EP2457246B1 - Discharge lamp, and method for the production of such a discharge lamp - Google Patents

Description

Technical area

The invention relates to a discharge lamp, in particular a D-lamp, according to the preamble of patent claim 1 and its manufacturing method according to the preamble of patent claim 11.

State of the art

The document DE 10 2006 042 178 A1 discloses such a discharge lamp used in a vehicle headlamp. This has a lamp cap with an approximately circular cross-section having recess in which a lamp bulb is inserted in sections. For holding collar four evenly around the recess of the lamp base around distributed metallic mounting tabs from the lamp base. These are welded to a one the lamp base assigning end portion of the lamp envelope firmly embracing metal clamp with a weld point, whereby the lamp envelope is mechanically connected to the lamp base.

The discharge lamp described is in use inter alia, a load transverse to a lamp longitudinal axis, for example, by vibrations or shocks exposed. This can result in addition to elastic and high plastic deformation of the welding point between the mounting tabs and the metal clip, the clamping of the mounting tabs or the mounting tabs of the discharge lamp. When used in a vehicle headlight In this case, the plastic deformations result in a deterioration in the performance of the discharge lamp due to a misalignment of the lamp bulb relative to the lamp cap.

Such discharge lamps may at a in the FIG. 1 This Bulb Deflection test according to IEC standard 60810 shown in this document does not exceed certain limits. In this test, the lamp base is firmly clamped and the lamp bulb in the longitudinal direction approximately centrally applied with a transverse force of 18 N. The lamp bulb is located approximately diametrically opposite to a force application point of the lateral force a measuring point, which may be spaced a maximum of 0.13 mm from its original position after relieving the lamp bulb. Another such discharge lamp is in EP 1 439 569 A2 disclosed. A disadvantage of the discharge lamps described above are the high plastic deformations of the welding point and the fastening tabs, in particular with transverse load of the lamp envelope.

Presentation of the invention

The object of the present invention is, on the one hand, to provide a discharge lamp which has low plastic deformation under external loads and, on the other hand, to provide a production method for such a discharge lamp which has low production and manufacturing costs and corresponds to high quality standards.

This object is achieved with regard to the discharge lamp by the features of the claim and in terms of Method solved by the features of the independent claim 5.

The discharge lamp according to the invention, which is in particular a D-lamp, has a lamp bulb supported by a lamp base. From the lamp base four four evenly about a lamp longitudinal axis offset from each other arranged metallic mounting straps. These are welded to the lamp base firmly embracing metal clip. Each fastening tab has a holding section and a subsequent welding section. A weld cross section in a connection plane lying between the metal clamp and the weld section has an area of at least 0.5 mm ² .

This solution has the advantage that plastic deformation, in particular the welding and / or the fastening tabs are reduced and the elastic deformations are increased. In the case of a welding cross-section with an area of at least 0.5 mm ² , the mechanical stresses in the area of the welding are so greatly reduced that the elastic limit of the metallic material is essentially not reached in the case of an initially explained Bulb Deflection Test or under conditions of use of the discharge lamp , By at least one recess in the mounting strap is their torsional and bending stiffness reduced compared to the prior art with extremely simple means, which leads to a relief of the welding between the fastening tab and the metal clip. By the concerns of the lamp bulb on the inner wall of the lamp cap at a deflection, the welding and / or the mounting straps can be relieved, since the deflection is limited by the concern.

Advantageously, a recess of the holding portion is formed as a through hole between longitudinal edges and the fastening tab and / or in the form of a groove in one or each of the longitudinal edges. As a result, the bending and torsional stiffness is reduced by extremely simple means, with an otherwise substantially constant geometric configuration of the fastening tab.

Preferably, the holding portion of the respective fastening tab is angled towards the lamp longitudinal axis and the welding portion extends away from the lamp base in the direction of the lamp longitudinal axis. The longitudinal edges of each fastening tab are in each case substantially in a plane, the planes being approximately parallel to one another and to the lamp longitudinal axis.

Preferably, the through-hole has substantially the shape of a rectangle, wherein inner longitudinal edges of the through-hole extend approximately parallel to the longitudinal edges of the fastening tab and have a greater length than inner transverse edges of the through-hole, and this is arranged approximately centrally in the fastening tab, thus totaling a homogeneous Course of mechanical stresses is achieved.

