US3080890A - Pressure responsive operator - Google Patents

Description

March 12, 1963 D. M. PAPA PRESSURE RESPONSIVE OPERATOR Filed April 2, 1959 PRESiURE RESlONSlVE OFERATGR Donald M. Papa, Milwaukee, Wis, assignor to Cutler- Hammer, Inc, Milwaukee, Wis, a corporation of Delaware Filed Apr. 2, 1959, Ser. No. $03,763 1 Ciairn. ill. 137-484) This invention relates to pressure responsive operators and more particularly to those for use in the vacuum range.

Pressure responsive operators designed foruse in the vacuum range of pressure commonly employ two diaphragms, a main diaphragm for transmitting movement to an operating rod and a second diaphragm to afford a flexible seal about an opening in the vacuum chamber as the operating rod moves inwardly and outwardly thereof.

Therefore, a principal object, of this invention is to provide an improved pressure responsive controller wherein the necessity of providing a second diaphragm to seal the vacuum chamber is eliminated.

\ A further object is to provide a controller of the aforesaid character in which the vacuum chamber may be evacuated through a pushrod element penetrating said vacuum chamber.

Another object is to provide a pressure responsive control device which is characterized by simplicity of design, low cost of manufacture, and extended operational life.

Other objects and advantages of the invention will hereinafter appear.

In the drawings:

FIGURE 1 is a top plan view of an electric switch controller constructed in accordance with, my invention;

FIG. 2 is an elevational view partly in section taken along lines 2-2 of FIG. 1 and further schematically illustratingan attached switch mechanism; and

FIG. 3 is an enlarged sectional view of a subassembly shown in FIG. 2.

As best illustrated in PEG. 2, the operator device comprises a diaphragm housing 19, a pushrod 12, a flexible diaphragm 14, a diaphragm follower 16, an annular bearing bushing 18 and a fitting 20. Also shown in FIG. 2 are portions of one form of switch mechanism 30 suitably constructed'for operation by my pressure responsive operator. The cooperation of certain parts of the switch mechanism 30 and the operator will be hereinafter described in detail.

The housing 10 comprises two symmetrically formed, shallow, bell-shaped members Ida and itlb. The latter are preferably formed of a metal such as steel or aluminum. The flanged peripheral portions 10c of members 10a and 1011 are provided with radially spaced apertures 10d, best shown in FIG. 1, which are alined to receive threaded screws 22. Additional apertures lite and 10 are provided in housing members 18a and 10b, respectively. Apertures ltle are open to the atmosphere, while apertures 10 are alined with like dimensioned apertures 32a in switch frame 32 to accommodate threaded fasteners 24 which secure the housing 10 to the switch frame 32. Housing member 10a is provided with a central circular opening 10 for receiving a reduced portion Zita of fitting 20. The bushing 18 has a reduced portion 18a which projects outwardly of housing 10 through a central opening 10k in member liib. Fitting 2t) and bushing 18 are preferably brazed to their respective housing members 10a and 10b to provide an airtight seal therebetween.

As shown in FIG. 2, diaphragm 14, which is circular and formed of a suitable resilient material, extends transversely of the assembled housing 10 bisecting the same into an upper chamber 10h and a lower chamber 103..

The outer periphery of diaphragm 14 is compressively 3,080,8% Patented Mar. 12, 1963 ice sealed between the opposing flanged portions 10c of housing members 10a and 10b while the periphery of a central opening 14a therethrough is, as best shown in FIG. 3,

, compressively sealed between an annular flange 12a on pushrod 12 and the diaphragm follower 16.

As best illustrated in FIG. 3, the pushrod 12 is substantially cylindrical in shape and may be machined from a single piece of stock. A stepped body portion 12a comprising a portion 12b and an annular flange 12c is integrally formed intermediate the ends of the pushrod 12. The diaphragm follower 16 which comprises a flat, rigid disk overlying a greater portion of diaphragm 14 is permanently secured at its center to pushrod 12. As shown in FIG. 3, the inner peripheral wall of the centrally located opening 164: in the diaphragm follower 16 surrounds the portion 1212 on the pushrod 12. The diaphragm 14 and diaphragm follower 16 are compressively held between the annular flange 12c and the outwardly flared portion 1211 of the portion 12b. The flaring operation is completed subsequent to assembly of the diaphragm 14 and diaphragm follower 16 on the pushrod 12 and may be accomplished by ring staking or peening over the upper surface of the portion 12b.

Toroids or O- rings 26 and 28 are preferably formed of a resilient material, such as neoprene or Buna N synthetic rubber, and may be lubricated with pneumatic grease. The annular grooves 12d and 12:: which are oppositely located outwardly of the midpoint of the pushrod along its longitudinal axis accommodate the toroids 26 and 28 and prevent their displacement upon longitudinal movement of the pushrod 12 within fitting 20 and bearing 18, When the above described parts are properly assembled as shown in FIG. 2, the grooved portions and 12a of pushrod 12 which carry the toroids 26 and 28 are disposed within the aligned openings 18b and Ztlb of the bearing 18 and the fitting 20, respectively. The toroids are of such dimension to provide a sliding seal between the pushrod and the walls of openings 13b and 2% as the pushrod 12 reciprocates within said openings.

