clockwise direction. The

arm 51 has spaced fingers 64 and 65 disposed on opposite sides of the end portion 430 of the spring system 43 for the purpose of engaging the end 430 and snapping the spring overcenter in either a clockwise or a counterclockwise direction.

Disposed along opposite sides of the arms 61 and 58 are loading. means, in this instance comprising loading springs 66 and 61 having fingers 66 and 69 projecting inwardly toward the free end of the arm 51, the springs being normally tensioned to bear against stops 1| and 12 in the absence of contact of the fingers ,68 and 63 against the sides of the arm 51. Adjusting screws 13 and 14 are arranged to bear againstthe springs 66 and 61 to adjust the force of the passes through the channel or orifice-25 and thence to the supply tube l5, assuming the valve I6 is open, there can be no escape of gas from the mask, pressure builds up in the supply pipe IS, in the patients lungs, in the exhaust tube l2, in the tube 41 and in the puff 48. This pressure in the puff produces movement of the diaphragm 52 and consequent rotation of the lever 54 about its pivotal support 56 in a counterclockwise direction against the tension of the spring 59. As this rotation/of the lever continues, the finger 65 comes into contact with the end 430 of the spring system 43, rotating the spring system in a clockwise direction. Since the spring 43 is free to move to a limited degree independently of the stem 28, the position of the stem is not affected by this preliminary movement as shown in Fig. 2. Rotation of" the lever 54 eventually brings the spring system 43 into and beyond its position of unstable equilibrium, causing the spring 43 to move with a snap action into engagement with the collar 45, thereby moving the stem in .a direction to close the valve |6 as shown in Fig. 3. During the early part of this movement, the force of the spring system 43 is utilized to bring the spring system 42 to its position of unstable equilibrium aiid thereafter the force of both the spring systems 42 and 43 acts to effectuate closing of the valve l6 and simultaneous opening of the valve l4.

It should be noted that an important feature of the construction lies in this spring and valve system. whereby the valve stem 28 is forced to remain in either of the two extreme positions and is prevented from stopping or remaining in any intermediate position.

Another important feature of the construction is the structure of the valve system which makes it possible for the system to be driven directly by the energy derived from the pressure in the applicator. To this end it will be observed that the stem 26 is supported near one end by the diaphragm 3| and at an intermediate oint by the spring 42, both of these elements supporting the stem loosely in what might be called a floating condition. This avoids the friction which might result from the use 01' conventional bearings for the purpose. Obviously with this arrangement the diaphragm 3| does not accurately align the end 21 with its seat, but instead the bore is provided with the conical end 26 and the stem has the rounded end 21a so that as the stem is moved to seat the valve IS, the end portion 21a may strike the conical walls of the bore and slide therealong into seated and aligned position. Likewise the plate 4| is mounted on the stem for limited universal movement so that as the stem is moved to bring valve M to seated.

position, the plate 4| will align itself, in spite of misalignment of the shaft, so as to seat flush against the plate 35.

Prior to the time that the spring 43 reaches its position of unstable equilibrium, the arm 51 engages the end of finger 68 and it thereupon becomes necessary for the pressure in the puff 49 to overcome not only the force .of the spring 56 and spring system 43, but also the force exerted by the spring 66. Therefore, by adjust ing the adjusting screw 13 it is possible to bring the lung pressure to any required value before the gas is released from the mask. It will therefore be apparent that the rapidity with which the gas is introduced to the lungs and therefore the duration of the inhalation period is determined by the setting of the reducing valve l1, and the maximum lung pressure is determined by the setting of the screw 13 so that both of these factors are under the control of the operator.