In a further preferred embodiment, the through hole is formed substantially triangular. In this case, an inner transverse edge of the through-hole extends approximately transversely to the longitudinal edges of the fastening tab, and two inner longitudinal edges of the through-hole each have an approximately equal angle of attack to the respective adjacent longitudinal edge of the fastening tab, wherein the two inner longitudinal edges each have a greater length than the inner transverse edge. This leads advantageously to a uniform mechanical stress distribution.

In a further embodiment, the transverse edge of the triangular through-hole is arranged adjacent to the transition region between the holding section and the welding section of the fastening strap.

If the recesses are introduced as grooves, then these are preferably arranged symmetrically to each other, whereby a homogeneous voltage profile is achieved.

To avoid stress peaks in the holding section, a groove has in each case a groove longitudinal edge and two bevelled edges obliquely to the groove longitudinal edge.

The welding portion may be formed approximately circular or elongated and extends in the latter case substantially transversely to the lamp longitudinal axis.

Preferably, the metal clip has a thickness of about 0.3 to 0.6 mm and a width of 4 to 7 mm and each fastening tab has a thickness of 0.2 to 0.5 mm and a width of 3 to 6 mm.

In a further preferred embodiment of the invention, the edge between an end face and an outer circumferential surface of the crimping end is formed. A radial distance of the edge from the inner wall is preferably less than 1 mm and a distance between the edge and the welded portion is advantageously 10 to 25 mm.

According to the invention, in the method for producing a discharge lamp, the welding section of a respective fastening tab is connected to the metal clip by laser welding.

The laser welding is preferably carried out with single-pulse welding, with spot seam welding, with line seam welding, with welding with line focus or with welding with a bi-focal optics or trim spot optics.

Short description of the drawing (s)

Fig. 1

Eine schematische Darstellung eines Bulb-Deflections-Tests;

Fig. 2

eine perspektivische Darstellung einer Entladungslampe gemäß einem ersten Ausführungsbeispiel;

Fig. 3

eine schematische Darstellung einer Schweißverbindung zwischen einer Befestigungslasche und einer Metallklammer eines Lampenkolbens gemäß dem Ausführungsbeispiel;

Fig. 4

eine perspektivische Darstellung der Entladungslampe gemäß einem zweiten Ausführungsbeispiel;

Fig. 5

eine perspektivische Darstellung der Entladungslampe gemäß einem dritten Ausführungsbeispiel;

Fig. 6a - 6d

eine schematische Darstellung unterschiedlicher Ausgestaltungen einer Schmelze der Verschweißung zwischen der Befestigungslasche und der Metallklammer;

Fig. 7

eine Längsschnittansicht der Entladungslampe gemäß einem vierten Ausführungsbeispiel.

In the following, the invention will be explained in more detail with reference to several embodiments. The figures show:

Fig. 1

A schematic representation of a Bulb Deflections Test;

Fig. 2

a perspective view of a discharge lamp according to a first embodiment;

Fig. 3

a schematic representation of a welded connection between a fastening tab and a metal clip of a lamp envelope according to the embodiment;

Fig. 4

a perspective view of the discharge lamp according to a second embodiment;

Fig. 5

a perspective view of the discharge lamp according to a third embodiment;

Fig. 6a - 6d

a schematic representation of different embodiments of a melt of the weld between the fastening tab and the metal clip;

Fig. 7

a longitudinal sectional view of the discharge lamp according to a fourth embodiment.

Preferred embodiment of the invention

In the FIG. 2 is a perspective view of a discharge lamp 1 according to a first embodiment shown. This is a high-pressure discharge lamp which can be used as a D-lamp, in particular as a D1, D2, D3 or D4 lamp in a vehicle headlight of a vehicle. The discharge lamp 1 has a lamp bulb 4 made of quartz glass held by a multipart lamp base 2 and having electrodes arranged therein for generating a gas discharge. The lamp base 2 is constructed substantially parallelepiped with a base lower and upper base part 6, 8. In an upper side 12 of the upper base part 8, an approximately cylindrical base element 10 is inserted, through which the lamp bulb 4 is held. The base element 10 has an annular web 14 extending away from the upper side 12, on which a retaining ring 16 is formed as part of a bayonet closure for fixing the discharge lamp 1, for example in a vehicle headlight.

