Note: Descriptions are shown in the official language in which they were submitted.
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Electric Vehicle Lamp With Inserted Insulation Plug
Field of the Invention
The invention concerns an electric lamp with a
lamp bulb and with lead wires leading out from the lamp bulb
and with a base which incorporates a connection region made
of electrically insulating material and provided with
electrical connections.
Background
A lamp of the type described above has been
disclosed, for example, in patent EP 0 172 529. That
document describes an electric incandescent lamp, in
particular a lamp for a motor vehicle headlight, with a lamp
bulb pinched on one side and a lamp base consisting of metal
and plastic parts. The pinch base of the lamp bulb is
mounted in a metallic holder part of the lamp base, whereas
the electric connections of the lamp are configured as
contact lugs and are housed in the lower part of the base
which is made of plastic. The lower part of the base
manifests a cavity into which extend the feeding lines or
lead wires of the lamp coming from the pinch base. These
lead wires are each welded to an end of a contact lug inside
the cavity of the lower part of the base. A potting compound
is paured into the cavity to seal off the base. This seal
ensures that no moisture, which would cause corrosion of the
reflector, enters the headlight through the lamp base.
Summary
Embodiments of this invention make available an
electric lamp with a gas-tight base which manifests improved
construction and, in particular, require no cement or
potting compound for the seal.
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Accordingly, in one aspect of the invention there
is provided an electric lamp with a lamp bulb having lead
wires leading out from the lamp bulb, the bulb being
supported by a base which incorporates a connection region
made of electrically insulating material and provided with
electrical connections, wherein the connection region
manifests a cavity into which at least one lead wire of the
electric lamp projects, and at least one electric connection
of the base is formed by a contact lug which projects into
the cavity in an electrically conducting manner with a lead
wire of the lamp, at least one shaped part consisting of a
heat-resistant, elastic material is located in the cavity of
the connection region, the shaped part has at least one
passage for a lead wire of the electric lamp, the shaped
part sits on at least one contact lug and abuts in a press
fit the wall delimiting the cavity and the at least one lead
wire passed therethrough.
The electric lamp in accordance with an embodiment
of the invention incorporates a lamp base with a connection
region made of
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electrically insulating material in which the electrical
connections of the lamp are housed. The connection region
manifests a cavity into which project one or more lead wires
coming from the lamp bulb. There they are each connected in
electrically conducting manner to the end of an electrical
connection configured as a contact lug. The lamp base is
sealed off according to the invention by means of one or more
shaped parts provided with passages for the lead wires and
made of heat-resistant, elastic and slightly compressible
material. The shaped parts) sits on at least one contact lug
and abuts with a press-fit both the wall that delimits the
cavity and the lead wires) lead through. The press-fit is
advantageously produced by the at least one contact lug which
exerts a pressure on the shaped part(s). In addition the
shaped parts) is (are) advantageously located in precisely
matching recesses, The pressure exerted by the at least one
contact lug on the shaped parts) is thus evenly distributed
across the entire body of the shaped part(s), and an optimum
press-fit of the shaped parts) is achieved on the adjacent
cavity walls and the lead wires) lead through. In the
preferred embodiment the shaped parts) advantageously consist
of silicon. The use of several comparatively thick-walled,
tube-like, silicon shaped parts) which each have a passage
for one of the lead wires projecting into the cavity of the
connection region has proven successful.
The ends of the contact lugs extending into the cavity
advantageously have a claw-like shape and either hook or claw
the cavity wall. A secure provisional mounting of the contact
lugs which are under mechanical tension can thus be assured
before the welding of the contact lugs to the lead wires. To
facilitate the welding of the lead wires to the associated
contact lugs, the contact lugs are advantageously each
provided with a passage for the lead wire.
The passages for the contact lugs) in the connection region
of the base are each preferably provided with an insert bevel
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which permits an inclined introduction of the contact lugs
relative to the base axis and then tipping of the contact
lugs in the base axis.