As shown in FIG. 2, a reduced end portion 12 of pushrod 12 extends upwardly into interfitting engagement with a central opening 34a in the spring gland 34 of the switch mechanism 30.

As best illustrated in FIG. 3, cylindrical bore 12g extends coaxially through the pushrod 12 from the lower end wall 12m thereof to a point intermediate the annular recess 12d and the annular shoulder 12b. Intersecting the innermost extreme of bore 12 is an aperture 12k which extends transversely through pushrod 12 and opens into chamber lilh. It will be understood that the longitudinal bore 12g and the transverse aperture 12k provide an airtight connection between the interior bore Ztic of fitting 2t) and the sealed chamber 10h.

An essential feature of this invention is the elimination of all exterior connections to the vacuum chamber 14th. As shown this result is achieved by providing a passageway through the pushrod 12 itself which functions as a vacuum connectionto the vacuum chamber 10h.

In operation the interior bore Ztic of fitting 20 is connectcd to a vessel, pipeline or other enclosure in which a pressure less than atmospheric is to be created and maintained by a vacuum producing device. As a vacuum is created in the interior bore 200 of fitting 29, the pressure in chamber 16h acting upon diaphragm 14 is reduced to less than atmospheric. As shown previously, the chamber ltlg opens to atmosphere through the apertures 10a in housing member 10a; therefore, the underside of the flexible diaphragm 14 is continuously subjected to atmospheric pressure. The resulting pressure differential on opposite sides of the-diaphragm 14 tends to flex the latter I V j upwardiy. The diaphragm iollowerle'is urged upwardly by the underlying diaphrgam 14 thereby transmitting a 'force upwardly throughpushrod 12 and spring gland 34 against the downward bias of compression spring 36 of the switch mechanism 3%. As the pressure differential acting upon diaphragm i i-overcomes this downwardbias of spring lid, the pushrod -12. carries the spring gland 34 out of engagement with an underlying portion 33a of the lever 25% which extends transversely of the switch housing 32, thereby permitting lever 38 to pivot in a counterclockwise direction about a pivot member 40' in response to the biasing action of spring 42. As lever fis'pivots in'the manner just described, an insulating contact actuator bar 44 attached to the lever 38 moves its associated contractor as intoycir-cuit completing engagement with stationary.

. contacts 48. V, r

As the pressure differential actingupon diaphragm 14 guesses Although my invention is particularly suitedfor operatron as a vacuum sensing control device,.from the. foregoing description it will be apparent to one skilled in the 7 art that this device is likewise adapted for'operation as a positive pressure actuated controller. Furthermore, while the embodiment hereinde-scribed in detail suggests that the controller is particularlywell suitedto actuate an electric switching mechanism, it is' apparent that my invention will perform various mechanical as well as electrical con-' decreases to a predetermined value, the biasing action of tional diaphragm as a seal between the driving element of the controller and the switchmechanism housing 32.

' Therefore, the vertical displacement of the pushrod 12 is limited to the normal distance shownin FIG. 2 between the upper surface ofthe flared portion 12a of the pushrod 12 and the lower surface 18c of the bearing 18. This distance is ,such'that the aforedescribed sliding seal between the pushrod l2 and thebearing 1'3 and fitting 20 is maintained when the pushrod is moved to its upper limit.

The "afored'escribed embodiment of my invention may be used with many known forms of switching mechanisms to translate the vertical displacement of the pushrod intoi a switching function. "While one form of such a switch mechanism-has been shown partially in diagrammatic form in FIG. '2, the structural details of an electric switch rnechanisrnwell suited for operation in response tomy controlling device is disclosed in U.S. Patent No.

trol functions in response to a predetermined pressure differential.

Iclaim: I

In a pressure-responsive operator,- in combination, a diaphragm housing comprising mating, bell-shaped members, a flexibie diaphragm having its outer periphery secured between the matingsuriaces of saidbell-shaped membersto'divide said housing into a first chamber sealed to t e atmosphere and a second chamber open to the at f mosphere, apushrod axially penetrating the end walls of said housing and said diaphragmsealing means between said pushrod and said end walls comprising resilient toroidal gaskets seatedin annular recesses in said pushrod, a diaphrag. i follower disk substantially overlying said diaphragm in said first chamber and movable therewith, said dish being rigidly attached at its center point to saidfp'ushrod, a fitting attached jexteriorly of. said second chamber, a vacuum connection between said fitting and said first chamber provided by a longitudinal bore intersected by a transverse aperture in said pushrod, said bore communieating with said fitting and said aperture communicating with said first chamber.

'Refcrencesflited in the file of this patent UNITED STATES PATENTS 1,994,835 Sanford et al. Q Mar. 19, 1935' r 2,069,016. Newton ..-Jan. 26, 196-7 2,438,723. 7 setter -Mar. 30, 194 8 2,554,266 7 Pauly May 22, :1951 2,655,573. 1 Szwargulskitet al. Oct. 1-3, 1953 2,664,108 VonWeise Dec. 29, 1 953 2,767,277 Wirth Oct.'l6, 1956 2,825,361 Seljos ..'-Mar. 4, 1958

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