Upon movement of the stem 28 to close the valve I and open the exhaust valve H, the pressure within the mask and the lungs begins to fall at a rate dependent upon the size of the orifice in the valve 14. Since the effective size of the openings in the valve I4 is adjustable as heretofore described, it is possible for theoperator to select the desired exhalation period. With this fall in pressure, the pressure in the puff 48 likewise drops, permitting clockwise rotation of the lever 54, first under the force of thesprings 59 and 56 until the spring 68 engages the stop 1|, and thereafter under the force of the spring 59 acting alone until the point is reached at which the arm 51 engages the finger 59. Thereafter it is necessary for the spring 59 to overcome not only the force of the spring system 43, but the additional force exerted by the spring 61. Therefore, by adjustment of the adjusting screw 14 and adjustment of the tension of spring 59, the stem 28 can be tripped to close the exhaust valve [4 and open the supply valve l8 and initiate a new respiration cycle when the pressure in the mask and lungs is still at a substantial positive value, or these control elements may be adjusted so that a new cycle is initiated only when the lung pressure falls substantially to zero or to a negative value.

The portion of the device heretofore described is equally applicable for the control of either a conventional mask or a belt, the belt being substituted for the mask H of Figure 1, and these elements I have herein referred to as an applicator regardless of whether the gas pressure is applied to the lungs through a mask or is applied through a belt, such as that hereinafter described.

An important feature of the invention lies in the fact that the structure is such that by adjustment of the tension of the spring 59 and the spring 61 the.device can be so arranged that there must be a slight negative pressure in the lungs and the mask before the valves are operated to produce a new phase in the cycle, this negative pressure acting on the diaphragm 52 to exert a slight force to move the lever 54 in a clockwise direction. For this purpose the spring 59 comprises two separate spring elements 59a and 59b, the spring being substantially stronger and having a loop 60 trained over the shank of a pin 68a on the lever 6i so that the spring 59b can operate within the iengthof-the spring 59a. The spring 591) is of such strength as to be just capable of overcoming the frictional resistance of the operating lever 54 and associated parts to collapse the diaphragm 52 upon reduction in pressure in the applicator. This has a distinct advantage in that the respiratory rate is under the control of the patient who initiates each new cycle by a very slight gasp and the negative pressure requirement of the instrument can be made so slight that the patient is entirely unaware of the fact that he does initiate the cycle but instead the instrument appears to automatically follow his natural breathing rhythm. Since with the last mentioned adjustment the rate of ventilation 8,. falls under the control of the patients natural ventilating mechanism, hyper ventilation and the concurrent alkalosis are avoided.

Where the instrument is to be set. to operate in response to a negative pressure within the mask, novel means are provided for taking over initiation of the cycle in the event that the patient fails to do so. Thus where this method of operation is employed there may occur certain instances where the patient may for a time prove incapable of initiation of the cycle, in which case death would ensue, and I have therefore incorporated means whereby automatic resuscitation spontaneously occurs if the patient ceases to initiate the respiratory cycles at a reasonable rate. This mechanism comprises a second puff 1B similar in construction to the puff 48 having a diaphragm 11, the interior of the puff being connected to the tube 41 by a tube 18 having a check valve 19 therein arranged to permit the flow of gas from the tube 41 to the put! but to prevent return flow. The puff also has an adjustable bleeder valve 8| whereby the rate at which the gas escapes from the puff can be manually adjusted and regulated. A spring 82 acts on the diaphragm in a direction to collapse the puff and a rod 83 extends outwardly from the diaphragm and is moved in a longitudinal direction in response to movement of the diaphragm and consequently in response to changes in pressure within the puff. The end of the rod 83 has a hook 84 adapted to cooperate with the hooked end 85 of a rod 86 attached to the free end of the leaf spring 81 and movable with the finger 69. It will be seen that during each inflation or inhalation phase of the respiratory cycle gas is delivered through the check valve 19 into the puff 16 so as to normally maintain the puff in an inflated condition whereby the rod 83 and hook 84 are effectively disconnected from the rod 86 and the spring 51. However, as the gas escapes through the bleeder valve ill, the diaphragm 11 tends to collapse under the action of the spring 82 during the exhalation phase of the cycle, and unless the patient by a gasp initiates a new cycle within the prescribed interval as determined by the setting of the bleeder valve 8|,

. the hook 84 engages the hook 85 thereby relieving the pressure applied by the spring 51 and causing the lever system 58 to be immediately rotated in a clockwise direction to initiate a new cycle. The elapsed interval between the start of the exhalation period and the time at which the puff 81 takes command of the situation is, of course, determined by the adjustment of the bleeder valve 8 I.

