US2202725A - Periodic switch - Google Patents

Description

May 28 1940 P BEAR 2,22,725

PERIODIC SWITCH Filed July 15, 1958 Patented May 28, 1940 UNITED STATES PATENT OFFICE PERIODIC SWITCH Paul S. Bear, Elkhart, Ind., assignor to Bucklen- Bear Laboratories, Inc.,' Elkhart, Ind., a corporation of Indiana.

The present improvements are directed to a time ratioing mechanism which may be advantageously employed in various installations. Such a mechanism includes, (1) an actuator slowly moving and constantly operating through a fixed cycle, (2) a control for a force imparting medium, such as electricity, fluid, etc., and (3) an operative connection therebetween which includes a yielding transmission, the connection being adjustable in such a manner that periodical operation of the control may be limited to a desired interval of time. A mechanism of this character may be advantageously used with conditioning apparatus where it is desired to maintain temperature, humidity, or other factors under close control.

In the ensuing description, I shall refer by way of example to an electrical circuit connecting a source of eiectromotive force with a heating ele- 90 ment, together with a mercury switch interposed in the circuit by which to open or close the circuit so that the heating element may be energized periodically for desired intervals of time. In such an installation the switch is the control.

With other types of mechanism, such, for example, as employ a fluid which passes through a valve controlled pipe, the valve would be the control.

Certain exemplifications of my invention are 39 shown in the accompanying drawing, wherein:

Figure l is a diagrammatic view of a time ratioing mechanism as used in connection with a mercury switch which, as shown, is in the open position;

5 Fig. 2 illustrates the same mechanism with the switch in the closed position;

Fig. 3 which is a view similar to Fig. 1, shows a modified form of the mechanism;

Hg. 4 shows the apparatus of Fig. 3 with the switch in the closed position; and

Fig. 5 illustrates a modification in the means by which to vary the efiective stroke of the actuator, through its connection with the transmission, to operate the control.

In the form of mechanism shown in Figs. 1 and 2, I employ a base plate B which is slidably supported within guides 6. Extending from this plate is a pin I on which is rockably mounted a yielding transmission which may comprise two elements swingingly movable toward or from each other, an example of the latter, as herein shown, comprising a secondary arm 8 whose oscillations are confined between upper and lower stops 9 and I0, and a primary arm H of the transmission which is also pivoted to rock upon the same pin, and is connected yieldingly to the secondary arm as by a spring l2. 7

Upon the secondary arm is affixed a clip 15 in which is supported a switch S, preferably of the well known mercury type, interposed in an elec- 5 trical circuit which comprises two leads a and b extending from a power source. Also interposed in this same circuit is a heating element H or other device which is to be energized periodically for' variable time intervals. This is accomplished 10 by ratioing the time during which the switch, i.e., the control, is maintained in its on and oh positions, respectively.

Operative connections, including the yieldable transmission arms already described, extend from 15 the control to a motor M which may be electrically connected through leads d and c with the main power line. From a pinion it on the motor shaft motion is imparted to a gear wheel 69 which revolves about an axis 20 to rotate 20 through an orbit an eccentric pin it to which is connected one end of a pitman 2?; whose opposite end is connected at 23 to the primary arm. By this arrangement the actuator, i. e., the pitman, working through the yielding transmission, operates the control constantly so as to periodically make and break the circuit associated therewith.

