US3294977A

US3294977A - Emergency power supply unit

Info

Publication number: US3294977A
Application number: US311095A
Authority: US
Inventors: Edward T Duncan
Original assignee: Maintenance Co Inc
Current assignee: Maintenance Co Inc
Priority date: 1963-09-24
Filing date: 1963-09-24
Publication date: 1966-12-27
Anticipated expiration: 1983-12-27

Description

Dec. 27, 1966 DUNCAN EMERGENCY POWER SUPPLY UNIT Filed Sept. 24, 1965 {HHIHIII l NVENTOR. 5 1 WW HZ'TORN'EYSI United States Patent Ofitice 3,294,97 7 Patented Dec. 27, 1966 3,294,977 EMERGENCY POWER SUPPLY UNIT Edward T. Duncan, Westport, Conn., assignor to The Maintenance Company, Inc., Long Island City, N.Y., a corporation of New York Filed Sept. 24, 1963, Ser. No. 311,095 8 Claims. (Cl. 307-66) This is a continuation-in-part of my copending United States patent application Serial Number 242,787, now abandoned, filed December 6, 1962 for Emergency Lighting Unit.

This invention relates to an emergency power supply unit and, more particularly, to such a unit especially adapted for use in elevator cabs.

In my copending United States patent application Serial No. 222,574, filed September 10, 1962, for Emergency Lighting Unit, now Patent Number 3,159,755, there is disclosed a novel circuit and mounting arrangement for an emergency light which is actuated solely by loss of ambient illumination. Such a unit has a number of advantages, particularly in enclosed areas having a limited number of illumination sources. However, it is realized that some persons will prefer a unit actuated more con ventionally by loss of power. Accordingly, the present invention is concerned both with an unusual elevator cab mounting arrangement for an emergency lighting unit and also with a novel power supply circuit arrangement having many of the advantages of the aforementioned invention but actuated by loss of electrical power.

One of the major disadvantages of the emergency lighting units known to the prior art is that, in most instances, they are separate accessories which are attached to the elevator cab as distinct entities. Accordingly, such units are seldom integrated into the functional and decorative arrangements of the elevator interior but, rather, have the appearance of being afterthoughts. Furthermore, the fact that such units are not functionally integrated with the elevator cab means that separate wiring facilities must be provided for supplying power to the units. If rechargeable batteries are used, ventilation should be provided for the battery charging components. The units must be positioned so as to illuminate the entire cab, which often requires the use of unsightly goosenecks and similar contrivances. If actuation by illumination failure is desired, as disclosed in the aforementioned application, they must be positioned in a location which is continually exposed to ambient light.

Present-day elevators are commonly provided with cove lighting including recessed fluorescent or incandescent lamps positioned around the edges of the elevator ceiling.

In addition, the central portion of the ceiling is usually occupied by a ventilating unit containing a fa for circulating air between the elevator shaft and the cab interior. Accordingly, the mounting of an auxiliary emergency light in such an environment presents both functional and decorative problems.

Another undesirable feature of prior art emergency lighting units and of emergency power supply units in general is that they are controlled by relays which receive their power from the building power circuit. Many additional problems are presented by the use of relays. For example, relays are normally energized at all times. This means that the coil is continually consuming power and, therefore, generating heat. This causes the life of the relay to be shortened and the unit to become inoperative after a relatively short period of time. Furthermore, the fact that the relay is consuming power is an additional expense, which it would be desirable to overcome. Finally, the use of relays means that moving mechanical parts are being relied upon to accomplish the switching function. Mechanical parts are subject to wear and sticking, and are sensitive to vibration.

For the foregoing reasons, it is the primary object of this invention to provide an improved emergency power supply unit. Other objects are to provide such a unit which has storage batteries maintained in a continuously charged state; which is free of relays and other powerconsuming elements; which is insensitive to vibration; which is functionally integrated into an elevator cab for providing emergency light; which has adequate provision for cooling the circuit components; which is centrally located both for providing emergency light and for receiving ambient illumination; Which is resistant to lamp filament burnout; which is substantially maintenance-free; and in which acuation of an emergency light is by loss of power to an elevator cab.

The manner in which the foregoing objects are attained will be more apparent from the following description, the appended claims, and the figures of the attached drawing wherein:

FIG. 1 is an illustration of an emergency light unit constructed in accordance with this invention;

FIG. 2 is an enlarged cross section of a portion of the emergency light of this invention;

FIG. 3 is a cross section taken along the line 33 of FIG. 2; and

FIG. 4 is a diagram illustratin a novel circuit in accordance with this invention.