The instrument is furthermore so constructed that a desired respiratory action may be pr0= duced both by applying gas pressure directly to the lungs and by inflating and deflating a belt placed around the body of the patient, and to this end a supplementary valve mechanism is provided for controlling the how of gas to and from the belt. the operation thereof being synchronized with the operation of the valves con trolling the flow of gas to and from the mask. This valve mechanism comprises inlet and outlet valves 81 and 88 identical in structure with the supply and exhaust valves i8 and it having a stem 89 interconnecting the valves. The inlet valve 81 is connected to a source of gas under pressure, such as a pressure cylinder, through a tube 9! and a pressure reducing and control valve 82 of conventional design having a handle 92a for controlling the pressure in the tube 9|. A

pressure gauge 92b is provided on the outlet side of the valve, preferably calibrated in cubic feet per minute flow. The tube 8i may be interconnected with the tube l8 through a cross connection 98 and hand operated shut-off valves 94, 95 and 98 are interposed in the tubes 9| and I8 and in the cross connection so that gas may be supplied to the inlet valve 81 through either of the tubes 91 or I8. Through this arrangement different gases may be employed in the mask and belt or if desired the gases may be mixed in desired proportions. For example, when used as a simple resuscitator, oxygen may be supplied to the mask through the valve I8 and compressed air or an inert gas may be supplied to the belt through valve 81. On the other hand,if a secnd source of gas is'not available, oxygen may also be supplied for operating the belt by closing the valve 94 and opening the valve 98.

While the belt may take many difierent'forms, that herein shown comprises a band of fabric 91 of suitable width and strength adapted to pass around the body of the patient ancl having means, such as straps and buckles 98 for securing the same in place. Disposed within the band 91 is a gas-tight sack 99 adapted to expand inwardly and decrease the effective internal size of the band, moving as shown diagrammatically in Figure 1 from the position indicated by dotted line I M to the full line'position indicated at I02 a relatively large tube I09 connects the interior of the sack 99 with the outlet valve 88 and a tube I04 connects the inlet valve 81 with the sack, in this instance connecting with the tube I03. Under some circumstances it may be desirable to use only the belt and in that case it may be substituted for the mask by connecting tube I03 to fitting I3 and tube I04 to the valve I6. Thus the mask and belt may be used together or they may be used interchangeably as the applicator.

It will be seen that when the valve 81 is opened and the valve 88 simultaneously closed gas is admitted to the sack 99 inflating the belt and forcing air from the lungs of the patient and when the position of the valves is reversed, gas flows out of the sack through tube I08 and'outlet valve 88 at a rate dependent upon the setting of the outlet valve as heretofore described in connection with valve I4.

The valve stem 89 and associated valves may conveniently be driven by the same drivingmeans I which drives the stem 28, and for this purpose a link I05 is provided pivoted at I08 having one end pivotally connected to the stem 28 and the opposite end pivotally connected to stem 89. It will be apparent that as the stem 28 movesto the right facing Figure 1 to close valve I8 and open .valve I4 to thereby permit the escape of gas from the lungs during the exhalation phase of a respiration cycle, the stem 89 is concurrently moved to the left, thereby opening'valve 81 and closing valve 88, admitting gas to the belt to inflate the same and mechanically collapse the lungs. When the stem 28 is moved to the left, the reverse action occurs to produce the inhalation phase of the respiration cycle.

With the apparatus heretofore described the valves I4, I8, 81 and 88 are operated in response to changes in pressure withinthe mask II and the maximum pressure within the belt is dependent upon the rate at which gas is admitted thereto. However, the device is so constructed that the valves may be operated in response to the pressure in the mask as heretofore described control, another pufl I0! is provided connected by a tubeI08 to the outlet valve 88 and having a diaphragm I09 responsive to pressure in the tube I03 and sack 89. A rod III is attached to thediaphragm and movable thereby and arranged for,attachment to the rod 53 of pufl! 49 or to the:

lever 54, the rod III in this instance being a continuation of rod 59.

