EP1911065B1 - Outer bulb electric lamp - Google Patents

Description

Technical area

The invention relates to an electric lamp with an outer bulb according to the preamble of claim 1. These are in particular metal halide lamps, high-pressure mercury discharge lamps, but also halogen lamps with outer bulb. The inner bulb of the lamp is sealed on two sides with sealing parts.

State of the art

From the EP 1 492 146 is known a lamp with outer bulb, which does not completely surround the inner piston. The outer bulb is attached to one or both sealing parts in each case by a neck portion at the end.

From the DE 10 2004 056 452.3 (not yet disclosed) it is known to provide such an outer bulb each with a narrow neck portion at the end, which is fixed to a bead at the end of the seal of the inner piston.

From the US Pat. No. 5,253,153 For example, a metal halide discharge lamp for automotive headlamps is known which has an inner piston and an outer bulb surrounding it, which is connected to the inner bulb via a glass bead.

A disadvantage of these joining techniques is that the film in the sealing part of the inner piston is very heavily loaded with temperature, which can lead to premature failure of the lamp.

Garstellung of the invention

It is an object of the present invention to provide a lamp according to the preamble of claim 1, which keeps the temperature load on the current-carrying metallic components, which are in contact with oxygen-containing atmosphere, as low as possible.

This object is solved by the characterizing features of claim 1. Particularly advantageous embodiments can be found in the dependent claims.

The lamp according to the invention has a vacuum-sealed internal piston, in particular a discharge vessel, which defines a lamp axis, and to each other opposite ends is closed by sealing parts. The sealing part is a pinch or meltdown. The luminous means inside the lamp is a discharge arc between two electrodes or a luminous element. It is electrically connected to the leading to him internal power supply lines. The sealing part is provided in particular with an outwardly projecting extension, which is formed as a hollow tube.

Metallic power feedthrough components on quartz glass lamps, especially power supply and foil, are exposed to a temperature load during lamp operation which, if too high and the surrounding atmosphere is oxygenated, can lead to premature lamp failures. Failure mechanism is oxidation-induced burn-through of the power supply or due to oxidation of the metal parts damage to the glass, which can lead to an opening of the combustion chamber. In the case of lamps of the generic type, it has been found that typical service life values of 10,000 h and more are only achieved if excessive oxidation processes in the area of the power supply wires and fused-in films are largely avoided. A measure of a sufficiently safe lamp design is the temperature of the molybdenum foils at the outer end of their vacuum-tight embedding in the quartz glass. At this point, the thermal load should always be below about 350 ° C. Known measures to achieve this are, for example, sufficiently long Folienquetschungen or greatly enlarged surface of the sealing parts made of glass. An increase of the stated limit of 20 to 40 ° C can be achieved by an additional oxidation protection of the metallic components via coatings such as chromium or platinum.

The described problem of temperature-dependent oxidation of the power supply components does not occur in lamps with evacuated and sealed by pinching outer bulb, because thereby the access of atmospheric oxygen to the hot spots of the current feedthrough by a double-sealed system over two successive molybdenum foils is prevented.

The invention describes a special geometric design. A gas-filled protective piston by tapering its usually tubular diameter at the ends so far over its length, so that the convection of hot Außenkolbenfüllgas over the length of the lateral sealing parts of the lamp is significantly hindered. By the inventive taper of the ends of the outer bulb the temperature gradient increases from the inside to the outside, so that the ends also become colder. This effect is also transmitted to the metallic current-carrying components of the lateral sealing parts of the lamp. On the glass surfaces of the sealing parts better or faster temperature can be delivered to the colder Außenkolbenfüllgas and outer bulb glass. Thus, the temperature drops faster from the inside to the outside over the length of the sealing parts. This allows for lower temperatures at the end of the film or shorter film fusions / squeezes.

