US2473094A - Control mechanism - Google Patents

Description

June 14, 1949.

Filed Dec. 27, 1945 2 Shets-Sheet 1 mm m H L m m m 6N T.

June14, 1949. A. K. GAYLORD- 2, 3

CONTROL MECHANISM Filed Dec. 27, 1945 2 Sheets-Sheet 2 A TTOZQNEY Patented June If}, 1949 UNITED STATES-- PATENT OFFiCE CONTROL MECHANISM Asa K. Gaylord, Portland, Oreg.

Application December 27, 1945, Serial No. 637,350

Claims. 1

This invention relates to an electrical control mechanism, and has particular reference to a novel mounting for a gang of control switches for performing sequential switching operations in a predetermined order.

The general object of the invention is to provide a novel mounting means for a plurality of individual switches to cause them to make and break circuits in a. predetermined order.

Another object is to provide an improved mercury switch mounting having concealed wiring to present a neat and clean appearance and to prevent tamperin therewith by unauthorized persons.

Another object is to provide an improved rotary control mechanism adapted to be driven by a motor for performing successive switching operations at predetermined time intervals.

Another object isto provide an improved smp controller of simplified and economical construction for circuits involving a considerable amount of power to exert a modulating control over such circuits in relatively small increments of power, and to prevent sudden changes involving a large load.

These and other objects are accomplished in a control mechanism comprising a hollow insulating mounting tube or drum carrying a plurality of mounting clips for individual switches on its exterior surface. The tube is mounted at its ends for rotation in suitable bearings, and is preferably driven at a slow constant speed by an electric motor through appropriate reduction gearing. The electric motor may operate as a servo-motor .in a control system where the motor moves the mounting tube back and forth to difierent positions within a range of tube rotation less than 360 degrees "in answer to demands from some condition responsive device. The invention is particularly suited for exerting a modulating control over the heat output of abank of electric heating units in response to demand from a thermostat mechanism which causes the motor to assume difierent positions in accordance with the temperature of the space being heated. The control system for producing operation of the motor in this manner forms no part .of the present invention, nor do the particular circuits in which the mercury switches are included, the present invention being concerned only with the mechanical construction of the control mechanism as exemplified in the preferred embodiment illustrated in the accompanying drawings.

The supporting clips for the switches are mounted on the rotatable insulating tube at angular intervals defining stations or control steps for the system which is controlled thereby. The invention utilizes a characteristic feature of conventional mercury tube switches whereby they eiiect a quick and clean make or break, even when tilted with a very gradual movement from one position to another. Therefore, as the mounting tube is slowly rotated in the proper direction the mercury switches will slowly be tilted so that as one after another reaches its critical position it will be caused to make or break a circuit, as the case may be, without arcing or burning the contacts as would be the case with switches having solid metal movable contact elements. Although the action of the mercury in the switch tubes produces in efiect a certain amount of lost motion between the make and break positions in any given switch tube, the make position is always the same and the break position is always the same, so that when rotation of the mounting tube in a given direction is halted in a predetermined position, the same circuit connections will invariably be established. The exact angular position in which the mounting tube comes to rest is, however, not critical, inasmuch as there is a mounting tube rotation corresponding to the angular spacin of the switch tube clips between successive switching events. In any intermediate position of the mounting tube, between its limits of movement, certain of the switches will be definitely off and others will be definitely on, so that there are no positions which must be passed over quickly or by a continuous motion as in streetcar controllers or the like. For this reason, it is not necessary to provide indexing mechanism to stop the rotation'of the mounting tube in predetermined positions with relation-to the stations at which the switch tubes are mounted, and the driving motor may .be allowed to find its rest position after each movement solely in accordance with the demand of the condition responsive device. As a matter of fact, in the operation of a system of this kind, there may be many small movements of the mounting tube which are insufficient to produce .55 would be affected.

