US 3491249 A
Description (OCR text may contain errors)
Jan. 20, 1970 J. RABlNow 3,491,249
i TIMER SWITCH WITH DOUBLE WINDING ELECTRIC CLOCK Filed July so, 196e FIG. l. @x4
fvnov. l' L 2 L3 INVENTOR Jacob Rabinow ATTORNEY United States Patent O U.S. Cl. 307--141 6 Claims ABSTRACT oF THE DISCLOSURE A clock-controlled electric timer system for controlling a load, eg. a remote lamp load from an existing switch box without adding to the previously-installed wiring. The electric clock which controls the load is connected in series with the load and has itself two series windings, one of very high resistance and the other of very low resistance. When the high resistance winding is in series with the load, the clock runs normally but the load, being of much lower impedance, is eectively oli as only a negligible current passes through it. When only the low resistance winding is in series with the load, the load is on, drawing normal current, which current passing also through the negligibly low resistance of the low resistance clock winding, is still suflicient to operate the clock, so that it never stops in either condition of the load, and can thus operate a timer switch to control the load.
BACKGROUND OF THE INVENTION It is often desirable to control electric lights automatically by a clock timer so that the lights will be turned off and on at predetermined times, for example, so that a house will appear occupied when the owner is away, or for any other reason. In an existing house installation, the power leads often come into a connection box near the ceiling or pole lights which are to be controlled, and the switch which normally controls these lights is placed at a location convenient to a door, and at some distance from the said connection box. The leads to the switch are therefore only leads in the hot or ungrounded side of the circuit, and at the junction box there is no insulated |wiring lead available which is connected to the grounded side of the circuit, and therefore, in order to control these lights by an automatic electric clock driven timer, it has heretofore been considered necessary to add additional wiring for this purpose, which makes the installation more expensive, and often is not feasible in an existing installation without considerable rewiring of the circuits. The present invention provides an arrangement whereby, 'm such a situation, a single unitary wall installation which will fit into the standard switch box is provided, which contains an electric clock 4which runs continually, and which can turn the remote lights on and oif at preset times, without requiring any additional wiring.
SUMMARY OF THE INVENTION The above problem is solved, according to the present invention, by providing a timer clock having two windings in series, one of which is of normally high impedance, and the other is of very low impedance; this winding combination is placed in series with the load to be controlled, and is so arranged that the high impedance Winding can, in effect, be shorted out so that only the low impedance winding remains in series with the load, this action being accomplished by switching means under control of the timer itself. When the high impedance winding is in series with the load, the load is eifectively turned off, since the power requirement of an electric clock is of the order of 2 watts, which means that it draws current in the order of $60 of an ampere, and this 3,491,249 Patented Jan. 20, 1970 ICC current passing through the low resistance of the load is entirely negligible, as the load requires typically 50` to 100 times as much current when in normal operation. When the low impedance winding, typically in the order of one ohm is the only clock winding in series with the load, then the load operates normally, drawing a current typically in series of one ampere, and this current passing through the low resistance clock winding still provides two Watts of power necessary to run the clock. It will thus be seen that by putting this arrangement in series with the switching line already provided by the normal house wiring, no additional wiring is required, and the timer clock will continue to run under both conditions of operation, namely, when the light load is on or oli "The specific nature of the invention, as well as other objects and advantages thereof, will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings, in which:
FIG. 1 is a schematic wiring diagram showing the conventional switching arrangement;
FIG. 2 is a wiring diagram showing the arrangement according to the invention;
FIG. 3 is a front View of a clock unit according to the invention, mounted on the conventional switch box;
FIG. 4 is a sectional view taken on line 4 4 of FIG. 3; and
FIG. 5 is an enlarged sectional view of the switch mechanism.
DESCRIPTION OF PREFERRED EMBODIMENT FIG. l shows a conventional arrangement for controlling a remote lighting fixture, as a ceiling xture or an outdoor lamp post xture from a switch conveniently located, e.g., near a doorway. The power line 2 supplies 110 volts to a connection box 3 typically located adjacent the light xture 4, one side of which is connected to the grounded side of the power line as shown at 6, this connection being made within the connection box 3. The other side of the lighting ixture is connected to one lead 7a of a line leading to the switchbox 8, typically located near the doorway or at some other location convenient to the user. Lead 7b is connected to the ungrounded side of line 2, and switch 9, located in switchbox 8, thus controls the light 4, which in practice may be a number of lights, typically illuminating the entranceway and sometimes the garage and driveway of a house. The lights therefore represent a considerable load, being generally at least in the order of watts, and sometimes up to 400 or 500 watts. When it is desired to control the switch 9 automatically by a clock timer, for which purpose many electrically driven clock-controlled switches are commercially available, it is necessary to so connect the clock to the circuit that it is running at all times. It is therefore either necessary to provide a separate power source for the clock, or else run an extra lead from the switchbox 8 to the connection box 3, which in the case of previouslyinstalled wiring in an existing house is often both inconvenient and expensive to do.
