US2261695A - Lighting unit - Google Patents

Description

Nov. 4, 1941.

w. NERL'ICH ETAL LIGHTING UNIT Filed May-23, 1939 2 Sheets-Sheet l- Willi $5 WITNESSES:

INVENTORS. Nerlzch s Sezdel A noa EY w. NERLICH ETAL' LEIGHTING UNIT r%/ Fi led May 23, 1939 2 She ets-Sheet 2' INVENTORS Willi Nerlich 8: Hot 8 Nov. 4, 1941.

WITNESSES:

Patented Nov. 4, 1941 UNITED STATES PATENT. OFFICE LIGHTING UNIT Willi Nerlich, Berlin-Spanda'u, and Hans Seidel,

Berlin-Falkensee, Germany, assignors to Westinghouse Electric & Manufacturing Company, a corporation of Pennsyl East Pittsburgh, Pa,

vania Application May 23, 1939, Serial No. 275,194 In Germany July 26, 1938 7 8 Claims.

Our invention relates, generally, tolighting units, and, more particularly, to lighting units of the explosion-proof type.

The object of our invention, generally stated, is to provide a lighting unit which shall be of simple and rugged construction, which may be readily and economically manufactured and maintained, and which will provide a high degree of safety in its operation and use.

A more specific object of our invention is to provide a lighting unit of the enclosed or explosion-proof type which cannot be opened to gain access to the lamp therein until the lamp,

switch contained therein has been actuated to its open position to interrupt the lamp circuit.

Another object of our invention is to provide a lighting unit having the lamp controlling switch mounted within the unit and switch actuating means on the outside of the unit so arranged that the unit cannot be disassembled while the switch is in its closed position.

A further object of our invention is to provide an explosion-proof lighting unit having a safety chamber containing the terminals and a pressure chamber containing the lamp socket with electrical connections extending between said chambers through explosion-proof seals of predetermined length.

A still further object of our invention is to provide for forming an explosion-proof lighting unit 1 by an assembly comprising a cap member, a housing member detachably secured thereto to form a safety chamber for housing the terminal members and a globe attached to the housing member to form a pressure chamber for housing the lamp socket, lamp and lamp-controlling switch.

Another object of our invention is to provide, in an explosion-proof lighting unit of the character described, for mechanically interlocking the various parts comprising the cap member, housing meter and globe, together in such manner that they cannot be disassembled until the lamp. controlling switch mounted within the unit has been opened.

These and other objects of the invention will become more apparent from the following detailed description when read in conjunction with the drawings in which:

Figure 1 is a sectional view partly in elevation of a lighting unit embodying the principal features of our invention;

Fig. 2 is a view of one of the elements of the unit of Fig. 1;

Fig, 3 is a partially sectionalized top plan view safety chamber Ill.

of the unit of Fig. 1 showing the lamp controlling switch within the unit;

Fig. 4 is an elevational view of the unit of Fig. 1 showing the arrangement and the relative position of the switch actuating device and the locking device for the globe ring;

Fig. 5 is a View in section of the unit taken along lines V-V of Fig. 3; and

Fig. 6 is a detail view taken along line VIVI of Fig. 4 showing details of the locking device for the globe ring.

In the preferred embodiment of the invention, the lighting unit is provided with a built-in switch and is constructed in such manner that it can only be opened after the circuit of its incandescent lamp has been interrupted, while on the other hand, the latter circuit cannot be closed unless all parts of the unit have been properly put together and brought into the closed positions. The lighting unit in line with the invention has a. closed safety chamber containing the terminals to which the lead-in wires must be fastened, and a sealed pressure chamber containing the incandescent lamp, lamp socket and the switch. Between these two chambers there have been provided conductive connections in the form of contact-making pins or plugs which lead from the safety chamber that contains the terminals, through explosion-proof seals.

of predetermined length, into the pressure chamber, where they are inserted in contact-making sleeves.

Referring now to the drawings, the lighting unitcomprises a cap I, a housing 2, a glass casing or globe 3, and a supporting ring 4 with bayonetcatch for the dome-shaped wire-guard 5. Inside the cap I of the lighting unit is mounted a terminal cleat 6, of insulating material, which carries the terminals I. The housing 2-of the lighting unit is held against the cap I and is fastened to the latter by means of screws 8. At the joint of the two parts I and 2 there has been provided .a gasket '9 of rubber or other suitable material, so that these two parts form a sealed The glass casing or globe 3 bears against the bottom part of the housing 2 of the lighting unit to form a pressure chamber lila. This glass casingv or globe 3' is pressed against the bottom part of the housing 2 by the ring 4 with bayonet-catch, a rubber gasket H being inserted between the surfaces of 3 and 4 that are being pressed together, and a ring [2 of aluminum foil being inserted between the surfaces of 2 and 3 that are being pressed together.

The arrangement of the bayonet-catch is indicated in Fig. 1. The supporting ring 4 has a bayonet-catch in the form of a nose l3 which slides into position behind a corresponding nose M of the housing 2 of the lighting unit.