Disposed in the tube I08 is a three-way cock" II8 arranged so that by turning the cock through 90 communication is cut off from the valve 88 connected or the puff I01 opened to atinosphere' and communication is set up between the puff I01 and the atmosphere so that the diaphragm may be moved freely.

It will be observed that with the rod III disat the valve H8, the valves 98 and 84 closed, and the valve 98 open the valves I6 and I4 will be controlled wholly in response to the pressure in the applicator II regardless of whether this be a mask or belt. and the belt 91 will be entirely out of service. By opening valve 94 the belt may be placed in service but the respiration rhythm will be determined solely by the puff 49 and associated mechanism. If valve 94 is left closed and valve 98-opened the belt will be placed in service utilizing the same source of gas as used in the mask. By connecting rod III with the lever 54 and placing vent valve H3 in closed position the pressure at which the valves I4, I8, 81 and 88 are operated will be determined by the average of the pressure in the mask and the belt. With this setting of the valves the puff I8 may, if desired, be utilized to give a time delay at the end of the inhalation phase of the cycle to permit complete deflation of the belt and remove all pressure therefrom. These and other combinations may be made and from this it can be seen that the device is highly versatile inuse and can be easily applied to use in most any situation which may arise.

Iclaim: v

1. The combination in a respiration apparatus of the type having an applicator and a source of gas under pressure, of a conduit for conducting said gas to said applicator, a supply valve for controlling the .ilow of gas in said conduit to said applicator, an exhaust valve for controlling the flow of gas out of said applicator, means for driving said valves in unison between an inhalation position with .the supply valve open and the exhaust valve closed and an exhalation position with the supply valve closed and the,

exhaust valve open, an operator for actuating said driving means, pressure applying means for urging said operator in one direction to actuate the valves to said inhalation position, and pressure responsive means connected to and movable with changes in pressure on said applicator connected to said operator to oppose movement of the latter under action of said pressure applying means to cause said operator to move in said one direction in accordance with a drop in pressure in said applicator to actuate said driving means and move said valves to the inhalation position at a preselected minimum pressure in said applicator, said pressure responsive means acting to move said operator in the opposite direction against the force of said pressure applying means upon increase in pressure in said applicator to actuate the valves to the exhalation position at a preselected maximum pressure in the applicator, and loading means for augaesaese menting the force applied to said operator by said pressure applying means and by said pressure responsive means, said loading means being adjustable to preselect the pressure in said ap plicator at which said operator actuates the driving means and thereby operate said valves between said positions at preselected maximum and minimum pressures in the applicator.

2. The combination in a respiration apparatus of the type having a source oi gas under pressure and a mask for administering said gas to the lungs of a patient of a conduit for conducting said gas to the mask, a supply valve for controlling the flow of said gas in said conduit, an exhaust valve for controlling the flow of gas out of the mask, means for driving the valves in unison between an inhalation position with the supply valve open and the exhaust valve closed and an exhalation position with the supply valve closed and the exhaust valve open, an operator for actuating said driving means, pressure applying means for urging said operator in one direction to actuate the valves to the inhalation position, pressure responsive means connected to and movable with changes in pressure in the mask and connected to said operator to oppose movement of the latter under action of the pressure applying means to cause the-operator to move in said one direction in accordance with falling pressure in the mask to actuate the driving means and move the valves to the inhalation position at a minimum pressure in the mask, the pressure responsive means acting to move the operator in the opposite direction against the force of the pressure applying means upon increase in pressure in the mask to actuate the valves to the exhalation position at a preselected maximum pressure in the mask, loading means disposed to oppose the pressure applying means, means for adjusting said loading means and the pressure applying means to prevent the pressure applying means from moving the operator to a position to operate the valves to the inhalation position upon a reduction of pressure in the mask to atmospheric to cause the actuator to be moved in said one direction a short distance at the end of its movement by said pressure responsive meansvupon a reduction in pressure below atmospheric to operate the valvesto inhalation position upon a gasp by the patient, and means for rendering said loading means inoperative a preselected interval after opening of the exhaust valve in the event the patient does not,reduce the pressure in the mask by gasping to operate said driving means and move the valve to inhalation position.