So that the on and off periods of the switch may be ratioed, as desired, I provide an adjusting 30 shaft 25 having a threaded connection with an ear 26 extended from the base plate, the shaft being equipped with a manipulating knob K, hereinafter referred to as the manual, and with a dial 2? having graduations which are successively movable to position opposite a pointer 26. Through rotation of the manual, the base plate, together with the transmission carried thereby, may be moved back and forth whereby to vary the efl'ective working stroke. The dis-. tance between the wheel axis and the pivotpoint of the transmission arms is all important in this connection. In one extreme position of adjustment (where the zero mark on the dial lies opposite the pointer) motion will be imparted to only the primary arm of the transmission, the secondary arm remaining positioned against the lower stop because of insufiicient tension in the spring which constitutes the yielding operative connection therefor. In the opposite extreme position, 50 however, (Where the pointer will lie about opposite the mark on the dial) the primary arm will be oscillated through a difie'rently located range wherein the tension in the spring is sufiic ntly great to sustain the secondary arm 55 against the upper stop (see Fig. 2) where the switch remains constantly in an on position. The eifect of any adjustment, effected through the manual, is to change the location of the pivot pin 1 with a consequent shifting from one are to another of the movement range of the primary arm of the transmission whose range of movement, however, remains unchanged; as a result, the point at which motion is communicated to the secondary arm is likewise afiected, the range of adjustments being such that this secondary arm motion may take place concurrently with movement of the primary arm, or at any succeeding point in its cycle of movement, or not at all. Any selected ratioing of the time may accordingly be efiected, i. e., the switch may be maintained in an on or an ofi position for any desired portion of the full operating cycle of the actuator. Whatever be the adjustment, the operator is apprised by a glance at the dial whose graduations will accurately indicate the time ratio for which the mechanism is set.

In Figs. 3 and 4 I have shown a similar mechanism in which all partswhich correspond to those of Fig. 1 are designated by like numerals. Instead of the pin 2| I employ in this case a cam or essentric wheel 30 mounted to revolve with the gear wheel. This cam is in engagement with one end of an actuator in the form of a block 3i slidingly supported within a guide frame 32 and normally held against the cam as by a spring The block end opposite the cam is beveled at 34 to engage with a roller 35 on an extension 36 which proceeds from the primary arm of the transmission, a spring 3? interconnecting this extension with a fixed point on the base plate to normally hold the extension in a down position against a I stop 38. Between the primary and secondary arms of the transmission is a spring 02 forming a yielding operative connection therebetween.

By rotation of the manual the base plate, together with the transmission thereon, will be shifted toward or from the cam axis whereby to vary the position of the roller with respect to the beveled end of the actuator.v If the roller be advanced toward this beveled end sufliciently to remain always in engagement therewith, the effective operating stroke of the actuator will be shortened so that the control which is operated by the secondary arm will remain constantly in the closed position; if the adjustment be such that the roller is in the opposite extreme position, then the control will remain constantly in the closed position or substantially so; and in intermediate positions of adjustment any desired ratio of time, during which the control is held in its on and off positions, may be attained within the limits permitted by the spaced stops 9 and Ill and the spring i2. Exactly the same result is obtained with the mechanism of Figs. 3 and i as in that of Figs. 1 and 2, the only difference being in certain details of the actuator-transmission assembly.

In Fig. 5 I have shown an actuator having in. its own construction provision for varying the eifective length of its working stroke. The parts shown in this figure bear reference numerals the same as those previously used insofar as they correspond therewith. The pitman 22 in this case extends between the pin 2! and a beam 48 which is mounted to rock freely upon a shaft M to which is afiixed a beveled gear 42 in mesh with a second gear 43 at one end of an adjusting shaft 25 having an operating knob K, the same as previo ly described. Upon this rocking beam are carried bearings 44 for a threaded rod 45 whose lower end is equipped with a spirally toothed wheel 48 in mesh with a worm gear 41 that is carried fast on the shaft ll. By rotation of the adjusting shaft 25, a turning movement will be imparted to the threaded rod 45 on which is mounted a collar 50 with which is pivotally connected as at 5| a second pitman 52 which joins with the primary arm of the transmission. It will be apparent that the rocking beam through the second pitman communicates to the primary arm of the transmission an oscillatory movement the extent of which is determined by the position of the collar upon the threaded rod; by raising or lowering this collar, the effective stroke of the actuator may be varied. In this way I am enabled to obtain a desired ratioing of time for operation of the control within the limits permitted by the spaced stops 9 and Hi.

