US2511509A - Pressure responsive switch for indicators - Google Patents

Description

June 13, 1950 K. L; M GUIRE PRESSURE RESPONSIVE SWITCH FOR INDICATORS Filed Aug. 25, 1947 f W 8 W4 G w Y 3 3 R G E F m Q Wm W m 6 T 2 L J A H M T E N N m 7 0w 2 B 0 3 8 n z 6%, a r I A g 4 w H \Y. 7 Z 407 Ti ,5 743u/flr3u/3 G H F Patented June 13, 1950 UNITED STATES PATENT OFFICE PRESSURERESPONSIVE SWITCH FOR INDICATORS Kenneth L. McGuire,. Beloit, Wis., assignor to. Fairbanks, Morse & 00., Chicago, 111., a corno ration of Illinois Application August 25, 1947, Serial No. 770,475

7 Claims. (Cl. 200-83) This invention is directed to the general class;

combustion space, usually include apressurere sponsive pick up unit which embodies a diaphragm member exposed at one side to the pressurebeing studied and exposed at its opposite side to the influence of a controllable test pressure. The flexing of such a diaphragm under certain differential pressure conditions is utilized to close an electrical circuit associated with a suitable recording or indicating instrument. Most, if not all, of the pressure units now in; use are constructed with the diaphragm member securely clamped at its periphery'whereby to effect a positive separation between. the diaphragm chamber spaces: exposed to the test pressure and the'pressure being investigated. ihe fixed type of diaphragm is, therefore, subjected to destructive fatigue stresses which will eventually develop into permanent deformation of the diaphragm, cause errors in the fidelity of the pressure response, retard the desired rapidity of response, and in other respects cause the introduction of errors materially affecting the true pressure conditions.

Accordingly, it isalso an important object of the present invention to design and construct a pressure responsive ::unit which will'notsbeaffected bythe above noted objections almost invariably found in the devices currently in use.

It is also an object to-simpliiy' the-construction of a pressure responsive unit. such that the pressurized diaphragm may be entirely unrestricted and .freely movable over its full area, securely retained in a closely defined chamber for rapid response to the net efiect of opposed pressure from a test source and. a source under investigation, .and required to have a minimum of movement'into or out of a position of contact with an electrode element of the associated electrical indicator circuit.

Other objects andtadvantagesof the present invention will be more fully pointed outsin connec- 2 tion with the detailed description of a preferred embodiment hereof as is disclosed in the accompanying drawing.

In the drawing:

Fig. 1 isa diagrammatic layout of a pressure indicator system serving to show the operative relation of the pressure responsive unit in con-- nection' with an internal combustion engine, the latter being shown in schematicand partly sectioned' elevation;

Fig. 2 is an enlarged longitudinal sectional elevational view of the improved unit forming the subject of the invention; and

Fig. 3 is a greatly enlarged and fragmentaryportion, in section, of the improved unit in which certain details are shown to better advantage.

Inthe view of Fig. 1, the-engine under test isrepresented bythe single cylinder ill, piston 1.1 and crankshaft l2 to which the piston is oper ativel-y connected by the connecting rod 13. The cylinder has the usual head member 14 which cooperates with the cylinder and piston to define a combustion space I5. My improved unit i6 is suitably mounted in the head 14 for communication with the space t5 whereby pressure conditions therein may be investigated. The unit ii is associated with an. engine indicator instrument, shown onlygenerally at I'Lthrough the electrical line ['8 and the pressure line 1.9, each of these lines l8 and i9 having a suitable connection with sources (not shown) of electrical energy and fluid under pressure respectively. It is, of course, understood that the cylinder I0 is grounded to complete the circuit through line l8 and unit 16.

