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Publication numberUS3139493 A
Publication typeGrant
Publication dateJun 30, 1964
Filing dateAug 28, 1962
Priority dateAug 28, 1962
Publication numberUS 3139493 A, US 3139493A, US-A-3139493, US3139493 A, US3139493A
InventorsKrieger Sr Irving W, Parmann Edwin A
Original AssigneeFurnas Electric Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Pressure switch with low pressure cut-out
US 3139493 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

June 30, 1964 l. W. KRIEGER, SR., ETAL PRESSURE SWITCH WITH LOW PRESSURE CUT-OUT Filed Aug. 28, 1962 2 Sheets-Sheet l June 30, 1964 1. w. KRIEGER, sR., ETAL 3,139,493

PRESSURE SWITCH WITH LOW PRESSURE CUT-OUT Filed Aug. 28, 1962 2 Sheets-Sheet 2 1NV ENTOR5. im@ Wffgef: 5f,

UnitedStates Patent O of Delaware Filed Aug. 28, 1962, Ser. No. 219,938

7 Claims. (Cl. ZOO-67) The invention relates to electric switches, and has reference more particularly to pressure actuated switches havingv mechanism for eiiecting an opening of the contacts of the switch at a low pressure below the low pressure of the normal operating range.

The pressureswitch of the invention employs the basic switch elements as shown in the Elsner and McGary Patent No. 3,015,006, grantedDecember 26, 1961, the said elements including a toggle member having snap action in response to certain pressure conditions to effect opening andclosing of the contacts of the switch. Heretofore low pressure cut-off required two separate switches, one to operate between the normal low and high pressure range, and a second switch connected in series with a manual reset for opening the contacts in the event the pressure should fall below that of the normal operating range. This sometimes happens when the pressure fluid fails completely for some reason or other.

. The switch of the invention incorporates mechanism in` addition to that shown in Patent No. 3,015,006 which,

without interferring with the normal operation of the switch, also provides a cut-out at a third` pressure that is below Athe low pressure of the normal operating range. A reset lever is provided for obtaining normal operation of the switch and which must be held depressed by the operator until the pressure in the system builds up to exceed that of the low pressure switch-closing setting. The switch thereafter will automatically maintain the pressure requirements of the system.

Another object of thefinvention is to provide a switch havinga low pressure cut-olf as described and which will have general utility as regards pressure switch application and uses, since all of the contacts of the switch may be the normally closed or the normally open type with both ofthe` connecting members being either push rods or pull rods, respectively. A l

With these and various other objects in View the invention may consist of certain novel features of construction and operation, as .will be more fully described and particularly pointed out in the specification, drawings and claims appended thereto.

In the drawings which illustrate an embodiment of the device and wherein like reference characters are used to designate like parts- FIGURE l is an elevational view showing a pressure switch having incorporated therein the improved features `of the invention;

FIGURE 2 is a vertical sectional View through the switch device of FIGURE l taken substantially on line l2--2 of said ligure;

FIGURE 3 is a sectional View on line 3-f3 of FIG- URE 1 and showing the pressure lever and adjustable coil spring which form part of the toggle mechanism f the switch;

FIGURE 4 is a horizontal sectional View showing the toggle member and tensioning spring and which is taken substantially along line 4-4 of FIGURE 2;

FIGURE 5A is a sectional view taken horizontally on line 5-5 of FIGURE 2;

FIGURE 6 is a top plan view of the contact block of the switch and which is taken substantially on line 6-6 of FIGURE 2;

FIGURE 7 is a vertical sectional view through the switch of FIGURE 1 and which shows the position of the parts when the pressure uid has failed completely; and

FIGURE 8 is a vertical sectional View similar to FIG- URE 7, but showing the position of the parts during normal operation.

