US3335242A

US3335242A - Condition responsive devices

Info

Publication number: US3335242A
Application number: US575194A
Authority: US
Inventors: Carl N Johnson
Original assignee: Texas Instruments Inc
Current assignee: Texas Instruments Inc
Priority date: 1963-10-18
Filing date: 1966-08-25
Publication date: 1967-08-08
Anticipated expiration: 1984-08-08
Also published as: DE1490817B1; GB1077825A

Description

Aug. 8, 1967 C. N. JOHNSON 3,335,242

A CONDITION RESPONSIVE DEVICES Original Filed Oct. 18, 1965 l. v2 W /40 l, 3

INVENTOR. cmu M ./omvso/v,

W/r/vess: A777.

United States Patent of Delaware Continuation of application Ser. No. 317,338, Oct. 18,

Ser. No. 575,194

1963. This application Aug. 25, 1966,

Claims. (Cl. 200-83) This application is a continuation of application Ser. No. 317,338 led Oct. 18, 1963, and now abandoned.

This invention relates generally to condition-responsive devices and more particularly to pressure-responsive de- /ikces adapted for actuating electrical switches and the Among the several objects of the invention is ythe provision of a pressure responsive device particularly adapted for miniaturization and for lightweight, hermetically sealed construction.

Another object of the invention is the provision of a pressure responsive device capable of sensing relatively small values of pressure.

It is a further object of the invention to provide a pressure-responsive device having a high degree of sensitivity and being capable of operating within a relatively narrow range of pressure values.

Other objects will be in part apparent and in part pointed out hereinafter. The invention accordingly comprises the elements and combinations of elements, fea` tures of construction and arrangements of parts which will be exemplified in the structures hereinafter described and the scope of the application of which will be indicated in the appended claims.

In the accompanying drawings in which several of the vvarious possible embodiments of the invention are illus- 'tratedz FIG. 1 is an elevational view, partly in section, of a device according to the instant invention;

FIG. 2 is an enlarged perspective view of a portion of the device shown in FIG. l; and

FIG. 3 is a sectional view taken along line 3 3 of FIG. 1.

Similar reference characters indicate corresponding parts throughout the several views of the drawings. Dimensions of certain of the parts as shown in the drawings may have been modied or exaggerated for the purposes of clarity of illustration.

Referring now to the drawings, particularly FIG. 1, a pressure-responsive device according to the instant invention is generally designated by reference numeral 10. Pressure-responsive device includes upper and

lower casing members

12 and 14, respectively, which are formed of a material having suitable strength and corrosion resistance such as, for example, stainless steel.

Casing members

12 and 14 are provided with peripherally extending, opposed and aligned

flanges

22, 24, respectively. Interposed between

flanges

22 and 24 is an imperforate diaphragm member 20, preferably formed of a relatively thin corrosion-resistant and strong material such as, for example, stainless steel in the form of a disc of substantially uniform thickness.

Casing members

12 and 14 in the assembled form shown in FIG. l provides cavities or

compartments

16 and 18, respectively separated by diaphragm member 20.

Flanges

22 and 24 are each xedly and rigidly secured to the marginal periphery 26 of diaphragm member 20 as, for example, by herliarc Welding as at 28 to thereby separate and seal compartment 16 from compartment 18. Although it is preferred that housing or

casing members

12 and 14 be Welded to the marginal periphery of diaphragm member 20, it will be understood that other means may be employed to clamp and seal the 3,335,242 Patented Aug. 8, 1967 diaphragm member between the

casing members

12 and 14.

Casing members

12 and 14 are preferably cylindrical in configuration and diaphragm member 20 is of `a ycomplementary circular shape corresponding to the cylindrical configuration of the casing members. It should be noted, however, that

casing members

12 and 14, as well as diaphragm member 20, may have other convenient cross sectional congurations such as, for example, rectangular, octagonal or other polygonal shape.