FIG. 2 shows the manner in which this problem is solved according to the present invention without the necessity of providing either a separate power source or 1unning an extra line between the switchbox and the connection box. The incoming power line 2, connection box 3, light 4, and switch line 7a, 7b are unchanged, and are therefore the same as in FIG. 1. At the location of switchbox 8, the same Ibox may be employed as before, or a new and larger box 11 may be installed; it is however possible, by using suitably small elements, to insert all of the necessary elements into the original switchbox 8. However, in place of the switch 9, a number of smaller switches are employed, as will be described below. A
-small electric clock 12 has a dual winding 13, 14, preferably connected in series as shown, although these two windings could also be independently switched to per form the functions described below. Winding 13 is the normal high-impedance winding customarily employed in standard electric clocks, and for a 2-watt clock, should typically have an impedance in the order of 5,000 ohms.
While there is no difliculty in manufacturing timer motors with high impedance, there are on the market very small timing motors that draw very little power and use resistors in series with their windings to limit the current to the desired value. One such motor uses only about 1/s watt of power for normal operation. It should be understood throughout this specification that when reference is made to high impedance winding of the timer motor this includes a combination of a winding and an outside irnpedance that, together, produce the desired impedance to limit the current into the desired range of values for proper operation. One advantage of using an external series resistance is that different line voltages can be easily accommodated, such as 110, 220, 250, etc.
The low impedance winding 14 would typically have an impedance in the order of one ohm. Both low and high impedance windings will be wound on the same magnetic core so that a suitable current for either winding will run the clock. The clock controls the operation of switch 16, which in the position shown in FIG. 2, connects lead 7a through conductor 17 to one side of high-impedance coil 13, low-impedance coil 14, contact 18, switch 19, Switch 21, back through lead 7b. It will be seen that in this condition high-impedance winding 13 is connected to the power line 2 in series with lamp load 4. Since the impedance of the lamp load, assuming it to be in the order of 100 watts or more, is in the order of less than 100 ohms, where the impedance of winding 13 is more than 50 times as great, it is apparent that only a negligible voltage drop will occur across the lamp, and that it will not be operated by the tiny amount of current in the line (0.025 ampere). On the other hand, practically the entire normal voltage drop occurs across winding 13, and the clock will operate in its normal fashion, the slight amount of voltage drop in lamp 4 being less than the variation in line voltage which is ordinarily encountered. Thus the clock is running and the lamp circuit is effectively turned off.
When the pre-set time has arrived for the light to :be turned on, clock 12 operates switch 16 down to its lower position in which it connects line 7a to line 22, thence through the upper blade of double-pole switch 21 to line 23, thence through low impedance winding 14, and back through switch 19 to line 7b. In this condition, only the low impedance winding 14 is in series with the lamp load 4, and since this is only in the order of one ohm impedance, while the lamp load is in the order of 100 ohms impedance, it is apparent that now practically all of the voltage drop occurs across the lamp load at 4, which is operated in the normal manner and is effectively turned on. The lamp current of approximately 1.2 amperes running through the low impedance winding 14 still generates the 1.5 watts of power required to operate the clock, so that the clock continues to run as before. It is apparent that the amount of power in winding 14 will depend upon the size of the lamp load, and if this load is, say, 400 or 500 watts instead of 100 watts, then the clock will draw considerably more power than is necessary, and although the winding can readily be made to withstand this load without damage, it will be more efcient to reduce the amount of winding 14 for this condition; therefore, a tap 24 is provided and switch 19 can be set to connect line 7b to this tap and thereby adjusting the winding for a heavier load.
It should be understood that the voltage drop across the low impedance winding can be adjusted to desired values by not only having a tapped or sectioned winding in the timer motor, but can also be adjusted -by means of suitable low-resistance shunts. The exactmethod will .depend on cost, compactness, heat dissipation and other factors well understood in the art.
As will be explained below, switch 21 can be operated manually to the position shown in Adotted line to disconnect the clock, so that the lights can be controlled solely by using buttons 46, 47.
Referring to FIGS. 3-5, the above mechanism is housed within the box 11, which may be a standard switchbox such as is commonly used in house wiring, and contains all of the elements shown Within the dotted line in FIG. 2. The box contains electric motor 12, which through suitable gearing 26 drives dial ring 27, at the rate of one revolution each 24 hours. The dial ringv 27 .is suitably marked with hour indications as shown, and the time is read with reference to a stationary pointer 28 fixed to the face plate 25. The dial is set by overdrive against a friction clutch, or alternatively, it can be arranged to be pulled back against the spring to disconnect the dial from the driving pinion, both methods being well known in the art and not a part of the present invention. Dial 29, the on dial, is coupled to dial 27 by friction, such as a split spring ring 31, so that it normally follows dial 27 in its rotation, it can be set by turning it relative to dial 27 against the friction of ring 31. Fixed to dial 29 is sleeve 32 which carries on its end triangular projection 33, which therefore also makes one rotation each 24 hours, and sometimed uring that rotation engages boss 34 and thus pivot lever 36 about its axis 37 for the purpose of turning the load on, as will be described below.
