Abstract:
A fastening element including a shaft; a shaft head arranged at an end of the shaft, wherein the shaft head has a larger diameter than the shaft, wherein the fastening element is provided for arranging a first component and a second component at each other, wherein the first component is provided as a circuit board provided with a LED and the second component is provided as a heat dissipating lamp element, wherein the shaft is insertable through a pass through opening of the first component and the shaft head is configured at least for an indirect contact at the first component, wherein the shaft is arrangeable in a recess of the second component, wherein the shaft is fixable at least through friction locking in the recess of the second component.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation of International Application PCT/DE2014/200230 filed on May 21, 2014 claiming priority from German patent applications 
         [0000]    DE 20 2013 006 326.2 filed on Jul. 15, 2013,
 
DE 20 2013 006 325.4 filed on Jul. 15, 2013,
 
DE 20 2013 007 589.9 filed on Aug. 24, 2013, and
 
DE 20 2014 001 330.6 filed on Feb. 17, 2014,
 
all of which are incorporated in their entirely by this reference.
 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a fastening element. 
       BACKGROUND OF THE INVENTION 
       [0003]    Fastening elements of this general type are not known in the lamp field. 
         [0004]    Similar fastening elements, however, are used in the automotive industry and are designated as expansion rivets. A similar fastening element is known from example from WO 2005/071273 A1 relating to different art. This expansion rivet is typically used in the automotive industry to fixate interior fairing elements at a vehicle body. 
         [0005]    In the lamp industry LEDs are increasingly used as illuminants. LEDs are typically arranged on a circuit board which typically provides good heat dissipation. Conductive paths are arranged on a top side of the circuit board in order to electrically connect the LEDs. These conductive paths have to be offset relative to metal elements or they have to be insulated. These circuit boards are attached on a reactive bearing which is configured for example as a cooling element and which represents a lamp element or forms a portion of a lamp housing. During assembly of the circuit board on the lamp element selecting a correct contact pressure is very important since the contact pressure is a significant factor for quality of the heat dissipation from the LED to the lamp element. 
         [0006]    A fastening element which fixates individual circuit boards provided with LEDs on a lamp element is known for example from DE 10 2008 005 823 A1. Thus, an annular connecting element is placed onto the circuit board and supports the circuit board between itself and a reaction bearing, for example a cooling element. The connecting element is connected with the reaction bearing through bolts. The tightening torque of the bolts defines the contact pressure between the circuit board and the reaction bearing. 
         [0007]    Increasing mass production of LED lamps of various types requires fastening elements for the circuit boards provided with LEDs which fastening elements are configured for automated manufacturing methods. Thus, fastening elements of this type have to satisfy stringent requirements with respect to permanently supporting the circuit board and permanently maintaining the contact pressure. These requirements are due to a projected service life of the LED illuminant of up to 50,000 hours. 
         [0008]    Thus, it is an object of the invention to provide a fastening element which is configured for an automated fabrication of lamps and which provides a defined contact pressure between the LED and the lamp element. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    The object of the invention is achieved by a fastening element including a shaft; a shaft head arranged at an end of the shaft, wherein the shaft head has a larger diameter than the shaft, wherein the fastening element is provided for arranging a first component and a second component at each other, wherein the first component is provided as a circuit board provided with a LED and the second component is provided as a heat dissipating lamp element, wherein the shaft is insertable through a pass through opening of the first component and the shaft head is configured at least for an indirect contact at the first component, wherein the shaft is arrangeable in a recess of the second component, wherein the shaft is fixable at least through friction locking in the recess of the second component, wherein the fastening element is provided with an insulating element which is arranged between the shaft head and the first component and prevents a contact of the shaft head and the first component, wherein the fastening element is provided with a clamping element which clamps the first component against the second component through the shaft head, wherein the insulating element is made from a spring elastic material and functions as the clamping element, wherein the shaft includes diameter expending support elements configured as interlocking hooks which are configured to enter a form locking engagement with the second component, wherein a free end of at least one shaft lobe is crimped and forms a support element which is supported at another shaft lobe, wherein the support element supports the at least one shaft lobe and the other shaft lobe in a rigid manner in a normal position in which the interlocking hooks protrude beyond an inner radius in a circumference expanding manner. 
         [0010]    The object is also achieved by an arrangement including the fastening element recited supra; the first component; and the second component, wherein the shaft head contacts an insulation element, wherein the insulation element contacts the first component, wherein the first component contacts the second component, wherein the clamping element is supported at the shaft head and induces a contact force between the first component and the second component. 