3. The combination in a respiration apparatus of the type having an applicator and a source 01' gas under pressure, of a conduit for conducting said gas to said applicator, a supply valve for.

controlling the flow of gas in said conduit to said applicator, an exhaust valve for controlling the flow of gas out of said applicator, means for driving said valves in unison between a first position with the supply valve open and the exhaust valve closed and a second position with the supply valve closed and the exhaust valve open, an operator for actuating said driving means, pressure applying means for urging said operator in one direction, pressure responsive means connected to and movable with changes in pressure in said applicator connected to said operator to oppose movement of the latter under action of said pressure applying means to cause said operator to move in said one direction in accordance with a drop in pressure in said applicator to actuate said driving means and move said valves to the first position at a preselected minimum pressure in saidapplicator, said pressure responsive means acting to move said applicator upon increase in pressure in said applicator to actuate the valves to the second position at a preselected maximum pressure in the applicator, loading means operating in opposition to said pressure applying means adjustable to preselect the pressure in said applicator at which the pressure applying means actuates said driving means to thereby operate said valves from the second to the first position at a preselected pressure in the applicator, asecond pressure responsive means communicating with said mask, a check valve disposed between said second pressure responsive means and said mask, means for permitting es- ?cape of gas from and reduction of pressure in said second pressure responsive means at a preselected rate, and means operated thereby for rendering said loading means inoperative when the pressure in said second pressure responsive means reaches a preselected minimum.

4. The combination in a respiration apparatus of the type having an applicator and a source of gas under pressure, of a conduit for conducting said gas to said applicator, a supply valve for controlling the flow of gas in said conduit to said applicator, an exhaust valve for controlling the flow of gas out of said applicator, means for driving said valves in unison between a first position with the supply valve open and the exhaust valve closed and a second position with the supply valve closed and the exhaust valve open, pressure responsive means connected to and movable with changes in pressure in said applicator for actuating said driving means to drive the valves between said positions, means for loading said pressure responsive means through a portion of its movement adjustable to preselect the pressure in said applicator at which the pressure applying means actuates the driving means to thereby operate said valves from the exhalation to the inhalation position at a preselectedpressure in the applicator, a second pressure responsive means'communicating with said mask, a check valve disposed between said second pressure responsive means and said mask, means for permitting escape of gas from and consequent", reduction of pressure in said second pressure responsive means at a preselected rate, and means operated thereby for rendering said loading means inoperative when the pressure in said second pressure responsive means reaches a preselected minimum.

5. The combination in a respiration apparatus of the type having an applicator and a source of gas under pressure, of a conduit for conducting said gas to said applicator, a supply valve for controlling the flow of gas in said conduit to said applicator, an exhaust valve for controlling the flow of gas out of said applicator, means for driving said valves in unison between a first position with the supply valve open and the-exhaust valve closed and a second position with the supply valve closed and the exhaust valve open, an operator movable in opposite directions to actuate said driving means, spring means for urging said operator in one direction, pressure responsive means connected to and movable with changes in pressure in said applicator connected to said operator tooppose movement of the latter under action of said spring to cause said operator to move in said one direction in accordance with a drop in pressure in said applicator to actuate said driving means and move said valves to the inhalato move said operator in the opposite direction against the force of thespring upon increase in pressure in said applicator to actuate the valves to the exhalation position at a preselected maximum pressure in the applicator as indicated by the pressure responsive means, spring loading means for resisting the movement of .the actuator, and means for separately adjusting the loading means in opposite directions to preselect the value of the pressure in said applicator at which said operator actuates said driving means to drive the valves betweensaid positions. l

