US 3110784 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
NOV-V -1'2 1963 P. H. WILLIAMS E'rAl. 3,110,784
` PRESSURE SWITCH CONTACTS Filed July l, 1960 lh l1 2 Sheets-Sheet 1 f-Io v /-f--Uw vz?" 1...'. 1- 1 ir.. I6
44 l 6 54 56 I 8 5B v se I 7l 5a 4 56 58 41|. l r: 'h1 l*I 1| l 1H, d
.11; INVENTORS 54 IH Paul H. Williams und lll FI G2 IW/Z// Attorney NOV 12, 1963 P. H. wlLLlAMs ETAI. 3,110,784
PRESSURE SWITCH CONTACTS Filed July 1, 1960 2 sheets-sheet 2 FIGS .A se
INVENTORS Paul H. Williams und BY Joseph J. Koleba ,fw/,WMM
Aftorney 3,llt),74 PRESSURE SWHCH CNECTS Paul H. Williams, Elmhurst, and laseph E. Kalcba,
Roselle, lll., assignors to Controls Company of America, Schiiier Park, lll., a corporation ot Delaware Filed Early-l., 196?, Se No. 40,267 l2 Claims. Cl. 26d-83) This invention relates to pressure switches of the type used to determine the water level in washing machines and the like.
Pressure switches of the generalV type shown here have a diaphragm subjected to water pressure to actuate a switch `when a predetermined pressure (corresponding to a desired water level) obtains. The usual operation is to have the switch continue the filling of thecontainer until yit reaches the desired level, whereupon the control shuts off water ilow and continues the washing machine cycle. Therefore, the function `of the pressure switch is to signal when the desired level is reached. The level is selected by manually actuating a cam which varies the bias on the diaphragm opposing lthe water pressure. The cam is preferably shaped -as in Beller Patent Ser. No. 2,934,618 and is provided with lobes which act to reset the switch to its normal (not full) position between different settings. lt is possible, however, to hang-up the Beller selector on a lobe with the result that the switch is held closed-calling for water and unable to openaiiowing the water to continue to flow, causing a ilooding condition.
The primary object `of this invention is to prevent locking of the pressure switch in the till position under the aforementioned conditions.
Other objects and advantages lwill be pointed out in, or be apparent from, the specification and claims, as will obvious modicaticns of the single embodiment shown in the dpawings, in which:
FIG. l is a side elevation of a fluid pressure responsive switch;
FIG. 2 is taken on line 2--2 of FIG. l showing the v switch in the closed position;
FlG. 3 is similar to RIG. 2 showing the switch in the neutral or inoperative position;
FIG. 4 shows the plunger extension used to lock the switch in neutral; and
lFlG. 5 is a fragmentary exploded perspective further illustrating the arrangement of the parts.
Referring more particularly to the drawings, the iluid pressure responsive device includes pressure tube lil secured to cup i4 which is mounted Von the shoulder 16 of an insulated housing i8. Diaphragm Ztl is clamped between the housing and the cup and divides the housing into a pressure chamber 22 and a switch chamber 24. The pressure tube is provided with orice l2 so that the pressure chamber will be in communication with the huid being measured. Diaphragm pa-d 2o has a downwardly extending stud 28 having a reduced lower end portion which projects through a cooperating hole in tongue 32 of switch blade 34. One end of the blade is secured to external Contact y36 by rivet S8 and is provided with double contact 4d on its free end. Barrel spring d2 is compressed between the tongue and the blade to normally bias the double contact into engagement with upper switch contact ed which is connected in the water till circuit.