With particular reference to FIG. 1, there is illustrated in cross section a portion of the ceiling 10 of an elevator cab. The ceiling 10 includes an opening 12 which is normally centrally located within the ceiling and receives therein a ventilating unit V. The ventilating unit V comprises an external cage C which may be formed of expanded metal or may be any other type of housing which allows air-flow therethrough. An electric motor M operates a fan F for circulating air through the elevator cab. On the underneath side of ceiling 10 and within the elevator cab enclosure there is provided a louver L, which, as illustrated, may be of circular form consisting of a plurality of

concentric rings

14, 16, 18 which are curved in vertical cross section so as to direct the air fiow outwardly and downwardly within the elevator cab. The louver L is surrounded by a mounting ring 20 which is mounted flat against the elevator cab ceiling 10. Mounted within the innermost ring 14 there is an emergency lighting unit E which is constructed as shown in FIGS. 2 and 3.

The emergency lighting unit E comprises a base 21 which is disc-shaped and positioned within the inner louver ring 14. The base 21 is secured to the louver assembly L by means of a screw 22 which is threaded into a central stud 24 of the louver assembly. The

remaining rings

16, 18 and the external mounting ring 20 are secured together by means of the horizonally extending

rods

26, 28 and two

similar rods

27, 29 which extend perpendicular to

rods

26, 28 and in the same plane. Mounted on base 21 are a pair of lamp-supporting

brackets

30, 32 to which are attached a supporting rim 34 securing a lamp 36 in a vertical position for downward illumination. Encircling the lamp 36 is a lamp housing 38 having an upper edge 39 which contacts the lower dependent edge of louver 14 around its circumference. The lamp housing 38 also includes a central opening 40 for the extension of lamp 36 therethrough. Lamp housing 38 may be constructed of either an opaque material, such as metal, or a transparent or tanslucent material, such as certain plastics. The use of a translucent material may be particularly desirable when the emergency light is of the type disclosed in my previously referred to copending application for Emergency Lighting Unit. In such a case the light-sensitive photocell for actuating the unit may be positioned within the housing but behind the translucent material where it is protected from dirt and physical damage but is suitably positioned for the reception of ambient light. The remaining circuit components of the emergency light are retained within the compartment formed by the inner louver ring 14 and the lamp housing 38. These may be, for example, the transformer 42, the

rechargeable cells

441, 442, 443, and 444-, all of these cells comprising a" single battery 44. The

electrical terminals

46, 48 for lamp 36 are also mounted conveniently within the housing, as are the various circuit components, such as resistors, capacitors and rectifiers, which are indicated in FIGS. 2 and 3 but not specifically numbered.

A number of advantages result from the novel emergency li ht mounting described above. For example, the emergency light becomes an integral, functional part of the elevator cab and also becomes incorporated into the decor of the elevator interior. This is in sharp contrast to the separate and distinct emergency light units which form the prior art. Furthermore, if the emergency lamp unit is of the photo-actuated type, as disclosed in the aforementioned copending patent application, the cen tral location of the emergency unit allows it to be continually exposed to the ambient illumination of the cab.

It is also important to note that the emergency light unit is positioned in such a manner that its external housing is continually cooled by a flow of ventilating air. During normal operation with the lamp off, this provides cooling for the transformer and the other components which maintain the battery charge. During the period that the light is on, the operative elements of the emergency lamp circuit will produce heat. Even though the fan may be off under these conditions, the location of the unit within the open ventilating passage in the cab roof allows a natural circulation of air to take place from the elevator cab to the elevator shaft. When power returns to the unit and to the fan motor M, rapid cooling of the emergency actuated units will then take place by the action of the fan F.

In FIG. 4 there is illustrated an emergency lighting circuit suitable for use with this invention which is especially adapted for actuation by power failure. This circuit includes a rechargeable battery 44 which may be, for example, of the nickelcadmium type. A transformer 42 including a primary winding 47 and a tapped secondary winding 49 is arranged for energizationfor example, from the same power supply as motor M illustrated in FIG. 1. The secondary winding 49 is in series with battery 44 and is further in series with a solid state diode 50 and a current-limiting resistor 52. The orientation of diode 50 is such that, when the transformer 42 is energized from the primary side, the secondary voltage will be greater than and in opposition to the voltage normally produced by battery 44. In this manner, battery 44 is maintained in a continual state of charge during the time transformer 42 is energized. The tap of transformer secondary winding 49 is connected to the cathode of a solid state controlled rectifier 54, such as a siliconcontrolled rectifier. The anode of rectifier 54 is connected in series with the lamp 36 and the opposite side of the lamp is connected to the positive terminal of the battery 44. A filter network including a capacitor 55 in series with the parallel combination of a diode 57 and a resistor 59 is connected across rectifier 54. Connected in parallel across the series circuit of diode 50 and resistor 52 is a series circuit comprising a capacitor 56 which is characterized by a relatively high 60-cycle impedance, a relatively low resistance 58, and a relatively large resistance 60. A diode 62 is connected from a point between

resistors

58 and 60 to the gate of the rectifier 54. In addition, a resistor 64 of relatively high value is connected in parallel between the gate and the cathode of the controlled rectifier 54.

