US3529106A - Sanitary pressure switch - Google Patents

Description

Sept 15, 1970 c. w. LITTLE, JR S 3,529,106

SANITARY PRES SURE SWITCH l Filed Jam. 4, 1968 2i 6 54.

ev MJMJQWMMWW AT'TQRNEYS 3,529,106 SANITARY PRESSURE SWITCH Clarence W. Little, Jr., Brookfield, Wis., assignor, by mesne assignments, to Waukesha Foundry Company, Inc., a corporation of Wisconsin Filed Jan. 4, 1968, Ser. No. 695,753 Int. Cl. H01h 35/40 U.S. Cl. 200-83 7 Claims ABSTRACT OF THE DISCLOSURE Fluid is admitted under pressure to a tube readily removable for cleaning or replacement. A portion of the tube is indented between a fixed boss and a boss mounted on a lever which is subject to adjustable spring pressure and which, when displaced by pressure within the tube, actuates the operating plunger of a microswitch.

BACKGROUND OF INVENTION The instant invention was developed to meet a specific demand in the food industries for a sanitary pressure switch that would start and stop a pressurizing pump to hold a liquid food product within a narrow range of pressures.

All presently available commercial switches require the provision of extra operating parts exposed to the food and therefore necessitating extra cleaning work. Moreover, they are relatively expensive. It is further true of some of the commercially available switches that the switches themselves are exposed to contamination and to corrosion and are Aobjectionable from this standpoint.

While the instant switch has been developed for controlling pressure of liquids, the invention is applicable wherever pressure response is desired to be held within a predetermined range.

SUMMARY IOF THE INVENTION The instant device has solved all problems in that itis simple and inexpensive and holds the fluid within an adequately narrow pressure range without exposing either the fluid or the switch itself to any possibility of contamination, the fluid which effects the operation of the switch being confined within a tube which requires no special cleaning, either being a part of the food handling apparatus and periodically cleaned therewith, or being discarded and replaced from time to time.

The switch and pressure responsive apparatus are preferably connected. As disclosed, the connection is effected by a bracket which either supports the switch from the fluid-containing tube, or supports the actuating device from the switch.

In practice, the unitary assembly of bracket, switch operating mechanism, and switch have been hung on a disposeable tube. The bracket carries laterally spaced fulcrum pins with conical points engaged in sockets of greater taper angle formed in the pressure-responsive switch-actuating lever. The bracket further includes an adjustable spring support for the bifurcated free end of the lever for the regulation of the pressure at which the lever will yield to operate the switch.

Also mounted on the bracket is a tube-confining means through which passes the pressure tube upon which the assembly is suspended and within which is confined the` fluid whose pressure is to be regulated. In the preferred construction, the tube confining means comprises a chamber having a removable top to facilitate introduction and removal of the tube. The tube is compressed between a relatively fixed boss connected with the chamber top, and a relatively movable boss on the lever. These opposed 'United States Patent O ice 3,529,106 Patented Sept. 15, 1970 BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a view of an embodiment of the invention taken in section on the line 1-1 of FIG. 2.

FIG. 2 is a view in side elevation of the device shown in FIG. 1.

DESCRIPTION OF ,PREFERRED EMBODIMENT A uid under pressure is confined within the resiliently fiexible tube 6, which may be closed at one end or -may be an integral part of a fluid transporting system. The entire apparatus is preferably unitary and suspended on the tube. Alternatively, a base may be provided at 8 for the microswitch 10. This switch is a conventional piece of equipment including a threaded stem 12 through which the switch actuator 14 is reciproca-ble. Bracket 20 is adjustably positioned by the nuts 16 and 18 on the stem 12 to support the switch 10, or be supported thereby, as the case may be.

A lever fulcrum preferably comprises laterally spaced fulcrum studs or pins 22 which are desirably threadedly adjustable in the base 2.0. The pins have conical points 24. Their positions are fixed by set screws 26.

The apices 24 of pins 22 are seated in conical sockets 2-8 of greater angle, these being formed in the proximate surface of the switch operating lever 30. Thereby the lever is pivotally operable with precision.

The free end 32 of lever 30 is bifurcated to pass bolt 40 and is supported with adjustable bias by spring 34 on the bolt. A washer 36 spanning the bifurcation of leVer 30 provides one seat for the spring. The washer 38 on bolt 40 is adjustably supported by nut 42 to provide an opposite seat for the spring. The bolt 40 is mounted in the wall 44 of tube confining means, here exemplified by a pressure chamber 50. The position of the bolt is adjustably fixed by a set screw 46. The pressure switch is held to the bracket 20 by appropriate means such as the fiat head screws 48.

The resiliently fiexibly walled tube `6 extends through the tube confining means, where it is confined under pressure between opposing side walls and top wall 54 of the pressure chamber 50 and the lever 30 which serves as the bottom thereof. Preferably, tube 6 is not only deformed by flattening but somewhat indented by engagement therewith of at least one boss. Preferably there is a boss 52 on the removable top wall 54 of the pressure chamber and an opposing boss 56 which is carried by the lever 30. The spacing between these bosses is less than the undeformed diameter of tube 6.,Wing nuts 58 on bolt `40 and 60 on bolt 62 hold the top wall 54 to the.

chamber and permit ready removal thereof for the insertion or replacement of the tube 6.

