US2023361A - Fluid-pressure operated diaphragm device - Google Patents

Description

DSC., 3, A. 1, TIGGES 2,023,361

FLUID PRESSURE OPERATED DIAPHRAGM DEVICE Filed Jan. l2, 1929 Patented Dec.A 3, 1935 UNITED STATES PATENT OFFICE FLUID -PRESSURE PERATED DIAPI-IRAGM DEVICE sachusetts Application January 12, 1929, Serial No. 332,034

42 Claims.

This invention relates to fluid-pressure operated diaphragm devices having a wide range of usefulness, including application to refrigeration, compressed air, steam, gas, water and other systems, timing elements, and other purposes too numerous to mention. 'Ihe term pressure as herein used may be a depression,that is, pressure below that oi the atmosphere. In the specific application of the device herein disclosed,

the device includes a valve which controls the pressure of a uid whose pressure in turn is utilized to actuate the diaphragm.

The invention will be best understood by reference to the following description, when taken in connection with the accompanying drawing of one specific embodiment thereof, while its scope will be more particularly pointed out in the appended claims.

In the drawing:

Fig. 1 is an elevation of a part of a refrigeration System in which the device is employed for regulating the p-ressure of a refrigerant of the class in which the refrigerant is changed from a gas to a liquid, and vice versa, during the cycle of 'z5 operation;

Fig. 2 is a sectional view of a fluid-pressure operated diaphragm device embodying the invention, the same including a pressure controlling valve;

Fig. 3 is a sectional View, on a reduced scale,

on line 3 3 of Fig. 2; and

Fig. 4 is a sectional view, on a reduced scale, on line 4 4 of Fig. 2.

Referring to the drawing, and to the embodiment of the invention which is illustrated therein, there is shown a body i9, presenting a iluidenclosing chamber Il having one side formed by a resilient, buckling diaphragm l2, adapted to buckle in opposite directions, but prevented by its own resiliency from remaining in a medial position. The diaphragm is conveniently secured to the body by a cap I3 and screws ld, which extend through the cap and diaphragm, and are threaded into the body. Leakage is prevented at the joint between the diaphragm and the body by interposing between them a gasket i5 of suitable material, such as lead.

Superimposed upon the diaphragm is a pres?- sure-distributing fluent body, herein a cushion 50 I6, in the present example composed of resilient,

compressible material, such as rubber. In the present example, this cushion is provided with a central opening ll, and the cushion increases in thickness outwardly toward the margin of the 55- diaphragm. The exact taper will depend upon conveniently applied to the cushion by superim- 10 posing upon the latter a plate 22, which spans the opening Il, while a hollow plunger 23, working in and guided by the sleeve 20, presents a movable abutment 24 for the lower end of the spring, and this abutment rests upon the plate 22. Adjustl5 ment of the pressure which is exerted by the pressure-distributing cushion on the diaphragm is accomplished by rotating the sleeve 20 in the proper directon. The effect of the fluent, pressure-distributing means, as compared with a 2o rigid, unyielding body interposed between the loading spring and the diaphragm, will be explained hereinafter in connection with the operation.

An important feature of the invention is the 225 fact that there is provided means by which the diaphragm, when on one side of its medial position (herein below such position) is prevented from buckling to the full extent to which it would buckle were it not for said means. This feature 30- is of great practical utility, because the working range of the diaphragm, and consequently the range of pressure which it controls, can be held within much closer limits than has been possible heretofore. By making this means adjustable, 35 the range may be varied at will within reasonable limits, and the diaphragm, when buckled toward one side of its medial position, can be so close to that position that it takes but slight movement to carry it across to the other side. To these ends, 40 there is provided an abutment 25, which limits the movement of the diaphragm in one direction (herein downwardly), and which therefore produces in the center of the diaphragm a depression 26, which I term a dimple. The formation of this dimple, of course, is determined by the shape of the abutment, which, in this example,

is rounded where it contacts with the diaphragm. 'I'he range oi movement may be varied by adjusting the abutment by suitable means presently to be described.

