US1834517A - Pressure operated electric circuit controller - Google Patents

Description

Dec. 1, 1931. E. J. DASHNER PRESSURE OPERATED ELECTRIC CIRCUIT CONTROLLER Filed Jan. 4, 1929 Patented Dec. 1, 1931 UNITED STATES PATENT OFFICE EMERY J. DASH'NER, OF BELMONT, MASSACHUSETTS, ASSIGNOR TO J. E. MCALMAN, OF

WINCHESTER, MASSACHUSETTS PRESSURE OPERATED ELECTRIC CIRCUIT CONTROLLER Application filed January 4, 1929. Serial No. 330,312.

This invention relates to systems of electric circuit control in which the circuit is opened and closed by a main switch operated by a relay device, which in turn is governed by a primary switch. Its object in this regard is to provide in a primar switch for the purpose indicated, adjusta le pressure operated means for causing the relay con trolling circuits to be opened and closed at definitely established limits of a pressure or temperature ditferential. That is, my ob ect is to enable the differential between the pressures or temperatures at which the main switch is respectively opened and closed to be set, adjusted and maintained at accurate points in a range of temperatures or pressures.

In another phase the invention relates to features of construction of a pressure operated switch with the object of improving the same in particulars which are described in the following specification.

These and other objects and the princi les of which the invention consists can be est set forth in connection with a detailed description of one embodiment of the invention Fig. 5 is a cross section on line 5-5 of Fig. 3;

Fig. 6 is a cross section similar to Fig. 5, but showing a dilferent form of switch con; taining certain features of the invention which are claimed herein;

Fig. 7 is a wiring diagram of a circuit conwhich may be a heating coil or other heating unit, an electric motor, a set of electric lights,

or any other contrivance operated by electric current under circumstances of use which require the current flow to be turned on and oil from time to time. 1) represents genericalw ly a relay switch device, which may be an apparatus of any character adapted to close and open the circuit in which the load is included, under control of different primary electric circuits, current flow through one of 55 which causes the relay switch to be closed, and flow through the other of which causes the relay switch'to be opened. 1 is the controller in which particularly the present invention is embodied, the same being connected with the relay device by three wires, herein designated as C, H and L, respectively. C is the center wire of the three and is in connection with the source of current, whatever that may be, which delivers current to the load circuit. When thecircuit is completed between wires C and L by the controller 1, the

relay is operated to complete the circuit through the load, and when connection be tween C and L is broken, and a connection is made from C to H, the relay switch in the circuit of the load is opened. That is, these results occur when the conducting elements of the circuit and of the controller are'ar ranged and connected as shown in the present opposite to those just described will occur.

; construction, the back may be made as a casting having a peripheral flange 9 rabbeted at its edge to receive the side walls 3; such side walls may be made of a section of seamless tubing of suitable diameter and length, and the cover may be made of sheet metal with '1 its flange 4a drawn or spun at its circum- The dial 7 is supported by being ference. fastened to two, or permissi y a eater number of, lugs 10 which are partially severed from the side walls by cuts extending inwardly from the forward edge thereof, and bent toward the interior of the case.

A base plate-11 'of insulating material is mounted on the back of the case, in an adjustable manner presently described, and on this plate are fastened bars 12 and 13 of conductmg material and a pivot 14 of a lever 15, which likewise is made of conducting material. The bar 12 is connected by a conductor 16 with a binding post 17 to which also the wire H is connected. Said bar contains a socket 18 in which is a sliding contact piece 19 under pressure of a spring, shown in Fig. 5, which tends to ex 1 it from the socket to the limit permitted a stop 20 on the stem of the.contact piece. The bar 13 is connected by an electrical conductor 21 with the binding post 22 to which the wire L is connected. In

this bar is a stationary contact 23 which re jects toward the contact 19 and is secure by a set screw 24 in a manner permitting it to be adj usted endwise so that it will protrude more or less. The lever 15 is connected by means of a conductor 25 with the binding post 26 to which the wire G is likewise connected. This lever extends between the contacts 19 and 28 and has opposite faces adapted to en distance between such faces, the distance to which the sliding contact 19 projects, and the range of adjustment of the contact 23 have such values that the lever may be caused to leave either contact when coming into engagement with the other, but theexcess of space between the contacts may be diminished to the vanishing point.

A curved spring tube 27 of flattened cross section, closed at one end and open at its other end, is secured to a socket 28 with its open end. entering the socket and in communication with the passage 29 therein. Such socket passes through the side wall of the casing and is provided with flanges which are secured thereto by screws. This 5 ring tube corresponds to the familiar Bour on spring of a pressure or vacuum gauge, and the socket to the usual socket of such gau es. To the socket is connected a pipe 30 which conducts fluid, whether liquid, gas or vapor, from any source whatsoever,

