US2729243A - Catenated multiple aneroid capsule - Google Patents

Description

Jan. 3, 1956 i J. A. sENN 2,729,243

CATENATED MULTIPLE ANEROID CAPSULE Filed June 16, 1952 2 Sheets-Sheet l NVENToR. m' d. JLM@ E; 7

- l* MM d $5! Jan. 3, 1956 J. A. sENN 2,729,243

CATENATED MULTIPLE ANEROID CAPSULE Filed June 16, 1952 2 Sheets-Sheet 2 Fys INVENTOR.

United Sat-@S Par-fit 25,729,243Y ,j t,

l cATENArED MULTIPLE ANE-nom CAPSULE l Jurg A. Senn, Shorewood, wis. Application June 16, 1952, Serial No. 293,867 `4 crains. (C1. rs1-.i875 A This invention relates to so calledV capsule pressure motors for use in aneroid altimeters and barometer-s or other pressure responsive devices and it resides more particularly in improvements in such capsules, wherein the effective area and scop'eof displacement are large relative to the overall externalldimension'sof `the capsuleA and in which an external inwardlyv collapsible member` houses and is joined to one or Vmore internal outwardly expandable members to form a multiplecapsule with a single void in which-the displacements of the several members are additive. The invention at times includes the use of4 idle reenforciug diaphragrns lto assure precise positioning and travel of the internal capsules Within the limited space availablethereforand at times includes abutments positioned to interfere with dis-V placements of the idle diaphragrns and the external capsule to cause displacements to approximatelogar'ithmic or other functions of the pressure differentials applied.

`Heretofore, pressure responsive motors employed for` sensitive altimeters, including those employed. in radio sonde instruments and the like, haveconsisted of a plurality of diaphragm' capsules housing 'separate' voids which capsules are joined to one another in multiple to provide the necessary large effective area and the sub1 stantial displacement which thefsensitive forms of such` instruments require. A vbank-of such diaphragms` inl multiple, has an overall longitudinal dimension yseveral times the scope of the displacement` range. Multiple capsules of this type furthermore are often lacltin'gV in radial stability and have aresponse such that complex' linkages and adjusting systems are required if 'an even scale instrument is to be provided. l

" It is an objectof this invention to provide 'an aneroid pressure motor of greater compactness.` l Y Itis another object'of this invention to provide -ari aneroid pressure motor inV which the thickness of material employed may be chosen to limit'maxir'num h're`- stress without loss of radial stability.`l

It is another object of this invention to providean aneroid pressure motor having a response sueh that adjustment is simplified and such thatan altimeter iiistruf ment with even scale deflection maybemore easily constructed therefrom. f i i' .The foregoing and other objects and advantagelsof` this invention will appearfrom the description following which is `set forth byreference to the-accompanying drawings forming a part hereof, in which thereis set forth, by Way of illustration andnotlof limitation, specificforms in which the apparatus ofhthisinvention may be embodied. i t 1 Fig. l is a side view inY elevation and inisectionv of one form of altimeter capsule of this invention including motion hindering means, thecapsule beingshown in a.; condition of minimum stress corresponding tomexposure to maximum altitude,` o

Fig. 2 lis a side view inr elevation and partly in section of the capsule shown in Fig. l'the parts being shown in a conditionof maximum stress corresponding to exposure to minimum altitude,

Fig. 3 is a side View in elevation and partly in section of another formof capsule constructed in accordance with this invention in which two internal outwardly eX- pandable members are housed within and contribute their displacements to an external inwardly collapsible member, 'f

Fig.- 4 is a top plan view of the capsule shown in Figs. l and 2, parts beingshown brokenaway, and f Fig. 5 is a side view in elevation and in section of a capsule entirely inwardly collapsible in which the motion hindering apparatus of this invention is embodied.