Inside the housing 2 is mounted a socket |5 for the incandescent lamp IS; The housing contains in addition a switch I! which is actuated by a shaft |8 equipped with a coupling-pin IS. The shaft 8 is led through a hole of the housing 2 of the lighting unit, in such a manner that an explosion-proof seal of predetermined length, such for example, as about seven-tenths of an inch, is formed.

The switch is actuated with the aid of a key 20 which has two jaws 2| and 22 that engage the coupling-pin l9. The key 2|] is supported by a hinged part 23 that can be swung around a fulcrum 24. The chamber 25 which accommodates said key is partly closed by means of a disc 26 of sheet metal as shown in Fig. 2. This disc can be equipped, for instance with two'slits21, so that the key 20 can only be inserted into the chamber 25 when it is being held in a quite definite position, i. e., in the position corresponding to the off position of the switch.

A rotational displacement of the supporting ring 4 with bayonet-catch with-respect to the housing 2 of the lighting unit is made impossible by a threaded bolt 28, as shown in Fig. 6, which is attached to a lug 29 of the supporting ring 4. This threaded bolt passes through the hole of a lug 30 and is held in position by a nut 3|. This nut may be equipped, for instance, with a triangular head 32. As soon as one loosens this nut 3|, it is pushed outward in the direction of the arrow by the force of a spring 33 until it protrudes beyond the part 30. The hinged part 23 has been so designed that upon the insertion of the key 20 into the key-chamber 25, part 23 will be standing directly in front of the triangular head 32 of the nut 3|. In other words, the nut cannot be loosened after the insertion of the key 20 into the key-chamber, and it is impossible, therefore, to open the pressure-chamber of the lighting unit in this case. The triangular head 32 of the nut 3| will only be accessible after the key 20, upon being brought into the off position, is removed by swinging the hinged part 23 downward. On the other hand, the nut 3| will remain in the position in which it partly protrudes beyond the part 30 as long as it is not screwed again on the threaded bolt 28, and as long as the nut remains in this position, the hinged part 23 cannot be swung upward again for the purpose of inserting the key of the switch into the key-chamber.

In order to make it impossible to separate the cap I from the housing 2 of the lighting unit under operating conditions, the supporting part or ring 4 has been equipped with lugs 34 which, when this part is in the closed position, are placed directly in front of the heads 35 0f the screws 8, so that the latter are not accessible in this case. This means that the chamber ||l cannot be opened until after the switch has been brought into the off position, the connection established by the threaded bolt 28 and the nut 3| has been loosened, and the supporting ring 4 with the bayonet-catch has been turned through a certain angle.

Current is transmitted from the safety chamber ID to the pressure chamber 0a of the lighting unit by means of contact-making pins or plugs 36 which are led through a part 31 of insulating material in'such a manner that explosion-proof seals are formed. It is preferable to make these seals about seven-tenths of an inch in length. Inside the pressure chamber, these pins or plugs are inserted in contact-making sleeves 38 which may be connected to the switch I! and socket IS in any suitable manner to complete the electrical connection to the lamp 6.

In view of the foregoing it will be apparent that we have provided a lighting unit of the explosionproof type, wherein the various parts of the unit are assembled in such manner that they cannot be disassembled or the unit opened while the lamp controlling switch, positioned within the unit, is in the closed position and the switch cannot be actuated to its closed position to supply current to the lamp until the various parts of the units have been properly assembled. The unit is also provided with separate chambers, one of 'which houses the terminal members and the other houses the lamp, its socket and controlling switch, and sealed explosion-proof connectors provided between the two chambers. Likewise, the switch is actuated by means of a shaft extending through a sealed explosion-proof opening in the side of the housing, thereby providing a completely enclosed unit of the explosion-proof type which is of simple and inexpensive construction and which provides a maximum degree of safety.

It may be stated, in conclusion, that while the illustrated example constitutes a practical embodiment of our invention, we do not wish to limit ourselves strictly to the exact details herein illustrated, since modifications of the same may be made without departing from the spirit of the invention, as defined in the appended claims.

We claim as our invention:

1. A lighting unit comprising, a housing member, a globe, a supporting ring for the globe, said ring being attached to the housing by a bayonet joint, said globe and housing forming a chamber, a lamp socket mounted within said chamber, a lamp controlling switch mounted within the chamber, a shaft extending through the housing for actuating the switch from outside the housing, key means mounted on the outside of the housing and movable into and out of engagement with the exposed end of the shaft for actuating the shaft, and locking means mounted on the outside of the housing for holding the globe ring in locked position, said key means and locking means being so disposed that the key means cannot be moved into engagement with the end of the shaft to actuate the shaft unless the locking means is in its locking position, thereby to en-' sure that the globe is securely attached to the housing before the lamp controlling switch may be operated.

2. A lighting unit comprising, an inverted cup-shaped cap member, a housing disposed to be attached to the bottom of the cap member to form a, first chamber, a plurality of screws extending through the rim of the housing into the cap member to detachably secure the housing thereto, a globe disposed to be attached to the bottom of the housing to form a second chamber, a globe ring attached to the housing to hold the globe in position, and lug portions on said globe ring disposed to cover the exposed heads of said screws to render them inaccessible when said globe ring is in a predetermined position, thereby to prevent the opening of the safety chamber while the pressure chamber is closed.