While the device as thus far described is susceptible of a wide variety of uses, and may be employed to actuate valves and switches, and to furnish signals or warnings, in the device shown in the drawing, the diaphragm operates a valve 21, which cooperates with a valve seat 28, the latter being conveniently formed as a part of a sleeve 26, which aords a guide for the valve, and is threaded into a boss 30 presented by the body l0. This valve controls communication between the chamber i I and a chamber or passage 3|, formed in the body, while the sleeve is provided With one or more lateral ports 32 close to the valve seat. Another passage 33 vleads from the outside of the body into the chamber It should be observed that the diaphragm, by its own resiliency, furnishes a pressure which, in the position of the valve shown in Fig. 2, maintains the valve yieldingly upon its seat.

Adjustment of the abutment 25 relatively to the valve is conveniently accomplished by providing a nut 34, herein formed as an integral part of the abutment, and threaded onto a screw 35, herein formed as an integral part of the valve. Rotation of the nut is prevented by appropriate means, such as tongues 36, working in grooves or slots 3l formed in the sleeve 29. Relative adjustment of the screw and nut is accomplished by rotating the valve by suitable means, such as that now to be described. While the adjustment might be effected by taking the device apart to afford access to the valve to rotate the latter, the valve in the present example is provided with a tongue 38 received in a groove 39 provided in a shaft 46, whose outer end is accessible from the exterior of the body. To this end, there is provided a sleeve 4|, having a reduced threaded portion screwed into the body l0, said sleeve being provided with a chamber 43 for a packing 44 and a gland 45, the latter being threaded into the sleeve 4|, and provided with a slot or groove 46, for the application of a screw-driver thereto, to tighten the packing about the shaft. Leakage of fluid about the threads of the reduced portion 42 is prevented by the use of a gasket 4l of suitable material, such as lead. Lengthwise movement of the shaft is prevented by providing the same with a lateral flange or collar 48, received between a ring 49 and a shoulder 50 presented by the sleeve 4|.

A hollow cap 5|, threaded into the sleeve 4|, provides a chamber to receive the depending end of the shaft 40, and leakage at this joint is prevented by providing the cap with a circumferential rib 52, which is pressed rmly against the lower end of the sleeve 4|. By removing this cap, access is had to the shaft, which herein is provided with a squared end 53 for the application of a wrench to turn the shaft. Thus the adjustment of the abutment may be accomlished convenientlyfrom the exterior of the device, and without the necessity of taking it apart. A suitablyv arranged, valve lifting spring 54, herein interposed between a shoulder 55 presented by the abutment 25 and a shoulder 56 presented by the/body I0, constantly tends to lift the valve and to cause the latter to follow the diaphragm when the diaphragm moves in an upward direction. t should be understood, of course, that the load which this spring imposes on the diaphragm is insufficient to move the latter past its medial position.

Referring again to the pressure distributing cushion, if the threaded sleeve 20 be screwed down, it causes a pressure to be exerted through the plate 22 on the cushion 6, and therefore the latter distributes this pressure over the surface of the diaphragm. As the operation of the diaphragm is determined by the difference in pressure between the chamber and the pressure exerted by the cushion, by adjusting the pressure on the latter, an adjustment of the device for operation at different pressures can be 5 effected.

The eiects of the top and bottom adjustments will be outlined briey. First, consider the device wth no loading means on the top of the diaphragm. By screwing upwardly on the bot- 10 tom adjustment, that is, by raising the abutment 25 relatively tothe valve 21, an upward bend or dimple 26 is formed in the diaphragm. The diaphragm is thus stressed locally, and the resulting spring pressure in a downward direc- 15 tion on the valve causes the latter to be seated rmly and thus to produce an effective seal. 'Ihe dimple also affects the opening point of the valve in the following way: Let us start with a minimum dimple, and take for illustration a case 20 where the opening point of the valve is at fteen pounds pressure and the closing point is at zero pounds pressure. Now, as the dimple is increased, the closing point remains the same, that is, at zero but the pressure at which the valve 25 opens drops. This could be arranged to show graphically an inclined line which would represent the increase of dimple plotted against the decrease in opening pressure. The closing point, therefore, would be represented by a horizontal 30 line and the opening point by a sloping line ruiming from say fifteen pounds pressure to zero pounds pressure at the maximum amount or depth of dimple.

From this, it will readily be understood that 85 he bottom adjustment enables me to obtain the required dimple in the diaphragm, which accomplishes, rst, the obtaining of an effectual seating of the valve with consequent absence of leakage, and second, the increased or decreased pres- 40 sure at which the valve will open, but in no case is the closing point of the valve affected.