When water is -run into the machine, pressure will build up in chamber 22 pushing the diaphragm down and compressing spring 46 between stud 28 and cylinder The tongue will move down with the stud compressing the barrel spring until it passes the plane ofthe blade, snapping the blade upward with the double contact enarent Patented Nov. l2, lQS
. in the housing. Lobes 5d .are provided on the cam between the `valleys -to reset the switch when the cam is rotated by pushing the cylinder up and causing projection ed to push the tongue up until the blade snaps-back into engagement with the till contact 44.
in the prior Beller device it was possible in some instances `for the cam 'follower 55 'on the cylinder to hang up on the lobes with the projection 60 holding the tongue down so that it coul-d not respond to the pressure on the diaphragm, .thus preventing interruption of the till circuit and allowing the machine to -overll and flood the area. To prevent this situation bracket 62 is mounted in hole to normally rest on overtravel spring i66 positioned between the bracket and flange 7l of cylinder 48 (see FRG. 2). ln this position the bracket has no elect on the switch operation but when the resetcam 54 is rotated to bring a lobe 5S under thewfollower 55 the cylinder moves up .and raises the bracket until tabs 68 abut the underside ot ange itl (with spring 66 accommodating overtravel of the cylinder while holding the bracket firmly against the iiange). At this time the positive reset pin i9 `forces diaphragm pin Z8 upwardly so spring te can move the tongue 32 overcenter to tend to trip tie switch back to contact 44. With the bracket positioned las shown in FlGS. 3 and 5, however, the legs 72 of the bracket prevent the rails 65 of the blade 34 from moving down, thus acting to hold the switch 4in an incompleted tripped position -as shown in FIG. 3. This incompleted tripped position is held as long as the lobe is under the -follower, thus preventing machine operation so long as the reset is hung-up. The contacts del and Si? are located a relatively small distance apart so that a small motion of blade 34 will open one circuit and close the other. Since the mounts for these contacts and iiange "tl are mol-ded with lthe housing, the vertical distance between them can be very accurately determined. With this relationship known, the sides of the bracket can be easily made equal to the distance ifrom the tlange to a horizontal line drawn between the contacts. Since these relationships are all predetermined, the bracket lends itself readily to mass production type fabrication.
ln operation, cam 5d is manually rotated to the desired level. Normally, the cylinder will be aligned with the valley S52 which has been selected, providing the proper pressure on .the spring 46. When the pressure in chamber 22 is sutcient to move the diaphragm down, the bias of the barrel spring on the switch blade will be reversed, snapping the switch from contact i4 to contact 50 to open the water lill circuit. When the pressure on the diaphragm is reduced, spring i6 will push the tongue upward, again reversing the bias of the barrel spring on the blade and closing the water ll circuit for the next cycle. lf the pressure is maintained in the pressure chamber and it is desirable to obtain a higher water level, the cam is rotated and lobes 53 will raise cylinder d8, causing pin 49 to push the tongue up, snapping the blade down. Bracket 62 will also move upward, preventing the blade :from engaging contact ed. lf the cylinder hangs up in lthis position, the water ll cincuit will be open and water will ynot flow. It can :be seen that the switch blade will always be biased in the down direction when the cam is rotated for resetting, due to the action of the plunger, so that the lill circuit will be closed whenever the resetting motion is properly completed.
Although but a single embodiment of the present invention has been illustrated and described, it will be aparias/st- .9 parent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.
l. A manually adjustable condition responsive device operated in accordance with a condition comprising, control means, a member movable fto opera-te said control means in response to a change in saidcondition, loading means Iexerting a force on land opposing movement of said member in one direction, cam means operatively connected to the loading means and having multiple elevations each providing a different bias on the loading means, reset portions between adjacent elevation portions ofthe cam, reset means operated by the reset portions, and means operative while the reset portion is effestive on the reset means to prevent resetting and allowing completion of reset when the reset portion is not effective.
2. A manually adjustable condition responsive device operating in accordance with a condition comprising, control means, a member movable to operate said control means in response to a change in said condition, loading means exerting a force on and opposing movement of said member in one direction, cam means manually operable to diierent positions to adjust the force exerted by said loading means on said member, the `torce exerted by said loading means on said member being different in different positions of said cam means, resetting means actuated by the cam means between the ditierent positions of the cam means, said loading means including means for preventing resetting when the resetting means is effective and allowing completion of reset when the resetting means is not etiective.
