US2378468A - Pressure regulator - Google Patents

Description

June 19, 1945.

G. MI DEMING PRESSURE REGULATOR Filed May 20, l1942 FIGA.

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RATE OF FLOW GEORGE M. DEM/N6 ATTORNEY Patented June I9, 1945 PRESSURE4 REGULATOR George M. Deming, Orange, N. J., assignor to Air Reduction Company, Incorporated, New York, N. Y., a corporation of New York Application May 20', 1942, Serial No. 443,719

''claima (01128-142) 'l This invention relates to pressure regulators such as are used for oxygen therapy, and by aviators for breathing at high altitudes. 'I'he inven- A face mask I includes a metal shield. I I with a cushion I 2 attached around the edge of the shield for Contact with the face of the wearer. The mask Aregulating the degree of opening is connected with a'source of oxygen by a soft rubber hose I 4 that lits over al nipple I6 at the bottom of the mask. v

The interior of the mask communicates with the surrounding atmosphere throughan air port I1 that opens through the side o1' the mask.' The extent of opening of the air port I1 is controlled tion relates especially to apparatus for supplying a mixture of gas and air. 5 In its broadest aspects it is an object of the invention to provide an improved pressure regulator for supplying gas to a breathing mask, or for other purposes where it is desirable to prevent changes in the force required to operate the valve 1U of the regulator. by a valve that comprises a plate I8 movable It is an object of the invention to provide irntransversely of the air port I1 and about a screw proved. breathing apparatus in which the ratio of I9 as a pivot. The valve plate I8 has an edge that oxygen and air is determined by the relative moves along a scale 20 (Fig. 2) which indicates opening of the respective supply passages. 1;, the= 'concentration of oxygen that the wearer o1' the mask will receive for any position of the plate I8 as it is moved over the air port I1. The screw I9 can be tightened to hold the valve plate I8 inw any selected position along the scale 20.

. For an aviation breathing mask the air port I1 `is left fully open at sea level and closed progressively further as the altitude increases until at some altitude the air port is completely closed and the aviator breathes pure oxygen.

The mask comprises the reduced-pressure chamber of a, pressure regulator of dthe inverse Atype that controls the supply of QXygen. A regulating spring 23 presses against a bearing disk 24, which may be made of paper and secured to the front of a diaphragm 25, The edge of the diaphragm 25 is clamped between the metal shield I I and a front cover 26 that is fastened to the shield` by screws 21. There are openings 28 in the cover`- 26 for exposing the front of the diaphragm 25 to the pressure of the surrounding atmosphere.

A. regulating valve lever 30 is connected to the -mask by means of two loosely tting fulcrum pins 3| and has a head 32 against the back of the diaa phragm 25. Hence, any inward thrust upon the 4o diaphragm 25 and the head -32 of the regulating lever 30 results in a downward thrust of a toe 34 of the lever 35. This downward thrust is communicated to a valve 36 through a, thrust pin 31 which slides freely in a drilling in a wall`38.' f

The valve 36 controls passage of gas through a port Il0. The thrust pin 31 is in axial alinement with the port 40 and the lower end of this thrust pin 31 fits into a centralsocket in the top face of the valve 36. The t of the thrust pin 31 in the socket of the valve 36 is loose enough to permit the valveto rock slightly `on the end of the thrust pin and thus insure tight closure of the valve 36 when the diaphragm 25 moves'and the valve 36 is 55 orced upward by the pressure of the gas beneath In one type of oxygen breathing device a mask is provided with an air inlet through which air may be drawn into the mask with each inspiration of the wearer. The mask has also a diaphragm that controls a valve for admitting gas, such as oxygen, to the mask..l The oxygen-air ratio is controlled by partially obstructing, in varying amounts, the air inlet passage, often by aneroid control in aviation breathing masks, but usually by manual setting in masks for oxygen therapy La', or anesthesia. It is another object of the invention to stabilize the Qperation of the gas-inlet valve of such masks and to obtain an air-gas ratio that is substantially independent of the demand rate (i. e., rate of oW) The oxygen supply valve .is subject on one side to the pressure in the mask and on the other side to the pressure in the supply line. This invention prevents the pressure diierential across the valve from changing sufiiciently with the rate of iiow to impair the operation of the breathing apparatus.

This application is a continuation-impart of my application Serial No. 386,618,` iiled April 3, 1941.