Now, let us consider the distributed pressure (top loading) as accomplished by the means herein employed, that is, the rubber cushion. 15.

For example, assuming that the bottom adjustment is set to give an opening pressure of fifteen pounds and a closing pressure of zero pounds, let us screw down the loading screw at the top so that the cushion exerts a substantially uniform pressure over a predetermined area of the diaphragm. The effect of this is to lift the whole pressure range bodily to a higher point. For instance, when the loading screw is down far enough, we still have the fteen pound range but the opening and closing pressures are changed to twenty pounds and ve pounds, respectively. Thus, once the bottom adjustment is made, no readjustment of the bottom adjusting means is necessary to effect this lifting of the entire range. 60

In contrast with the described means of adjustment, let us consider what the eiect would be to use at the top a concentrated center loading by means of a solid or non-fluent body resting on the top of the diaphragm but with the same type of bottom adjustment, that is, the dimple idea. If, for instance, the bottom adjustment is screwed up so that we have an appreciable dimple in the diaphragm and then the concentrated (undistributed) center, top load is applied, there would result a decreased intensity of the dimple, and if the top loading were increased sufciently, but without changing the bottom adjustment, leakage past the valve would result. Then, to avoid this leakage, it would be necessary to reset the bottom adjustment to increase the dimple suficiently to obtain a proper seal. In addition to this, a concentrated (nondistributed) center load would not enable one to move the entire range up or down as set forth inthe description of the device as herein constructed.

On the other hand, if the diaphragm were loaded at the top by super-imposing a ring upon the diaphragm, and with a definite dimple in the diaphragm, and a denite pressure is applied to the ring, the range, that is, the dierencebetween the opening and the closing pressures, is

changed because the eii'ect of a ring about the dimple directly increases the depth of the dimple. This would make it necessary to re-set the bottom adjustment in order to get back to the original range.

Thus it is evi-dent that, by the use of the distributed pressure, top-loading means, the bottom adjustment, when once made to determine the range, need not be changed. Therefore, the device can be quickly and conveniently adjusted to obtain the desired range and the desired closing pressure. The simplicity of the adjusting operation is therefore apparent.

The described device may be used to advantage in a refrigerating system of Well known form, a part of which is shown in Fig. 1, the same including two or more cooling elements, such as the elements 51 and 58, operated at different temperatures, the element 51 being the low-temperature element, and the element 58 being the hightemperature element. The low-temperature element is used, for example, in an ice-cream cabinet which requires a relatively low temperature, and the high-temperature element in a Water cooler, which requires a relatively high temperature. Each of these cooling elements is partially lled with a liquid refrigerant, such as sul- 'ohur dioxide, or ammonia, supplied through a liquid pipe 59 from a condenser (not shown), in which the liquid refrigerant is stored under pressure. The admission of liquid refrigerant to nach cooling element is regulated by a suitable valve (not shown), as, for example, a float valve.

The vapor spa-ce above the liquid refrigerant in the low-temperature cooling element 51 is in direct communication, through a pipe 60, the passage 3I and a pipe 6I, with the suction side of the usual compressor (not shown). The vapor space above the liquid refrigerant in the hightemperature element 58 is in direct communication with the chamber II, through a pipe B2. It will be remembered that this communication between the chamber I I and the passage 3l is controlled by the valve 21, communication being opened when said valve is raised, and closed when said valve is lowered.

When the compressor is operated, it causes a reduction of pressure in the pipes 60 and 6I, and "n the cooling element 51, thereby causing the liquid refrigerant in the element 51 to boil, and `o absorb heat from the apparatus in which it is placed. The vapor is r-ecompressed and liquefied in the compressor and condenser, and is then ready to complete the cycle. The compressor may be controlled by any convenient means, to maintain a sufciently low pressure in the pipe 6I and in the cooling element 51 to produce whatever degree of refrigeration is desired in the cooling element 51.