The spring tube is desi ed to shift the switch lever 15 when flexe by variations in its contained fluid pressure,-and to that end a lost motion connection is provided consistin of a bar 31 carried by the sprin tube, and a oop or frame 32, through whic said bar extends; the loop or frame being secured on the end of'a post 33 which in turn is rigidly secured to an arm 34 projecting forwardly from the lever 15. By this means, distortion of the spring tube caused by increasing-pres-- to return into engagement with the fixed contact, being actuated tothat end by a spring 35, and by gravity also when the controller is placed 1n an upright position. The spring 35 is here shown as made of a length of spring wire coiled about a stud 36, which holds it in position, and pressing at one end on the switch lever at a point remote from the pivot of the latter, while its other end bears on the hub portion of the lever which serves as an abutment. 7

The bar 31 previously mentioned extends approximately parallel to a portion of the spring tube 27. It is connected to the spring tube by arms 37 and 38 at its opposite ends which are soldered or otherwise suitably fastened to the spring tube. The arms 37 and 38 ma be conveniently made from the opposite en s of a. single, suitably bent, piece of wire, the central part of which is passed through the tubular bar 31 which is a sleeve or sec tion of tubing made of rubber or other suitable insulating material. However, an equivalent structure may be constructed other wise as to its details. Important features, however, are that the bar has substantial length, is spaced away from the s ring tube toward the center about which t e tube is curved, and has substantially less width than the space enclosed by the loop or frame 82, as well as that it extends generally arallel to that part of the spring tube besi e which it lies. These characteristics permit lost motion between the spring tube and the switch arm and likewise permit an adjustment whereby the switch will be operated on a greater or less pressure diiferential.

To permit of the adjustment last referred 39 which passes through a hole in the back of the case and has a flange 4O bearing against the inner surface of the back wall, to which the base plate 11 is secured. An arm 41 on the outside of the back wall is secured to the protruding end of the pivot, the latter preferably having a non-circular outline and the arm 41 having a hub with a hole complemental thereto, which is held thereon by the overlying head of a screw 42 threaded into the pivot stud. The adjusting arm 41 has a -widened slotted part 43 throu h which rotrudes a stud 44, mounted on t e back the of the loop 32 in paths approximately conb case and carrying a clamp nut 45. The arm also has a handle or finger piece 46 extending beyond the circumference of the case. By means of this handle the entire switch (comprising the base plate, contacts and switch lever, with their electrical connections) may be rotated as a unit about the axis of the case within the limits of the slot in the ad'usting arm. As the s ring tube 27 is curve about a center near t eaxis of the case, these ad justments shift the inner and outer membersv centric with the tube. Thebar 31, however,

i is not concentric with the axis of adjustment but is so inclined that, when the switch is in one extreme position, that illustrated in Figs. 1, 2, 3 and 5, the lost motion between the bar and the upper member of the frame is a maximum, while in the other extreme adjustment, shown in Fig. 4, the lost motion is 8.

a minimum. -In the tter position, moreover, the frame is brought nearer to the end pointer or index 8, and for that purpose a pair of arms or jaws 47 are connected to the 4 index and receive between them a rod 01 finger 48 which is mounted on the switch base 11. As a convenient detail of construction,

the 'aws or arms 47 are made as integral proshaped bar 49, the ends of which are parallel to one another and are apertured and placed upon a fixed stud 50 which is mounted in a lug 51 on the socket 28, and serves as a pivot. The index 8 is secured to the forward end or leg of this U-shaped bar. This construction enables the U-sha ed bar and the jaws 47 to be formed out o a single blank of sheet metal.

The foregoing description is given with reference to the normal or relaxed condition of the spring tube, which is the condition shown in the drawings. The action of a Bourdon spring, of which the tube 27 is one example, when distorted by increasing internal pressure, is to approach a straight line, and that part of the tube to which the bar 31 is attached moves in a direction conforming in 32 is constrained by the pivot 14 to move.

The first part of this movement has no effect on the switch, when the adjustment is such that any space is left between bar 31 and the top of loop 32, but after the bar 31 has crossed-the space provided for lost motion it engages the upper member of the loop and withdraws the switch lever from contact 23, shortly afterward bringin it into contact with the other contact 19. y means of the adjusting arm 41, the preliminary 10st motion may be varied between zero and any desired maximum; while by adjustment of the fixed contact-23 the movement of the switch lever after leaving one contact and before reaching the other may be made as great or little as desired, some lost motion being necessaiiy in all cases, however.

11 the foregoing description it has been assumed that the shifting of the switch occurs between atmospheric pressure and pressures higher than atmospheric. However, the same principles are applicable to situations in which the action is controlled y vacuum conditions. The same Bourdon spring, or other pressure responsive a ent, which is displaceable in one direction mm a condition of rest by internal pressures greater than atmospheric, is displaceable in the opposite direction by atmospheric pressure when a artial vacuum is created in its interior. A are reversal of the contacts 19 and 23 is sufiicient to make the controller hereinbefore described operate under vacuum conditions; and indeed it may be so of the spring tube whlch has the greatest amplitude of movement when distorted by pressure. I

operated even without such reversal by ad justment or arrangement of the parts in such fashion that the switch lever engages the contact 1 9 and'is se arated from the contact 23 when the Bour on spring is in the normal position of rest. 9

-A somewhat different construction organized for vacuum operation is shown in Fig.

