US2041658A - Hygroscopic controlling mechanism for an electric circuit - Google Patents

Description

May g; i936@ W. B. HODGE HYGROSCOPIC CONTROLLING MECHANISM FOR AN ELECTRIC CIRCUIT Filed Jan. l5, 1934 ZMLGS lnvenor.

WiHum B. Hodge byfaw wif/SWW ATB/s.

Patented May 19, 1936 UNITED STATES PATENT OFFICE HYGROSCOPIC CONTROLLING MECHANISM FOR AN ELECTRIC CIRCUIT Application January 13, 1934, Serial No. 706,574

6 Claims.

This invention relates to improvements in hygroscopic controlling mechanism for an electric circuit and is particularly adapted for controling mechanism for supplying moisture to the air of an enclosure.

In usual types of regulators for controlling the supply of moisture to the air of an enclosure thermo-sensitive or hygroscopic elements are employed to control a relay having an electric circuit of low voltage which in turn controls a commercial circuit of higher voltage having means for actuating the valve or valves which control the supply of moisture delivered to the air of the enclosure.

One of the principal objects of the present invention is to provide a regulator of simple and eflicient construction embodying an instantaneous non-sparking switch for controlling a commercial circuit carrying a current of the usual 110 or 220 volts having means for directly actuating the valve or valves of the humidifying system to turn on or off the supply of moisture to the air.

Another object of the invention is to provide a regulator of this character of such sensitivity and accuracy as not only to be applicable to the severe requirements of industrial service, but which may be made of such small size as to be conveniently attached to the structure of selfcontained electrically-motivated humidiers for non-industrial service.

Another object of the invention is to provide a regulator of the character described with manually operated means which may be employed alternatively to interrupt or resume the operation of the regulator itself and of the apparatus controlled by it without in any Way disturbing the adjustments or operating mechanism of the regulator or the controlled apparatus.

Most of the relatively inexpensive regulators which are now available for household and other non-industrial service in general are characterized by sensitive elements composed oi rigid materials, such as wood, and other similarhygroscopic materials. Elements of this nature are commonly preferred for such service because of the considerable force which they are able to generate and transmit in response to variations in the humidity and which forces are commonly utilized for purposes of switch or valve actuation. The movements, however, of such elements due to their dimensional distortion in consequence of changing humidity are relatively slow and so minute that levers, or other multiplying means, are usualy necessary to transmit these motions to produce the necessary actuation of the switch (Cl. ZOU-52) or valve. Certain other hygroscopic materials, such as hair, and yarns composed of certain textile materials, and the like, are known to respond more quickly to variations in humidity and to experience greater dimensional distortion by change in length than the more rigid materials. Such flexible materials,v however, being elastic and flexible are less capable of generating and transmitting forces of the intensity generally required for regulator actuation and are much more susceptible to permanent impairment by excessive strain. They have, therefore, been chiefly used only in regulators of relatively expensive construction, while the cheaper forms of regulators have relied chiey upon the rigid materials.

The present invention comprises means of a simple and inexpensive nature for utilizing the more sensitive flexible hygroscopic materials in such manner as to attain a degree of accuracy and sensitivity that is unusual in devices of simple and inexpensive construction.

My invention contemplates the employment of certain types of instantaneously acting switches, such as snap switches having a iiexible resilient member subject to a distortional stress, maintaining the member in a certain predetermined position, as opened or closed position, and which may be operated by the proper application of pressure of comparatively small value to cause the switch to change from its normal condition, whether open or closed, to the opposite condition.

Other instantaneously acting switches, and non-sparking switches such as Mercoid switches, may also be used in connection with my invention. Switches of these types are capable of opening and closing usual commercial one hundred ten and two hundred twenty volt circuits, so that regulation of the humidifying device may be accomplished without the use of relays which are employed in usual types of regulators, and the elimination of such relays obviously greatly reduces the expense of the equipment.

Where the actuating element for the switch is of rigid material it is usually necessary to employ lever systems, or other equivalent means for multiplying the expansion or contraction of the hygroscopic element in order to produce the necessary movement of the switch-operating member. It is also necessary to provide springs or other mechanical devices for absorbing any surplus expansion or contraction of the actuating member above that value which produces actuation in order to avoid structural strains that otherwise would be caused.