Variations of pressures to which the iiuid in the tube 6 is subject will tend to permit the lever 30` to rise or fall subject to the adjustable bias of spring 34. The tube 6 will normally be made of natural or synthetic rubber or the like. However, even the relatively slight changes in temperature to which such a tube may be subject may result in changes of resilience in the wall of the tube, with resulting changes in the range of response of the switch 10. It is found that by the use of the bosses 52 and 56 for the deformation of the tube by indentation thereof, the variations in response, otherwise attributable to temperature-induced variations in tube resilience at a given bias of spring 34, can be minimized.

If the tube 6 is an integral part of the fluid handling aparatus, whatever that may be, it will be cleaned and sterilized by routine procedures, together with the rest of such apparatus. If not, it still does not require a separate cleaning operation because its cost is so low that the tube is disposable. It is only necessary to remove the top plate 54 to permit the tube 6 to be withdrawn, discarded, and replaced, if desired.

The balanced fulcrum provided by the adjustable pins 22 promotes accuracy of response of the lever 30' and accuracy is further enhanced by the fact that the resiliently walled tube 6 is deformed between the opposing bosses 52 and 56, which have the effect of minimizing the result of changes of temperature.

Contamination and dirt are preferably excluded from the vicinity of the switch 10 by the use of a housing 64. The uid to be controlled being permanently enclosed in tube 6, no packing is required and no leakage can occur to foul the switch.

The whole construction is extremely simple and inexpensive and has operated eifectively to hold within a narrow range the pressures to which the fluid in tube 6 is subject.

Because it may be desired to use the switch for various purposes, and because the pumps and other equipment used in pressure control are conventional, no showing is required as to these, novelty being predicated upon the device illustrated.

What is claimed is:

1. The combination with a tube for fluid under pressure, of a bracket having tube-confining means through which the tube extends and including an opposed plate and lever having tube-deforming portions, means on the bracket providing a fulcrum for said lever, a spring biasing a portion of the lever toward said tube, means supporting the spring, and a switch mounted on the bracket and having actuating means engaged by the lever to be operated when the tube expands to oscillate the lever on said fulcrum means against the bias of said spring, the tube-deforming portions of the plate and lever including at least one boss engaged with the tube, the spacing between said plate and lever portions being less than the undeformed diameter of the tube, the tube being somewhat indended by said boss.

2. The combination with a tube for fluid under pressure, of a bracket having tube-confining means through which the tube extends and including an opposed plate and lever having tube-deforming portions, means on the bracket providing a fulcrum for said lever, a spring bias ing a portion of the lever toward said tube, means supporting the spring, and a switch mounted on the bracket and having actuating means engaged by the lever to be operated when the tube expands to oscillate the lever on said fulcrum means against the bias of said spring, the tube-conining means comprising a pressure chamber having side wall portions with which sides of the tube are engaged, said plate being removable to open said contining means to provide an opening through which the tube may be introduced and withdrawn respecting said chamber.

3. A combination according to claim 2 in which said lever has a slotted free end portion, the slot being spanned by a spring seat with which said spring is engaged, a bolt connected with said chamber extending through the slot and being provided with a second spring seat adjustable thereon and with which is engaged an end of the spring remote from the lever.

4. A combination according to claim 3 in which the switch has a threaded sleeve through which said switchactuating means is operable, said bracket having an arm mounted on said sleeve, the fulcrum means for said lever comprising pointed pins mounted on said arm in laterally spaced positions, said lever having conically tapered sockets with which the extremities of said pins are en gaged.

5. A combination according to claim 4 in which the pins are threaded in said bracket arm and individually adjustable therein.

6. The combination with a tube for fluid under pressure, of a bracket having tube-conning means through which the tube extends and including an opposed plate and lever having tube-deforming portions, means on the bracket providing a fulcrum for said lever, a spring biasing a portion of the lever toward said tube, means supporting the spring, and a switch mounted on the bracket and having actuating means engaged by the lever to be operated when the tube expands to oscillate the lever on said fulcrum means against the bias of said spring, said switch having a stem in which its said actuating means is reciprocable, the said bracket being physically connected with the stem and having a portion projecting laterally therefrom, the fulcrum means being mounted on the lateraly projecting bracket portion and comprising transversely spaced studs with pointed ends, the lever having tapered sockets in which the pointed ends of said studs are engaged, said bracket carrying a pressure chamber constituting said tube-conining means and having side Walls between which said tube extends and with which the sides of the tube are in contact, the said lever and top plate extending across said chamber at opposite sides thereof, the top plate and lever having opposing bosses which are convex toward the tube and engaged therewith in pressure contact suicient to indent the tube.

7. A combination according to claim 6 in which means removably connects the top plate with the side walls of the chamber, said means including a bolt extending through one of said side walls remote from said fulcrum studs, the said lever being bifurcated to receive said bolt and the bolt having a spring seat washer engaging the lever, the said spring being seated against said Washer, the bolt having a second spring seat washer remote from said lever and with which said spring is also engaged.

References Cited UNITED STATES PATENTS 2,302,923v 11/ 19412 Zimarik. 2,439,561 4'/ 1948 Cressey. 2,520,660 8/ 1950 Sedgwick. 2,740,858 4/ 1956 Euler. 2,742,544 4/ 1956i Lovick. 2,885,506 5/ 1959 Anderson. 2,9923 02 7/ 196 1 Schuler.

ROBERT K. SCHAEFER, Primary Examiner J. R. SCOTT, Assistant Examiner

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