6. In this case the normally stationary contact 23a is carried by a bar 52 projecting from the base 11a, and the circuit is closed and opened by movement of a contact 1902 into and out of engagement with the contact 23.

The movable contact 19a is virtually a re-v versed duplicate of the contact 19 except that I y in place of the stop collar 20, a frame 53 is secured to its protruding shank, and its gulde 1s ofiset so that it may be embraced y such frame. The to bar of the frame lies beneath the operating bar 31 (when the controller'is in t e position shown in the drawlugs) so th t contraction of the Bourdon spring by vacuum causes the movable contact to be Withdrawn from the fixed contact. In

other respects, including the capacity for adj ustment of the switch and the effects obtainable thereby, this form of controller is essentially like that previously described.

Inasmuch as the controller connected in gages either contact, current flows only long enough-to actuate the relay so as to open or close the main switch, as the case may be, and the relay may be operated b a current of small magnitude, and after eing operated breaks the circuit. That is, various relay devices known to the art do so, and my controller is desi ned to cooperate with such relay devices. hen used in such conditions there is no sparking or tendency to create an electric are when the switch arm is withdrawn from either contact. The form of switch shown in Fig. 6, however, is adapted to carry a heavy current continuously and for that purpose its contacts are large and massive, having plane faces which are perpendicular to the line in which the contact 19a is constrained by its guide to move. Thus the contact members have a multitude of points in contact when they are brought together, through which current may flow, and such points are simultaneously and equally separated when the movable contact is withdrawn from the other; wherefore the heating efiect at the contact area is small even though a large current is passed, and sparkin upon separation is largely prevented.

ontrollers embodying the principles of this invention are usable in many situations for a great variety of purposes, whether for the purpose of generating heat, mechanical power, or light. The actuating force in the controller here illustrated is pressure, which may be created in a fluid by heat or by mechanical power. If control by temperature differential is desired, the pipe or tube 30 may be connected with a closed bulb or the like containing the fluid, and if the limiting temperatures are both low, the fluid used may be a volatile fluid having a low boiling point. Or the pressure may be transmitted by expansion or contraction, without vaporization, oi a liquid; or by like actions of a fixed gas.

The Bourdon s ring here shown is merely one illustration 0 a pressure responsive element. Other pressure responsive devices are known and may be applied to the purposes of the invention as equivalents of the specific one shown. Since pressure developed by heat is a function of the temperature, t e pressure responsive element when used under temperature control. is likewise a temperature responsive element, for which various other equivalent temperature responsive devices of specifically different construction may be used within the scope of the invention. Therefore the term temperature responsive element is used in a generic sense to include all equivalent devices which are distorted by temperature diiferences, whether by direct effect on the element or indirectly through conversion into pressure differences, or are capable of being so distorted.

What I claim and desire to secure by Letters Patent is:

1. A circuit controller comprising a curved temperature responsive element, an electric switch mounted for angular adjustment about-an axis nearly coaxial with the curvature of said element, a bar carried by said element and extending generally len thwise thereof near the end thereof which as the greatest movement when distorted in response to temperature changes, a frame connected to the circuit closin and opening member of said switch having a portion crossin said bar adapted to be engaged and moved y the latter when the temperature responsive element is distorted.

2. A circuit controller comprising a curved temperature res onsive element, an electric switch mounte for angular adjustment about an axis near the center of curvature of said element, a bar carried by said element near the end thereof which has the greatest movement when distorted in response to temperature changes, a frame connected to the circuit closing and opening member of said switch having a portion crossing said bar adapted to be engaged and moved by the latter when the tern )erature responsive element is distorted, sai bar occupying a position inclined to the path in which the said frame portion is moved by adjustment of the switch, whereby such adjustment causes a distance of varying width to exist between the bar and frame ermitting greater or less movement of t c temperature responsive element to occur before the switch member is shifted.

3. In a controller of the character described, an angularly adjustable switch, an

index pivoted independently of the switch, and a rejection on said switch engaging said in ex at one side of its pivot and arranged to move the index angularly when the switch is so adjusted.

4. In a controller of the character described, an adjustable movable switch, a bar having upturned parallel apertured ends, a stationar ivot occupying the apertures therein and aliout which the bar is oscillatable, saidbar having also arms or jaws extendin side by side from its opposite edges, an index secured to one of the upturned ends of the bar and a projection from the switch entering between said jaws adapted to move the same and the index about said pivot when the switch is adjusted.

5. A circuit controller comprising a casing, a switch base mounted in said casing with provision for rotative adjusted movement, separated electrical contacts and a pivoted switch lever between them, mounted on said base and insulated from one another, separate conductors leadin respectively from said contacts and switch lever a and ads ted to be se arately connected with the con uctors of a t rec-wire electrical stern, a curyed temperature responsive e ement mounted in said case substantially coaxial with the switch base, being secured at one end and free at the other, a bar carried by said element near the free end of said element and extending generally longitudinally thereof; and a frame connected to said switch lever and having a member extending across said bar and the path of movement thereof.

' In testimonyv whereof I have afiixed my signature. EMERY J. DASHNER.

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