Other objects, features and advantages of the invention will appear or be pointed out as the specification proceeds.

In the accompanying drawing, forming a part hereof:

Fig. 1 is a fragmentary sectional view through a mask and regulator embodyingthis invention.

Fig. 2 is a detail view of the air inlet valve for of the air inlet passage shown in Fig. 1.

Fig. `3 is a sectional View, on a reduced scale, taken on the line 3-3 of Fig. 1,. but with the gas valve in open position. i f

Fig. 4 is a graph showing the performance of this invention compared with devices of the prior art.

A the maximum opening oi' this valve 36 is limited by a stop 42. I have found that the pressure of oxygen in the mask can be made independent of the demandrate by restricting the ilow of the gas to the port 40. The ilow is restricted by limiting the lateral or peripheral lclearance between the valve 36 and the surrounding wall 44. The pressure .on the downstream side of the valve 36 gradually increases with increasing rates of discharge, that is, with increasing displacements of the valve 36 from the lip against which the valve 36 seats at the end of the port 40.

The regulating spring 23 is preferably made sufliciently Weak so that oxygen flows into the mask when the pressure in the mask is slightly less than that of the surrounding atmosphere, for example at a pressure of about .05 of an inch of water below that of the surroundingatmosphere. As long as the pressure within the mask is above that level, no oxygen will 4be discharged to the mask. Hence, as long as air can be inspired through the air inlet port I1 without creating a pressure differential greater than .05 of an inch of Water, no oxygen is supplied to the mask. If, however, the valve plate I8 covers part of the air inlet I1, there are periods in each respiratory cycle when more or less oxygen flows into the mask.

To permit adequate exhaust of exhaled air from the mask when the Valve I8 is partly or completely closed, the mask is equipped with an exhaust valve 45 that covers an exhaust port in the side of the Y mask. The-valve 45 is lightly loaded by a spring.

The pressure drop through the port 40 is a function of the rate of flow of the oxygen. As the rate of now increases, the pressure drop through the port 40 increases. In an ordinary regulator of the inverse type the pressure at the valve-end of the port 40 would increase, and this would make the pressure differential on the opposite sides of the valve 36 less, so that less thrust would be required on the pin 38 to open the valve 36 wider. Such a condition causes instability of the regulator. When the air port I1 is open or partly open, any variation in the amount of suction inthe mask required to operate the oxygen supply valve 36 will change the proportion of air and oxygen that that amount of suction draws into the mask.

The dotted line 46 of the graph shown in Fig. 4 represents the variation in the amount of suction in the face mask that would be required to move the valve 36 toward open position if the gas passage around the sides of the valve 36 were of such large cross-section that there would be little pressure drop in the gas passing around the valve. As the rate of ilow increases and the suction required to open the valve decreases, it is apparent that a larger portion of oxygen and relatively less air will enter the mask when the wearer inhales.

The reduced cross-section of the gas passage between the wall 44 and the side of the valve 36 causes a pressure drop in the passage around the valve, and this drop is proportional to the rate of flow and increases the pressure dill'erential between the back oi the valve 36 and thatpart of the front o! the valve that extends radially beyond the valve seat. The valve seat comprises a raised lip, and the valve 36 has a substantial radial extent beyond the valve seat. The pressure drop in the annular passage between the wall 44 and the valve 36, therefore, counteracts the effect of the pressure change at the upstream end of the port 40.

If the gas passage around the sides of the valve 36 is sulcientlyrestricted, the pressure differential on opposite sides of the valve 36 will remain constant with variations in the rate oi?v flow, and the .suction to open the valve 36 under such conditions is represented by the line 41 in Fig. 4. Too much restriction of the gas passage around the valve 36 causes the line 41 to curve upward, with resulting increase in the proportion of air drawn into the mask.

If the port 40 has a diameter of .1495 inch (#25 drill) and the diameter of the valve 36 is .263 inch,

the diameter of the gas passage around the valve 36 (i. e., at the Wall 44) should be of the order of .344 inch in a regulator such as shown in the drawing. It should be noted that the effect of the raised valve seat is to cause a more abrupt change in the direction of the gas flow just before the gas enters the port 40. With the valve extending radially beyond the raised seat, this change in the direction of the gas flow results in some dynamic pressure head against a portion of the downstream face of the valve, and this pressure increases with the rate of i'low and must be countered by added pressure drop in the passage around the valve. The cross-sectional area of the annular gas passage around the valve is of the order of two times the cross-sectional area of the port, with the relation of diameters indicated above. These specific values are given by way of illustration only, and not as limitations of the invention. This illustration is for a raised valve seat, such as shown in the drawing and commonly used in pressure regulators. The dynamic pressure effects vary with diierent valve seats.

