US2594753A

US2594753A - Sealed beam lamp

Info

Publication number: US2594753A
Application number: US119925A
Authority: US
Inventors: Robert N Falge
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1949-10-06
Filing date: 1949-10-06
Publication date: 1952-04-29
Anticipated expiration: 1969-04-29

Description

April 29, 1952 R N, FALGE 2,594,753

SEALED BEAM LAMP Filed 0G13. 6, 1949 uventor (ttornegs Patented pr. 29, 1952 SEALEDi BEAM LAMP I-tobert N, Falgc, Andersomlnd., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application october s, 1949, serial No. 119,925

The present invention relates to vehicle lamps and particularly to lamps of the type comprising a metal reector, a lamp bulb and a lens sealed as a unit,` such lamps being commonly known assealed beam lamps. Y.

Heretofore Athe sealing of suchlampunits has been accomplished by clamping the lens and reflector flanges on 'an interposed .rubber gasket cured to provide optimum elasticity and toughness. Such rubber gaskets would deform `to receive projecting flanges in the lens and-reiiector but would not grip or adhere to the lens and metal reflector and consequently with aging or misalignment of lensand reector they .permitted the passage of air and containedmoisture causing condensation on the inner lens .surface and a reduction of reflection efciency of the reflector surface.V

Accordingly it is an object of the present invention to provide an improved lamp unit vconstruction of the sealed beam typewhich has a high degree of resistance to leakage over indenite periods of time.y

This and other` objects are attained in accordance with the present invention by providing a lamp unit construction having a sealing gasket of natural rubber characterized by a core of tough elastic cured rubber and a surface coating of a tacky or adhesive rubber constituent formed by a curing process known as reversion. Reversion as it is commonly known involves the heating of masticated rubber which has been mixed with sulphur. There is an improvement in mechanical properties as heating is continued until an optimum is reached. Thereafter with continued heating the physical properties decline, strength decreases and the rubber becomes shorter and shorter. If the heating is carried further the rubber becomes tacky and plastic. Advantage of this characteristic is taken in the present invention to provide a lamp unit construction in Which'van overcured rubber gasket provides means for a vsubstantially air-tight seal over indefinite periods of time.

For a better understanding of the invention reference may be had to the accompanying drawing in which Figure l isa side elevation view of a lamp unit embodying the present invention, and Figure 2 is an enlarged cross-sectional view in perspective of a fragment of thev 12 oiai'ms. (o1. 31a- 113) the lens to the reiiector with a rubber gasket 8 interposed therebetween. The reector flange is formed with a radially extending portion I!! and an axially extending portion I2 of sufficient length to be turned inwardly on ythe annular ange i4 of the lens. The lens flange i4 is provided witli axially extending annular projections lwhich cooperate with the gasket 8 and a similar axially extending annular ridge i8 on the reflector flange to form the seal for the lens and reflector.v

The gasket 8 is a natural rubber material which as has been hereinbefore indicated may be heat-treated to provide a tacky or adhesive surface which not only conforms to the contours ofnthe surfaces of'fianges IQ and i4 but adheres to the vsurfaces of the anges.

,Tobprovide the tacky,l or adhesive surface the assembled reflector 2 and bulb i is placed on a traveling belt with the reflecting face upwardly. The gasket 8 of natural rubber which is substantially free of volatile material is placed in positionon the flange I!! and passes with the reector assembly into a furnace which is heated tov a temperature of 360 to 380 F. The furnace and belt speed are arranged so that after a time interval of `seven minutes the gasket and reiiector assembly vpass a station where the lens is placed in position on the gasket and thereafter the reflector assembly, gasket and lens continue in the furnace for an additional three minutes. Thereafter the axially extending portion l2 of the reflector flange is bent inwardly on the lens flange I4 sealing the lamp assembly as a unit.

With the heat-treatment above described the gasket material reverts to a tacky or adhesive vstate on the surfaces thereof and to a suicient depth. to permit the plastic surface constituent to conform to the projections I6 and ridge I3 adhering with considerable tenacity to all flange surfaces in contact with the gasket. The core of the'gasket remains tough and elastic being substantially unaffected by the heat-treatment. With such a heat-treatment the gasket provides optimum sealing characteristics while retaining a high degree of elasticity and strength at the core i, to `withstand permanent deformation. With such a gasket. treated in the manner described, I have found that the lamp units remain impervious to the atmosphere over indefinite periodsof time.

While I have disclosed a preferred embodimentu'of the present invention, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow:

vWhat I claim as new and desire to secure by LettersPaten-t of the United States is:

l 1. In a unitary lamp in combination, a reector, alarnp bulb attachedto said reector, a lens clamped to said reflector and a gasket interposed between said reflector and said lens, said gasket having a tough elastic core and an adhesive or tacky surface for adhesively bonding said gasket to said lens and reflector surfaces to seal said lamp against the admission of atmosphere.