The cavity of the connection region is closed with
a cover which advantageously incorporates a web extending
into the cavity which sits on the surface of the contact
lugs) facing away from the shaped part or parts. This web
provides additional support for the contact lugs. The
connection region of the base preferably consists of heat-
resistant plastic.
Brief Description of the Drawings
The invention will be explained in more detail
below by means of a preferred embodiment.
Figure 1 shows a schematic, cross-sectional
illustration of the electric lamp according to the preferred
embodiment.
Figure 2 shows a cross-section of the connection
region of the base of the lamp according to the preferred
embodiment of Figure 1.
Figure 3 shows a top plan view of the contact lug
according to a second embodiment.
Figure 4 shows a side view of the contact lug
according to the second embodiment of Figure 3.
Detailed Description
The preferred embodiment of the electric lamp
according to the invention involves a single-filament,
halogen incandescent lamp for use in a motor vehicle
headlight. This lamp incorporates an essentially
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cylindrical glass lamp bulb 10 with a pinch-sealed lamp bulb
end l0a which is usually called a pinch end 10a. The dome
lOb of the lamp bulb 10 manifests a black, light-absorbing
coating. An incandescent filament (lOc), aligned parallel
to the lamp bulb axis and electrically connected to the lead
wires 11 extending from the pinch end 10a, serves as the
light source. The lamp bulb 10 is fixed in
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position with its pinch end 10a by a metallic holder 12
configured as a fastening ring. The fastening ring 12 is
supported by a ring-shaped, metallic support sleeve 13. The
support sleeve 13 manifests four shaped, weld tabs 13a which
are spot or laser welded to the fastening ring 12. In addition
to the metallic fastening ring 12 and the metallic support
sleeve 13, the lamp base incorporates a plastic base part 14
provided with the electrical connections 15 of the lamp in
which the support sleeve 13 is anchored. This plastic base
part 14 forms the connection region of the lamp base. The
electrical connections 15 of the lamp
are configured as contact lugs, each of which is welded to one
of the lead wires 11. The plastic base part 14 is an
injection- molded part into which the metallic support sleeve
13 is injected. The plastic base part 14 has three integrally
formed reference lugs 14a placed equidistantly along a
periphery which serve to align the incandescent filament lOc
and to secure the lamp in the reflector 17 of the headlight.
The reference lugs 14a engaging in opening 17a in the
reflector 17 which is designed as the lamp holder are each
covered by a~covering clip 13b integrally formed on the
support sleeve 13 and angled-off therfrom and are thus
protected from the infra-red radiation generated by the
incandescent filament 10c. The plastic base part 14 in
addition manifests a ring-shaped, circumferential, cylindrical
groove 14d in which a gasket 16 of rubber or silicon is
located. The gasket 16 rests on the outside of the reflector
wall 17 and seals off the reflector opening 17a that is
designed as the lamp holder. The inner diameter of the gasket
16 is accurately matched to the conical groove 14b and varies
linearly with the height of the gasket. The three reference
lugs 14a, the gasket 16 and a pressing spring 13c that is
integrally formed on the metallic support sleeve 13 below one
of the reference lugs 14a serve to secure the lamp in the lamp
holder 17a of the reflector. The lamp base and the lamp holder
17a form a bayonet connection.
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Details of the plastic base part 14 which forms the connection
region are shown in Figure 2. For the sake of clarity, the
pinch end l0a is not depicted in Figure 2 and the lead wires
11 are shown only in part, i.e., not in full length.