The space within the mounting tube is utilized to contain the wiring connections for the switch tubes. The wires from each switch tube are trained out through the remote end of the mounting tube to make available the greatest possible length of wire for twisting to accommodate the range of rotation of the mounting tube. The maximum rotation of the mounting tube between end limits being usually less than 180 degrees in modulating controls of the type hereinabove described, and the normal rotation thereof being only a few degrees at a time, no severe stress is imposed upon the wires to cause them to break or kink. All the wires leaving the switching device are thereby protected and concealed where they cannot be tampered with.

In the drawings:

Figure 1 is a plan view of a control mechanism embodying the principles of the present invention;

Figure 2 is an enlarged sectional View showing the construction and rotatable mounting of the driving end of the mounting tube;

Figure 3 is a sectional View, taken on the line 3-3 of Figure 2;

Figure 4 is a sectional view similar to Figure 2, showing the construction and mounting of the other end of the mounting tube;

Figure 5 is a fragmentary View showing a mounting clip and terminals for one of the mercury switches;

spacing of the successive stations on which the mercury switches are mounted;

Figure 9 is a developed View of the mounting tube showing the stations at which the mercury switches are mounted;

Figure 10 is a side view of the mounting tube without the switches, showing the manner of securing the removable closure in place; and

Figure 11 is a detail view in section showing a securing means for the removable closure in the mounting tube.

In the illustrated embodiment of the invention the reference numeral designates a hollow mounting tube of suitable rigid insulating material carrying a plurality of clips 2| for securing individual switching instrumentalities such as v mercury switch tubes 22 angularly spaced at a series of stations to operate in sequence when the tube 20 is rotated. The ends of the tube 20 are mounted for rotation in suitable bearings in hollow brackets 23 and 24 or other supporting members conveniently arranged on the apparatus to be controlled. These brackets also serve as wiring gutters for containing bundles of wires 25 and 26 leading into the tube 23 for 2 internal connection with the terminals of the mercury switches. In the present embodiment the tube 23 is connected with a shaft 28 on a modulating motor 29 for exerting modulating control over a system of circuits in the general manner hereinabove described. Figure I illustrates this general arrangement, it being understood that most of the mounting clips and wiring connections are omitted for clearness.

Figures 2 and 3 illustrate the manner in which the driving end of the tube 20 is mounted in the bracket 23 for connection with the shaft 28 and the flexible disposition of the wires 25. The bearing for the tube 20 may take various forms depending upon the nature of the bracket 23 in the particular installation. In the present arrangement the bearing comprises two segmental bearing elements 30 and 3| each extending half way around the tube and supplementing the other to constitute a full circular hearing. The element 3| is a semi-circular strip of fiber or like material secured to a side wall of the bracket 23 by means of bolts 32, the walls of the bracket being cut away at 33 to avoid contact with the tube. The bearing element 30 may comprise a semi-circular loop of sheet metal, or other material of which the bracket is made, formed to a cylindrical shape to fit the tube and hold it properly seated in the segment 3|. A disc 34 secured in the tube by means of screws 35 is adapted to receive bolts or rivets 36 securing a flange 3'! on the shaft 23 for rotating the tube. An opening 38 extending about threequarters of the way around the tube communicates with the interior of the bracket 23 for admitting the wires 25 to the interior of the tube in its difi'erent rotative positions. The bearing elements may, of course, be located on the other side of the opening 38, or the opening 38 may be eliminated by enclosing the extreme end of the tube within the bracket 23 so that the wires 25 may be brought out of the end instead of the side of the tube.

The bearing supporting the other end of the tube 20 is illustrated in Figure 4. Here a full circular bearing ring 40 of fiber or suitable wear resistant material completely surrounds the tube, and is secured by screws 39 to a vertical wall of the bracket 24 just inside a circular opening 4| through which the tube passes without fric- 40 tional contact. In this arrangement the end of the tube opens into the hollow interior of the bracket 24 to provide access for the wires 26. This bearing arrangement may also be used for the driving end of the tube by providing for passage of the wires 25 through the disc 34. To this end, the disc 34 might be entirely eliminated by providing an external ring gear or the like for rotating the tube.