In the mechanism of Figs. 1-4, a change in the time ratioing adjustment involves an increase or decrease in the distance between the transmission pivotal point and the axis of rotation from which the actuator movements proceed. For the mechanism of Figs. 1 and 2, the greater proportion of time the control is to be held in a closed position, the greater this distance should be, and vice versa, whereas, for the mechanism of Figs. 3 and. 4, just the reverse is true. With the mechanism of Fig. 5, this distance remains fixed, but, by what amounts to a shortening or lengthening of the working stroke of the actuator, I obtain a modification in the time ratio for operation of the control which remains closed for longer periods when the stroke is increased, the same as described in connection with Figs. 1 and 2. The essence of my invention resides in utilizing a continuous operating slow moving actuator, working through a yieldable transmission, to operate a control first to one position and then to another, the period of time for each position being adjustable with the aid of a manual having dial markings by which this time ratio is definitely indicated.

I claim:

1. In a periodic switch, the combination of a movable control, operating means for the control including an actuator and a yieldable transmission in operative relation therewith and with the control, the transmission consisting of a primary element and a secondary element pivotally mounted for relative movement, the primary member being operatively associated with the actuator and the secondary element being arranged to actuate the control and a spring connecting the primary and secondary elements and arranged to permit the primary element to move while the secondary element is stationary, and means for varying the timing of the actuator transmission operation whereby to advance or delay movements imparted to the control.

2. A periodic switch including, an actuator constantly operating through a fixed cycle, a mercury switch, a transmission comprising a pivotally mounted secondary arm carrying the mercury switch and adapted to be oscillated to tilt the mercury switch to open and closed positions, a primary pivotally mounted arm connected to the actuator, yieldable means operatively connected with the primary and secondary arms for transmitting motion from the primary arm to the secondary arm and arranged to absorb excessive movement of the primary arm and permit the secondary arm to remain stationary while the actuator and the primary arm are in motion, means for adjusting the yieldable transmission for limiting the periodical operation of the mercury switch to a definite period of time, and spaced stops receiving between them the secondary arm and limiting the mercury switch to substantially the same angular movement in each adjustment of the yieldable transmission.

3. A periodic switch including, an actuator constantly operating through a fixed cycle, a mercury switch and a yieldable and adjustable transmission comprising a pivotally mounted secondary arm carrying the mercury switch and adapted to be oscillated to tilt the mercury switch to open and closed positions, a primary pivotally mounted arm connected to the actuator arid a spring operatively connected with the primary and secondary arms for transmitting motion from the primary arm to the secondary arm and arranged to absorb excessive movement of the primary arm and permit the secondary arm to remain stationary while the actuator and the primary arm are in motion, means for adjusting the yieldable transmission for limiting the periodical operation of the mercury switch to a definite period of time, and spaced stops receiving between them the secondary arm and limiting the mercury switch to substantially the same angular movement in each adjustment of the yieldable transmission.

4. A periodic switch including, an actuator constantly operating through a fixed cycle, a movable control, transmission mechanism comprising a pivotally mounted secondary arm carrying the movable control and adapted to be oscillated to tilt the movable control to carry the same to two operative positions, a primary pivotally mounted arm connected to the actuator, yieldable means operatively connected with the primary and secondary arms for transmitting motion from the primary arm to the secondary arm and arranged to absorb excessive movement of the primary arm and permit the secondary arm to remain stationary while the actuator and the primary arm are in motion, means for adjusting the yieldable transmission for limiting the periodical operation of the movable control to a definite period of time, and spaced stops receiving between them the secondary arm and limiting the movable control to substantially the same angular movement in each adjustment of the yieldable transmission.

5. A periodic switch including an actuator constantly operating through a fixed cycle, a movable control and a yieldable and adjustable transmission comprising a pivotally mounted secondary arm carrying the movable control and adapted to be oscillated to tilt the movable control to move the same to two separate operative positions, a primary pivotally mounted arm con nected to the actuator and a spring operatively connected with the primary and secondary arm for transmitting motion from the primary arm to the secondary arm and arranged to absorb excessive movement of the primary arm and permit the secondary arm to remain stationary while the actuator and the primary arm are in 1110-- tion, means for adjusting the yieldable transmission for limiting the periodical operation of the movable control to a definite period of time, and spaced stops receiving between them the secondary arm and limiting the movable control to substantially the same angular movement in each adjustment of the yieldable transmission.

PAUL S. BEAR.

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