At the beginning of the operation, the diaphragm I2 is held up by pressure in the chamber II, which is in lcommunication with the cooling element 58, and allows the spring 54 to hold up the valve 21, thereby establishing communication between the cooling element 58- and the pipe 6I, and causing a reduction of pressure in the cooling element 58. Therefore, the liquid refrigerant in the cooling element 58 boils, and absorbs heat from the apparatus in which it is placed. As this process continues, the temperature and pressure in the cooling element 58 are both gradually reduced, until. at a predetermined pressure, the diaphragm I2 snaps downwardly, and forces the valve 21 against its seat 28, thereby stopping the flow of gas from the cooling element 58.V However, the liquid in the cooling element 58, being colder than its surroundings, absorbs heat, and the temperature and pressure gradually rise, until at a predetermined pressure the diaphragm I2 snaps upwardly, allowing the valve 21 to rise. Gas then flows from the cooling element 58 to the suction side of the compressor.

Having thus described one embodiment of the invention, but without limiting myself thereto, what I claim and desire by Letters Patent to secure is:-

1. In a device of the character described, the combination of a uid enclosing chamber having one side formed by a resilient diaphragm, pressure-applying means, and a pressure distributing cushion interposed between said pressure-applying means and said diaphragm and contacting with said diaphragm, said cushion being the sole operative connection between said pressureapplying means and said diaphragm, and a member actuated by said diaphragm.

2. In a device of the character described, the combination of a fluid enclosing chamber having one side formed by a resilient diaphragm, pressure applying means, and a pressure distributing cushion composed of resilient compressible material interposed between said pressure-applying means and said diaphragm and contacting with said diaphragm, said cushion being the sole operative connection between said pressure-applying means and said diaphragm, and a member actuated by said diaphragm.

3. In a device of the character described, the combination of a fluid enclosing chamber having one side formed by a resilient diaphragm, a pressure distributing cushion contacting with said diaphragm, a pressure-applying spring, means for r causing said spring to exert a pressure through said cushion on said diaphragm, and a member actuated by said diaphragm.

4. In a device of the character described, the combination of a iiuid enclosing chamber having one side formed by a resilient diaphragm, a pressure distributing cushion contacting with said diaphragm, a plate resting against said cushion, a pressure-applying spring, and means for causing said spring to exert a pressure through said plate and through said cushion on said diaphragm, and a member actuated by said diaphragm.

5. In a device of the character described, the combination of a uid enclosing chamber having one side formed by a resilient diaphragm, a pressure distributing cushion contacting with said diaphragm, a plate resting against said cushion, a plunger resting against said plate, a pressure-applying spring resting against said plunger, meansl for varying the load which said spring exerts through said plunger, said plate and said cushion on said diaphragm, and a member actuated by said diaphragm,

6. In a device of the character described, the

combination of a iluid enclosing chamber having one side formed by a resilient diaphragm, a pressure distribut-ing cushion contacting with said diaphragm, said cushion increasing in thickness outwardly toward the margin of said diaphragm, means for causing said cushion to exert a pressure on said diaphragm, and a member actuated by said diaphragm.

'7. In a device of the character described, the combination of a uid enclosing chamber having one side formed by a resilient diaphragm, a pressure distributing cushion contacting with said diaphragm, said cushion having a central opening and increasing in thickness from said opening outwardly toward the margin of said diaphragm, means for causing said cushion to exert a pressure on said diaphragm, and a member actuated by said diaphragm.

8. In a device of the character described, the combination of a uid enclosing chamber having one side formed by a resilient diaphragm, a pressure distributing cushion contacting with said diaphragm, said cushion having a central opening, a member spanning said opening, means acting through said member to cause said cushion to exert a pressure on said diaphragm, and a member actuated by said diaphragm.

9. In a device of the character described, the combination of a uid enclosing chamber having one side formed by a resilient diaphragm, a pressure distributing cushion contacting with said diaphragm, said cushion having a central opening and increasing in thickness from said opening outwardly toward the margin of said diaphragm, a member spanning said opening, means acting through said member to cause said cushion to exert a pressure o-n said diaphragm, and a member actuated by said diaphragm.

l0. In a device of the character described, the combination of a. fluid-enclosing chamber having one side formed by a resilient buckling diaphragm adapted to buckle and to bow in opposite directions past a medial position but prevented by its own resiliency from remaining in such medial position, and means by which said diaphragm, when buckled toward the opposite side of said chamber is prevented from buckling to the full extent to which it would buckle were it not for said means.

l1. In a device of the character described, the combination of a huid-enclosing chamber having one side formed by a resilient buckling diaphragm adapted to buckle and to bow in opposite directions past a medial position but prevented by its own resiliency from remaining in such medial position, and means to cause said diaphragm, when buckled inwardly, to be stressed toward such medial position.