Upper casing 12 is provided with a mounting projection or member 31, a portion of the external surface of which is provided with a threaded portion 34. Threaded portion 34 provides a means of mounting or securing the pressure responsive device to a source of pressure which is to be sensed. Because of the lightweight, miniaturized construction afforded by the pressure-responsive device of the present invention, fitting 31 can constitute the only mounting required for the device 10.

Mounting member 31 also includes an orice or port aperture 30 which communicates with the interior of compartment 16 and which serves as an inlet to admit a surce of pressure to which diaphragm 20 is to respond. In the embodiment shown in FIG. l, port 30 is of generally circular cross sectional configuration. Mounted along the interior path of port 30 from the exterior of casing 12 to the interior of cavity 16 are, respectively, a stop or retaining member 36, a resilient spring member 38 and a 'spring seat 40. Spring seat 40 may be of any desired configuration and, in the embodiment shown in FIG. l, includes a plate-like member 41, the lower surface of which abuts the upper surface of diaphragm member 20. A post portion 42 is formed on the upper surface of plate 41 and extends into the interior of the lower portion of port 30. Plate 41 and post 42 thereby provide a seat for the lower portion of spring member 38. Spring member 38 may be of any desired type of resilient member capable, when compressed against seat 40, of exerting a force through seat 40 on diagram member 20 in the downward direction as viewed in FIG. l. In the embodiment shown in FIG. l, resilient member 38 takes the form of a coil spring whose lower end (as viewed in FIG. l) is seated in p'late 41 and post 42 and whose upper end abuts the lower survface of retainer 36. It should be noted that resilient member 38 does not completely occupy the interior of port 30 so that the source of pressure to which the diaphragm is to respond is admitted to plate 41 and diaphragm 20. By varying the degree of compression of spring member 38 the force exerted by spring 38 through spring seat 40 on diaphragm member 20 may be varied to thereby adjustably vary the values of pressure to which diaphragm member 20 will respond.

Spring 38 develops a force on diaphragm 20 in the same direction as the applied pressure force (i.e., the product of the pressure applied over the effective area of the diaphragm). There is a critical force depending on the construction of the diaphragm required for actuation of the diaphragm. When the resultant of the spring force and the applied pressure force equals the critical force, the diaphragm is caused to snap. By adjusting the spring force applied the pressure capable of snapping the diaphragm may be predetermined.

Further, in practice, individual diaphragms vary somewhat in the critical force required to achieve snap movement. Application of the spring force absorbs these variations to permit more accurate predetermination of the pressure required for actuation of the diaphragm.

When diaphragm 20 is in the snapped through position shown in dashed-lines in FIG. l, spring 38 exerts a smaller force in the diaphragm. For this reason, a relatively small decrease in the applied pressure force permits return of the diaphragm to the solid-line position. In this manner, the pressure differential or dead band area of the device is narrowed or diminished.

When spring 38 is compressed to the point at which the desired diaphragm loading is achieved and hence the desired pressure value to which diaphragm 20 will respond, retainer 36 is fixed to member 31 as, for example, by welding at 35 to retain spring 38 in its compressed calibrated state.

To provide a Itemporary fixing of retainer 36 to member 31 during the production process, retainer 36 is provided with a slot or channel 37 to provide retainer 36 with spring characteristics when subjected to a compressive force in a transverse or radial direction. In the uncompressed condition, the outside diameter of retainer 36 is greater than the inside diameter of port 30. Retainer 36 is compressed to permit its insertion into port 30 to the desired point and then released to provide a spring engagement between retainer 36 and the walls of port 30. Retainer 36 is formed of a material of suitable strength, corrosion resistance and material compatibility with member 31, such as stainless steel. Retainer 36 also includes an open-ended aperture 39 running throughout its axial length to permit entry of the source of pressure to be sensed.