Various changes and modiiications of the invention can be made, and some features of the invention can be used Without others.

I claim: y

1. An aviation breathing mask having an oxygen inlet port and an air inlet port, and including a valve commanding the oxygen inlet port, said valve including a movable valve body and a seat for said valve body, another Valve commanding the air inlet port, a device for changing f the extent of opening of the air inlet valve with increase in altitude, a diaphragm forming a wall of the mask and movable in response tov pressure changes within the mask, motion-transmitting connections between the diaphragm and the oxygen inlet valve body, and means for causing a substantially constant air-oxygen mixture to be drawn into the mask regardless of the demand rate, said means including a passage of yrestricted cross-section around the side of the movable body of the oxygen inlet valve, said cross-section being so correlated with the cross-section of the oxygen inlet port -that it produces a pressure Ldrop in the gas ilowing around the valve body that approximately offsets the effect on the oxygen inlet valve body of the changes in the pressure 'drop through the oxygen inlet.

2. An aviation breathing mask that comprises the reduced-pressure chamber of a pressure regulator of the inverse type, said mask including an oxygen inlet port, a valve commanding the oxygen inlet port, said valve including a movable valve body and a seat for said valve bodya ilexible diaphragm forming a wall of the around the valve body f or causing an increase in the pressure drop of the gas flowing around the valve body as the rate of such ilow increases,

upstream end of the port, the improvement which` comprises a passage with a lrestricted cross-section around the valve for increasing the pressure drop of the gas iiowing around the the cross-section' of. the restricted passage being so correlated with the cross-section of the oxygen inlet port that the increase inthe pressure drop around the valve body approximately offsets the increased pressure on the downstream side of the valve body caused by the increased pressure drop through the oxygen inlet port.

3. A pressure regulator comprising a reduced-pressure chamber, -a port through which oxygen enters the reduced-,pressure chamber, a

valve seat, a valve. commanding the pcrtV and movable toward and from the seat in the direction of the axis of the port, and an oxygen passage around the sides of the valve, said passage having a cross-section correlated with the crosssection of the port so that at different rates of flow the pressure drop in the passage around the valve substantially oisets the effect on the valve of the pressure drop through the port.

4. A pressure regulator as called for by'claim 3 in which'the valve seat is raised to cause a change in th direction of gas flow and the crosssection of the passage around the valve is of the order of twice as great as the cross-section of the port.

5. In a pressure regulator of the inverse type in which gas flows 'into a reduced-pressure chamber through a port and a valve in a passage on the upstream side of the port closes `in the direction of the gas flow and against a seat at the sides of the valve and tothe seat as the rate of ow increases, said passage cross-section being so related to the cross-section of the port that the pressure drop around the valve substantially offsets the eiect on the valve of the increased pressure at thev upstream end of the port with increased rates of ow.

6. In a pressure regulator as described in claim 5I the further improvement which comprises a valve that extends radially for a substantial distancebeyond the valve seat, and an annular lip at the upstream end of the oxygen inlet port, which lip serves as the valve seat. n

7. An aviation breathing mask having an oxygen -inlet port and an air inlet portl a valve commanding the oxygen inlet port, said valve including a movable valve body and a seat for said valve body, an adjustable valve commanding the air inlet port, a diaphragm forming a wall of the mask and movable in response to pressure changes within the mask, motion-transmitting connections between the diaphragm and the movable body of the oxygen valve, the oxygen inlet port at the downstream side of thev movable body of the oxygen valve having a sufcient length in the direction of iiow through the port to cause a pressure drop through it which increases with increasing displacements of said movable body and thus tends to increase the pressure on the downstream side of said movable c body with increasing displacements thereof and means for causing a substantially constant airoxygen mixture to be drawn into the mask regardless of the demand rate, said means including a passage of restricted cross-section around the side of the movable body of the oxygen valve,

said cross-section being so correlated with the cross-section of the oxygen inlet port that it produces a pressure drop in the gas flowing around the valve body that substantially prevents any increase in pressure on the downstream side of the movable body of the oxygen valve when its displacement` is increased.

GEORGE M. DEMING.

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