In detail, it is an inner bulb, which contains a lighting means (2) and at opposite ends by sealing parts (6, 15), the foils (7) included, wherein the outer bulb (14) has two narrowed neck portions (13 ) has at its ends and is slipped over the inner piston, and wherein at least one neck part (13) is fixed to a connecting portion (12) at the end of the sealing part of the inner piston, characterized in that there is a terminal portion (Z) of the sealing part, in the distance (D) between the neck part and the sealing part is at most 4 mm, preferably at most 2.5 mm, wherein this distance (D) towards the inner piston is at least as far adhered to, that the narrowed portion of the neck portion of a portion (Y) of the film enclosing at least 20%, in particular at least 40%, of the axial length of the film encloses. The sealing parts are either fusions or bruises, which are H-shaped, preferably the longest dimensions are approximately square, in particular to 30% accurate.

Preferably, the connecting portion is formed by an annular bead on the sealing part.

In order to prevent convection as well as possible, the distance between the neck parts, and sealing should be as small as possible, but it should be at least 0.1 mm, in particular at least 0.7 mm.

An improved cooling effect is achieved in that the outer bulb is filled with a cooling-mediating gas, in particular more than 50% of an inert gas such as argon.

Sufficient cooling is already achieved if the axial length of the narrowed region is at least 4 mm, in particular at least 6 mm.

Depending on the manufacturing process, it may make sense to ensure that the outer bulb with the two narrowed neck parts closes a hole located on the sealing part.

Depending on the lamp type and wattage, it may be helpful if the diameter of the neck part in the narrowed area is either constant or smaller towards the outside.

The total length of the necked neck portion should normally be at most 20 mm, preferably at most 12 mm. In this case, the constriction of a tubular glass body as a precursor of the outer bulb can be generated solely by Formroll- or Formblasprozesse after preheating. The shorter the neck part, the easier this manufacturing process can be applied. In particular, this applies to lengths up to 6 or 10 mm.

When the total length of the necked neck portion is at least 6 mm, preferably at least 11 mm, the necking of the tubular glass body as a precursor of the outer bulb is produced by roll forming or shape blowing processes after preheating combined with hot deformation by drawing out the already necked portions of the outer bulb.

The production of such tapered areas is particularly material-saving. The tapering of the ends of the outer bulb should thereby, including the radii or bevels connecting the maximum and minimum radial spreads of the outer bulb, at least over a length of 2 mm and at most over the entire length closely surround the area with the vacuum-tight sealing parts of the lamp. The minimum inner diameter of the usually tubular outer bulb should be removed at its tapered portions not greater than 4 mm from the maximum outer diameter of the lateral sealing parts of the lamp. Also, the minimum inner diameter of the outer bulb may correspond to the maximum outer diameter of the sealing parts and may even be partially interconnected.

Advantageously, the outer bulb geometry is designed similar to the geometry of the inner vessel, which basically means that the distance between the outer bulb and the extension parts of the discharge vessel, ie the areas with the vacuum-tight current feedthrough components, should be at most 4 mm.

A particular problem is the cost-effective production of such an outer bulb shape. There are essentially two options. On the one hand the production of several individual parts mostly different dimensions, which are firmly connected by glass melting processes. On the other hand, such an outer bulb can also be formed from a blank by glass forming processes. be brought out to the desired shape, which describes a particularly cost-effective embodiment.

By way of example, this technique is suitable for a relatively low power metal halide lamp of 35 to 250 watts.

The taper of the outer bulb over a greater length can preferably be carried out in combination with a bead / bump attachment technique on the sealing part, in particular the extension part of a seal of the inner vessel. This technique of creating a bead is known per se, for example EP-A 588 602 or EP-A 465 083 such as DE 10 2004 056 452.3 ,

Equally combinable is the taper with the Puniplochverschlusstechnik a hole on the burner tube and subsequent closure over the outer bulb glass. This is another advantage, because the pre-rolled area can be reduced by an additional extraction, which has resulted in a particularly favorable embodiment, glass mass, which makes the closure of the underlying pumping hole easier.

Challenging is the production of the tapered ends of the outer bulb by glass forming over a greater length. A "normal" taper over a maximum of 55% of the diameter of the outer bulb can be made relatively easily by a multi-stage roll forming process with rotating glass. A typical example is a length of the tapered portion, defined here as neck length, of 2 to 12 mm with a typical diameter of about 22 mm of the outer bulb.