The pressure switch of FIGURE 1 has been selected for illustrating the improved features of the invention and which are best shown in FIGURES 7 and '8. The basic structure of the switch proper includes an adaptor or base portion 10 having a threaded inlet 11 for admitting a fluid under pressure', said base portion 10 being secured by the screws 12 to the supporting ring 13 of the switch structure. The bottom Wall 14 of the housing 15, together with the ilexible diaphragm 16 are interposed between the parts 10 and 13 so that the switch structure, housing and adaptor are fixedly joined together as a unit. The bottom wall 14 of the housing has an opening 17 in alignment with the inlet so that the pressure iluid in the inlet is in direct Contact with the undersurface of the diaphragm 16 to iex the same in a manner depending on the pressure conditions to which the diaphragm is subjectedl The toggle mechanism of the present switch is in turn actuated by the exing of the diaphragm 16 and as the toggle mechanism is caused to oscillate from one side of a dead center position to the other, the contacts of the switch are respectively actuated.`

The supporting ring structure 13 is accordingly lixedly secured to the housing and said ring structure has associated therewith the frame assembly 20 and the pivot device comprising the pivots 21 for the pressure lever 22, the said lever comprising the actuating means for the toggle member as will be presently described. The frame assembly 20 as best shown in FIGURES 2 and 3 provides the upstanding side walls 23 and 24 which are bent outwardly at their upper ends to form the flanges 25 and 26. Said flanges in turn support the contact block which is designated in its entirety by the numeral 28. The screws 27 extend through side extensions formed on the contact block and the said screws are threaded into the flanges 25 and 26 for releasably securing the contact block to the frame assembly 20. The side walls 23 and 24 are each slotted ornotched at 30, FIGURES 7 and 8,

and the pivot ends of the lever 22 are located in the notches for pivotally mounting the lever on the framev assembly 20 with the movable end of the lever 22 being disposed at the right asin FIGURES l, 7 and 8.

The coil spring 32 has encircling relation with the rod 33 which is anchored at its base end in the ring structure 13, and which extends upwardly from the structure to approximately the top surface of the contact block 28. The top end of the coil spring 32 is confined by the cap 34 which is threaded on the upper end of the rod 33. The cap can be adjusted on said rod as regards its vertical position so as to vary the compressive force exerted by the coil spring on the lever 22.

The pivot device providing the pivots 21 includes the base 35 and which is located in contact with the flexible diaphragm 16 on the top side thereof and thus the pivot device will move bodily in a vertical direction as the pressure fluid on the diaphragm causes the same to flex. This bodily movement of the pivots 21 will be transmitted yto the lever 22 and accordingly the said lever will oscillate on its pivot axis 30.

One of the improvements of the invention resides in the provision of a ilat spring member 36, one end of which is retained between the head of the rod 33 and the wall of the ring 13. The other end of the spring member 36, and which is the left end as seen in FIG- URES 7 and 8, is riveted at 37 to the base 35 and also to the diaphragm 16, the rivet 37 extending through the several parts. The tension exerted by the at spring memberv 36 is downward so that the base 35 and the pivots 21 arel yieldingly biased `in a downward direction. The toggle member v38 having the shape as shown in frame assembly 20. Whereas the pivot ends 30 for the leverw22 are located at the left edge of each side wall,

the pivot extremities 40l of the toggle member 38 engage in notches on the right edge of the said side walls.

Also whereas the lever 22 is disposed in surrounding relation with the frame assembly 2.0, the toggle member 38 is located within the frame assembly. This locates the movable end of the toggle member adjacent the headed screw 41 located in plate 42. Said screw is adjustable -in a vertical direction to limit upward movement of the cured to the frame assembly by the screws 27 is preferably formed of a moldable plastic although other insulating materials'may be'used. Said block is cored externallyvto provide the recesses for receiving the metal stripsri on one side of the contact block FIGURE 6 and the metal strips 46 on lthe other side. The terminal screws 47 secure the metal strips 45 to the block whereas the'screws 48 secure the strips 46 to the block and said screws extend into internal recesses and provide the stationary contacts of the switch. The screws 48 provide the contacts for the movable contact bar 50 and the screws 47 provide the contacts for the movable contact bar' 51 which is not shown, but which is similar to bar 50. Each bar is carried by a pull rod 52 in coml bination with a coil spring 53, as Vshown in FIGURES 7 and 8. A pair of the spaced pull rods 52 is shown in FIGURE 3. The coil springs are each confined between Y FIGURE 4 is pivotally mounted at its extremities as Y at 40 on the upstanding lside walls 23 and 24 of the ypositions above and below deadr center.

