US 2699491 A
Description (OCR text may contain errors)
Jam 1955 c. J. STERNAMAN.
ELECTRIC LAMP HOLDER Filed May 3, 1950 FIG.2
United States Patent ELECTRIC LAMP HOLDER Chester J. Sternaman, Springfield, Ill. Application May 3, 1950, Serial No. 159,678
3 Claims. (Cl. 240-3) The invention relates to the mounting of electric lamp bulbs of the type used for illuminating substantial areas out of doors, such as driveways, automobile service station islands, etc. Such lamps are now commonly designated as PAR 38 sealed beam lamps or R40 special service lamps and commonly vary in size from 75 to 300 watts. The invention comprises a holder and may include an associated gasket and lamp bulb.
One object of the invention is to mount a lamp of the type described so that the major portion of the external surface of the lamp other than its lens or light emitting surface will be protected from the weather.
This object is attained by providing a seal between the lamp bulb and its holder adjacent to the periphery of the lens and it is another object to provide for circulation of air to the body of the lamp behind the seal.
Another object is to avoid rupture of the threaded socket, into which the base of the lamp is inserted, as the seal is formed.
These and other detail objects as will appear from the following description are attained by the structure illustrated in the accompanying drawings, in which:
Figure 1 is a longitudinal vertical section through a holder casing provided with a terminal socket and fitted with a flat annular gasket, a beam bulb being inserted in the casing. The section is taken upon the line 1-1 of Figure 2.
Figure 2 is a view looking at the front of the casing with the lamp and gasket removed.
Figure 3 is a similar section through a modified holder rim fitted with a tube-like gasket, a bulb being indicated in the position assumed when the lamp is inserted in the holder.
Figures 4 and 5 are similar sections illustrating other forms of the invention.
The deep cup-shaped casing consists preferably of cast metal and has an elongated neck 1 and a flaring body 2 terminating in a rim 2a. The casing has a rear end wall 4 and the bottom of the casing includes a projecting trough-like chamber 5 having a lateral opening 6. A hollow bracket 7 fits over opening 6 and is clamped to the body by a bolt 8. An insulating receptacle 9 1s secured to the casing rear wall 4 by screws 10 and is provided with the usual sheet metal threaded socket 11. Wiring W is passed through bracket 7 and suitable recesses in the lower and rear portion of the casing and receptacle 9 and leads to the socket terminals in the usual manner. Bracket 7, receptacle 9 and socket 11 in themselves do not constitute the present invention.
The inner wall of the rim portion of the casing includes a conical surface 12 facing inwardly towards the casing longitudinal axis A and outwardly towards the open end of the casing. A ledge 13 and a shoulder 14 are formed at the edges of surface 12 which extends diagonally of the casing axis.
These elements form a recess in the casing inner wall adapted to mount and receive an annular gasket 15 of leather-like or rubber-like material. This gasket may be of desired size and material and contour to best mount a selected lamp bulb 16.
Ledge 13 constitutes an annular initial seat for an outer corner portion of the normally fiat annular gasket 15 which assumes the position shown in dot-dash lines at 15a when first applied to the casing. As the lamp bulb 16 is screwed home in receptacle 9, the wider portion of the bulb near the periphery of the lens 16a contacts the inner periphery of gasket 15 and deflects the 2,699,491 Patented Jan. 11, 1955 ICC gasket by pivoting or rolling it upon the diagonally opposite outer corner seated against ledge 13 and swings the gasket 15 towards conical surface 12 and shoulder 14 to the position approximately as indicated in full lines in Figure 1. The entire rear face of the gasket may contact with the conical surface of the recess, or there may be clearance between them as indicated with exaggeration for better illustration. However, with continued inward movement of the bulb even with an irregular gasket, or if the bulb is out of round, some contact will result between the casing and the gasket throughout 360 of its periphery.
With this arrangement, the inward movement of the bulb axially of the casing thrusts the gasket outwardly away from the casing longitudinal axis A and may distort the gasket longitudinally of the casing. The seal between the casing and the lamp bulb is formed by resistance of the rubber to twisting and to shear rather than by the resistance of the rubber to compressive forces applied directly transversely of the thickness of the gasket.
Lamp bulbs of the type described have been mounted previously with a much smaller diameter gasket applied to a portion of the bulb nearer its base and the gasket has been of such material or so seated as to be relatively unyielding. The leverage exerted by the hand of the person installing the bulb and gripping the bulb about the relatively large diameter lens periphery is so great that it is a comparatively easy matter for the person forcing the bulb against its gasket having a seat facing longitudiually of the bulb to unintentionally flatten the center contact 17 and then rupture the threads in socket 11. With the present arrangement, the increase in the area frictional surface between the bulb and the gasket resulting from the large diameter gasket applied to the bulb near its greatest diameter and the gradual increase in the frictional resistance due to the yielding of the gasket as the bulb is screwed home makes it unlikely or impossible for the person installing the bulb to exert enough thrust unintentionally on the threaded socket to rupture the threads or to tear the tabs by which the socket is attached to receptacle 9. The yielding of the gasket as it shifts from the position shown in dot-dash lines to the position shown in full lines will result in a tight seal between the bulb and the casing, irrespective of manufacturing variations in these items.
Figure 3 shows another form of the invention in which the gasket 21 may be described as in the form of a short tube with its inner edge seated upon a shoulder 22 formed in the inner wall of casing 23 and with its outer edge initially well-spaced from the conical surface 24 formed on the casing inner wall between shoulder 22 and the extreme outer end of the casing.