It should be noted that retainer 36 may take other forms and may be retained in port 30 by other means. For example, retainei 36 may include extensions or arms extending exteriorly of member 31 through axially extending slots in the vvalls of member 31. In such a case, retainer 36 may be held in position by a threaded nut or the like, threadedly engaged with threaded portion 34. Alternatively, the exterior of retainer 36 and the interior wall of member 31 may be threadedly engaged to lix retainer 311 in its adjusted condition.

It should also be noted that spring 38 may bias diaphragm 20 in the upward direction to permit diaphragm 20 to operate at higher pressure values. In addition diaphragm 20 may be spring biased from its lower side asl viewed in FIG. l.

As best seen in FIG. 1, diaphragm or disc 20 comprises a monometallic disc having a deformed configuration which provides a nondevelopable portion to provide the diaphragm with inherent snap-acting operation. The principle of operation of the non-developable surface in providing ,for snap action is described in United States Patent No. 1,448,240 to J. A. Spencer and assigned to the assignee of the instant application. Snap-action diaphragm 20 is of the so-called automatic resetting or monostable type. i.e., the snap-acting element has only one position of'relative stability (the position shown in solid lines in FIG. 1) and when the element snaps to an opposite unstable coniiguration (as shown in dashed lines in FIG. 1) its inherent spring force tends to snap it back to its stable configuration which will automatically occur when the forces acting on the element tending to keep it in its unstable position, are either removed or diminished sufficiently to the extent where they are overcome by the spring forces in the element.

Upon the application of a predetermined pressure through port 30, diaphragm 20 will snap downwardly 'from the solid line position sh-own in FIG. 1 to assume an opposite concave configuration as shown in dashed lines in FIG. l. Upon the release of the pressure applied vthrough port 30 or upon a predetermined diminishing of this pressure, diaphragm 20 will snap back from the dashed line position to the solid line position.

It will be understood that diaphragm member 20 may be of the creep-type, i.e., of the type which will move in a more or less gradual or continuous manner from the solid-line position to the dotted-line position shown in FIG. l. Alternatively, whether the creep or the snap-acting type, diaphragm 20 may be formed of thermally-responsive composite or bimetallic material. In such a form, diaphragm 20 will be responsive to predetermined temperature conditions as well as to predetermined conditions of pressure.

An exemplary mechanism to be actuated by the pressure responsive device 10 is generally indicated by reference numeral It will be understood that exemplary mechanism 100 can be any device capable of being actuated by pressure responsive device 10. In the embodiment shown in FIG. l, the exemplary mechanism takes the form of an electrical switch generally indicated by reference numeral 100. Switch 100 is substantially identical with that described in co-pending application Ser. No. 133,385, now abandoned in favor of Ser. No. 432,067, filed in the name of Lawrence E. Cooper and Edmunds Kadisevskis and assigned to the assignee of the instant invention (particularly FIG. 2.). Other exemplary mechanisms actuable by pressure responsive device 10 include the several other switch species disclosed in the above application of Cooper et al.

Numerals corresponding to those in the aforementioned application of Cooper et al. indicate corresponding parts and reference is made to the Cooper et al. application for a complete description of the construction and function of switch 1001. Switch 100 is preferably of the hermetically sealed type. Briefly, the lower portion of casing member 14 is cup-shaped and provides a recess 40` for the reception of electrical switch 100. Switch 100y includes metallic header plate 10'2 having a pair of open-ended

apertures

104, 106, in which are respectively disposed, in hermetically sealed relationship, electrically

conductive terminals

108 and 110. A glass sealant 112 is supplied about each of

terminals

108 and 110 in

apertures

104 and 106 to hermetically seal and maintain

terminals

108 and 110 in electrically insulated spaced relationship with respect to header member 102.