12. In a device of the character described, the combination of a fluid-enclosing chamber h-aving one side formed by a resilient buckling diaphragm adapted to buckle and to bow in opposite directions past a medial position but prevented by its own resiliency from remaining in such medial position, and an abutment which limits the inward travel of said diaphragm to less than the full extent of which it is capable under the influence of its resilience.

13. In a device oi the character described, the combination of a Fluid-enclosing chamber having one side formed by a resilient buckling diaphragm adapted to buckle in opposite directions but prevented by its own resiliency from remaining in a medial position, an abutment which limits the inward travel of said diaphragm, and adjusting means for Varying the position of said abutment.

14. In a device of the character described, the combination of a duid-enclosing chamber having one side formed by a resilient buckling diaphragm adapted to buckle in opposite directions but prevented by its own resiliency from remaining in a medial position, an abutment which limits the inward travel of said diaphragm, and adjusting means accessible from the outside of said chamber for varying the position of said abutment.

15. In a device of the character described, the combination of a fluid-enclosing chamber having one side formed by a resilient buckling diaphragm adapted to buckle in opposite directions but prevented by its own resiliency from remaining in a medial position, an abutment which rests against said diaphragm within said chamber and limits the inward travel of said diaphragm, a spring which tends to urge said abutment toward said diaphragm, and means for adjusting said abutment toward and from said position.

16. In a device of the character described, the combination of a fluid-enclosing chamber having one side formed by a resilient buckling diaphragm adapted to buckle in opposite directions but prevented by its own resiliency from remaining in a medial position, an abutment which rests against said diaphragm within said chamber and limits the inward travel of said diaphragm, pressure controlling means actuated by said abutment, and means for adjusting said abutment toward and from said position to predetermine the working range of said diaphragm.

17. In a device of the character described, the combination of a duid-enclosing chamber having one side formed by a resilient buckling diaphragm adapted to buckle in opposite directions but prevented by its own resiliency from remaining in a medial position, an abutment which rests against said diaphragm within said chamber and limits the inward travel of said diaphragm, a pressure controlling element actuated by said abutment, means to limit movement of said element under the influence of said abutment, and means adjustably connecting said abutment to said element to predetermine the working range of said diaphragm.

18. In a device of the character described, the combination of a duid-enclosing chamber having one side formed by a resilient buckling diaphragm adapted to buckle in opposite directions but prevented by its own resiliency from remaining in a medial position, an 4abutment which rests against said diaphragm, a member actuated by said abutment, means to limit movement of said member under the influence of said abutment, a screw and nut connection between said abutment and said member, and means connected to said member to operate said screw and nut connection to vary the position of said abutment.

19. In a device of the character described, the combination of a huid-enclosing chamber having one side formed by -a resilient buckling diaphragm adapted to buckle in opposite directions but prevented by its own resiliency from remaining in a medial position, an abutment which rests against said diaphragm, a member actuated by said abutment, means to limit movement of said member under the inuence of said abutment, a screw and nut connection between said abutment and said member, and means connected to said member and accessible from the exterior of said chamber to operate said screw and nut connection to vary the position of said abutment.

20. In a device of the character described, the combination of a huid-enclosing chamber having one side `formed by a resilient buckling diaphragm adapted to ybuckle in opposite directions but prevented by its own resiliency from remaining in a medial position, an abutment which rests against said diaphragm, a member actuated by said abutment, means to limit movement of said member under the influence of said abutment, 1a screw and nut connection between said abutment and said member, a rotatable shaft :having an axially -movable and non-rotatable connection with said member to operate said screw and nut connection to vary the position of said abutment, and means rto vhold said abutment against rotation while permitting it to move with said diaphragm.

21. In a device of the character described, the combination of a fluid-enclosing chamber having one side formed by aresilient buckling diaphragm adapted to buckle in opposite directions but prevented by its own resiliency from remaining in a medial position, an abutment which rests against said diaphragm, a member actuated by said abutment, means to limit movement of Vsaid member under the influence of said abutment, a screw and nut connection between said abutment and said member, a rotatable shaft having an axially movable and non-rotatable connection with said member to operate said screw and nut connection to vary the position of said abutment, means to hold said abutment against rotation while permitting it to move said diaphragm, and means enclosing said shaft and including a part which is removable to afford access tol said shaft.