The plastic base part 14 includes a cavity 18 into which
project the two lead wires 11 coming from the pinch end 10a of
the lamp bulb 10
as well as the ends of the two contact lugs 15. Two tube-like,
shaped parts 19 of silicon are located in the cavity 18 and
are placed in an exactly matching recess 18a formed by the
walls of plastic base part 14. The outer diameter of the tube-
like, shaped parts 19 is significantly greater than the inner
diameter thereof. Each of the lead wires 11 is led through the
passage in a tube-like, shaped part 19 and through an opening
15b in the end of the contact lug 15 welded to it which
projects into the cavity 18. The shaped parts 19 each sit on a
contact lug 15. Each contact lug 15 exerts a pressure on the
corresponding shapec! part 19, so that the shaped part is
slightly compressed in the tube axis and thereby abuts by a
press fit the walls defining the recess 18a and the lead wire
11 led through. In this manner a gas-tight seal of the lamp
base is made in the region of the lead wires 11.
The ends 15a of the contact lugs 15 projecting into the cavity
18 are shaped like claws and hooked into the rear wall of the
plastic base part 14. The passages 20 in the plastic base part
14 for the contact lugs 15 each manifest an insert bevel 20a
which facilitates the mounting of the contact lugs 15. The
cavity 18 is closed by means of a snap-on cover 21. The inside
of the cover 21 is equipped with an integrally formed web 22
that extends into the cavity 18 and sits on the surface of the
contact lugs) 15 facing away from the shaped parts 19 and
provides additional support for the contact lugs 15 which are
under mechanical tension.
When assembling the base of the lamp, after securing the
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fastening ring 12 bearing the pinch end 10a to the support
member 13, the tube-like shaped parts 19 are threaded on the
corresponding lead wires
11 and inserted in the respective, exactly matching recess
18a. Then the contact lugs 15 are passed through the passage
20 in the plastic base part 14, coming from the cavity 18
along the insert bevel 20a extending at an angle to base axis
A-A. Finally the contact lugs 15 are tipped in the base axis
A-A, so that the lead wires 11 extend through the opening 15b
in the corresponding contact lug 15. The tube-like shaped
parts 19 are pressed by the contact lugs 15 into the recesses
18a and slightly compressed, so that shaped parts 19 abut by a
press fit on the walls delimiting the recesses 18a and on the
lead wires 11 passed through the shaped parts 19. When the
contact lugs 15 are tipped in the base axis A-A, the claw-like
ends 15a of the contact lugs 15 simultaneously hook into the
rear wall of the plastic base part 14. The axial alignment of
the contact lugs 15 is thus provisionally fixed. Finally the
ends of the lead wires 11 extending through the openings 15b
are welded to the contact lugs 15. The cavity 18 is then
closed by means of the snap-on cover 21.
Figures 3 and 4 show a second embodiment of a contact lug. The
contact lug 15' according to the second embodiment manifests a
rectangular support surface 15d' with an opening 15b' for a
lead wire 11 on which the contact surface 15e' is integrally
formed. The support surface 15d' and the contact surface 15e'
are positioned vertical to each other and connected to each
other by a twisted region 15f'. A total of three claws 15a',
15c' are integrally formed on the support surface 15d' of the
contact lug 15' pressing against the shaped part 19 which hook
into the base wall during the mounting of the contact lug 15'.
Two 15a' of these claws 15a', 15c' are formed on the side of
the support surface 15d' opposite the contact lug 15e', while
the third claw 15c' is formed on the same
side of the support surface 15d' as the contact surface 15e'.
In contrast to the contact lug 15 of the first embodiment the
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claws 15a', 15c' are not bent from the support surface 15d'
but instead are in the same plane.
The invention is not limited to the embodiments described
above. Instead of several tube-like shaped parts, a single
shaped part, for example, consisting of heat-resistant,
elastic and slightly compressible material and with several
passages for the lead wires coming from the lamp bulb can be
used. In addition the shaped parts do not have to be made of
silicon, but instead can consist of other material with
similar heat-resistance, elasticity and compressibility as
silicon. Furthermore the ends of the contact lugs extending
into the cavity of the plastic base part can, for example,
engage behind a protrusion in the cavity wall. They do not
have to be designed in a claw-like fashion. Duro-plastic and
thermal plastic cL~stomarily used in lamp technology are
suitable material for the plastic base part 14.