Referring now to the drawings, the capsule of this invention, in the form appearingj in Figs. 1v, 2 and 4, is housed within an inwardly collapsible external housing made up of a lower corrugated cup diaphragm 2. VThe diaphragms v1 and 2, for convenience, are referred to herein as a free diaphragm and a reference diaphragm respectively. The referencediaphragrn 2 is soldered at 4 to a sealing; boss 5 having an access channel 6 which is'closed by low melting solder 7 'after the gas contained has been reduced tothe quantitydesir'ed. The boss 5 also constitutes oneof two relatively movable attachment members through which displacement of the motor may be communicated to parts intended to be moved thereby'.4 L f The center of free `diaphragm 1 is open as indicated at 8, where itmeets and is joined by solder 9, withthe open center of an internal'corrugated cup diaphragm 10. Cup diaphragm 10 is of reduced diameter small enough to b'e'en'tirely housed within the cup diaphragm 2. The outer upturned rim of diaphragm 10 receives in nested relation and yis welded to the rim` of an idle stilening member 1K1, the rim of which receives in turn and is welded to the nested rim of internal corrugated cup diaphragm 12.

i The center of diaphragm 12 is soldered to and closed by the head 13 of a threaded stem 14 which threadingly engages the internally threaded bore of an adjustable sleeve 15 having a collar bearing stepV flanges 16 and 17. `Flange ,16 is indented with a vent groove 18 and ilange 17 by a vent groove 19'to ensure free access ofV the atmosphere at all times to the space above and below the idle member 11. Stern 14 and sleeve 15' constitute the second attachment member which is relatively movable with respect to the attachment member provided by boss 5.

l-'Th'e assembly of diaphragms 1, 2, 10 and '12 is such as to provide an enclosure for a single connected void which is evacuated to anrappropriate degree through the channel 'and sealed by solder 7 as previously indicated. When so evacuated and when subjected to a pressure corresponding v'vith a low altitude, environmental pressure, acting on' the diaphragms l'and 2 deects'the same inwardly as indicated inV Fig. 2. At the same time, the environmental pressure acting on the diaphragms ltland 12 causes rthem to separate from the idle member 11jas shown in the same gure. The displacements of all four ofthe diaphragms mentioned thus act additively to produce a combined relative displacement of the lmembers 5 and'lS,"

Diaphragms ,1 and 2 are'lpre'fe'rably made o'f a .di-I ameter largeenough so that metalof sutlicient thickness 12, being smaller in diameter'than-the diaphragms 1 and 2 are preferably made of thinnermetal in order'that theymay-be capable ofthe substantial displacement'rej quired without harmful maximum fibre stress occurring.'V

The diaphragms 10 and 12, being made thin enough to comply with the above requirements, are weakened radially, but the reenforcing effect of the thicker idle member 11 lends adequate radial strength to the assembly; Y

As the capsule is carried to higher altitudes the members relax resiliently toward a conguration such as is illustrated in Fig. l. In traveling to and from extreme operating positions the step flanges 16 and 17 engage with and separate from elements disposed in the path of their movement. As indicated in Fig. 2, in going from an environment of lower pressure to higher pressure the flange 16 comes into engagement with the stiffening member 11. As pressure is further increased deflection of diaphragm 12 ceases to occur since the spacing between it and the stiffening member 11 is thereafter held constant. Resistance to deformation of the assembly as a whole is therefore increased.

As environmental pressure continues to rise the flange 17 eventually comes into contact with diaphragm 1. Further pressure rise then occurs without alteration of the spacing between diaphragm 10 and the stiffening member 11 and the resilient properties of the assembly as a whole are characterized by the stiffer action of diaphragms 1 and 2 which are the only members functioning as free members under such conditions. Resistance to displacement is thus further increased.

As a result of the action above, a plurality of pressure displacement functions are brought successively into play. These successive functions may be chosen to closely approximate any desired pressure displacement relationship such as a logarithmic function or otherwise.

The pressure displacement relationship of a corrugated disc diaphragm is nearly linear when the diaphragm is in a relatively unstressed condition. As stress increases displacement for a given increment of pressure becomes smaller as an inherent property of such a diaphragm, but not to an extent sufficient to approximate a logarithmic relationship. A nearly logarithmic relationship, however, can be closely approached as noted by correlating the state of stress of the diaphragms with the engagement and disengagement of the interfering members referred to, taking advantage of the inherent departure from a linear relationship to ease the transition between successive integral members of free diaphragms.

