US2412095A - Pressure switch - Google Patents

Description

Dec. 3, 1946. R. w. MUERLE 1 PRESSURE SWITCH Filed Feb. 23, 1942 fig. 7

lllqllll [/2 06/2 tor Ez'chardCU/VI z/er/e A f for/2 e9 Patented Dec. 3, 1946 PRESSURE SW'ITCH Richard W. Muerle, Springfield, I ll.,- assignor to Montgomery Ward (SE-1C0. Incorporated, Chicago, 111., a corporation of Illinois Application February 23, 1942, Serial No. 432,051

4 Claims.

I 1 This invention is directed primarily to prevention of clogging of orifices or apertures in the baffle used for dampening sudden pressure variationsin fluid pressure switch apparatus such as is used on automatic water pumps, air compressors, I

and the like.

The invention is concerned particularly with the type of apparatus having a switch operating diaphragm forming part of a pressure chamber or other expansible chamben. Such a pressure chamber, in turn, communicates with a pump or compressor, or with a pressure tank, through a constricted orifice Or aperture in order to dampen out the pump pressure pulsations before they can reach the switch operating diaphragm. In such devices the orifice tends to clog from corrosion or caking, caused by foreign matter such as minerals and the like in the fluid beingpumped, and it is the primary object to provide means to prevent clogging of such orifice.

In ordinary practice, a typical arrangement is a pressure water system which comprises pump, an electric motor, a pressure tank, and a fluid pressure regulator or switch. This fluid pressure switch is connected to, or close to, the pressure side of the pump-that is, the side of the pump 1 from which fluid is forced into the pressure tank after leaving the pump.

Switches of this type usually are equipped with a standard switch mechanism in which the diaphragm is forced by fluid pressure to exert the necessary pressure on the standard switch mechanism to actuate the switch. In this arrangement, the current pulsations of reciprocating pumps may cause the switch mechanism to flutter, particularly if the tank is remotely located, in turn causing arcing and burning of contact points and consequent injury to the switch with possible failure of the mechanism. In this connection, it is not a rare occurrence for such arcing to lead to fusing of the contact points of the switch, resulting in continued operation of the motor and building up a dangerous pressure.

To counteract or dampen these surges or pulsations, it has been almost universal practice to restrict the water passage opening from the pump to thediaphragm pressure chamber of the switch by inserting into the water way a. plug or disc in which is usually drilled a small hole, commonly from .010 of an inch up-depending on the power unit involved. This resists flow so that the pulsations are sufficiently dampened to prevent fluttering or flickering,

' While this arrangement above described is generally satisfactory, it has the serious weakness or disadvantage that the small diameter holeclogs readily, particularly when the water contains such impurities as lime or other minerals, of corrosive composition. In actual use, the clogging of these small holes leading to the diaphragm is more frequent than would ordinarily be supposed,

and'it is a persistent source of trouble and danger where-clogging and stoppage occurs. As the pressure'drops in the tank, th motor will start and will not cut off, and dangerous pressures may result. It will be appreciated that the smaller the aperture, the more effective will be the damping action and the more likely the aperture to clog. Thus, by providing means preventing such clogging, the aperture may be made smaller and more effective.

It is therefore an object to provide a means for keeping the orifice from the water way to the diaphragm pressure chamber open.

It is a further object of the invention to provide a diaphragm having means projecting into and automatically moving (with changes in pressure) in the orifice, which means operates to keep the orifice open at all times.

It-is-a further object in this connection, to provide a diaphragm which has a wire or spring attached thereto or operated thereby, in such arrangementthat the wire or spring extends into the orifice whereby movement of the wire will occur under changes of pressure, forceably breaking loose any obstruction, deposit or corrosion tending to close the orifice.

It is a further object to provide such an arrangement in which the wire is wavy or angular or provided with projections or serrations which serve to cut, scrape, or break the deposits of lime or other foreign material in a very efficient manner.

It is another object of this invention to provide a modified construction in which the pressure chamber is intercepted by a disc or supplemental diaphragm construction having one or more slits or slots, the arrangement being such that movement of the switch diaphragm distorts said intermediate diaphragm, whereby lime and other deposits and the like will be broken loose under the stress of said distortion.

Other objects and advantages of the invention will appear as the nature of th improvements is better understood, the invention consisting substantially in the novel construction, combination and arrangement of parts hereinafter fully described, illustrated in the accompanying drawing, and finally pointed out in the appended claims.

In the drawing:

enacts Figure 1 is a fragmentary sectional side elevational view showing my improvement as applied to a conventional switch, only a portion of the switch mechanism being shown and the cover or box being cut away;

Figure 2 is an enlarged side elevational view showing a desirable form of projecting wire member or orifice cleaner which attaches to the diaphragm;

Figure 3 is a bottom view of the device of Figure 2;

Figure l is a fragmentary perspective view showing one form of my device as applied to the diaphragm of a conventional pressure switch;

Figure 5 is a plan view of a modified construction showing a disc member with slits or slots;

Figure 6 is a fragmentary side elevational view showing the device of Figure 5 applied to a conventional switch mechanism; and

Figure 7 shows a schematic arrangement of a pump and motor with a pressure switch (of the type described herein) attached, the View being a side elevational view.