The annular web 14 and the retaining ring 16 engage around an approximately cylindrical recess 18 of the base element 10, in which the lamp bulb 4 is partially immersed.

The lamp bulb 4 has an approximately circular cylindrical main body 20 with two multi-radially stepped back end portions 22, 24. A lying adjacent to the lamp base 2 end portion 26 of the main body 20 of the lamp envelope 4 is firmly encompassed with a metal clip 28 which cantilevered with four of the lamp cap 2 Attachment tabs 30 welded to the holder of the lamp bulb 4 is welded.

The mounting tabs 30 collar about one in the FIG. 2 upper inner edge 32 of the retaining ring 16 of the base element 10 from. The four fastening straps 30 are distributed uniformly around a lamp longitudinal axis 34 (FIG. 4). With a in FIG. 2 invisible fixing portion, the mounting tabs 30 are firmly embedded in the base member 10. The projecting part of the fastening straps 30 has a holding section 36 which is angled toward the lamp longitudinal axis 34 and subsequently has a welding section 38 extending approximately parallel to the lamp longitudinal axis 34. The attachment tabs 30 are then welded to the metal bracket 28 via the weld portion 38, respectively.

The welding portion 38 is slightly curved, whereby a surface facing the metal bracket 28 is convex and a repellent surface is concave, so that an end portion 40 of the welding portion 38 extends away from the lamp base 2 and the lamp longitudinal axis 34, and the lamp bulb 4 during assembly at the weld portions 38 can easily slide off.

The metal clip 28 has two fixed hinges 42, one of which in the FIG. 2 can be seen, which are formed as approximately cylindrical bulges with an axis parallel to the lamp longitudinal axis 34. The fixed hinges 42 are offset relative to each other with respect to the lamp longitudinal axis 34 by 90 ° and arranged in the assembled state of the lamp bulb 4 between two fastening tabs 30. To close the metal clip 28 are each formed at one end portion of the metal clip 28 and provided away from the lamp envelope 4 tabs are provided, which are welded together, which in the FIG. 2 not shown. The tabs, not shown, are formed approximately opposite to the illustrated fixed hinge 42 on the metal bracket 28 and arranged correspondingly between two fastening tabs 30.

Between in the FIG. 2 middle and left mounting tab 30, in which neither a fixed hinge 42 nor tabs of the metal clip 28 are arranged, extends a partially outwardly insulated power supply 44 from the lamp base 2 along the lamp envelope 4 for contacting an electrode 46 of the discharge lamp first

The welding portions 38 of the fastening tabs 30 are welded together with the metal bracket 28 via a laser welding process, which in FIG. 3 is explained in more detail.

In the FIG. 3 is the welding of the welding portion 38 of the fastening tab 30 from FIG. 2 with the Metal bracket 28 shown schematically according to the first embodiment. The laser welding is carried out by means of single-pulse welding, wherein a laser beam from an attack surface 48 facing away from the lamp bulb 4, see FIG. 2 and 3 , whereby a mushroom-shaped melt 50, as in the FIG. 3 apparent, arises. The melt 50 is in the FIG. 3 shown in a section. This extends through the entire thickness of the welding section 38 and a part of the thickness of the metal clip 28. A welding cross-section 52, which lies in a connecting plane 53 between the welding section 38 and the metal clip 28, has an area of at least 0.5 mm ² .

For loads, in particular lateral loads, as explained in the introduction in the prior art, the highest stresses occur in the region of the weld cross section 52. From an area larger than 0.5 mm ² , for example, in a bulb deflection test or under conditions of use of the discharge lamp, the voltages are remarkably lowered, thereby greatly reducing the plastic deformation and increasing the elastic deformation. A yield point of the weld is essentially no longer achieved here.

In order to relieve the welding of the welding portion 38 and the metal bracket 28, the mechanical torsional and bending stiffness of the mounting tabs 30 is made FIG. 2 reduced, which is explained below.