2. In a unitary lamp in combination, a reilector, a lamp bulb attached to said reflector with its filament substantially coinciding with the focal axis of said reflector, a lens clamped at its annular edge to said reflector, a cured rubber gasket interposed between said reflector and said lens, said gasket having been heat-treated to provide an adhesive or tacky reverted rubber surface for adhesively bonding said gasket to the engaging surfaces of said lens and reflector and seal said lamp against the admission of atmosphere therein.

3. In a unitary vehicle lamp in combination, a metal reflector having an annular clamping flange thereon, a lamp bulb having its base attached to said reflector to provide substantial alignment of its filament and the focal axis of said reector a substantially air-tight seal between said base and said reflector, a lens clamped to said reflector by said flange and a heat-treated natural rubber gasket interposed between said rellector and said lens, said gasket having a tough, elastic cured rubber core and a tacky, adhesive, reverted rubber portion surrounding said core for adhesively bonding said gasket to the engaging surfaces of said reflector and said lens to provide a substantially air-tight seal.

4. In a vehicle lamp unit in combination, a substantially parabolic metal reflector having an annular clamping flange with an axially extending ridge, a lamp bulb having its base attached to said reflector to provide a substantially air-tight seal, said bulb having its lilament in substantial alignment with the focal axis of said reflector, a lens having an annular flange with axially extending projections clamped to said reflector by said ange, and a heattreated natural rubber gasket interposed between said reflector and said lens, said gasket having a tough, elastic cured rubber core and a reverted rubber portion surrounding said core to provide a tacky, adhesive surface for receiving said ridge and said projections and adhesively bond said gasket to the engaging surfaces of said reflector and lens to provide a substantially air-tight seal.

5. The process of sealing a unitary lamp assembly comprising a metal reflector, a lamp bulb and a lens which includes interposing a natural rubber gasket between said reflector and lens, heating said gasket to form a tough elastic cured rubber core surrounded by a tacky adhesive surface layer of reverted rubber and clamping said gasket between said reflector and lens to cause said surface layer to adhesively bond said gasket to the engaging surfaces of said reflector and said lens.

6. The process of sealing a unitary lamp assembly comprising a metal reflector with an annular flange, a lamp bulb attached to said reflector and a lens which consists of placing a natural rubber gasket on the annular flange of said deflector, subjecting said reflector and gasket to a temperature of about 360 to 380 -F. for about seven minutes to cause a revision of the rubber at the surface of said gasket, placing said lens with its annular edge in engagement with said gasket, further heating said lens, reflector and gasket at about 360 to 380 F. for about three minutes to cause further reversion of the rubber adjacent the surface of said gasket and thereafter clamping said lens and reflector together on the adhesive or tacky reverted rubber surfaces formed on said gasket.

7. A gasket for positioning between the lens and reflector of a unitary lamp assembly including a reflector, lens and light source, said gasket comprising a tough, elastic core surrounded by adhesive or tacky surface portions for adhesively bonding said gasket to said lens and reflector surfaces to seal said lamp against the admission of the atmosphere.

8. A rubber gasket for positioning between the lens and reflector of a unitary lamp assembly including a lens, reflector and light source to seal said assembly against the admission of the atmosphere, said gasket comprising a tough elastic cured rubber core surrounded by reverted rubber portions providing tacky surfaces for adhesively bonding said reflector and lens.

9. An annular rubber gasket for positioning between the lens and reflector of a unitary lamp assembly including a lens, reflector and light source to seal said assembly against the admission of the atmosphere, said gasket comprising a tough elastic core of cured natural rubber surrounded by a layer of reverted natural rubber providing tacky gasket surfaces for adhesively bonding said gasket to the engaging surfaces of said reilector and lens.

10. An annular rubber gasket adapted to be interposed between the lens and reflector of a unitary lamp assembly commonly known as a sealed beam lamp, said gasket comprising a tough elastic core of cured natural rubber surrounded by a layer of permanently reverted natural rubber providing tacky gasket surfaces for adhesively bonding said gasket to the engaging surfaces of said reflector and lens.

1l. In a unitary lamp assembly having a lens, reflector and light source, a gasket for positioning between said lens and reflector, said gasket comprising a tough, elastic core of cured rubber surrounded by a layer of permanently reverted rubber providing tacky gasket surfaces for adhesively bonding said gasket to said lens and reflector to seal said assembly against the admission of the atmosphere.

12. The process of sealing a unitary lamp assembly comprising a metal reflector with an annular flange, a lamp bulb attached to said reflector and a lens, said process comprising the steps of placing a natural rubber annular gasket on said flange, positioning said lens on said gasket, heating the assembly to a temperature and for a period of time to provide said gasket with a tough elastic core of cured rubber and a surrounding layer of tacky reverted rubber and thereafter clamping said lens, gasket and reflector together to adhesively bond said gasket to the engaging surfaces of said lens and reflector to seal said assembly against the admission of the atmosphere.

' ROBERT N. FALGE'.

REFERENCES CITED The following references are of record in the file of this patent:

Dana Apr. 20, 1943