Where the actuating element for the switch is of flexible hygroscopic material, resilient means, such as spring mechanism, has heretofore been employed to relieve the strain upon the hygroscopic element produced by extreme changes in humidity beyond the point at which the regulator is set to operate, and the additional continued strain produced by the spring, after the switch has been actuated, is likely so to stretch the hygroscopic element as to cause it to lose its initial adjustment setting. For example, if a humidity controller is set to close an electric contact at (S0-degrees relative humidity, thereby completing the circuit to actuate a valve of the humidifying system, and the humidity of the atmosphere should continue to become lower, there would be an additional strain upon the hygroscopic member which would cause it so to stretch that it would lose its initial adjustment.

The tendency to stretch the hygroscopic element by continued strain produced by the spring, when the hygroscopicI element becomes moist by higher humidities, is more pronounced and such strain consequently more readily causes the hygroscopic member to lose its initial adjustment setting.

IThe present invention avoids all necessity for the use of either of these compensating expedients by making use of a simple metallic weight supported by a flexible element composed of hygroscopic material subject to elongation in response to rising humidity and contraction in response to falling humidity, such as gold-beaters skin, gut, or other membranous material. Preferably the weight is so suspended as to be located directly above the operating member of the switch. The weight has suflicient mass when resting upon a strut or stylus engaging the operating member of the switch, as to cause the actuation of the switch and the length of the hygroscopic element is such that its change of length due to the permissible variation in humidity and corresponding vertical travel of the weight slightly exceeds the required vertical operating movement that is characteristic of the switch.

By reason of the construction above described the tension imposed upon the hygroscopic member by the weight is immediately relieved when the weight rests upon the switch or its operating member, or the casing enclosing the switch, and if the humidity continues to rise no additional strain is imposed upon the hygroscopic member which would continue to stretch it. When, upon the other hand, the weight is raised by the hygroscopic member out of contact with the switch or its actuating member by reason of decrease in humidity of the air of the enclosure, the drying out of the hygroscopic member decreases its tendency to stretch, and as no additional strain is imposed upon the hydroscopic element by a spring, or otherwise, it will not be caused to lose its initial adjustment setting. It has, as a matter of fact, been found in actual practice that although the hygroscopic member embodying the present invention has been left in a quiescent state for several months its operation can be resumed upon practically the same initial setting.

The hygroscopic element must have sufficient tensile strength to support the weight without being strained beyond its elastic limit and such strength may be provided either by composing the element of multiple strands in suflicient number or by selecting an element of the character described of sufficient width and cross sectional area to insure the necessary strength. Because of the superior sensitivity of a hygroscopic element of this type and the elimination of unnecessary mechanism heretofore employed, it is possible to provide a hygroscopic controlling device ior an electric circuit of very compact dimensions and one which is chiefly characterized by its direct actuation of the switch by the vertical movement of a weight in the absence of multiplying and strain-absorbing mechanism.

Where the controlling device is employed for the regulation of a commercial electric current, it is essential to the purpose of my invention that the switch should have instantaneous actuation both in opening and closing to insure the prevention of sparking and consequent corrosion and deterioration of the Contact surfaces which otherwise would be unavoidable.

These and other objects and features of the invention will more fully appear from the following description and the accompanying drawing and will be particularly pointed out in the claims.

In the drawing:

Fig. 1 is a view, mainly in vertical section, of a preferred form of the invention;

Fig. 2 is a detail view of an upper portion of the apparatus shown in Fig. 1 in vertical section at ight angles to the section shown in Fig. l; an

Fi'g. 3 is a diagrammatic view illustrating another method of supporting the weight upon the flexible hygroscopic element and illustrating the advantage in the vertical movement of the weight obtained by such construction.

The preferred embodiment of the invention illustrated comprises a frame having a hollow, preferably rectangular, base l provided with end flanges 2 having suitable screw holes by means of which the same may be secured to a post wall or other support. The top of the base de-7 sirably is provided with an upwardly extending annular flange 3 forming a seat for a metallic tubular member 4 which is provided with a suitable aperttue 5 to permit the passage oi air therethrough. The tubular member' 4 encloses and provides a guide for a weight 6 which is suspended by a hygroscopic element l in a suitable support in the upper end of the tubular member, as will hereinafter' more fully appear.