In the apparatus shown in Figs. l, 2 and 4, a nearly smooth transition occurs from a capsule having the characteristics of four free members to one having the characteristics of three free members and finally to one having the characteristics of two free members, By the use of a larger number of diaphragm members and a larger number of transitions even closer approximation t any desired pressure displacement relationship may be achieved.

In the case of an altimeter it is desirable that the dial or scale of successive elevations be evenly divided or nearly so, such being called an even scale instrument. The pressure altitude relationship, however, roughly approximates a logarithmic function. In accordance with this invention a capsule may be provided in which increments of displacements are linearly related to altitude rather than pressure. This being the case, multiplying linkage in the instrument may be greatly simplified and initial adjustment and calibration of the instrument can be reduced to a single simple adjustment. For example, the adjustable actuating sleeve 15 may be turned on the threaded stem 14 to bring about a very close approximation of the pressure displacement relationship which the capsule unit is intended to exhibit in spite of inevitable variations in manufacture. Diaphragm assemblies as heretofore constructed have not been adjustable in this sense, a factor which has caused thel rejecting or discarding of a very high proportion of diaphragm capsules manufactured for use 'in altimeters.

In the apparatus shown in Figs. l and 2, it may be desirable to close the juncture, held and sealed by solder 9, by means of a weld, in which event the only soldered junctions remaining are those formed by solder 4 and the solder joining the member 13 to the diaphragm 12. These two junctures are so related that thermostatic effects, unavoidable where solder is employed, are opposed and substantially equal, thus rendering the capsule selfcompensating in this regard. If proper known alloys having exceptionally low temperature coefficients of change of physical properties are employed, a capsule having overall properties of exceptional thermal stability may thus be constructed in accordance with this invention. This is true to a surprising degree even when solder 9 is employed since such introduces but a single uncompensated juncture.

In the event that compactness is sought but the features of adjustability and modification of pressure displacement ratios, above described, are not desired, the apparatus of this invention can be constructed as appears in Fig. 3. In the apparatus here shown a pair of inwardly collapsible diaphragm.members 20 and 21 are joined at their outer rims by solder as shown. The free diaphragm 21 is open at the center and is joined by solder with a set of internal outwardly expandable diaphragms 22 and 23 which meet at their outer rims and are welded to a radial stiffening member 24.

The members 22, 23 and 24 are open at their centers and diaphragm 22 is joined at its center with a second set of internal outwardly expandable diaphragm members 25 and 26. The diaphragms 25 and 26 meet at their outer rims and are welded to a radial stiffening member 27. The members 25, 26 and 27 are likewise open at their centers and the center of diaphragm 25 is joined with and closed by the head of an actuating stem 28.

The center of external reference diaphragm 20 is closed by a mounting sleeve 29 having a channel 30 which is closed by solder 31 after evacuation. The capsule assembly shown in Fig. 3 thus is possessed of six members, the deflections of which are additive, although they house but a single void. The several diaphragm elements furthermore are closely nested and occupy a total space not greatly in excess of that of the well known two element diaphragm. The total displacement available, without subjecting the metal to harmful maximum stresses, is approximately three times that available with the well known two element diaphragm. These results are achieved, moreover, without sacrifice of radial stiffness since the stifening members 24 and 27 adequately supplement any deficiency in this regard which would otherwise arise from the use of adequately yieldable diaphragms 22, 23, 25 and 26.

The displacements of the external collapsible housing and the internal expandable assembly are rendered additive in the forms of this invention above described by means of a junction between the internal and external parts which junction surrounds a central opening and by means of an actuating member movable through the cen- Vtral opening, the actuating member engaging a remote part of the internal expandable assembly.

If desired, the advantages of the successive hindering of multiple diaphragms, in accordance with this invention, may be obtained in apparatus which consists of externally collapsible members, as shown in Fig. 5. In this form of apparatus a pair of inwardly collapsible diaphragms 32 and 33 are joined and sealed at their rims to an intermediate idle member 34. A similar pair of . diaphragms 35 and 36 are assembled in like fashion against the opposite faces of an idle member 37 and this assembly is joined with diaphragm 33 by a sleeve 38 and solder as shown. Diaphragm 32 has a central opening closed by a sealing and attachment fitting 39 and by solder as shown. Diaphragm 36 is similarly closed by an actuating member 40. Vents 41 and 42 in idle members 34 and 37 respectively join the several enclosures into a single connected void.

