Patent US3723724A successfully refreshed from Google Patents.
US3723724A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Safety mounted explosion proof light fixture
Assignee: Emerson Electric Co
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Filing: 1969-06-27
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Granted: 1973-03-27
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Expires: 1989-06-27
Abstract
Abstract Light bulbs in a safety-fixture which includes an enclosure of glass or other translucent material, are replaced after removing the fixture from its mounting. As the fixture is mated with the mounting, it moves through a sufficient distance to pass the fixture through three distinct zones; a first zone in which the fixture and mounting form a first explosion-proof enclosure therebetween; a second zone in which non-energized electrical connectors of the mounting and fixture engage; and a third zone in which the non-energized electrical connectors become energized by switch means on the housing, within the first enclosure. Withdrawal of the fixture from the third to the second zone automatically causes the connectors to be de-energized by the switch means. Making and breaking of electrical connection with live contacts only takes place within a second explosion-proof enclosure in the switch means. The danger of arcing during replacement of bulb or fixture is thus virtually eliminated, even though the lighting circuit energizing fixture is, itself, energized.
Inventors
- 👤 A Appleton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 21:02
CPC Classifications
F; F21; F21V; F21V25/00; F21V25/12
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
556 words
In the combination of a removable lighting fixture, and mounting means for mounting the fixture, said means being adapted for permanent installation, said fixture and said mounting means being adapted to provide a complete barrier to the passing of ignited gas from the interior of said fixture and said mounting means when the fixture is attached to said mounting means, said fixture being attachable to said mounting means by direct threaded engagement therebetween, the improvement comprising: the fixture having a first set of electrical contacts, each of said contacts forming a complete circular path at or centered around the center of rotation of the fixture when the fixture is being threaded into said mounting means, said first set of electrical contacts being positioned within the threads for face-to-face engagement with corresponding contact elements in the mounting; switch means fixed within said mountings, said switch means defining an enclosed space which is sealed with respect to passage of igniting gases therefrom, said switch means including a second set of electrical contacts enclosed within said space, means for directly and continuously connecting each of said second set of contacts to a power source, and a third set of electrical contacts adapted to engage corresponding contact elements of said first and second sets of contacts, said third set being located in said switch means, and being adapted to be inaccessible to said first set of contacts when the fixture is first being threaded into said mounting, said third set being adapted to abut at least a portion of each of the corresponding elements of said first set substantially before the fixture is completely threaded onto the mounting, each of said third set of contacts being movably mounted in said switch means having one portion of said contact externally exposed with respect to said switch, and having a second portion adapted to make and break coNnection with corresponding contact elements in the second set within said switch; resilient means for urging said third set of electrical contacts to a position spaced apart from each of the corresponding second set of contacts; whereby said first and third set of contacts do not engage until after the fixture is partially threaded onto the mounting, and the making and breaking of connection between first and third set of contacts takes place within a space sealingly enclosed by the fixture and the mounting as a result of the threading of the fixture onto the mounting; whereby the third set of contacts are not connected to the power source while the fixture is separated from the mounting; whereby the continued threading of the fixture onto the mounting causes the third set of contacts to be compressed by said first set of contacts until each of the third set of contacts moves into engagement with corresponding contact elements in the second set of contacts, the last named engagement taking place within the space sealed within the switch means; whereby during removal of the fixture from the mounting means each of said second set of contacts breaks engagement with corresponding members of said third set of contacts within the space inside the sealed switch means, at a point in time before connection is broken between said first set of contacts and said third set of contacts within the space closed by the fixture and the mounting means.
Claim 2
Dependent Claim
556 words
In the combination of a removable lighting fixture, and mounting means for mounting the fixture, said means being adapted for permanent installation, said fixture and said mounting means being adapted to provide a complete barrier to the passing of ignited gas from the interior of said fixture and said mounting means when the fixture is attached to said mounting means, said fixture being attachable to said mounting means by direct threaded engagement therebetween, the improvement comprising: the fixture having a first set of electrical contacts, each of said contacts forming a complete circular path at or centered around the center of rotation of the fixture when the fixture is being threaded into said mounting means, said first set of electrical contacts being positioned within the threads for face-to-face engagement with corresponding contact elements in the mounting; switch means fixed within said mountings, said switch means defining an enclosed space which is sealed with respect to passage of igniting gases therefrom, said switch means including a second set of electrical contacts enclosed within said space, means for directly and continuously connecting each of said second set of contacts to a power source, and a third set of electrical contacts adapted to engage corresponding contact elements of said first and second sets of contacts, said third set being located in said switch means, and being adapted to be inaccessible to said first set of contacts when the fixture is first being threaded into said mounting, said third set being adapted to abut at least a portion of each of the corresponding elements of said first set substantially before the fixture is completely threaded onto the mounting, each of said third set of contacts being movably mounted in said switch means having one portion of said contact externally exposed with respect to said switch, and having a second portion adapted to make and break coNnection with corresponding contact elements in the second set within said switch; resilient means for urging said third set of electrical contacts to a position spaced apart from each of the corresponding second set of contacts; whereby said first and third set of contacts do not engage until after the fixture is partially threaded onto the mounting, and the making and breaking of connection between first and third set of contacts takes place within a space sealingly enclosed by the fixture and the mounting as a result of the threading of the fixture onto the mounting; whereby the third set of contacts are not connected to the power source while the fixture is separated from the mounting; whereby the continued threading of the fixture onto the mounting causes the third set of contacts to be compressed by said first set of contacts until each of the third set of contacts moves into engagement with corresponding contact elements in the second set of contacts, the last named engagement taking place within the space sealed within the switch means; whereby during removal of the fixture from the mounting means each of said second set of contacts breaks engagement with corresponding members of said third set of contacts within the space inside the sealed switch means, at a point in time before connection is broken between said first set of contacts and said third set of contacts within the space closed by the fixture and the mounting means.