The preparation of a longer neck portion is known with a multi-stage free rolling process extremely difficult to produce or from lengths of at least 75% of the diameter of the outer bulb, for example, of about 17 mm at a 22 mm diameter, no longer technically useful. An alternative is a technique in which several glass tubes of different diameters are placed one behind the other. The disadvantage of this, however, is the manufacturing and cost overhead, due to additional lamp components.

Easier and less expensive is the production via a combined rolling and drawing process. Initially, the maximum possible length HTL of the neck portion, that is made in about 50% of the outer diameter of the outer bulb with the known free rolling process. The actual final length of the neck portion is achieved in a further step by pulling in the region of the already rolled section. This has the additional advantage that any accumulations of material on the pre-rolled area can be pulled out again to uniform wall thicknesses.

The outer bulb is advantageously a piston with central belly and terminally adjacent thereto, in particular attached or molded, pipe sections, which are referred to here as neck parts.

A preferred embodiment provides for the inner vessel a tubular extension piece of the sealing part, on which a bead adjoins. It is especially applied or molded. As a result, the provision of a radially symmetrical bead is possible even with a non-radially symmetrical pinch. The bead can be produced from the sealing part, for example by upsetting, or placed on it as a separate bead. The breaking strength of the connection between outer bulb and bead increases, the more intimate the contact between the two.

Both inner flask and outer flask made of quartz glass or hard glass are preferred.

1. a.) Bereitstellen eines bestückten Innengefäßes aus Glas, insbesondere eines Rohres aus Quarzglas, der ein inneres Volumen definiert und der zwei Enden besitzt, wobei jeweils ein Stromdurchführungssystem von außen über die Enden in das Volumen ragt, wobei das System insbesondere ein Elektrodensystem ist, das zumindest eine Elektrode, eine Folie und eine Stromzuführung umfasst, wobei das innere Volumen mit einer gashaltigen Füllung befüllt ist, wobei das Ende des Innengefäßes mittels eines Abdichtungsteils, das einen zentralen Teil des Stromdurchführungssystems gasdicht umschließt, und evtl. eines Verlängerungsteil, das einen außen liegenden Teil des Stromdurchführungssystems enthält, gebildet wird;
2. b.) Bereitstellen eines zweiten Rohrs aus Quarzglas mit gegebenem maximalen Außendurchmesser mit größerer Abmessung und zwei offenen Enden, wobei die Abmessung des zweiten Rohrs so bemessen ist, dass das zweite Rohr das innere Volumen, und zumindest den Abdichtungsbereich und evtl. einen gewissen Teil des Verlängerungsteils überdeckt,
3. c.) Überstülpen des zweiten Rohrs über das Innengefäß
4. d.) Formen eines verengten Halsteils an einem ersten Ende des zweiten Rohrs über eine Länge von typisch 4 bis 10 mm mittels eines Formrollprozesses; dazu wird der zu verformende Bereich am Glasteil erwärmt und mit einer sich drehenden Formrolle soweit nach innen geschoben, dass sich ein Halsteil mit einem kleineren Durchmesser ergibt; für typische Längen von größer als 10 mm des Halsteils wird das beschriebene Formrollen zusätzlich mit einem Ausziehen am bereits vorgeformten Glasteil durch Erwärmen und anschließendem axialen Ziehen kombiniert, so dass das Halsteil zusätzlich verlängert wird;
5. e.) Formen eines zweiten verengten Halsteils am zweiten Ende analog Schritt d.)
6. f.) Verbinden des äußersten Endes des geformten Halsteils der ersten Seite mit dem Verlängerungsteil des Innengefäßes.
7. g.) Verbinden des geformten Halsteils der zweiten Seite mit dem Verlängerungsteil des Innengefäßes.