3. A manually adjustable -condition responsive device operated in accordance with a condition comprising, control means, a member movable to operate said control means in response to a change in said condition, loading means exerting a force on and opposing movement of' said member in one direction, cam means manually operable to different positions to adjust the force exerted by said loading means on said member, the force exerted by said loading means on said member being diiierent in different positions of said cam, said loading means including means ttor preventing operation of the control means when the loading means is loca-ted between the different positions on the cam` means.
4. A manually adjustable condition responsive device operated in accordance with a condition comprising, control means, a member movable to operate said control means in response to a change in said condition, loading means exerting a force upon and opposing movement of said member in one direction, a single multiple position cam manually operable to different positions thereof to adjust the forces exerted by said loading means on said member, the force exerted by said loading means on said member being diierent in different positions on said cam, a reset member operated by said single cam when and as it is manually moved between its multiple positions to operate said control means, said loading means including means for preventing operation of the control means when the iloading means is located between the different positions on the cam.
5. A manually adjustable condition responsive'device operated in accordance with a condition comprising, a housing having a top wall with a hole therethrough opening tothe top of the housing, control means in said housing, an actuator in said housing movable to operate said control means in response to a change in said condition, a plunger slidably guided in said hole for endwise up-anddown motion, a iirst spring confined underV compression between said plunger and said actuator, a sleeve slidably guided in said hole `for endwise up-and-down motion,
d said sleeve operatively engaging said contrJol means', a second spring confined under compression between said plunger and said sleeve, and cam means mounted on the outside of said top wall of said housing, said cam means acting upon said plunger and being manually oper-able to different positions to adjust the force exerted by said plunger on said actuator, the force exerted by said plunger on said sleeve between different positions of said cam member being sufficient to move the sleeve into contact with the control means to prevent operation of the control means, the force exerted by said plunger on said actuator being different in different positions of said cam means. 6. A manually adjustable condition responsive device according to clainr 5 including resetting means operated by said cam means as said cam means is manually operated between its diterent positions to operate said conv' posing torce, the cam including re-set lobes between each position and acting on thevfollower, the follower including a reset member acting on the switch when a lobe is eieotive to positively move the switch in a direction returning it to its normal position, and means effective only when the reset member is eiieotive to blocl; return of the switch to said normal position. Y
8. A pressure switch according to claim 7 in which the means comprises a rigid member limiting the switch motion toward the normal position so that when so limited the switch is biased to said normal position but held between its positions.
9. A pressure switch according to claim 8 including a second spring acting between the follower and the rigid member and effective to seat the rigid member against a iixed stop :for eiieotive limiting of the switch motion only when a lobe is eiective, said second spring being compressible to take up any overtravel of the follower with respect to the rigid member during resetting.
10. A pressure switch comprising, Ia housing including a diaphragm movable in` response to pressure variations, a snap acting switch of the type having elements stressed by an overcenter spring with one element carrying a contact movable between normal and actuated positions, an operative connection between the diaphragm and the switch, a spring for loading the diaphragm, manual-ly operable means for determining the degree of compression of the spring and actuatable to select any one of a plurality of compressive loads, reset means operative whenever the compressive load on the spring is changed to positively act on the switch to move it overcenter in a direction returning the contact to its normal position, and means operative only when 4the reset means is effective to prevent movement of the Contact to the normal position and to hold it in a position between said contact positions whereby movement to the normal position can occur only when the reset means has become inoperative.
1l. A pressure switch according to claim l() in which f the manual means includes a plunger mounted in the housing, the loading spring being compressed between the switch and the plunger, said last named means comprising a rigid member operative to seat against a housing portion and a second spring acting between the plunger and the rigid member and eiective to yieldably hold the rigid member seated as the plunger moves to reset theswitch, said member acting against one of the switch elements during resetting to prevent completion of movement of the Contact to its normal position.
12. A pressure switch according to claim 11 in which the manual means includes a multi-position cam having valleys determining the position of the plunger and the force of the loading spring, said valleys being separated by reset lobes, the reset means comprising a rigid projec- References Cited in the le of this patent UNITED STATES PATENTS Tyzack Nov. 19, 1957 Hager Feb. 3, 1959 Lung Dec. 29, 1959 Beller et al Apr. 26, 1960