The operation of the circuit of FIG. 4 will now be explained by assuming, first, that alternating current is being supplied to the primary of transformer 42. The secondary voltage rating of transformer 42 is such that, under these conditions, the clockwise current flow around the outer loop of the circuit through diode 50 and resistor 52 is sufficient to maintain battery 44 in a charged condition. In one application, for example, the secondary voltage rating of the transformer is 12 volts and the battery is rated at 7.5 voltes. Diode 50 acts as a half wave rectifier so that the secondary winding 49 is polarized as shown and current flows from the positive terminal of secondary 49 to the positive terminal of battery 44. In one embodiment of the invention, capacitor 56 has a rating of .22 microfarads and 12 volts D.C., resistor 58 is a 33 ohm resistor, and lamp 36 is a 2.1 watt lamp rated at 4.7 volts D.C. With components of these values, it has ben found that a very low value of half Wave rectified current passes through capacitor 56 and diode 62 to the gate of silicon-controlled rectifier 54 and out the anode of the rectifier in a reverse direction. This constitutes a small pre-heating current through the lamp 36 and battery 44 to transformer secondary 49. This results in a great increase in the life of lamp 36. Normally, incandescent lamps have a relatively short life due to the fact that the thermal shock resulting from rapid heating of a cold filament results in stress and early filament breakage. By the circuit of this invention, however, the small current flow maintains the filament in a warm, ready condition even though the lamp is not lighted. The visible glow within lamp 36 also serves as a check on the operability of the unit without requiring actual operation. The value of resistance 60 is suificiently high to prevent triggering of the gate of the controlled rectifier 54. In the described example the resistance 60 has a value of 100,000 ohms. As a further aid in extending the life of lamp 36, it may be desirable to use a normal operating voltage in the circuit of less than its rated voltage. The filter

network comprising elements

55, 57, and 59 serves to protect the controlled rectifier 54 from possible transient peaks.

When the AC. power to the primary of transformer 42 goes off, the secondary winding 49 becomes, for all practical purposes, a normal electrical conductor. Under these circumstances a reversal of current and polarities takes place. Capacitor 56, becomes an open circuit to the D.C. current from battery 44. Gate current now flows through resistance 60 and diode 62 to controlled rectifier 54. The rectifier is thereby triggered into the on state and current immediately begins to flow in a reverse direction from the positive side of battery 44, through lamp 36, and through the rectifier 54 back to the negative terminal of the battery. As long as the AC. current supply remains off therefore, lamp 36 remains lighted.

Upon the recurrence of AC. voltage to the primary of transformer 42, the first negative (or reverse current) pulse toward the controlled rectifier 54 will cause the rectifier current flow to stop. The lamp 36 goes off once again and the circuit completely reverts to its original state.

In the foregoing illustration, a two winding transformer 42 has been described as a component of the circuit of the invention. However, it will be understood that other apparatus, such as the autotransformer, may be employed. Accordingly, in the claims, a recitation of primary and secondary windings is to be construed as meaning either separate windings or portions of the same physical windmg.

It will be apparent that a number of advantages accrue from the novel circuit and apparatus of this invention. It will also be apparent that a number of variations and modifications may be made by those skilled in the art without departing from the spirit and scope of this invention. Although the foregoing description has described the use of the circuit of the invention to provide emergency light in an elevator cab, it is not so limited but may be equally adapted to other uses. For example, the illustrated circuit may be installed in a portable carrying case and plugged into a standard outlet. It would then be available as an emergency light in the event of power failure in factories, hospitals, schools, and other locations. In addition, the circuit may be employed in numerous capacities for responding to power failures. Its output, for example, may be used for actuating alarms or functioning as an auxiliary power supply to maintain powered equipment, such as clocks, in operation during a power failure. These applications may be in addition to, or in place of, its use as an emergency lighting circuit. Certain applications may require minor modifications of circuit elements; however these can be easily effected by one skilled in the art to which the invention pertains. Accordingly, the foregoing description is to be construed as illustrative only, and the invention is limited only by the scope of the following claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An emergency lighting apparatus for an elevator cab which comprises: a ventilator arranged to be mounted in the ceiling of said cab; an emergency lighting unit positioned within said ventilator, said unit comprising transformer means having a primary winding connectable to an alternating power source and a secondary winding including first and second terminals, rechargeable battery means and first diode means connected in electrical series relationship, said battery means being connected to said first terminal and said first diode means being connected to said second terminal to maintain said battery in a charged condition from said transformer means, solid state switching means including an anode, a cathode, and a gate, emergency lamp means positioned to direct emergency light downward from said apparatus and connected in series with said anode and cathode, the series circuit being connected in parallel with said battery, and a series circuit comprising second diode means and relatively high impedance capacitor means connected between said second terminal and the gate of said solid state switching means.