Electrical terminal 108 mounts an electrically conductive contact 114 at one end thereof. The switch 100 further includes an electrically conductive contact-carrying spring member 116 which is electrically connected to and cantilever mounted adjacent one end thereof on a portion 118 of terminal member 110 as shown. Spring member 116 carries electrical contact 120V adjacent the free end thereof positioned for movement into and out of engagement with stationary contact 114 as shown. Spring member 116 may be formed, for example, of beryllium copper and is spring biased to move contact 120 in the direction away from engagement with stationary ncontact 114 toward the solid-line position shown in FIG. 2.

The inner peripherally extending wall of casing member 14 is recessed to provide a shoulder 44 to position and limit the extent of insertion of switch 100 in the casing 14. Switch 100 is secured to and preferably, although not necessarily, hermetically sealed within casing 14 as by welding of header 102 to the wall of casing 14 as at 122. Casing member 14 includes a centrally located, threaded aperture 132 in which is threadedly received an adjustable bushing or stop member 130. Stop member includes a centrally located open-ended aperture 138 in which is loosely received for relative slidable movement, a motion transfer pin l formed of a suitable electrical insulating material such as, for example, ceramic or phenolic resinous material. The length of pin 140 is such that its upper end engages the underside of diaphragm member 20 while its lower end engages the upper surface of spring arm 116 intermediate its ends.

It should be noted that the lower surface of cavity 18 has a concave surface 134 to protect diaphragm 20 against over-pressures as described in the abovementioned application of Cooper et al. In addition, the point at which diaphragm 20 will return to the solid line position in FIG. l may be varied by adjusting bushing 130l as described in the above mentioned Cooper et al. application.

The operation of the device is as follows:

The pressure-responsive device 10 is calibrated by compressing spring 38 to the point at which diaphragm 20 will snap from the solid-line tion to actuate mechanism 100` in response to a predetermined value of fluid pressure admitted through port 30. In this manner the level of pressure at which diaphragm 20 will snap may be predetermined with great accuracy. In addition, diaphragm 20 may be made responsive to to pressures below those to which it would normally respond. Upon the application of the predetermined level of pressure through port 30' to move diaphragm 20 to the dashed-line position, a downward movement of motion transfer pin 14 is effected which in turn effects movement of contact arm 116 to move contact arm 120' from the solid-line contacts-open position tothe dashed-line contacts-closed position as shown in FIG. l. Upon release or a predetermined diminishing of the pressure applied to the port 30, diaphragm member 20 will snap bac-k from the dashed-line position to the solid-line position to permit contacts 120 to move out of engagement with contact 114 under the bias of spring arm 116.

to the dashed-line posi- In view of the above, it will be seen that the several 2 objects of the invention are tageous results are obtained.

It is to be understood that the invention is not limited in its application to the details of construction and arrangements of parts illustrated in the accompanying drawings since the invention is capable of other embodiments and of being practised or carried out in Variousways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

As many changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense, and it is also intended that the appended claims shall cover all such equivalent variations as come within the true spirit and scope of the invention.

I claim:

1. A pressure-responsive device comprising first and second casing members respectively providing first and second cavities; a snap-acting diaphragm positioned intermediate and secured to said first and second casing members so that said diaphragm separates and seals said first cavity from said second cavity, said diaphragm having a deformed portion therein responsible for its snap action; an orifice provided by said first casing member communicating with said first cavity to admit fluid under pressure against one side of said diaphragm to effect snap action of said diaphragm in a direction toward said second casing member; means mounted and positioned on said second casing for actuation thereof in response to snap movement of said diaphragm; a motion transfer member positioned intermediate said actuable means to transmit said snap movement to said actuable means; resilient means mounted in said first cavity and having a portion adjacent one end thereof bearing against the deformed portion of said diaphragm to stress said diaphragm; and a stop member positioned within said orifice and against which the other end of said resilient means abuts, said stop member having an opening vtherethrough to permit the How of fluid pressure therethrough into said orifice and first cavity; said stop member being located relative to said diaphragm member such that the position of the stop member is effective to determine the stress achieved and other advanexerted by .the resilient means on said snap-acting diaphragm to thereby calibrate said device.