6. The combination in a respiration apparatus of the type having an applicator and a source of gas under pressure, of a conduit for conducting said gas to said applicator, a supply valve for controlling the flow of gas in said conduit to said applicator, an exhaust valve for controlling the fiow of gas out of said applicator, means for driving said valves in unison between a first position with the supply'valvev open and the exhaust valve closed and a second position with the supply valve closed and the exhaust valve open, an operator movable in opposite directions to actuate said driving means, spring means for urging said operator in one direction, pressure responsive means connected to and movable with changes in pressure in said applicator connected 'to said operator to oppose movement of the'latter under action of said spring tothereby cause saidv operator to move in said one direction in accordance with a drop in pressure in said applicator to actuate said driving means and move said valves to the inhalation position at a preselected minimum pressure in said applicator, means for adjusting said spring to preselect the value of said minimum pressure, said pressure responsive means acting to move said operator in the opposite direction against the force of the spring upon increase 'in pressure in said applicator to actuate the valves to the exhalation position at a preselected maximum pressure in the applicator as indicated by the pressure responsive means, and spring loading means positioned for engagement with said operator toward the end of its movement adjustable to preselect the pressure in said applicator at which said operator actuates said driving means to drive the valves between said positions. j

7. The combination in a respiration apparatus of the type having an applicator and a source of gas under pressure-of a valve system for controlling the flow of gas to and from said applicator comprising a supply valve, an exhaust 14 controlling flow 0! gas in said conduit tosaid applicator, an exhaust valve for controlling the flow of gas outoi said-applicator, an operating linkage connecting said valves movable between a first and a second position to move said valves between a first position with the supply valve open and theexhaust valve closed, and a second position with the supply valve closed and the exhaust valve open, anv overcenter snap mechanism operative on said linkage for driving thesame between its positions, said snap mechanism having opposed positions of maximum thrust on the linkage defined by the seated position of the valves, to hold the valves in said position, and an intermediate position oi! unstable equilibrium, a second snap mechanism having lost motion connection with the linkage, said lost motion extending from one of the opposed positions directions to move Said second snap mechanism from either of its Opposed positions past its posivalve, a mechanical linkageconnected to both of said valves movable between preselected positions for simultaneously opening one and closing the other of said valves in alternation, a first overcenter snap mechanism connected to'said linkage holding the same at either of said positions, and a second overcenter snap mechanism having lost motion with respect to said linkage for driving the same from either of said positions a distance sufiicient to bring the first overcenter snap mechanism beyond its center position.

,8.The combination in a respiration apparatus of the type having an applicator and a source tion of unstable equilibrium, pressure responsive means connected to said operator movable in opposite directions with increasing or decreasing changesin pressure in said applicator, the degree of which movement closely approximates the jchanges in pressure in the applicator, said operator acting on saidsecond snap mechanism to move said valves between the first and second positions thereof at preselected maximum and minimum pressure in said applicator.

9. The combination in a respiration apparatus of the type having an applicator and a source of gas under pressure, of a conduit for conducting said gas to said applicator, a supply valve for controlling flow of gas in said conduit to said applicator, an exhaust valve for controlling the flow of gas out of said applicator, an operating linkage connecting said valves movable between a first and a second position to move said valves between a'first' position with the supply valve open and the exhaust valve closed, and a second position with the supply valve closed and the exhaust valve open, an overcenter snap mechanism operative on said linkage for driving the same between its position, said snap mechanism having opposed positions of maximum thrust on the linkage defined by the seated position of the valves, to hold the valves in said position, and an intermediate position of unstable equilibrium, a second snap mechanism having lost motion connection with the linkage, said lost motion extending from one of the opposed positions thereof to a point beyond its position of unstable equilibrium to move the linkage after-the second snap mechanism haspassed its position of unstable equilibrium andthereby move the first snap mechanism through its position of unstable equilibrium to drive the valves from one of said positions to the other, an operator for engaging said second snap mechanism movable in opposite directions to move said second snap mechanism from either of its opposed positions past its position of unstable equilibrium, pressure responsive means connected to said operator movable in opposite directions Withincreasing or decreasing changes in pressure in said applicator, the degree of which movement closely approximates the changes in pressure in theapplicator, a lost motion connection between said operator and said second snap mechanism to bring the operator into engagement with the second snap mechanism toward the end of movement of said pressure responsive means.