In order to provide a maximum twisting length for the wires, they are led out from each switch through the remote end of the tube. The wires 26 coming in through the right bracket 34 are connected with mercury switches on the left end of the tube, and the wires 25 coming in through the left bracket 23 are connected with mercury switches on the right end of the tube. The connections for the mercury switches near the center of the tube may then be led out the end having the fewest wires. Thus the twisting lengths of all the wiring connections are considerably longer than the flexible connections ordinarily used on mercury switches, so as practically to preclude the possibility of mechanical failure of the wires from twisting stresses, and to reduce the load on motor 29 to a minimum.

The mounting of the mercury switches and their terminals is shown in Figures 5 to '7. Each clip 24 is secured transversely on the outer surface of the mounting tube 20 by means of a bolt 45 having its head within the tube and a nut 46 on the outside of the tube. In this way the mercury switches may easily be mounted in definite positions or stations at predetermined angular intervals on the'tube 20 by drilling a single hole desigteam hated generally at 41 at the proper oint to receive the bolt 45 for each clip.

Adjacent each clip 2 I there are mounted a number of terminals 48 in accordance with the number of wires 49 on the mercury switch tube used in that particular clip. However, when connections are made between different switch tubes, they may be soldered together exteriorly oi the mounting tube without the use of. terminals. Each terminal 48 comprises a bolt having a head 50 which is disposed within the tube 20 so that a pair of nuts 5| may be applied to the outer end for securing the terminal in the wall of the tube and for engaging the end of the wire 49. The head 50 is preferably of hexagon or other angular shape so that it may be held or turned by a suitable tool in tightening the nuts 5i, After the terminals ifi have been mounted in the tube and the wires 49 connected therewith the internal wiring connections may be made. The head 50 is enlarged in the manner shown so that it can be tapped to receive a screw 52, and this screw is then tightened on the ends of the proper wires within the tube without loosening the nuts 5|. In Figure 6 the switch tube 22 is the first switch tube at the left end of the mounting tube 20 and so the internal connections comprise certain of the wires 26, leaving the right end of the mounting tube.

Access for tightening the various bolts and screws in the tube 20 for mounting the parts and connecting the wires is had by the provision of a removable panel 55. The panel 55 may cut out in different Ways and in different shapes depending upon the size and material of the tube 20 and the extent of its surface embraced by the mercury switches mounted thereon. In the present embodiment the panel 55 is cut out of the tube 20 to substantially the configuration and proportions shown by means of a band saw so as to leave an opening 58 as shown in Figure 9, having a length and width sufficient for convenient access to all the screws and bolts mounting the clips 2| and the wiring connections. After all internal wiring connections have been completed, this panel may be secured in place by screws 56 engaging small plates or strips 57 at several points as shown in Figures 10 and 11,

It is also within the scope of the invention to bring the wiring connections out through open-' ings in the mounting tube 20 adjacent each switch for direct connection therewith so as to make the terminals 48 unnecessary. In such case the bolts 45 may be replaced by screws or other mounting means which may be tightened from the outside of the mounting tube so as to make the removable panel 55 unnecessary. It is further within the scope of the invention to mount the switch tubes within the mounting tube.

The mounting tube 20 may be rotated by any suitable means to perform the required switching operations but it is particularly intended for operation by a modulating motor 29 having a reduction drive which is adapted to rotate intermittently at a slow constant speed between end positions embracing a total range of movement of approximately 160. To exert a modulating control within this range of movement, an operating range comprising slightly less than the complete range of movement is divided up into equal parts in accordance with the number of control steps desired. Thus in the present embodiment there are thirteen control steps spaced twelve degrees apart to cover a modulating range 6 of 144 around thetube 20, as shown in Figure 8. If the tube may rotate through between its 'end positions, an end zone of 8 may then be allowed approaching each end position of the shaft to insure the turning on of the last switc and the turning 011* of the first switch.