Claim 3
Dependent Claim
386 words
In the combination of a mounting member adapted for permanent installation and a lighting fixture member, one of said members having fixed male threads and the other having fixed female threads engaging said male threads when the two are coupled with said threads being positioned about a vertical axis whereby rotation of the fixture member about said vertical axis will release the threaded engagement and disengage the fixture member from the mounting member after a given amount of vertical downward movement of the fixture member with respect to the mounting member starting from the coupled position, said members defining an internal opening which is closed when the members are coupled and open when the members are separated, mating connectors on the two members which provide an electrical circuit between the two when the members are coupled, said mounting member having electrical connections for power supply thereto, and switch means in the mounting member between said electrical connections and the connectors on the mounting member and actuated by an actuator on the fixture member for opening the circuit between the two in response to movement of the fixture member away from the coupled position and before said portion of said given amount of movement is accomplished, the improvement wherein said switch means comprises: an insulator defining a pocket therein closed at one end and with an opening at the other end, conductor means in the form of a piston in the pocket and movable axially in the pocket, said piston having a skirt only slightly smaller than the cross-section of the pocket and a head at one end of said skirt, said head being at said other end of the pocket, said skirt and the closed end of the pocket defining an enclosed chamber, a spring between the piston and the insulator resiliently urging the piston to a first position adjacent said other end of the pocket, said piston being moved, by said actuator extending into the opening, against said urging to a second position when the members are in the coupled position, and a conductive part extending from the insulator into said enclosed chamber in a position to be contacted by the conductor means when the piston is in the second position and spaced from the conductor means when the piston is in the first position.
Claim 4
Dependent Claim
386 words
In the combination of a mounting member adapted for permanent installation and a lighting fixture member, one of said members having fixed male threads and the other having fixed female threads engaging said male threads when the two are coupled with said threads being positioned about a vertical axis whereby rotation of the fixture member about said vertical axis will release the threaded engagement and disengage the fixture member from the mounting member after a given amount of vertical downward movement of the fixture member with respect to the mounting member starting from the coupled position, said members defining an internal opening which is closed when the members are coupled and open when the members are separated, mating connectors on the two members which provide an electrical circuit between the two when the members are coupled, said mounting member having electrical connections for power supply thereto, and switch means in the mounting member between said electrical connections and the connectors on the mounting member and actuated by an actuator on the fixture member for opening the circuit between the two in response to movement of the fixture member away from the coupled position and before said portion of said given amount of movement is accomplished, the improvement wherein said switch means comprises: an insulator defining a pocket therein closed at one end and with an opening at the other end, conductor means in the form of a piston in the pocket and movable axially in the pocket, said piston having a skirt only slightly smaller than the cross-section of the pocket and a head at one end of said skirt, said head being at said other end of the pocket, said skirt and the closed end of the pocket defining an enclosed chamber, a spring between the piston and the insulator resiliently urging the piston to a first position adjacent said other end of the pocket, said piston being moved, by said actuator extending into the opening, against said urging to a second position when the members are in the coupled position, and a conductive part extending from the insulator into said enclosed chamber in a position to be contacted by the conductor means when the piston is in the second position and spaced from the conductor means when the piston is in the first position.
Claim 5
Dependent Claim
82 words
In the combination of claim 1, wherein said conductive part extends substantially axially within said skirt from the closed end of the pocket, said conductive means includes a contact within the enclosed chamber and movable therein toward and away from the piston Head, means in the piston to limit the extent of movement of the contact away from the head of the piston, and a spring between the contact and the piston head and urging the contact away from the piston head.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-03-26 | 1976-09-25 | 1977-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-26 | 1980-09-25 | 1981-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-26 | 1984-09-25 | 1985-03-27 | $7700.00 | Window Closed / Lapsed |