10. The combination in a respiration apparatus of the type having an applicator and a source of gets under pressure, of a conduit for conducting said gas to said applicator, a supply valve for controlling flow of gas in said conduit to said applicator, an exhaust valve for controlling the flow of gas out of said applicator, an operating linkage connecting said valves movable between a first and a second position to move said valves between a first position with the supply valve open and the exhaust valve closed, and a second position with the supply valve closed and the exhaust valve open, an overcenter snap mechanism operative on said linkage for driving the same between its positions, said snap mechanism having opposed positions of maximum thrust on the linkage defined by the seated position of the valve, to hold the valve in said positions, and an intermediate position of unstable equilibrium, a second snap mechanism having lost motion connection with the linkage, said lost motion extending from one of the opposed positions thereof to a point beyond its position of unstable equilibrium to move the linkage after the second snap mechanism has passed its position of unstableequilibrium and thereby move the first snap mechanism through its position of unstable equilibrium to drive these valves from one of said positions to the other, an operator for engaging this second snap mechanism movable in opposite directions to move said second snap mechanism from either of its opposed positions past its position of unstable equilibrium, pressure responsive means connected to said operator movable in opposite directions with increasing or decreasing changes in pressure in said applicator, the degree of which movement closely approximates the changes in pressure in the applicator, a lost mo tion connection between said operator and said second snap mechanism to bring the operator into engagement with 'the second snap mechanism toward the end of movement of said pressure responsive means, /and adjustable means for loading said pressure responsive means in both directions of travel to alter the pressure value therein at which the operator is moved to position to operate said second snap mechanism and thereby preselect the'maximum and minimum pressure in said applicator.

11. The combination in a respiration apparatus having an applicator and a source of gas under pressure of a valve system for controlling the flow of gas to and from said applicator comprising a supply valve and an exhaust valve, an operating linkage common to said valves movable alters nately between seated positions of said valves with one of said valves open and the other closed, an overcenter snap mechanism operative on said linkage for driving the valves between said seated positions, said snap mechanism having opposed positions of maximum thrust on the linkage defined by the seated positions of the valves to hold the valves in said positions and an intermediate position of unstable equilibrium, and a second snap mechanism having lost motion connection with the linkage from one of the opposed positions thereof to a point beyond its position of unstable equilibrium to move the linkage after the second snap mechanism has started snap movement and to prevent the valves from coming to rest intermediate the seated positions, and means formoving the second snap mechanism to operate the valves,

12. The combination in a'respiration apparatus having an applicator and a source of gas under pressure of a valve system for controlling the flow of gas to and from said applicator comprising a supply valve and an exhaust valve, said valves having connecting linkage movable between opposed seated positions defined by seated positions of the valves to simultaneously open one of the valves and close the other, a plurality of overcenter snap mechanisms operative on said linkage for driving the same between said positions, said snap mechanism having opposed positions defined by the seated positions of said linkage and an intermediate position of unstable equilibrium, a first snap mechanism being secured to said stem and a second being movable with respect thereto, an operator for moving the second snap mechanism from either opposed position thereof to a point beyond its position of unstable equilibrium for snap movement thereof to the other of said opposed positions, said second snap mechanism having lost motion connection with the operator for completion of the movement of the snap mechanism by movement with respect to the operator, and abutment means on the linkage positioned for engagement by the second snap mechanism during its snap movement to move the linkage a. distance suflicient to carry the first snap mechanism from one of the opposed positions thereof past its position of unstable equilibrium-to move the linkage to the opposite seated position thereof.

13. The combination recited in claim 7 wherein said overcenter snap mechanisms each comprise a thin leaf spring supported at one end in cantilever fashion in spaced relation to said linkage with the other end free to move and an adjacent spring strip in longitudinal compression constem and the free .end of the leaf spring of the" other of said mechanism has lost motion connection to said stem.