2. A device as set forth in claim 1 wherein the means actuable in -response to movement of the diaphragm comprises an electrical switch including a contact-carrying arm capable of movement into and out of engagement with a vstationary contact in response to movement of said motion transfer member.

3. The device as set forth` in claim 1 an-d wherein said stop member comprises a fiexible cylindrical member having a longitudinally extending slot therein to permit radial exing thereof, said cylindrical member Abeing frictionally engaged by the walls defining said orifice to prevent relative movement between said cylindrical member and first casing member.

4. The device as set forth in claim 1 and wherein said motion transfer member comprises a pin slidably received for reciprocal movement within an aperture provided by said second casing member which last named aperture communicates with, Isaid second cavity whereby said motion transfer pin abuts said deformed portion of said diaphragm.

5. A pressure-responsive device comprising first and second casing members respectively providing first and second cavities; a snap-acting diaphragm positioned intermediate and secured to said first and second casing members so that said diaphragm separates and seals said first cavity from said second cavity, said diaphragm having a Ideformed portion therein responsible for its snap Iaction; an orifice provided by said first casing member communieating with said first cavity to admit fiuid under pressure against one side of said diaphragm to effect snap action of said diaphragm in a direction toward said second casing member; means mounted land positioned on said second casing `for actuation .thereof 4in response to snap movement of said diaphragm; a motion transfer member positioned intermediate said diaphragm and said lostnamed means; spring means mounted in said orifice and having a portion :adjacent 4one end thereof bearing against the deformed portion of said diaphragm to stress said diaphragm; and a stop member positioned Within said orifice rand against which the other end of said spring means abuts, said stop member having an opening therethrough to permit -the fiow of fluid pressure therethrough into said orifice and first cavity; said stop member being located relative to said diaphragm member such that the position of the stop member is effective to determine the stress exerted by the resilient means on said snap-acting diaphragm to thereby calibrate said device; said spring means including a coil spring, a plate abutting said diaphragm and a post mounted on said plate extending into engagement with said spring to provide Ia seat therefore.

References Cited UNITED STATES PATENTS 1,183,486 5/1916 Pardue 92-13 2,381,835 8/1945 Moorhead 200-6 2,392,077 1/1946 Wilson 219-431 2,581,737 1/1952 West 290-38 FOREIGN PATENTS 886,446 7/ 1943 France.

BERNARD A. GILHEANY, Primary Examiner. H. B. GILSON, Assistant Examiner.

Claims

1. A PRESSURE-RESPONSIVE DEVICE COMPRISING FIRST AND SECOND CASING MEMBERS RESPECTIVELY PROVIDING FIRST AND SECOND CAVITIES; A SNAP-ACTING DIAPHRAGM POSITIONED INTERMEDIATE AND SECURED TO SAID FIRST AND SECOND CASING MEMBERS SO THAT SAID DIAPHRAGM SEPARATES AND SEALS SAID FIRST CAVITY FROM SAID SECOND CAVITY, SAID DIAPHRAGM HAVING A DEFORMED PORTION THEREIN RESPONSIBLE FOR ITS SNAP ACTION; AN ORIFICE PROVIDED BY SAID FIRST CASING MEMBER COMMUNICATING WITH SAID FIRST CAVITY TO ADMIT FLUID UNDER PRESSURE AGAINST ONE SIDE OF SAID DIAPHRAGM TO EFFECT SNAP ACTION OF SAID DIAPHRAGM IN A DIRECTION TOWARD SAID SECOND CASING MEMBER; MEANS MOUNTED AND POSITIONED ON SAID SECOND CASING FOR ACTUATION THEREOF IN RESPONSE TO SNAP MOVEMENT OF SAID DIAPHRAGM; A MOTION TRANSFER MEMBER POSITIONED INTERMEDIATE SAID ACTUABLE MEANS TO TRANSMIT SAID SNAP MOVEMENT TO SAID ACTUABLE MEANS; RE-