The numerals l to I3, therefore, represent stations on the mounting tube at which switch tubes are mounted, and the angular spacing between these stations determines the amount of rotation of the tube 2i) between successive switching events. On a development of the mounting tube as shown in Figure 9, these stations appear as lines for locating centers for the holes 47. Switching events may be produced in any number and at intervals scheduled in a coordinated program to produce a desired cooperation between difierent instrumentalities. Thus, in this embodiment, there is a series of the mounting holes '41 located on alternate ones of the stations I to l3, beginning with station I and ending with station [3, this particular series of mountin holes being identified in Figure 9 by the numeral 6E3. There is also a series of mounting holes identified by the numeral 6i located on every station except station I. Mercury switches mounted in the holes 6i may be used in an electric furnace or like control system to exert a modulating heat control in twelve steps from a minimum heating step to amaximum heating step. A variable speed blower may then have its operation coordinated with the heat output by a program of switching events produced by mercury tube switches mounted in the holes 6E1. In the illustrated arrangement the blower would start at its lowest speed on station I and the lowest output heating step would be energized on station 2. Station 3 would energize the second heating. step and the second speed of the blower, and thereafter the blower would increase in speed at every other station, or each alternate heating step, until at station l3 the blower would operate at full speed and the heating units would produce maximum heat output.

The invention, however, is not limited to any particular arrangement or number of mercury switches. The foregoing example of one use to which the present control mechanism may be put is described merely for the purpose of illustrating an advantageous application of the invention and is not intended in any way as a limitation on the invention. Any system of electrical circuits, in addition to or in lieu of heating and fan circuits, may be controlled by this switching device, and

any number of switch tubes may be employed by choosing suitable dimensions for the mounting tube 20. The operation of successive switches may be scheduled at intervals either closer together or farther apart than 12 degrees and also at irregular intervals, and the driving agency for the tube 29 need not necessarily operate at a constant speed nor within the particular range of movement specified. Also, the invention is not limited to the use of mercury switches as any other type of switch capable of being carried by the mounting tube 20 and actuated by the rotation thereof may be employed.

Various other changes may be made in the construction and arrangement of parts in the rotatable mounting of the tube 20 and in the driving instrumentality therefor, and all such modifications within the scope of the appended claims are included in the invention.

Having now described my invention and in what manner the same may be used, what I claim as new and desire to protect by Letters Patent is;

l. A switching device comprising a hollow tubular member mounted for rotation in bearing means, a plurality of switches mounted on said vmember for operation by the rotation of said twisting length for the wires within the tubular member sufficient to accommodate a relatively large angular movement of the tubular member without damaging the wires and without imposing an appreciable torque load on the tubular member.

2. A switching device comprising a hollow tubular member mounted at its ends in bearing means for rotation, a plurality of switches mounted on said member for operation by the rotation of the member, and flexible wires extending longitudinally through the interior of said member from each switch to an end of the member, the wires from each switch near an end of the member extending to the more remote end of the member to provide a long twisting length for all the wires within said member.

3. A switching device comprising a hollow tubular member mounted for rotation in bearing means, a plurality of switches mounted on said tubular member for operation by the rotation of said member, flexible wires extending longitudinally through the interior of said member from each switch to an end of the member at sufiicient distance from the switch to provide a long twisting length for the wires within the member, and

hollow mounting means for said bearing means to support said device and enclose said wires where they leave said tubular member.

4. A switching device comprising a hollow tubular member mounted for rotation, a plurality of clips at difierent stations on said member for mounting switches to be operated by the rotation of the member, a pair of terminals on said member adjacent each clip and having terminal connections within said member, flexible wires connected with each pair of terminals within said member and extending longitudinally through the interior of said member to an end thereof sumciently remote from said terminals to provide a long twisting length for the wires, and an opening in said member to provide access to said interior connections.

5. A switching device comprising a hollow tubular member, a pair of hollow supports having bearing means receiving the ends of said member to mount said member for rotation on its longitudinal tubular axis, a plurality of switches mounted at difierent stations on said member for operation by the rotation of said member, and flexible wires extending longitudinally through the interior of said member from each switch to an end of the member at sufficient distance from said switch to provide a long twisting length for the wires, said wires thereby extending through said bearing means and being enclosed within said hollow supports.

ASA K. GAYLORD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,701,398 Vickery Feb. 5, 1929 1,754,494 Anderson et al Apr. 15, 1930 1,852,539 Ross Apr. 5, 1932 2,274,558 Murray Feb. 24, 1942

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