22. In a device of the character described, the combination of a fluid-enclosing chamber having one side formed by a resilient buckling diaphragm adapted to buckle in opposite directions but prevented by its own resiliency from remaining in a medial position, a valve actuated by said diaphragm, and va valve seat against which said Valve is normally seated by the spring pressure of said diaphragm.

23. In a device of the character described, the

l combination of a fluid-enclosing chamber having one side formed by a resilient Vbuckling diaphragm adapted to buckle in opposite directions but prevented by its own resiliency from remaining in a medial position, a valve actuated by said diaphragm, a valve seat against which said valve is normally seated by the spring vpressure of said diaphragm, and adjusting means for causing variation of said pressure.

24. In a device of the character described, the combination of a duid-enclosing chamber having one side formed by a resilient buckling diaphragm adapted to buckle in `opposite directions .past a medial position but .prevented by its own resiliency from lremaining in such medial position, a valve actuated by said diaphragm, and a valve seat toward which said diaphragm is normally buckled and against which seat said valve is normally seated by the resiliency of said diaphragm, said valve and said seat cooperating to prevent said diaphragm from buckling ltoward said seat to the fullest extent under the influence of the resilient action of said diaphragm.

25. In a device of the character described, the

combination of a fluid-enclosing chamber having v medial position, a'valve actuated'by said diaphragm, a valve seat against which said valve is normally `seated -by the spring pressure of said diaphragm, and means interposed between said diaphragm and said valve for adjusting the range oi movement of said diaphragm toward said seat.

26. In a device of the character described, the combination of a duid-enclosing chamber having one side formed by a resilient buckling diaphragm adapted to buckle -in opposite directions but prevented by its ownr-esiliency from remaining in a medial position, a valve actuated by said diaphragm, a valve seat against which said valve is normally -seated by the lspring pressure of said diaphragm, and means including a screw and nut interposed between said diaphragm and said valve for adjusting the range oi .movement of said diaphragm toward said seat.

27. In a device of the character described, the combination of afluid-enclosing chamber having one side formed-by a resilient buckling diaphragm adapted to buckle in opposite directions but `prevented by its own resiliency from remaining in a medial position, a valve actuated by said diaphragm, a valve seat against which said valve is normally seated by the spring pressure of said diaphragm, means including a screw and nut interposed between said diaphragm and said valve, means to prevent rotation oi said nut, and means for rotating said screw relatively to said nut.

28. In a device of the character described, the combination of a fluid-enclosing chamber having one side formed by a resilient buckling diaphragm adapted to buckle in opposite directions but prevented by 'its own resiliency from remaining in a medial position, a valve actuated by lsaid diaphragm, a valve seat against which said valve is normally seated by the spring pressure of said diaphragm, means including a screw and. nut interposed between said diaphragm and said valve, means to prevent rotation of said nut, and means accessible externally of said 'chamber' for rotating said screw relatively to said nut.

A29. In a device Vof the character described, the combination of a huid-enclosing chamber hav-- ing one side formed by va resilient buckling diaphragmadapted to buckle in opposite directions but prevented by its own resiliency from remaining Ain a medial position, a valve actuated by said diaphragm, a valve seat against which said valve is normally seated by the spring pressure of said diaphragm, a screw carried by said valve, a nut threaded onto said screw and interposed between the latter and saiddiaphragm, means to prevent rotation of said nut, and lmeans for rotating said valve to turn said screw in said nut.

30. In a device oi the character described, the combination of a fluid-enclosing chamber having one side formed by a resilient buckling diaphragm adapted to buckle in opposite directions but prevented lby its own resiliency rom'rernaining in a medial position, a valve actuated by said diaphragm, Aa valve seat against which said valve is normally seated by the spring pressure .offsaid diaphragm, a guide for said valve, an abutment resting against said diaphragm and presenting a nut having non-rotatable connection with said guide, a screw carried by said valve and threaded into said nut, and a valve-rotating shaft having sliding connection with said valve.