An instantaneous switch adapted to be operated by the raising and lowering movements of the weight, in response to varying conditions of humidity, is mounted in the hollow base. The instantaneous switch may be oi any suitable tvpe for controlling a commercial electric current` of one hundred ten or two hundred twenty volts without producing such sparking as will cause deterioration of the elements of the switch. Desirably an instantaneous snap switch is employed. but it will be readily understood that ahtilting Mercoid switch, a switch in which the conducting terminals are located in a Vacuum, or other types of instantaneous or non-sparking switches may be used.

The switch, which is illustrated in the accompanying drawing, is a snap switch of standardized construction that is available in the open market, and comprises a casing or" rectangular form having a base 8 of insulation which is suitably secured to` the bottom of the hollow base of the frame and rectangular vertical walls 9 which enclose terminals IU and l! for the electric circuit which is supplied through conductors IE! and !3 to the respective terminals l0 and l I. The movable switch element comprises a iiexible resilient thin plate I4 which is xedly secured to the terminal I I and which has been subjected to an initial distortional stress of suflicient value normally to maintain the free end thereof in contact with the terminal IIJ thereby to eect a normal closure of the circuit.

The plate I4 is of such character, due to the initial stress to which it is subjected, that pressure imposed upon the plate in proximity to its anchorage will overcome the distortional stress a-nd cause the free end of the plate to snap instantly toward open position. The amplitude of movement of the free end of the plate I4 may be and desirably is limited by an insulated stop I5 which is located above the end of the plate and spaced apart from the terminal end by a block of insulating material I6. A convenient means for applying force to the plate I4 to eiect the opening movement thereof comprises a pin I1 which is slidably mounted in a boss in the insulated cover I 8 of the switch-enclosing casing, The pin I1 is located axially beneath the weight 6.

Desirably a manually operable stop switch is interposed in the circuit leading tol the terminals of the switch and such a manually operable switch may be conveniently mounted in the hollow base. In the particular construction illustrated the conductors I2 and I3 lead through suitable laminated insulation I9 to a switch mechanism which is mounted in a screw threaded block 2U which extends through the upper wall of the casing and is secured thereto by upper and lower nuts 2I and 22. A suitable handle 23 for the switch extends upwardly through the central portion of the block 20 and may be moved laterally to open or close the stop switch.

The hygroscopic element may be of any suitable lexible material capable of producing considerable elongation and contraction in response to increasing and decreasing humidity in the air to which it is subjected. Preferably the hygroscopic element is composed of one or more strands or ribbon of animal tissue, such as gold-beaters skin or ox gut.

In the preferred construction the hygroscopic member is in the form of a loop which preferably extends beneath a sleeve 24 which is rotatably mounted upon a pin 25 the ends of which are anchored in bosses 26 extending upwardly from and integral with the weight 6. The upper ends of the hygroscopic element are secured to an adjustable support located in the upper end of the tubular member 4.

In the preferredconstruction illustrated the upper ends of the hygroscopic member 1 are clamped to a rectangular block 21 by plates 28 which are screwed to the block. The block 21 is provided near its upper end with a transverse bore 29 having a narrow slot 30 extending from the bore through the upper edge of the block. The block is suspended upon a screw 3| having at its lower end an integral cylindrical extension or stem 32 terminating in an enlarged| spheroidal end 33 which enters the bore 29 in the block 21.

In assembling the device the stem 32 and spheroidal end may be inserted laterally through the slot and bore as will be readily understood. The screw 3| extends axially through and its threads engage complementary threads in a metallic block or head 34 which is xedly secured in the upper end of the tubular member by screws 35. The head 34 is provided with an upwardly exthe humidifying means.

been depressed suiciently to cause the plate I4 tending annular flange 36 in which an adjusting member or knob 31 is rotatably mounted and spaced apart from the head 34 by a spiral spring 38, the lower end of which rests upon the head 34 and the upper end of which enters a recess in the adjusting knob 31. The screw 3| has threaded engagement with the adjusting knob 31, but is adapted to be rigidly secured thereto by a clamping screw 39, the end of which abuts against the screw 3 I.