3. A lighting unit comprising, a metal top portion, a globe detachably secured to the bottom thereof forming a closed pressure chamber, means for locking the globe in closed position, a lamp socket mounted in said chamber, a switch also mounted in said chamber, a shaft extending through the top portion for actuating the switch, a key for actuating said shaft, a lever pivotally mounted on the outside of the housing for supporting said key, whereby said key may be swung out of and into engagement with the shaft, said lever and locking means being mounted in mechanical interlocking relation to preclude operation of the locking means when the key is engaging the shaft and means positioned over the end of the shaft whereby said key and shaft may be engaged and disengaged only when the switch is in the ofi position.

4. A lighting unit comprising, a metal top portion, a globe disposed to be attached to the bottom of said top portion to form a pressure chamber, a globe ring for attaching the globe to the top portion, means for detachably securing the globe ring to the bottom of the top portion, means for locking the globe ring to the top portion after it has been secured thereto, a lamp socket and switch mounted in the pressure chamber, a shaft extending through the said top portion for actuating the switch, a key for actuating the shaft, a lever hinged to the outside of the top portion for movably supporting the key whereby said key may be moved into and out of engagement with the end of the shaft, said hinged lever being so disposed for movement with respect to the looking means for the globe ring that said locking means is rendered inaccessible by the hinged lever for operation to unlock the ring while said key is engaging the end of the switch actuating shaft.

5. A lighting unit comprising, a cap member, a housing member attached thereto to form a safety chamber, a globe disposed to be attached to the bottom of the housing member to form a pressure chamber, a globe ring for attaching the globe to the housing, said globe ring being attached to the housing by a bayonet connectionwhich functions to secure said globe ring to the housing on predetermined rotational movement of the globe ring relative to the housing, retaining means attached to the globe ring and engaging the housing to lock said globe ring in position, a lamp socket and switch mounted in the pressure chamber, a switch actuating member extending through the side of the housing, a key for actuating the shaft, a lever hinged to the outside of the housing for supporting the key, said lever and said retaining means being so disposed with respect to one another that said lever cannot be moved into position to cause the key to engage the shaft until said retaining means has been operated to lock the globe ring and said retaining means cannot be operated to unlock the globe ring while said lever is in position to cause the key to engage the shaft.

6. A lighting unit of the explosion-proof type comprising, a cup-shaped cap member, a housing attached to the bottom of the cap member to form a closed safety chamber, said housing having a pair of openings in the bottom thereof, a pair of terminal members supported by the cap member within the safety chamber, a globe detachably secured to the housing to form a pressure chamber, a lamp socket mounted in the pressure chamber, a switch mounted in the pressure chamber, a pair of contact members mounted on the underside of the housing within the pressure chamber directly beneath said openings, said contact members being connected to the switch and lamp socket, a pair of rigid contact pins stationarily mounted in the safety chamber and supported from the cap member and extending through the openings in the bottom of the housing into engagement with the contact members in the pressure chamber, said contact pins being connected with the terminal members in the safety chamber, means interposed between the contact pins and sides of the openings for sealing the joints therebetween, and a shaft extending through a sealed opening in the side of the housing for operating the safety switch.

7. A lighting unit of the explosion-proof type comprising, an inverted cup-shaped cap member having a plurality of threaded openings disposed around the periphery thereof, a housing member disposed to be attached to the bottom of the cap member to form a safety chamber for housing a plurality of wiring terminals, said housing having a plurality of outwardly extending ear portions provided with openings, a headed screw disposed in each of said openings in the ear portions and engaging the threaded openings in the cap member for clamping the housing against the bottom of the cap member, a globe, and a globe ring for attaching the globe to the bottom of the housing to form a pressure chamber for enclosing the lamp and lamp socket, said globe ring being attached to the housing by a bayonet joint and having outwardly extending lugs covering the heads of said screws when in its attached position to preclude opening of the safety chamber while the globe is in position.

8. A lighting unit of the explosion-proof type comprising, an inverted cup-shaped cap member, a housing member detachably secured to the bottom thereof with a sealed joint therebetween to provide a safety chamber, said housing having a plurality of openings therein, a globe, means for securing the globe to the housing with the joint between the globe and housing sealed to form a pressure chamber, a lamp socket and a control switch mounted within the pressure chamber, a shaft extending through an explosion-proof sealed opening in the side of the housing for actuating the switch, a plurality of terminal members fixedly mounted within the safety chamber, a plurality of contact members fixedly mounted within the pressure chamber and electrically connected with said lamp socket and control switch, and a plurality of rigid contact pins fixedly mounted within the safety chamber and electrically connected to the terminal members therein and extending through the openings in the housing into engagement with the contact members therein, said openings being provided with explosion-proof seals around the contact pins and said contact pins being disposed in sliding relation therewith.

WILLI NERLICI-li. HANS SEIDEL.

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