Briefly considered, the instrument I! carries means for recording the desired cyclic pressure events in space l5upona drum means 20 which is rotated in timed relation with crank movement through the clutch connected. shaft 2|. Thus a recordoi the combustion pressure conditions may be recorded on drum 20 for any position of the piston II- as determined by the angular position of the crankshaft l2. The instrument [1, of course, must be adjusted to provide a known pressure in line I .9 and when ever-the pressure in thespace 15 exceeds. this test pressure, an electrical circuit through line IE will be completed for energizing the means (not shown) adapted to mark drum 20. Thus a complete pressure diagram may beobtained in a;step-bystep manner.

The improved unit l6 shown in detail in Figs.

2 and 3 comprises a body 2 5 having external threads 25 by which it may be secured in the cylinder head I4, a lower end having a transverse wall or flange 26 through which port 2'! opens to the interior of the body, and an upper and enlarged end having internal threads 28 at the open end. zone of the body bore 29. The lower flanged end 26 of the body forms an internal annular seat 30 for receiving a diaphragm block 3! upon a seat gasket 32. The diaphragm element 33 is positioned on the upper recessed surface of block 3! and a second block 34 is positioned thereover to define a restricted chamber 35 within which the diaphragm is confined with a suiiicient working clearance so as to permit free bodily movement to a limited extent in the axial direction of the body 24. A holder element 36 for an electrode 7 34. Apertures 38 may be located in a circular pattern concentric with the axis of the unit and outwardly of an undercut central recess 4! in the liglder for the reception of an insulator element The electrode 31 is formed with an upper threaded stem 43, a mounting flange Ml and a lower tip 45 of reduced diameter. Flange 4 is positionable in the recess M of the holder 36 and is spaced therefrom by the insulator 42 upon positionment of the latter over the stem 43 and against the upper surface of the flange 44. Electrode 31 is clamped to the holder by means of the nut 49 threaded on stem 43 and bearing against a washer 46 and an insulatin washer 47, the latter being seated against the holder 35. The upper portion of the threaded stem 43 of electrode 31 engages the threaded socket element 48 of the elongate rod 59. The socket element 48 is formed of an electrical conductive material, and constitutes the circuit connection between the electrode 31 and the rod 50. Rod 5i! (Fig.2) extends toward the upper open end of the body 24 and carries an electrical connector element 5| which is press-fitted thereover by means of the socket portion 52 such that the integrally formed connector post 53 thereof is positionedwithin thezone of the threads 28 in the body 24.

The parts of the assembly above described are secured in the body 24 by means of the body cap, member 55 (Fig. 2) wherein the threaded portion 56 thereof engages in the body threads 28 and serves to press a spacer sleeve 57 positioned in the bore 29 against the electrode holder 36 and, hence, compress the diaphragm blocks 3! and 34 against the sealing gasket 32 upon seat 39 at the lower end 26 of the body 26. Suitable gasket elements 58 and 59 are interposed at opposite ends of the sleeve, 5! as shown. The portion 56 of the cap member 55 is internally recessed to provide a seat 60 for the insulator block 6| which maintains the connector element post 53 in axially concentric position relative to the bore 29 of the body 24. This latter block 6! is formed with a suitable number of radial notches 62 (only one being shown in Fig. 2) which permit communication between the space 39 within sleeve 51 and a pocket 63 provided above the Cap member 55 is also formed with an enlarged portion (i i in the nature of a tool engaging nut for effecting threaded positionment thereof in body 24, and a stem portion 65 extending above the boss 64 to provide a mounting surface for the slip ring element 65. The slip ring is held in position by the nut 67 threaded on stem 55, and is fully insulated therefrom by means of the sleeved insulator 68 and the an nular insulator 6t. Nut 61 bears on washer iii to protect the insulator 59 from damage by the rotation of the nut. An electrical lead H extends from its soldered connection at post 53 through suitable apertures in the boss 64 and insulator to a soldered connection in the slip ring 65, all as indicated in Fig. 2. The ring E6 is suitably formed of an electrically conductive material, such as copper.