Referring more in detail to the construction shown in the various figures, there is illustrated an embodiment of the invention as applied to a conventional fluid pressure switch. Figure '7 illustrates a typical fluid system in which a switch of this type is embodied. The device shown in Figure '7 comprises a motor 112, the pump 43 and a storage tank for water and the like 2 5. This tank 44 is the pressure tank to which the switch (here shown in its entirety as switch it) is attached. Conventional electrical connections lead from the switch 45 to the motor 42, and the pressure line or pipe 3| connecting the pressure tank to the switch, as hereinafter more fully described, is shown.

Referring next to Figures 1 and 4, in particular, the switch 45 comprises a switch housing ll, shown here in fragmentary form. One conventional switch embodiment comprises a pressure spring i2, which is held in position by means such as a bolt l3, attached to the switch housing i I. This bolt I3 is provided with a nut It threaded on the bolt, and a washer orferrule I5. The-tension of' the spring i2 is adjustable by threading the nut I4 up or down on the bolt The spring l2 exerts downward pressure on one end of a rocker arm I 6, tending to resiliently bias the rocker arm to one position. This rocker arm is journaled at I! and is movable about the journal as an axis within the limits permitted by the other mechanism of the switch.

A diaphragm plate or base [8 is provided with upwardly extending prongs 20 resting against the rocker arm IS. The pronged plate I8 is situated on or attached to a diaphragm l9 and moves therewith. In the ordinary construction of the switch the rocker arm I6 is bifurcated, and there are two upwardly extending prongs from the pronged plate 18.

The rocker arm It is attached to a spring member 22 which, in turn, engages a movable arm 23. This movable arm 23 preferably is pivoted on trunions 2e, and the opposite or free end of the arm carries a contact point or points 25. a

In actual operation movement of the rocker arm 16 upwardly under pressure of the pronged plate I8 (or otherwise), shifts the direction of pressure on the spring 22, causing the movable arm 23 to move downward at its free end, separating the contact points 25 from the contacts 26 which are in turn ordinarily connected to the electrical starting and operating circuit of a motor and thus providing a circuit breaking snap action.

When the upward pressure is taken 01f of the upwardly extending pronged plate l8, as by downward movement of the diaphragm l9, the pressure spring l2 will move the rocker arm l6 downwardly at its outer end shifting the movable arm 23 and thereby change the direction of pressure on the spring 22, thus moving the movable arm 23 and causing the contact points 25 to snap into contact position with the contacts 26, in the position shown in Figure l.

The diaphragm is securely held in place on the housing H by means of a cover plate 27, which is in turn held in place by small bolts 28, as will be seen in Figure 4. The diaphragm L3 is pressure responsive and fits over an opening 29, see Figure 4, in the housing Ii, preventing water entering the switch housing and damaging the mechanism. The cover plate 27 forms, with the diaphragm It, a pressure chamber 30, sometimes herein referred to as diaphragm pressure chamber. The switch housing is coupled to a pressure line from a pump or pressure tank by pipe means, or otherwise, 3! (see Figure 7 which threads into or otherwise attaches to the inlet 32 of the pressure chamber 39. The pressure chamber proper is separated from the pressure line or pipe 3!, preferably at the inlet 32, by means such as a bafiie or plug 33 as shown in Figures 1, 2, and 4. The baffle 33 ordinarily is provided with a hole or opening of small size, but sufficiently large to permit water under pressure to pass therethrough from the pressure line or pressure tank, whereby the pressure in the pressure chamber 30, is varied according to the pressure in the pressure tank or pump, as the case may be. Change in pressure in the pressure chamber 33 operates to move the diaphragm l9 thus actuating the switch mechanism. The constructions now commonly on the market are arranged in the above described manner. the opening or hole being only large enough to reflect a change in pressure rather slowly, but not being large enough to allow pulsations from the pump or other vibration in the water system to move the diaphragm it suddenly or materially by changing the pressure in the pressure chamber 30, and by vibrations cause flickering of the switch mechanism with consequent damage to the switch, and the other objections heretofore mentioned.

In the past, the most serious objection to the arrangement above described has been that most water systems carry water with more or less mineral content such as lime, or carry corrosive water and the hole or opening in the bevel becomes plugged and closed. If this should happen when the pump is running, a dangerous pressure would be built up in the system because the liquid pressure in the pressure chamber 39 would not vary enough to move the diaphragm and cut off the motor.