Each fastening tab 30 has two longitudinal edges 54, 56, each lying in a plane which extend approximately parallel to each other and to the lamp longitudinal axis 34. By doing Holding portion 36 of each fastening tab 30 is centrally introduced an approximately rectangular through-hole 58. Inner longitudinal edges 60 of the through-hole 58 extend approximately parallel to the longitudinal edges 54, 56 of the fastening tab 30 and are slightly longer than inner transverse edges 62 of the through-hole 58. The through-holes 58 are produced, for example, by the stamping method. Through the through holes 58, the rigidity, in particular the mechanical torsional and bending stiffness, of the fastening straps 30 is reduced and the welding between the metal clamp 28 and the fastening straps 30 is relieved with little production effort. This leads to a reduction of the plastic deformation of the discharge lamp 1.

Further embodiments of the fastening tabs 30 are described in the following FIGS. 4 and 5 demonstrated.

FIG. 4 discloses in a perspective view the discharge lamp 1 according to a second embodiment. Here, the fastening tabs 30 have a different configuration than in the first embodiment. The through-hole 58 is triangular in this case, wherein an inner transverse edge 64 extends approximately transversely to the longitudinal edges 54, 56 of the fastening tab 30 and two inner longitudinal edges 66 are each formed at an angle to the longitudinal edges 54, 56. The inner longitudinal edges 66 have a greater length than the inner transverse edge 64. This is arranged approximately adjacent to the welding portion 38 of the fastening tab 30. Such a through hole 58 results in loads of the discharge lamp 1 to a homogeneous mechanical stress distribution.

FIG. 5 illustrates the discharge lamp 1 in a perspective view according to a third embodiment, in which the fastening tabs 30 instead of a through hole 58 as in FIG. 2 and 4 , Grooves 68, 70 have. The grooves 68 and 70 are respectively inserted from the longitudinal edges 54 and 56 into each fastening tab 30. These then each have an approximately parallel to the longitudinal edges 54, 56 of the fastening tab 30 extending groove longitudinal edge 72 and two obtuse angled to the respective groove longitudinal edge 72 inclined edges 74th

The FIGS. 6a to 6d show in a highly simplified representation different melts 50 (of different laser welding methods), as in the FIG. 3 shown formed between the welding portion 38 of the fastening tab 30 and the metal bracket 28.

In the FIG. 6a For example, the melt 50 of the laser welding method with spot welding is schematically shown, wherein a laser beam 76 is indicated. In this case, individual mutually spatially offset laser pulses, in this case five, are emitted, as a result of which a plurality of overlapping mushroom-shaped melts 50 are formed, which lead to a total melt 50 which extends approximately transversely to the lamp longitudinal axis 34 FIG. 2 extends.

In the FIG. 6b the laser welding process is shown with single pulse welding, which leads to a mushroom-shaped melt 50, as in FIG. 3 , leads.

FIG. 6c discloses the laser welding method with line seam welding, wherein here the indicated laser beam 76 moves in the direction of the arrow 78, whereby a elongated melt 50 is formed, which extends transversely to the lamp longitudinal axis 34 FIG. 2 extends.

FIG. 6d represents another laser welding process in which the laser beam is directed with a line focus, whereby an elongated transverse to the lamp axis 34 from FIG. 2 arranged melt 50 is formed.

In the FIG. 7 is a longitudinal sectional view of the discharge lamp 1 according to a fourth embodiment disclosed. Here, the lamp bulb 4 is supported in addition to the mounting tabs 30 at a deflection to the lamp longitudinal axis 34 through the lamp base, which is explained below.

The lamp bulb 4 has according to the FIG. 7 one of the metal clip 28 firmly encompassed outer bulb 80th In the FIG. 7 Furthermore, a squeezing end 84 extending away from the discharge vessel (not shown) and receiving a current supply 82 is shown. This is welded to the outer bulb 80 and immersed in the base member 10 sections. A second, in the FIG. 7 not shown crimping extends diametrically from the first crimping end 84th

The insulated power supply 44 of the lamp bulb 4 dips into an approximately hollow-cylindrical power supply receptacle 88 formed on an inner wall 86 of the recess 18 of the lamp cap 2. This has a contacting 90 for the power supply 44 at its end facing away from the lamp bulb 4 end.

The base element 10 is stepped back radially at its end portion 92 facing away from the lamp bulb 4. The annular and an L-shaped cross-section having contact 90 firmly engages around the end portion 92 and is embedded in sections in an annular end face 94 formed by the downgrading.