anaaass l ber is caused by the pressure lever in moving to and from l Such action, will take place during normal pressure vconditions and, accordingly, the contacts open when a pre-set high pressure is reached and the contacts closes when apre-set low pressure is reached. Should the pressure fluid fail completely then the pivot device, including the base 35 and Y the pivots 21, is caused to drop since the ilexible di- 58, as will be understood byv reference to FIGURES 7 porting structure. The down ymovement.` of the actuataphragm 16 is not under any 'pressure and, in addition, the Hat spring member 36 yieldingly biases the pivot device in a down direction.L This action drops the pressure Y lever 22 and said lever is thus caused to contact the top projection 62f0rmed on the arms of the actuating lever and 8. The projections 62 are locatedon the left side of the pivot axis as shown in said ',gures, and the pres- Y sure of the lever 22 will cause the actuating lever 58 to` move down until it rests on the bottom wall of the supand pump it is required thatr he cause the contacts of n This is done by actuating the lever the switch to close. 64 shown in FIGURES 1, 4 and 6. The lever 64 is pivotally secured to the housing 650i the switch and the end 66 of the lever is located under the pressure leverV 22.' The operator can rotate the. lever 64 to elevate the pressure lever 22, and this action will free the actuating lever 58 and allow the coil springs 53V to close `the contacts of the switch. Y

its contact bar and the insulating closure plate 54 throughy which the pull rods extend. The coil springs 53 exert a v compressive force against its contact bar to cause the respective bar to close against the `contacts of the terminal screwsV 47 and 48, respectively. Each pullv rod 52 has a head portion 55 which is located above the contact barso that when the pull rod is pulled down it also the contacts. t

The pull rods are each formed'with a hook `portion 56 and which extendl through openingsy in the toggle t member 38 and engage under the side extensions 57 of the actuating lever 58 FIGURES 5, 7 and 8. The actuating lever is part of the present improvement in that said a leverV ecects the opening of the switch contacts when the pressure on the diaphragm 16 fails completely.

The actuating lever58 is pivoted` on respective sides rby the U-shaped wire'member 60, the ends of which pass throughthe arms of the lever and also through the upstanding supports 61.k Since the lactuating lever is located below the toggle member and also below the pressure lever, these two elementsv have certain `particular Vaction on the actuating lever. 'V The hook ends of the pull rods extend Athrough openings in the toggle member and said hook ends are located under the lateral extensions S7 ofthey actuating lever. When the toggle member moves down the actuating lever is also caused tol move down and this'pulls on the rods 52 to effect an opening of thevswitch contacts. However, when the toggle memberfmove's up the actuating lever is not inuenced by it, but by the coil springs 53 which move the contact bars vand 51-into closing relation with the stationary contacts provided by the terminal screws 47 and 48. This spring action of the coil springs 53 will move the pull rods in an up direction and so the actuatinglever is caused to ,follow the toggle member when it moves upwardly.

Y This up and down, snap movement of the toggle memmoves its contact bar in ay downward direction to open 45' Vtoggle member 38 will oscillate as the pressure varies from a pre-set minimum to a pre-set maximum. When the toggle member moves down it contacts the Vactuating lever 58 and, accordingly, moves the leverdown toin turn open the switch contacts. When the togglemember moves up the pull rods 52'and the actuating lever also move up due to the action of the coil springs 53. The pressure lever 22 comes intoaction with the projections l62 only when a low pressure exists which is below the pre-set lowpressure. Then the actuating lever is positively depressed into its low position and the switch contacts are opened although the toggle member is in an up position. y y

What is claimed is: Y

l. In a pressure switch,the combination with a supporting base structure, of a frameassembly secured to said base structure vand Aproviding a pairV of spaced upstanding side frames, toggle mechanism pivotally 4supported by the side frames, said mechanism including a togglek member having pivotal movement in a direction parallel to the side frames, a contact block of insulating material xedly supported by.4 the side frames and located above" ber, the end of the rod extending through the toggle member having operative association with the` actuating lever, and spring means in associated relation with the rod for yieldingly forcing the movable contact into closed relation with the xed contacts.