3l. In a device of the character described, the combination of a fluid-enclosing chamber having one side formed by a resilient buckling diaphragm adapted to buckle in opposite directions but prevented by its own resiliency from remaining in a medial position, a valve unconnected to but moved by said diaphragm in one direction, a valve seat against which said valve -is urged by the spring pressure of said diaphragm in such direction, and a spring which causes said valve to follow said diaphragm in the opposite direction but has insufl'icient strength to move said diaphragm past said medial position.

32. In a device of the character described, the combination of a fluid enclosing chamber having one side formed by a resilient diaphragm, a fluent body contacting with the opposite side of said diaphragm, and means for urging said body against said diaphragm, said iluent body being the sole operative connection between said means and said diaphragm.

33. In a device of the character described, the combination of a iiuid enclosing chamber having one side formed by a resilient diaphragm, a diaphragm loading spring, and flexible means interposed between said spring and said diaphragm to distribute the load of said spring with substantially equal pressures per unit of area over a predetermined area of said diaphragm.

34. In a device of the character described, the combination of a fluid enclosing chamber having one side formed by a resilient, buckling diaphragm adapted to buckle and to bow in opposite directions past a medial position but prevented by its own resiliency from remaining in such medial position, a fluent body contacting with the opposite side of said diaphragm, and means for maintaining said body under pressure to cause the same to exert a pressure against said diaphragm, said fluent body being the sole operative connection between said means and said diaphragm.

35. In a device of the character described, the combination of a huid-enclosing chamber having one side formed by a resilient snapping diaphragm adapted to snap in opposite directions past a medial position but prevented by its own resiliency from remaining in such position, and means by which said diaphragm, when buckled inwardly, is stressed toward such medial position, said means having provision to vary the amount by which said diaphragm is so stressed.

36. In a device of the character described, the combination of a fluid-enclosing chamber having one side formed by a resilient snapping diaphragm adapted to snap in opposite directions past a medial position but prevented by its own resiliency from remaining in such position, and means by which said diaphragm when buckled inwardly is stressed toward said opposite side, said means comprising an abutment, and means for Varying the relationship between said diaphragm and said abutment.

37. In a device of the character described, the combination of a huid-enclosing chamber having one side formed by a resilient snapping diaphragm adapted to snap in opposite directions past a medial position but prevented by its own resiliency from remaining in such position, and means by which said diaphragm is held normally under a stress toward such position, said means comprising two members, one normally seated upon the other, the seating and unseating being controlled by said diaphragm, the pressure which moves said diaphragm from its normal position acting upon such member solely through said diaphragm.

38. In a device of the character described, the combination of a fluid-enclosing chamber having one side formed by a resilient snapping diaphragm adapted to snap in opposite directions past a medial position but prevented by its own resiliency from remaining in such position, and means by which said diaphragm is held normally under a stress toward such position, said means comprising a valve and a valve-seat, the pressure which moves said valve from said valve-seat acting upon said valve solely through said diaphragm.

39. In a device of the character described, the combination of a huid-enclosing chamber having one side formed by a resilient snapping diaphragm adapted to snap in opposite directions past a medial position but prevented by its own resiliency from remaining in such position, and means by which said diaphragm is held normally under a stress toward such position, said means comprising a valve and a valve-seat, said normal stress alone being relied upon normally to maintain said valve upon said valve seat.

40. In a device of the character described, the combination of a Huid-enclosing chamber having one side formed by a resilient snapping diaphragm adapted to snap in opposite directions past a medial position but prevented by its own resiliency from remaining in such position, and means by which said diaphragm is held normally under stress toward such position, said diaphragm being normally bowed in the direction of said chamber, and said stress being in the opposite direction.

41. In a device of the character described, the combination of a huid-enclosing chamber having one side formed by a resilient snapping diaphragm adapted to snap in opposite directions past a medial position but prevented by its own resiliency from remaining in such position, and means by which said diaphragm is held normally under stress toward such position, said normal stress producing in said diaphragm a dimple toward said medial position.

42. In an apparatus of the class described, the combination of a fluid-enclosing chamber having one side formed by a resilient, snapping diaphragm adapted to snap in opposite directions but prevented by its own resiliency from remaining in a medial position, a valve actuated by said diaphragm to release pressure uid from said chamber, a valve seat against which said valve is normally seated by the spring pressure of said diaphragm, and through which seat the pressure iiuid is released from said chamber, the pressure fluid within said chamber being at a higher pressure than that on the other side of said valve.

ALEXANDER J. TIGGES.

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