From the end portion 92 of the base member 10 projects an approximately cup-shaped pinch end 96 in the recess 18 of the base member 10 in the direction of the lamp base 4 inside. The pinch end receptacle 96 is formed substantially coaxially with the lamp longitudinal axis 34 and has a slightly towards the end portion 92 of the base member 10 towards tapered inner wall 98. In the pinch end 96, the squeezing end 84 of the lamp envelope 4 is partially immersed, wherein the power supply 82 by a in a Bottom portion 100 of the crimp receiving 96 formed through opening 100 extends therethrough.

Surrounding the passage opening 100, a recess 104 pointing away from the lamp bulb 4 is introduced into the end section 92, whereby a journal 106 is formed. The pin 106 is firmly embraced by a sleeve-shaped contact 108, which is contacted with the power supply 82.

The squeezing end 84 of the lamp bulb 4 is slightly spaced from the bottom region 100 of the squeeze end receptacle 96 with an end face 110. An edge 112 of the crimp end 84, which is formed in the transition region between an outer circumferential surface 114 and the end face 110 of the crimp end 84, is spaced from the inner wall 98 of the crimp end 96 by a radial distance b. The distance b is preferably less than 1 mm.

In the case of the transverse loads explained at the outset, the deflection of the lamp bulb 4 with respect to the longitudinal axis of the lamp 34 is limited by the pinch end receptacle 96 by abutment of the edge 112 of the crimp end 84 against the inner wall 98 of the crimp end receptacle 96, thereby avoiding plastic deformation.

In experiments, it has been found that a distance a, such as between the welding portion 38 and the edge 112 - parallel to the lamp longitudinal axis 34 - in size between about 15 to 20 mm is advantageous to support the edge 112, without plastic deformation of the Welding or the mounting tabs 30, to allow.

The in the FIG. 7 described geometric configuration of the discharge lamp 1, in addition to the preceding embodiments of the invention from the FIGS. 1 to 6 be used.

Due to the embodiment of the discharge lamp described in the preceding figures, the plastic deformation ei a bulb deflection test (see prior art) can be lowered to 0.1 mm.

Disclosed is a discharge lamp, with a lamp bulb held by a lamp bulb. From the lamp base four four evenly about a lamp longitudinal axis offset from each other arranged metallic mounting straps. These are welded to the lamp base firmly embracing metal clip. Each fastening tab has a holding section and a subsequent welding section. A weld cross-section in a connection plane lying between the metal clamp and the weld section has an area of at least 0.5 mm ² and / or the holding section has at least one recess.

Claims (6)

1. Discharge lamp having a lamp bulb (4) held by a lamp base (2), a plurality of metallic fixing lugs (30) arranged so as to be offset approximately uniformly relative to one another about a lamp longitudinal axis (34) projecting out of the lamp base (2) and being welded to a metal clamp (28) engaging firmly around the lamp bulb (4), each fixing lug (30) having a holding section (36) and an adjoining welding section (38), characterized in that at least one welding cross section (52) has an area of at least 0.5 mm² in a connecting plane (53) located between the metal clamp (28) and the welding section (38).
2. Discharge lamp according to Claim 1, wherein the holding section (36) of the respective fixing lug (30) is angled over towards the lamp longitudinal axis (34), and the welding section (38) extends away from the lamp base (2) approximately in the direction of the lamp longitudinal axis (34), and wherein the longitudinal edges (54, 56) of each fixing lug (30), each lying substantially in a plane, extend approximately parallel to one another and to the lamp longitudinal axis (34).
3. Discharge lamp according to one of the preceding claims, wherein the welding cross section (52) is formed so as to be approximately circular or elongated and, in the latter case, extends substantially transversely with respect to the lamp longitudinal axis (34).
4. Discharge lamp according to one of the preceding claims, wherein the metal clamp (28) has a thickness of about 0.3 to 0.6 mm and a width of 4 to 7 mm, and each fixing lug (30) has a thickness of 0.2 to 0.5 mm and a width of 3 to 6 mm.
5. Method for the production of a discharge lamp according to one of Claims 1 to 4, wherein the welding section (38) of a respective fixing lug (30) is connected to the metal clamp (28) by laser welding.
6. Method according to Claim 5, wherein the laser welding is carried out by using single-pulse welding, by using intermittent seam welding, by using line welding, by using welding with linear focus or by using welding with bifocal optics or twin-spot optics.

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