The apparatus as shown in Fig. 5 is in the configuration assumed when exposed to pressure corresponding with maximum altitude. As pressure increases and the several diaphragms collapse, shoulder 43 of actuator 40 cornes into contact with idle member 37 increasing the overall stiffness of the assembly. Further increase in pressure brings shoulder 44 of actuator 40 into contact with the central part of diaphragm 33 causing a further increase in stiffness of the assembly. A further rise in pressure then brings abutment 45 of actuator 40 into contact with idle member 34 with additional stillness thereafter being exhibited by the assembly. Notches 46 and 47 in the shoulders 43 and 44, ensure a connected void in cases where the capsule is not fully evacuated.

The diaphragms employed in the apparatus of this invention are preferably formed of a metal having a low temperature coeflicient of change of elastic modulus. If not, temperature compensation may be obtained in the usual fashion by adjusting the gas content of the capsule or by the imposition of thermostatically controlled external loads or both.

The diaphragms themselves and particularly the assemblies making up the internal outwardly expandable portions of the apparatus may be formed in multiple layers in a die to produce a precisely interlitting relationship between the diaphragms themselves as well as with the idle stiffening members. For this purpose, it is desirable that a precipitation hardenable alloy be employed such as beryllium copper, Z-nickel and the like. These alloys can be readily formed in their soft state and may be subsequently hardened through moderate heat treatment without substantial distortion.

I claim:

1. In a resilient capsule pressure motor the combination comprising spaced external free and reference diaphragrns joined and sealed to one another at their outer rims to surround an internal void, an attachment member engaging said external reference diaphragm, a central opening in said external free diaphragm, rst and second closely adjacent internal outwardly expandable diaphragms disposed within the space surrounded by said external diaphragms joined and sealed to one another at their outer rims, said rst internal diaphragm having a central opening adjacent the central opening in said external free diaphragm, means forming a sealed connection between said first internal diaphragm and said external free diaphragm adjacent the central openings thereof, and a second attachment member responsively connected with the second internal diaphragm extending outwardly therefrom through the openings in said internal and external diaphragms.

2. A resilient capsule pressure motor in accordance with claim l wherein an idle radial stiiening member is superimposed between and joined to the meeting rims oi said rst and second internal diaphragms.

3. In a resilient capsule pressure motor the combination comprising spaced external free and reference diaphragms joined and sealed to one another at their outer rims to surround an internal void, an attachment mem ber engaging said external reference diaphragm, a central opening o1' said external free diaphragm, rst and second closely spaced internal outwardly expandable diaphragms disposed within the space surrounded by said external diaphragms, an idle radial stiening member having a central opening interposed between said internal diaphragms, ysaid internal diaphragms being joined and sealed to one another and to said idle member at their outer rims, said first internal diaphragm having a central opening adjacent the central opening in said external free diaphragm, means forming a sealed connection between said lrst internal diaphragm and said external free diaphragm adjacent the central openings thereof, second at tachment member responsively connected with the second internal diaphragm extending outwardly therefrom through the openings in said internal and external diaphragms, and motion hindering means connected to said second attachment member positioned to engage and hinder the motion of said free external diaphragm and said idle member successively at predetermined positions of movement of said second attachment member.

4. A capsule in accordance with claim 3 wherein the motion hindering means are adjustably connected to the second attachment means to adjustably alter the positions of engagement with the external free diaphragm and the idle member.

References Cited in the le of this patent UNITED STATES PATENTS 1,109,499 Zierden Sept. 1, 1914 1,572,970 Stalker Feb. 16, 1926 1,830,780 Brennan et al. Nov. 10, 1931 2,255,005 Rodanet Sept. 2, 1941 2,435,716 Kearney Feb. 10, 1948 2,487,288 Williams Nov. 8, 1949 2,554,659 Branson May 29, 1951 2,565,472 Castel et al Aug. 28, 1951 2,593,129 Fisher Apr. 15, 1952

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