The lower end of the adjusting knob is provided with a cut-away portion or recess 40 and a stop screw 4I extending through the flange 36 of the head enters the recess in such manner that engagement with the shoulders at the end of the recess 40 will limit the rotative movement of the adjusting knob 31.

In the assembling of the device the clamping screw 39 is backed off to permit rotation of the screw 38. The knob 31 is then held in such position that the stop screw 4I is approximately midway of the length of the slot 40 and the screw 3I rotated to give a rough adjustment to the position of the lower end of the weight 6 relatively to the upper end of the pin I1. The clamping screw 39 is then set up and furthermore accurate adjustment of the weight produced by rotation of the knob to position the weight in such manner that the lowering and raising of the weight will actuate the flexible plate I4 of the snap switch to break or make the electric circuit in response to variation of humidity of the air from a predetermined standard.

The controlling device is primarily intended for regulation of humidifying apparatus for supplying moisture to the air of an enclosure, the electric circuit being employed to control a solenoid, or other electrically operated valve for turning on or off a supply of moisture to the air of the enclosure, or t-o control a humidifier.

When in operation the regulator herein disclosed is initially adjusted for actuation within a predetermined range or standard of humidity, rising humidity causes the hygroscopic element 1 to increase in length, whereupon pressure of the weight 6 upon the pin I1 causes the switch plate I4 to snap to open position, thereby interrupting the circuit and discontinuing the operation of When the pin I1 has to snap to open position, further descent of the weight will be prevented by the resistance of the pin I1 or by the engagement of the weight with the boss upon the cover plate IB so that the strain upon the hygroscopic member will be relieved and such stretching of the hygroscopic member, while subjected to high humidity as might otherwise cause it to lose its initial adjustment setting, will be avoided. Falling humidity causes the hygroscopic element 1 to contract and to lift the weight, thereby reducing the pressure applied to the actuating pin I1 until the distortional stress and resiliency of the fiexible plate I4 will snap the switch member to closed position, thereby completing the electric circuit and effecting resumption of humidiication upon which the cycle of operation is resumed and a standard of humidity is maintained within limits corresponding to the sensitivity of the regulator. By the rotation of the knob 31 in a proper direction the xed end of the hygroscopic element and the weight supported thereby may be raised or lowered to adjust the standard o-f humidity to any predetermined higher or lower degree as may be desired. The hand operated switch, which is con- 75 nected in series with the snap switch, may be opened or closed at will by manipulation of the handle 23 to make or break the circuit without disturbing any of the adjustment-operating parts, or other connections of the controller.

In order to prevent injury to the hygroscopic element or other portions of the device during storage and transportation, means desirably are provided for maintaining the weight 6 in fixed position. This is conveniently accomplished by providing a set screw 42 in the post which extends upwardly from the hollow base adapted when set up to engage the side of the Weight B and clamp it in a xed position, thereby preventing such movement of the weight as either would impose a tension or jerk upon the hygroscopic element or hammering of the pin which engages and actuates the movable plate I4 of the snap switch.

It will be understood that other means may be provided for supporting the hygrosc-opic member. In Fig. 3 a modification of the invention is illustrated diagrammatically which will enable the hygroscopic element to give a greater amplitude of vertical movement to the weight. In this construction the hygroscopic element 'l is illustrated in full lines as 43 and 44 normally distorted from horizontal position by the weight 6, it being understood that one or both ends are adjustably secured to a suitable support in substantially the same horizontal plane. The position of the hygroscopic member, when subjected to a predetermined increase in humidity, is illustrated by the dotted line position 45 and 46 and that of the weight by the dotted line position.

A comparison of the distances through which the weight would move vertically when the hygroscopic element is, first, in vertical position and, second, in horizontal position is illustrated by the dotted extension of the line which is located above the diagrammatic ligure. The normal length of the hygroscopic element before elongation is represented by the distance between the points a and b and this length corresponds to the combined lengths of the halves 43 and-44 of the hygroscopic element 1 shown in the diagram. The elongation of the element when subjected to rising humidity is illustrated by the dotted lines 45 and 46 and the length of the lines 45 and 46 when in alinement equals the distance between the points a and c. Therefore, the distance between the points band c represents the exact elongation of the hygroscopic element and the distance which the weight would lower under such conditions if the hygroscopic member and weight were suspended vertically. However, where the hygroscopic element is supported at its ends in a horizontal plane and the weight applied centrally, as shown diagrammatically, the vertical movement of the weight is the distance between the points d and e. If this distance d-e is measured from the point b upon the line, it will be observed that the distance through which the weight drops is much greater than the distance between b and c which is thedistance the weight drops when attached to the lower end of a vertically suspended hygroscopic element.