A possible concrete manufacturing process is based on the following steps:

1. a.) providing a filled inner vessel made of glass, in particular a tube of quartz glass, which defines an inner volume and which has two ends, wherein in each case a current feed-through system protrudes from the outside into the volume via the ends, wherein the system is in particular an electrode system comprising at least one electrode, a foil and a power supply, wherein the inner volume is filled with a gas-containing filling, wherein the end of the inner vessel by means of a sealing part, which encloses a central part of the current feed-through system in a gastight manner, and possibly an extension part which contains an outer part of the current feed-through system is formed;
2. b.) providing a second tube of fused silica having a given maximum outside diameter of greater dimension and two open ends, the dimension of the second tube being dimensioned such that the second tube defines the internal volume, and at least the sealing area and possibly a part of the Extension parts covered,
3. c.) Slipping the second tube over the inner vessel
4. d.) forming a narrowed neck portion at a first end of the second tube over a length of typically 4 to 10 mm by means of a roll forming process; For this purpose, the area to be deformed is heated on the glass part and pushed inwards with a rotating forming roller to the extent that results in a neck portion with a smaller diameter; for typical lengths of greater than 10 mm of the neck portion of the described form rollers is additionally combined with a withdrawal on the already preformed glass part by heating and subsequent axial drawing, so that the neck part is additionally extended;
5. e.) forming a second narrowed neck at the second end in analogy to step d.)
6. f.) connecting the outermost end of the shaped neck portion of the first side with the extension portion of the inner vessel.
7. g.) connecting the shaped neck portion of the second side with the extension portion of the inner vessel.

Brief description of the drawings

Figur 1

eine Halogenglühlampe in Seitenansicht (Fig. 1a) und im Querschnitt (Fig. 1 b);

Figur 2

ein Ausführungsbeispiel einer Metallhalogenidlampe in Seitenansicht (Fig. 2a) und im Querschnitt (Fig. 2b):

Figur 3 bis 5

die Verfahrensschritte der Herstellung einer Metallhalogenidlampe gemäß Figur 2.

In the following the invention will be explained in more detail with reference to several embodiments. Show it:

FIG. 1

a halogen bulb in side view ( Fig. 1a ) and in cross section ( Fig. 1 b) ;

FIG. 2

An embodiment of a metal halide lamp in side view ( Fig. 2a ) and in cross section ( Fig. 2b ):

FIGS. 3 to 5

the process steps of producing a metal halide according to FIG. 2 ,

Preferred embodiment of the invention

FIG. 1a shows the side view of a two-sided squeezed halogen bulb. It consists of an inner piston 1, in the middle part 4, a luminous body 2 is arranged axially.

The ends 5 of the filament are embedded in their function as an internal power supply directly into the pinch 6, which acts as a seal, and there connected to a pinch film 7.

The pinch 6 has the outside as an extension part, which can also serve as a base component, a tubular glass sleeve 11 which is integrally formed on the pinch.

On the sleeve. 11 is formed transversely to the lamp axis outwardly a bead 12. In this case, the end of an outer bulb 14 designed as a narrowed cylindrical neck portion 13 engages, so that the outer bulb with two neck portions 13 extends between the two beads 12 on both sides of the middle portion 4.

In addition, a base may be attached to one end of the sealing part, as known per se, wherein the base has an electrical contact element (not shown), which is electrically connected to a power supply leading to a light source, wherein the contact element in the tubular extension of Sealing part is housed.

The distance D between the narrowed neck portion and the H-shaped pinch 6 is 1.5 mm. Here, the distance D means the mean between the valley of the pinch on the broadside and the two peaks of H, see FIG. 1b , An H-shaped pinch has a large surface area and therefore cools the seal very well.

In FIG. 2a For example, a metal halide lamp 25 sealed by fuses 15 is shown. In this case, the one neck part 13a is designed to constrict to the outside, while the other neck part 13b has a constant diameter, but is made of a separate piece of pipe, which is attached to the outer bulb at the inwardly directed slope. The cold filling pressure in the outer bulb with argon filling is in particular 200 to 400 mbar.

The production takes place in such a way that first the discharge vessel is formed as a preparation step, equipped with a feedthrough system and filled with a gas filling and then closed. These steps are known per se.

In FIG. 3 a first step of further production is shown. In this case, a populated inner vessel 30 made of glass is provided, in particular a tube made of quartz glass, which defines an inner volume and which has two sealed ends 31, wherein in each case a current feed-through system 32 projects from the outside via the ends into the volume. This system is in particular an electrode system comprising at least one electrode, a foil and a power supply. The inner volume of the discharge vessel is filled with a gaseous filling, wherein the end 31 of the inner vessel is formed by a sealing member 34 which gas-tightly surrounds a central part of the current feed-through system, and an extension member with a bead 33 which contains an outer part of the current feedthrough system ,

In a second step, there is provided a second outer tube 35 of fused silica having a given maximum outer diameter larger in dimension than the discharge vessel and having two open ends, the dimension of the second tube 35 being such that the second tube is the inner volume of the second tube Discharge vessel and at least the sealing area and possibly a certain part of the extension part covered.