To remedy this situation, I provided means for keeping the hole clear of closing obstructions, such as the projecting member 34 shown in detail in Figures 2 and 3. This member 34 is attached to the pressure chamber side of the diaphragm l9 and extends through the hole 35 in the baflie 33. Preferably this projecting member 34 is in the form of a wire long enough to extend to the hole 35 regardless of the position of the diaphragm 19 within the limits of normal operation. The projecting member 34 is preferably provided with the crimps, serrations, small undulations, wrinkles or the like, such as shown at 3B. These, in moving through the hole 35, serve to break loose scale or deposits tending to plug the hole 35, or to scrape the hole clean, whereby the hole is maintained open at all times.

A simple arrangement for attaching the projecting member 34 to the diaphragm I9 is provided by the use of coils, as shown in Figure 3, which may be fastened to the diaphragm by any convenient'means such as by the retaining member 31 preferably made of leather or fabric material, metal or the like, and attached to the diaphragm l9 in any convenient means such as by sewing, cementing or bradding. In the arrangement shown the coils of the projecting member 34 fit between the retaining member 31 and the diaphragm l9, with the projecting portion containing the crimps 34, passing through the retaining member 31.

Obviously, burrs, serrated edges and the like would be effective instead of the crimps 36, and are believed to be the equivalent of the crimps for the purposes herein described.

The member 34 may be made out of stainless steel, spring wire, or other suitable materials and instead of the coils, may consist of a disc with a projecting member. While elimination of the crimps 35 still presents an improved arrangement over the devices now on the market, the preferred embodiment having the crimps seems superior.

The bafile 33 may be constructed of metal, Bakelite, or other material having sufficient strength to resist sudden changes in pressure caused by pump vibrations, or the like, and dampen such vibrations.

In the modified construction shown in Figures 5 and 6 the switch mechanism is the same but I have provided a disc 33 which is preferably made of light springy material such as a very light gauge spring steel. The disc takes the place of the baflie 33 as will be clearly apparent from Figure 6. Said disc contains slits 39, which are preferably small and serve the purpose of the hole 35.

In order to keep the slits 39 from closing" with lime deposits, corrosion or the like, the diaphragm 19, which is separated from the disc by the annular rin 40, is caused to bear against the center portion of said disc by one or more lugs 4 l. These lugs 4| may be either attached to the diaphragm l9, or the disc 38, or both, whereby the movement of the diaphragm will distort the disc, causing shearing action between the portions on opposite sides of the slits, which will serve to break the scale or deposits loose from the diaphragm surface as well as the slits and keep the waterway open.

The form of the invention herein shown and described presents a preferred embodiment thereof, and delineates its adaption to practical use, but it is to be understood that the present disclosure is to be considered from the illustrative standpoint and not as imposing restriction or limitation on the invention.

While I have herein shown and described certain features of my invention, still I do not wish to limit myself thereto, except as I may do so in the claims.

I claim:

1. In combination with a switch having fluid pressure actuated electrical contact means including a movable diaphragm, baiile means between said pressure responsive means actuating said electrical contact means, and a source of fluid pressure, a hole in said baiiie means for the passage of fluid under the pressure therethrough, said hole being restricted in size whereby the flow of fluid in response to pressure changes is restricted, and means maintaining said hole open against clogging due to deposits of foreign material, said means comprising a wire formed into a spiral base, and a centrally extending crimped portion, said base being secured to said diaphragm, and the crimped portion extending into said hole and adapted to move with respect to said hole upon movement of said diaphragm.

2. In an electrical switch of the type actuated by pressure transmitted through a movable diaphragm, the improvement which comprises the combination of baflie means provided with a surge-dampening orifice and a cleaning pin extending through said orifice and attached to and movable with said diaphragm, said pin being of sinuous contour so that foreign matter adhering to the periphery of said orifice will be broken away by the movements of said pin and so that there will always be an opening on at least one side of the pin, whereby permanent plugging of said orifice is rendered substantially impossible.

3. In a switch having movable fluid pressure responsive means and electrical contact means lactuated by said movable pressure responsive means, the improvement which comprises bailie means positioned between said pressure responsive means and a source of fluid pressure, said means being provided with a hole for the passage of fluid under pressure, said hole being restricted in size whereby the flow of fluid in response to pressure changes is retarded and restricted, and cleaning means mounted upon and carried by said movable means extending into said hole for maintaining said hole open against clogging due to deposits of foreign material, said cleaning means being sinuous in form at such portions as extend into and through said hole, whereby said cleaning means may catch upon and break away foreign deposits tending to clog said hole upon movement of said cleaning means relative to and axially of said hole.

l. In a fluid pressure operated device having a pressure chamber at least a portion of one wall whereof is movable, means providing an orifice for admitting and emitting fluid under pressure for actuating said movable wall portion, and cleaning means extending into said orifice and movable axially thereof in response to movement of said wall portion, said cleaning means comprising a crimped rod, the movement of which axially in said orifice acts to break away foreign matter and deposits and thereby to clean said orifice.

RICHARD W. MUERLE.

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