14. The combination recited in claim 7 including pressure responsive means secured to said linkage responsive to pressure in said applicator for urging the linkage in a direction to hold said exhaust valve closed to counteract the efl'ect of pressure in said applicator against the exhaust valve.

15. The combination in a respiration apparatus having an applicator and a source of gas under pressure of a valve system for controlling the flow of gas to and from said applicator comprising an exhaust valve connected to said applicator having relatively large outlet to atmosphere, and means for opening and closing said outlet, an inlet valve having a gas chamber, a gas inlet thereto and a gas outlet therefrom communicating with said applicator, a stem common to said' counter balancing the eflect oi pressure of the gas against the means for closing the outlet to the exhaust valve.

16. The combination in a respiration apparatus of the type having an applicator and a source of gas under pressure of a valve system for controlling the flow of gas alternately to and from said applicator in a respiration cycle comprising a supply valve having a valve stem provided with a conical point at one end thereof, a ported body having a bore of substantially larger diameter than said stem provided with a conical end, the body having an inet orifice at the apex of said conical end positioned to be closed upon seating of the conical end 01' the stem into the conical end oi! said bore, an exhaust valve having a ilat ported plate, a fiat valve disk shaped to seat thereagainst to close the ports therein and a universal connection for supporting said disk on the other end of said stem, a gas-tight, highly flexible diaphragm disposed across the bore of said body and passing said stem therethrough in gas tight relationship to apply pressure to the stem to hold the exhaust valve in seated position in response to gas pressure in the bore, overcenter spring means for driving said stem longitudinally to open and close said valves having an opening for the passage of said stem, said overcenter means and said diaphragm being the sole means for supporting said stem, spring means operated in response to preselected changes of pressure in said applicator for driving said stem in opposite directions between seated positions, said conical seat acting to guide the conical end of the stem into seating position when driven in one direction in spite of misalignment of said stem and said universal connection accommodating for misalignment between said plate and said disk when the stem is driven to seated position in the opposite direction.

17. The combination in a respiration apparatus of the type having an applicator and a source of gas under pressure, of a conduit for conducting said gas to said applicator, a supply valve for controlling the flow of gas in said conduit to said applicator, an exhaust valve for controlling the flow of gas out of said applicator, means for driving said valves in unison between a first position with the supply valve open and the exhaust valve closed and a second position with the supply valve closed and the exhaust valve'open, an operator for actuating said driving means, pressure applying means for urging said operator in one direction to actuate said valves to the first position, pressure responsive means connected to and movable with changes in pressure in said applicator for moving said operator in the opposite direction against the force of said pressure applying means to actuate the valves to the second position, and loading means operating in oppo- 18 sition to the pressure responsive means positioned to be engaged by said operator toward the end of its movement by the pressure responsive means adjustable to preselect the pressure in said applicator at which the pressure responsive means a'ctuates said driving means and thereby operate said valves from the first to the second position at a. preselected pressure in the applicator.

18, The combination in a respiration apparatus of the type having a mask, an expansible belt and a source of gas under, pressure of' a conduit -for conducting said gas to said mask a supply valve for controlling the supply of gas in said conduit to said mask, an exhaust valve for controlling the flow of gas out of said mask, means for driving said valves in unison between a first position with the supply valve open and the exhaust valve closed, and a second position with the supply valve closed and the exhaust valve open to alternately supply gas to said mask and exhaust gas therefrom in a respiration cycle, pressure responsive means movable with changes in pressure in said mask to actuate said driving means at preselected maximum and minimum pressures in said mask, a conduit for conducting gas to said belt, inlet and outlet valves for controlling the flow of gas to and from said belt to alternately inflate and deflate the same, means for driving the inlet and outlet valves in unison alternately between an inflation and deflation position in timed relation to said supply and exhaust valves to inflate and deflate the belt in a respiration cycle, a second pressure responsive means responsive to pressure in the belt, and means connecting said second pressure responsive means to the firstmentioned pressure responsive means to actuate the second valve driving means in response to the difference in pressure in the mask and in the belt.

EDWIN D. COLEMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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