In a third skirts the slipping over of the second tube takes place via the inner vessel.

In a fourth step, the forming of a first narrowed neck portion 36, at a first end of the second tube 35 over a length of typically 4 to 10 mm by means of a Formrollprozesses. For this purpose, the area to be deformed is heated on the glass part and pushed with a rotating forming roller 37 inward so far that the neck portion 36 results in a reduced diameter.

In a fifth step, the forming of a second narrowed neck portion at the second end 31 b by means of a second forming roller 39 is analogous to the fourth step, see FIG. 4 ,

In a sixth step, joining the outermost end of the formed neck portion on the first side 31a to the extension portion of the inner vessel (not shown).

In a seventh skirting, the bonding of the molded neck portion on the second side 31b to the extension portion of the inner vessel (not shown) occurs.

For typical lengths L of the neck of L greater than 10 mm, the described forming rollers are additionally combined with a withdrawal on the already preformed glass part by heating and subsequent axial pulling (arrow 40), so that the neck portion 36 is additionally extended; please refer FIG. 5 ,

In the latter steps, each can be purged with argon and possibly even a glovebox be used.

Claims (10)

1. Electrical lamp having an outer bulb (14) and an elongate inner bulb (1), which is closed in a vacuum-tight fashion and defines a longitudinal axis (A), contains a lighting means (2) and is closed at opposite ends by sealing parts (6; 15) that contain foils (7), wherein the outer bulb (14) has two narrowed neck parts (13) at its ends and is fitted over the inner bulb, and wherein at least one neck part (13) is fastened on a connecting section (12) at the end of the sealing part of the inner bulb, wherein there is a terminal section (Z) of the sealing part in which the distance (D) between the neck part and the sealing part is at most 4 mm, wherein this distance (D) from the inner bulb is maintained at least to such an extent that the narrowed portion of the neck part encloses a subportion (Y) of the foil, which includes at least 20% of the axial length of the foil, characterized in that the sealing parts (6; 15) are each configured in an H-shape.
2. Electrical lamp having an outer bulb according to claim 1, characterized in that the connecting section is formed by an annular bead (12) on the sealing part.
3. Electrical lamp having an outer bulb according to claim 1, characterized in that the minimum distance of the neck part in the narrowed portion is at least 0.1 mm, in particular at least 0.7 mm.
4. Electrical lamp having an outer bulb according to claim 1, characterized in that the outer bulb is filled with a gas that contributes to cooling, in particular with more than 50% of an inert gas such as argon.
5. Electrical lamp having an outer bulb according to claim 1, characterized in that the axial length of the narrowed portion is at least 4 mm, in particular at least 6 mm.
6. Electrical lamp having an outer bulb according to claim 1, characterized in that the outer bulb with the two narrowed neck parts closes a hole located on the sealing part.
7. Electrical lamp having an outer bulb according to claim 1, characterized in that the diameter of the neck part in the narrowed portion is either constant or becomes smaller in an outward direction.
8. Electrical lamp having an outer bulb according to claim 1, characterized in that the overall length of the narrowed neck part is at most 20 mm, preferably at most 12 mm, the narrowing of a tubular glass body as a precursor of the outer bulb having been produced only by rolling or blowing shaping processes after prior heating.
9. Electrical lamp having an outer bulb according to claim 1, characterized in that the overall length of the narrowed neck part is at least 6 mm, preferably at least 11 mm, the narrowing of a tubular glass body as a precursor of the outer bulb having been produced by rolling or blowing shaping processes after prior heating, combined with hot forming by pulling processes of the already narrowed parts of the outer bulb.
10. Electrical lamp having an outer bulb according to claim 1, characterized in that the outer bulb and the narrowed neck parts are composed of a plurality of components having different dimensions.

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