2. In a pressure switch, the combination with a supporting base structure, of a frame assembly secured to said base structure and providing'a pair of spaced upstanding side frames, a pressure lever pivotally engaging the sideframes parallel to the side frames, resilient means disposed between the pressure lever and the toggle member and connecting therewith wherebyy the toggle member has movement in opposite directions between given extreme positions when the pressure lever is oscillated to a predetermined degree, a contact block of insulating material ixedly supported by the side frames, a plurality of fixed contacts located within the block and disposed in pairs, a movable Contact mounted within the block for coaction with the pairs of Xed contacts, respectively, a rod operatively connected at one end thereof with each of the movable contacts, the other end of'each rod extending through the toggle member, an actuating lever pivotally supported by the frame assembly and located below the toggle member, the end of each rod extending through the toggle member having operative association with the actuating lever, and a coil spring in encircling relation with each rod for yieldingly forcing its movable contact into closed relation with its pair or" fixed contacts.

3. In a pressure switch as dened by claim 2, wherein each rod is a pull rod and wherein that end of each rod extending through the toggle member has operative association with the actuating lever by means of a hook end which is positioned under a side extension provided by the actuating lever, and additionally including a coil spring in compression relation with the oscillating end ofk lated in a down direction to a predetermined degree,

whereby the actuating lever is also forced into an extreme down position and the pull rods are actuated to open the contacts;

5. ln a pressure switch, in combination, a frame assembly providing spaced side walls, a pressure lever having side arms fulcrumed on the front edges of said side walls and located exteriorly of the walls, relatively movable contacts f carried by the side walls above the lever, a toggle member fulcrumed on the rear edges of the spaced vside walls and located between the Walls, a spring connecting said pressure lever and the toggle member to pro- Yvide a snap action toggle for said contacts, said toggle movable contacts and at its other end to the actuating lever, said pull rod extending through the toggle member so as not to interfere with the snap action of the toggle member, and said actuating lever having a projection on its top surface adjacent its pivotal axis for coaction with the pressure lever.

6. ln a pressure switch, in combination, a framek assembly providingl spaced side walls, a pressure lever having side arms fulcrumed on the front edges of said side walls and located exteriorly of the Walls, a pair of iixed contacts carried by an insulating block secured to the side walls above the pressure lever, a movable contact strip mounted within the insulating block for coaction with the xed contacts, a toggle member fulcrumed on the rear edges of the spaced side walls and located between the walls, a spring connecting the toggle member and the pressure lever to provide a snap actionl toggle for said movable contact strip, the said toggle member having snap action in a direction parallel to the side walls when the pressure lever is oscillated in a direction also parallel to the side walls, an actuating lever also fulcrumed on the front edges of the side walls below the pressure lever and extending between the side walls below the toggle member for pivotal movement, a pull rod operatively connected at one end to the movable contact strip and at its other end to the actuating lever, whereby down movement of the toggle member will eiect similar movement of the actuating lever to cause the pull rod to open the contacts, and spring means associated with the pull rod and with the -movable Contact strip to yieldingly force the contact strip into contact closing relation withthe iixed contacts.

7. In a pressure switch as deined by claim 6, wherein the actuating lever has a top projection relatively adjacentV its pivotal axis for coaction with the oscillating end of the pressure lever.

References Cited in the file of this patent Y UNITED STATES PATENTS y 3,015,006 Elsner et al a Dec. 26, 1961

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3015006 *Dec 16, 1960Dec 26, 1961Furnas Electric CoContact block and terminal arrangement
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3258552 *Mar 4, 1963Jun 28, 1966Miller Harris Instr CompanyCombined time-temperature switch device
US4200775 *Jun 19, 1978Apr 29, 1980Furnas Electric CompanyPressure responsive switch with low pressure cutoff
US5120915 *Feb 1, 1991Jun 9, 1992Johnson Service CompanyPressure-actuated pump control switch
US5672049 *Apr 26, 1994Sep 30, 1997Ciurlo; UgoElectromechanical device for the protection of a pump in waterworks of various types, in the absence of water
US6552284Feb 25, 2002Apr 22, 2003Derrin T. DragoWater pump low pressure cutoff switch
US20070177985 *Jul 20, 2006Aug 2, 2007Walls James CIntegral sensor and control for dry run and flow fault protection of a pump
U.S. Classification200/83.00P
International ClassificationH01H35/24
Cooperative ClassificationH01H35/242
European ClassificationH01H35/24B