Connection of the pressure line 19 to the unit it is efiected by means of the threaded fitting l2 engaging the upper end of the stem 65 above nut 6! so that the line l9 opens to the axial bore 13 of the member 55 for communication with the pocket 63 and thence through notches 62 in the insulator block 6| to the space 39. At the lower end of the body 24, the space 39 communicates with the upper face of the diaphragm 33 by Way of the annular space around the insulator 51, the annular ring of apertures 38 in the holder 36, recess id of the upper diaphragm block 34 and the several axially directed apertures formed in the latter block. The electrical circuit for this indicator it includes the body 24 and block 35 on one side of the diaphragm 33, and the electrode 3?, socket 8, rod 59, connector 5i, lead ll,

slip ring 6 5 and external lead wire it for the to provide an axially directed, peripheral rim Tl.

extended above the general facial plane thereof, and this plane is further milled out to form a series of annular and concentric notches orgrooves i3 separated by similar lands 19 of a co-planar character. Thus the diaphragm 33 is adapted to be supported on the lands 79 with a small Working clearance at the rim 71. In a similar manner, the upper block 34 is provided with a plurality of axially directed apertures 8| leading from the recess 43 to the diaphragm The lower face of this block 34 ischamber 35. formed with a series of annular notches or grooves 82 and intervening lands 83 which are in oppositely registering alignment with but spaced from the lands l9 on the lower block 3!. The spacing of the two blocks SI and as is determined by the rim ll. Electrode element 3'! is positioned, in assembly, with its tip 45 extending into the central one of the apertures 8i with small clearance and such that its diaphragm' contact face 84 is substantially flush with thecommon plane of the lands 83.

In a pressure responsive unit of this character the diaphragm chamber 35 defined by the blocks 3! and 34, is open through apertures 16 and port 2? to the source of pressure to be investigated,

and through apertures BI and recess 4% to the source of pressure under control of the instru-' ment i? as supplied through line I9 at fitting l2. Diaphragm 33 effectively divides this chamber 35 into sections, and effectively prevents cross flow by its seating contact on either one or the.

other series of land surfaces depending upon which source of pressure is dominant. A pre-.

ametes ferred construction; and "one which has proved entirely-satisfactory, embodiesa diaphragm element 33 having a thickness of substantiallyefll-fl inch workingin chamber. .35 .having an axial depth of substantially .011 inch; Thus the diaphrag'm is movable through a distance off ;001 inch from its'contact --on-b1o'ck -'3 to its contact with ditch s! and electrode tip iace 84 In this same embodiment,the-diaphragm was formed of Beryllium bronze for its strength and durability under the high pressure and temperature conditions encountered in internal combustion engine use.

The light weight and tough character of the diaphragm renders it extremely sensitive to pressure variations occuring in the different sections of the chamber 35. A further feature hereof resides in the provision of a minimum amount of movement for the diaphragm, thereby practically eliminating inertia effects and consequent time lag for the electrical make or break action on the tip face 84 of the electrode 31. Moreover, the free mounting of the diaphragm entirely eliminates the introduction of errors due to fatigue of the diaphragm, such as is encountered in the prior units where the diaphragm is peripherally clamped in situ.

Having now fully described my improved pressure responsive unit I6, it will be understood that I do not wish to be limited to the exact features of its construction but intend that all reasonable variants thereof be included within the spirit and scope Of the appended claims.

I claim:

1. A pressure responsive unit comprising a body having relatively spaced openings for communication with a periodically pressurized space and a source of known pressure respectively, an electrode element positioned in said body, 21 diaphragm element operatively mounted in said body adjacent said electrode element, said diaphragm element being freely and bodily movable toward or away from said electrode element under the influence of the differential of pressures from said space and known pressure source, and means in said body for confining said diaphragm to limited movement, said means :providing openings at each side of the diaphragm for pressure transmission thereto and said openings being located so as to be closed by diaphragm whereby to prevent cross-communication of the space and pressure source.