Dial 38, the off dial, is coupled to dial 29 by friction spring ring 40, preferably with less friction than that between dials 29 and 27, so that while it will normally turn with these dials, it can be, independently set without effecting them. Dial 29 has a pointer 30, which is turned to the scale reading corresponding to the time when it is desired to turn the lamp load on, and dial 38 has a similar pointer 39 which projects sufficiently far to interfere with pointer 30 so that both of the dials cannot be set to the same time. Sleeve 42 is fixed to dial 3S for rotation therewith, and carries a triangular projection 43 which engages boss 44 on switch lever 36 to turn the lamp load olf. Manual buttons 46 and 47 are provided for manually rocking lever 36 in either direction to thus turn the lamp load on or off under manual control if desired. Lever 36 is maintained in either position by an over-center spring 48. Switch 19 is conveniently located below the clock dial as shown, and has the manual or automatic control function described above in FIGURE 2.
As the dial revolves, sooner or later projection 33 will engage boss 34 and spring the lever counter-clockwise as seen in FIGURE 4, which turns the switch on. This may be accomplished in any fashion, and is shown as a magnetic reed switch 16, which is turned to one position by moving the magnet 51 closer to the switch 16, and to the other position by moving the magnet 51 suiciently far away from the switch 16 so that another set of contacts engaged to perform the operations described in connection with FIGURE l2. Such reed switches are commercially available and need not be described in detail. Alternatively, any other known form of double-pole switching mechanism may be employed.
While the above-described timer and switching mechanism show one conveniently compact manner in which the necessary control equipment can be housed within a standard switchbox, it will be apparent that 4conventional control elements can also be employed in the circuitry shown in FIGURE 2. However, it will be apparent that the maximum benefit can be derived from the invention by housing the control elements in a sufficiently compact form so that they can be put into a standard switchbox.
While the main use of the invention is shown in timing circuits using conventional clock motors, the invention can also be applied to switch motors of other types where accurate timing is not necessary. For example, il-
luminated signs may use control motors of non-precise timing to turn the sign alternately on and ofi:
1. (a) Electric switch control means for controlling a power load through a single two-wire switching line, comprising (b) an electric switch motor having at least two energizing circuits of different impedances, one of said impedances being much lower than the impedance of the said load, the other of said impedances being much higher than the impedance of said load,
(c) switch means controlled by said motor for switching one or the other of its two energizing circuits into a series connection with the said power load.
2. (a) Electric timer-switch control means for controlling a remote power load through a single two-wire switching line comprising (b) an electric timer clock having a two-section clock motor winding, one section being of very high impedance and the second section being of very W impedance;
(c) first switch means controlled by said clock for switching the high-impedance section in series with the load through said two-wire. line, the load being of sufficiently low impedance so that it is not effectively energized by the small clock current passing through it and is effectively turned ofi;
(d) second switch means controlled by said clock for switching said high impedance section out of circuit with said load and at the same time switching the low impedance winding into series circuit with said load, thereby effectively turning the load on, the impedance of the second winding being such that the load current through said low-impedance Winding runs the clock until the rst switch means again operates.
3. (a) An electric clock-driven timer device comprislng (b) an electric timer clock having two terminals for connection to a source of alternating current, said clock having an electric synchronous motor drive,
(c) a two-section motor winding for said clock motor drive, one section being of very high impedance and the second section of very low impedance, in the order of 1,000 times less than the high impedance winding,
(d) rst switch means controlled by said clock for switching the high impedance section in series with said terminals at a predetermined time setting of said clock,
(e) second switch means controlled by said clock for switching said high-impedance section out of circuit with said terminals and at the same time switching the low-impedance winding into series circuit with said terminals.
4. The invention according to claim 3, said low-impedance winding having a plurality of series sections, and means for manually and selectively connecting into the circuit desired sections to adjust said low-impedance winding to a given load.
5. The invention according to claim 3,
(f) said clock having an annular time-indicating scale means driven by the clock motor,
(g) a second annular scale means concentric with the first scale means and driven thereby, and adjustable with respect thereto,
(h) a third annular scale means concentric with said first scale means and driven thereby and adjustable with respect thereto,
(i) said first switch means having operating means therefor controlled by said second annular scale means to operate said first switch means to close the circuit position,
(j) said second switch means having operating means therefor controlled by said third annular scale means to operate said second switch means to close circuit position and simultaneously operate said first switch means to open said circuit position.
6. The invention according to claim 3, and manual switch-operating means for manually controlling said iirst and second switch means.
References Cited UNITED STATES PATENTS 3,385,972 5/1968 Bement 307-141 X ROBERT K. SCHAEFER, Primary Examiner T. B. IOIKE, Assistant Examiner