2. An emergency power supply unit which comprises: transformer means having a primary winding connectable to an alternating power source and a secondary winding including first and second terminals; rechargeable battery means and first diode means connected in electrical series relationship, said battery means being connected to said first terminal and said first diode means being connected to said second terminal to maintain said battery in a charged condition from said transformer means; solid state switching means including an anode, a cathode, and a gate; controlled means connected in series with said anode and cathode, the series circuit being connected in parallel with said battery; and a series circuit comprising second diode means and relatively high impedance capacitor means connected between said second terminal and the gate of said solid state switching means.

3. The apparatus of claim 2 wherein said solid state switching means is a controlled rectifier.

4. The apparatus of claim 3 wherein one side of said series circuit of rectifier and controlled means is connected to a tap on the secondary of said transformer.

5. The apparatus of claim 4 wherein both of said firstand second diode means are positioned to conduct current in the same direction relative to said second terminal.

6. The apparatus of claim 5 wherein said capacitor means discharges toward said gate and changes polarity upon failure of the power supply from said alternating power source, thereby activating said switching means.

7. The apparatus of claim 2 wherein said controlled means is a lamp.

8. An emergency power supply unit which comprises: transformer means having a primary winding connectable to an alternating current power source and a secondary winding; rechargeable battery means and first diode means connected in electrical series relationship across said secondary winding to maintain said battery in a charged condition from said transformer means; solid state switching means capable of being switched from a high impedance state to a low impedance state; control means connected in series with said solid state switching means, the series circuit being connected in parallel with said battery; and a capacitive triggering circuit connected across at least a portion of said secondary winding in switching relationship to said solid state switching means.

References Cited by the Examiner UNITED STATES PATENTS 2,359,021 9/1944 Campbell 315112 X 2,952,818 9/1960 Russell.

2,981,880 4/1961 Momberg.

3,049,642 8/ 1962 Quinn.

3,070,739 12/ 1962 Hansen.

3,114,095 12/1963 Palmer 307-66 X 3,158,799 11/1964 Kelley.

3,159,755 12/1964 Duncan 307-66 X 3,189,788 6/1965 Cady 30766 X OTHER REFERENCES Controlled Rectifier Manual, General Electric, First Edition, pages 9, 10 and 11, published March 1960.

ORIS L. RADER, Primary Examiner.

T. I. MADDEN, Assistant Examiner.

Claims

1. AN EMERGENCY LIGHTING APPARATUS FOR AN ELEVATOR CAB WHICH COMPRISES: A VENTILATOR ARRANGED TO BE MOUNTED IN THE CEILING OF SAID CAB; AN EMERGENCY LIGHTINT UNIT POSITIONED WITHIN SAID VENTILATOR, SAID UNIT COMPRISING TRANSFORMER MEANS HAVING A PRIMARY WINDING CONNECTABLE TO AN ALTERNATING POWER SOURCE AND A SECONDARY WINDING INCLUDING FIRST AND SECOND TERMINALS, RECHARGEABLE BATTERY MEANS AND FIRST DIODE MEANS CONNECTED IN ELECTRICAL SERIES RELATIONSHIP, SAID BATTERY MEANS BEING CONNECTED TO SAID FIRST TERMINAL AND SAID FIRST DIODE MEANS BEING CONNECTED TO SAID SECOND TERMINAL TO MAINTAIN SAID BATTERY IN A CHARGED CONDITION FROM SAID TRANSFORMER MEANS, SOLID STATE SWITCHING MEANS INCLUDING AN ANODE, A CATHODE, AND A GATE, EMERGENCY LAMP MEANS POSITIONED TO DIRECT EMERGENCY LIGHT DOWNWARD FROM SAID APPARATUS AND CONNECTED IN SERIES WITH SAID ANODE AND CATHODE, THE SERIES CIRCUIT BEING CONNECTED IN PARALLEL WITH SAID BATTERY, AND A SERIES CIRCUIT COMPRISING SECOND DIODE MEANS AND RELATIVELY HIGH IMPEDANCE CAPACITOR MEANS CONNECTED BETWEEN SAID SECOND TERMINAL AND THE GATE OF SAID SOLID STATE SWITCHING MEANS.