It will thus be seen that an increased weightmovement is obtained by initially positioning the hygroscopic element in horizontal position and it will be readily understood that the form of the casing and the manner of suspending and adjusting the tension upon the hygroscopic element may be readily made to secure the advantage of such construction by those skilled in the art.

It will be understood that the particular embodiment of the invention disclosed herein is of an illustrative character and is not restrictive, and that various changes in form, construction and arrangement of parts may be made within the spirit and scope of the following claims.

Having thus described the invention, what is claimed as new, and desired to be secured by Letters Patent, is:

1. A hygroscopic control for an electric circuit comprising a rigid frame, an instantaneous switch for the electric circuit mounted thereon, an hygroscopically extensible element adjustably suspended from said frame, a Weight suspended by said element directly above the operating member of said switch and operable upon elongation of said member in response to rising humidity to cause said weight to depress said operating member and thereby to actuate said switch at a predetermined condition of humidity.

2. A hygroscopic control for an electric circuit comprising a rigid frame, supporting means adjustably mounted on said frame, a hygroscopic element subject to elongation in response to rising humidity and contraction in response to falling humidity suspended from said supporting means, a weight directly suspended upon said hygroscopic element and acting to move vertically in accordance with elongation or contraction thereof, a self-closing instantaneous switch mounted on said frame below and in the path of said weight and having a conducting member movable to open position by the action of said weight upon elongation of said element in response to humidity rising to a predetermined value.

3. A hygroscopic control for an electric circuit comprising a frame, an instantaneous self -closing switch for said circuit mounted thereon, a weight suspended from said frame directly above the actuating member of said switch upon a hygroscopically extensible element composed of elastic material, said element being adjustably supported on said frame and having an elastic limit that exceeds the tensile strain imposed thereon by said weight, the said Weight in accordance with the extension of said element upon humidity rising to a predetermined value being operable directly to actuate said switch.

4. An article of manufacture comprising a casing having a hollow base, an apertured tubular member extending vertically upwardly therefrom provided with a vertically adjustable supporting member in its upper end, an instantaneous switch mounted in said hollow base, a flexible hygroscopic element subject to elongation in response to rising humidity and to contraction in response to falling humidity secured at its upper end to said supporting member, a weight slidably mounted in said tubular member and guided thereby suspended by said hygroscopic element directly above the movable element of said switch and operable upon elongation of said member in response to rising humidity to cause said weight to actuate said instantaneous switch.

5. An article of manufacture comprising a casing having a hollow base, an apertured tubular member extending vertically upwardly therefrom provided with a vertically adjustable supporting member in its upper end, an instantaneous switch mounted in said hollow base, a iiexible hygroscopic element in the form of a loop connected at its upper end to said adjustable supporting member, subject to elongation in response to rising humidity and to contraction in response to falling humidity, secured at its upper end to said supporting member, a weight slidably mounted in said tubular member and guided thereby suspended by said hygroscopic element midway of its length directly above the movable element of said switch and operable upon elongation of said member in response to rising humidity to cause said weight to depress said operating member and thereby actuate said switch at a predetermined condition of humidity.

6. An article of manufacture comprising a casing having a hollow base, an apertured tubular member extending vertically upwardly therefrom provided with a vertically adjustable supporting member in its upper end, an instantaneous switch mounted in said hollow base, a exible hygrof scopic element subject to elongation in response to rising humidity and to contraction in response to falling humidity secured at its upper end to said supporting member, a weight slidably mounted in said tubular member and guided thereby suspended by said hygroscopic element directly above the movable element of said switch and operable upon elongation of said member in response to rising humidity to cause said weight to actuate said instantaneous switch, and means for relieving said hygroscopic element from further extensional strain after the actuation of said switch.

WILLIAM B. HODGE.

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