When bulb 26 is screwed into the socket in casing 23, the upper portion of gasket 21 is deflected radially of the easing into the position shown in full lines and any distortion of the gasket longitudinally of the casing is caused by the gasket yielding in shear rather than under a compressive force, applied transversely of the gasket thickness with the same results in forming a seal and frictionally resisting relative rotation of the bulb as described above.
Figure 4 illustrates another form of the invention in which the casing conical surface 30 of the recess is bordered by an inwardly facing ledge 31 and an outwardly facing shoulder 32 about the same as shown. in Figure 1, although the angle between the conical surface of the axis of casing 33 is greater than that indicated in Fig ure 1. Also, shoulder 32 is deeper than shoulder 14.
Gasket 34 has a cross section which is substantially a trapezoid and it initially seats against surface 30 and shoulder 32. When a lamp bulb 36 is inserted in the casing, it first contacts the outer edge of gasket 34 and swings it outwardly of the casing to the position indicated in solid lines, decreasing the pressure against shoulder 34 and even moving the adjacent face of the gasket away from the shoulder as indicated in some exaggeration by the full line position of the gasket.
Figure 5 illustrates another form of the invention in which the gasket 40 comprises a ring of round cross section initially having a relatively small portion of its outer periphery in contact with an arcuate seat 41,
formed in the inner wall of casing 42, and having a relatively small portion of its inner periphery initially contacted by lamp bulb 46 as the latter is inserted into the casing. As the bulb is screwed in, the gasket is free to roll and distort under shear, to the position indicated in full lines where it may contact the adjacent portion of the casing wall tangent to the recess.
In all forms of the invention, the gasket is positioned near the open end of the casing and adjacent to the edge of the bulb lens rather than adjacent to the neck of the bulb which, in use, is much hotter than the rim of the lens. This reduces the tendency to injure the gasket material by high temperatures and reduces the pressure between the casing and bulb which might other wise arise from increased temperature. The bulb is sealed ofi from the weather on a line adjacent to the rim of its lens and this more effectively avoids the leakage of water to the neck of the bulb and the generation of steam adjacent those metal portions of the lamp applied to the neck. Air may circulate through opening 6 to the interior of the casing surrounding the bulb and there is little chance of moisture, condensation or precipitation collecting around the metal parts of the bulb to cause corrosion.
In the drawings, the clearance between the gasket and the casing inner wall is exaggerated for the purpose of more clearly illustrating the principles of the operation. Actually, these spaces will be reduced if not eliminated as the bulb is screwed down but, if so, the distortion of the rubber will be less at the portions of the gasket adjacent the spaces shown than at the point where the gasket is shown in contact with the casing.
The details of the invention may be varied substantially otherwise than as described and the exclusive use of those modifications coming within the scope of the claims is contemplated.
What is claimed is:
1. In an electric lamp bulb holder, a cup-shaped lamp-bulb-receiving casing having a threaded lamp socket at its inner end, there being an annular recess in the casing inner wall near its outer open end facing toward the longitudinal axis of the casing and towards the casing open end and having a surface flaring outwardly of the casing, and a gasket of rubber-like material with a restricted portion of the width of the outer periphery of the gasket seated against said surface and with a major portion of the width of the outer periphery of the gasket spaced inwardly from said surface so that the gasket is distortable by tilting of its cross section about said restricted portion under thrust applied against its inner periphery without substantial compression of the gasket material, there being a shoulder on said surface facing towards the open end of the recess and opposing movement of the gasket towards the socket.
2. In combination in an electric lamp, a rigid cuplike casing with a substantially closed inner end of relatively small diameter and an outer end of relatively large diameter, the side wall of the casing flaring from said inner end towards said outer end, a threaded lamp socket mounted on the inner end of the casing, there being an annular recess in the inner face of the casing wall near said outer end and having a surface flaring outwardly towards said outer end, an annular gasket of rubberlike material having a restricted corner portion of its outer periphery seated against the flaring side of said recess and having the remaining portion of its outer periphery spaced from the side of said recess and towards the axis of the casing, and a lamp bulb with a relatively narrow neck threaded into said socket and with a relatively wider outer rim inclined to the axis of the casing bearing against the inner periphery of said gasket and distorting the part of said gasket in contact with the bulb longitudinally of the casing towards the inner end of the casing and substantially free of compression against the casing.
3. In combination in an electric lamp, a rigid cup-like casing with a substantially closed inner end of relatively small diameter and an outer end of relatively large diameter, the side wall of the casing flaring from said inner end towards said outer end, a threaded lamp socket mounted on the inner end of the casing, there being an annular recess in the inner face of the casing wall near said outer end and having a surface flaring outwardly towards said outer end, an annular gasket of rubber-like material having a restricted corner portion of its outer periphery seated against the flaring side of said recess and having the remaining portion of its outer periphery spaced from the side of said recess and towards the axis of the casing, the space between the side of the recess and the outer periphery of the gasket accommodating the flaring of the gasket, by a bulb inserted in the casing, towards said surface without compressing the gasket against said surface.
References Cited in the file of this patent UNITED STATES PATENTS 2,286,448 Wahlberg June 16, 1942 2,305,934 Steber Dec. 22, 1942 2,357,322 Glocker Sept. 5, 1944 2,380,396 Berthold July 31, 1945 2,509,460 Transue May 30, 1950 2,511,937 Natale June 20, 1950 2,562,064 Rutledge July 24, 1951