2. A pressure responsive unit comprising a body having relatively spaced openings, one of which is adapted to communicate with a periodically pressurized space and the other with a source of known pressure, an electrode element positioned in said body and electrically insulated therefrom, and a diaphragm element operatively mounted in said body adjacent said electrode element and in position effectively to prevent cross flow between the pressurized space and known pressure source, said diaphragm element being freely, bodily movable toward or away from said electrode element under the differential pressure effects from said known pressure source and pressurized space.

3. A pressure responsive unit comprising a body having relatively spaced openings for communication with a pressurized space and a source of known pressure respectively, a pair of elements in said body formed to define a chamber therebetween, said elements each having an aperture therein to permit communication between said chamber and the pressurized space and known 6 sourceol pressure,sand a' diaphragm''freeiyinmvably disposed in said chamber-4m efie'ctingcios ure"oftne'-'apertures ineither of said elements" 'under th'e" in'iluen'ce -of a pressure differential across-the diaphragm.

4. pressure responsive unit comprising a bod-"y having an "inwardl-y'flanged end providing aport and an annular seat adjacent thereto, n: block element on said seat and having apertures therein and-a: recess in one face communicating:-

with saidiport through the aperturespa second block element positioned adjacent the recess "in said first block to deflne a recess chamber therewith, said second block having apertures formed therein, a diaphragm in the recess chamber between said block elements, said diaphragm being freely, bodily movable against either of said block elements to close the apertures therein, and means for communicating a known source of pressure through said second block element and against one face of said diaphragm, said port in the flanged end of said body being adapted for communicating a source of pressure to be investigated through said first mentioned block element and against the opposite faces of said diaphragm.

5. In a pressure responsive unit, an elongate body having a bore therein and a ported flange formed at one end thereof, the flange defining an internal annular seat in said body, an apertured block positioned against said annular seat and having a recess formed in one face to provide a peripheral rim directed axially of the body bore, a second apertured block positioned against the peripheral rim of said first block to define a chamber with the recess of the latter block, a diaphragm element freely, bodily movable in said chamber and adapted to contact either of said blocks in aperture closing relation, and an electrode element carried in the body bore and formed with a tip portion extended through an aperture in said second block for contact by said diaphragm upon movement of the latter into contact with said second block, said diaphragm being movable in response to the difference of pressure on its opposite sides due to disposition of said body between separate sources of pressure.

6. In a pressure responsive unit, a body having an axial bore and a ported flange at one end of the bore to define an internal annular seat, a body cap member engageable at the opposite end of the body bore, and having a passage communicating with said bore, a pair of complementary block elements in said bore formed with a plurality of axially directed apertures and defining a. chamber between their adjacent faces, means for securing said block elements against said annular seat upon assembly of said cap member, a diaphragm element disposed in said chamber for free bodily movement between said block elements, an electrode element projecting into an aperture of one block element for contact by said diaphragm upon movement thereof against said one block, electrical connection means carried by said cap member, means for electrically associating said connection means and said electrode element, and means on said cap member adapted to connect the body bore with a source of pressure such that said said diaphragm is urged to a position out of contact with said electrode and in opposition to a source of pressure communicated to said chamber at the opposite side of the diaphragm through said ported flange.

'7. A pressure responsive unit comprising a body having relatively spaced openings and a bore communicating said openings, the body 7 openings being adapted for communication re- REFERENCES CITED spectively with pressurized Space and June The following references are of record in the of known pressure, means in said bore defining me of this patent;

a chamber having apertures respectively afford- I ing communication of the chamber with the 5 UNITED STATES PATENTS pressurized space and known source of pressure, Number Name Date and a diaphragm element freely, movably dis- 2,072,984 Haskins Mar. 9, 1937 posed in the chamber and acting selectively and 2,085,203 Schlesman et a1. June 29, 1987 under the influence of difierential pressures to 2,362,874 Wiley Nov. 11, 1944 close certain of said apertures to prevent cross-' 10 communication of the pressurized space and known pressure source.

KENNETH L. MCGUIRE.

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