         [0011]    The object is also achieved by a method for arranging two components at each other by the fastening element recited supra, wherein the first component includes a pass through opening and the second component includes a recess, the method comprising the steps arranging the first component and the second component at each other, wherein the pass through opening and the recess are aligned with each other; inserting the fastening element assembled from the retaining clamp and the insulating element with a free shaft end forward in an insertion direction through the pass through opening into the recess until the insulating element contacts the first component; sliding the interlocking hooks at edges of the pass through opening and of the recess and spring elastic displacing of the interlocking hooks into an interior space of the fastening element; continuing an insertion movement in the insertion direction with an insertion pressure that compresses the insulating element in a spring elastic manner; building up reset forces by the insulating element which reset forces act against the insertion pressure; and penetrating the recess with the interlocking hooks and interlocking the interlocking hooks at a bottom side of the second component. 
         [0012]    An essential advantage of the fastening element according to the invention is its suitability for automated assembly. Two components, the first component corresponds to the circuit board with LED, the second component corresponds to the (amp element, are arranged at one another so that the pass through opening and the recess are aligned. The shaft of the fastening element is inserted into the recess through the pass through opening until the shaft head contacts the first component. The friction locking engagement of the shaft fixates the fastening element in the recess of the second component so that the components are fixated at each other. 
         [0013]    The assembly robots and assembly methods required for this purpose can be developed and implemented in a simple manner. The characterizing feature of the insulation element prevents that the fastening element comes in contact with the surface of the circuit board and the conductive paths arranged thereon so that they may suffer mechanical damage or shortening in case a metal fastening element is used. The clamping element provides a clamping force between the first and the second lamp element so that good heat transfer from the LED to the lamp element s provided. 
         [0014]    It is provided that the insulating element is made from an electrically non-conductive material, in particular since the fastening element itself is made from metal. 
         [0015]    Providing the fastening element from metal is preferred since a metal fastening element can bear the attachment forces over years. On the other hand plastic elements are known to deform over time under load so that they yield to impacting forces. This bears the risk in particular in view of a high service life of LEDs that the attachment function is not continuously provided. 
         [0016]    It can also be provided that the insulating element is made from a spring elastic material and used as a clamping element. 
         [0017]    The essential advantage of this embodiment is that a number of components is reduced. Since the insulating element is arranged between the shaft head and the first component anyhow, the insulating element can be loaded with a respective clamping force through the mounting forces directed in insertion direction when fixating the fastening element so that the reset forces of the insulating element are supported at the shaft head on one side and at the first component on the other side. Thus, a contact force between the first and the second component is induced. 
         [0018]    Under these conditions the embodiment of the fastening element made from metal has particular relevance since the fastening element itself is loaded with a force by the clamping element. 
         [0019]    In a particularly advantageous embodiment it is provided that the shaft includes diameter expanding support elements, in particular interlocking hooks which can enter into a form locking engagement with the second component. 
         [0020]    In particular when the fastening element cooperates with building up the contact force since the insulating device is configured as a clamping element a form locking connection is preferred. Contrary to a friction locking connection the form locking connection provides safe support of the fastening element in the recess of the second component. 
         [0021]    It is provided that the insulating element includes a pass through opening through which the shaft of the fastening element is run. The pass through opening facilitates to provide the insulating element as a disc arranged below the shaft head while still being able to use the shaft itself for attaching the components. 
         [0022]    In one embodiment it is provided that the shaft is formed by two shaft lobes which form an intermediary space between each other. 
         [0023]    It is furthermore provided that the free end of at least one shaft lobe carries a support element which is supported at the other shaft lobe and supports both shaft lobes in a rigid position where they are offset from each other. 
         [0024]    Another embodiment provides that both shaft lobes respectively include a support element and that the support elements are supported at each other. 
         [0025]    In view of the technical task at hand the invention also relates to an arrangement according to one of the claims  1 - 9 , a first component and a second component wherein the shaft head contacts an insulating element, the insulating element contacts the first component and the first component contacts the second component. 
         [0026]    This arrangement achieves the object of the invention in that a clamping element is supported at the shaft head and imparts a mutual contact force between the first component and the second component. 
         [0027]    In a first embodiment that the first insulating element is clamped by the fastening element against the first component and the reset force thus introduced generates the contact force between the first component and the second component. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    Further advantages and a better comprehension of the invention are apparent from the subsequent description of an embodiment with reference to the drawing figures, wherein: 
           [0029]      FIG. 401  illustrates a fastening element according to the invention including a support bracket and an insulating and clamping element in an exploded view; 
           [0030]      FIG. 402  illustrates a sub assembly of the fastening element including a support bracket, and an insulating and clamping element in a perspective view; 
           [0031]      FIG. 403  illustrates the sub assembly according to  FIG. 402  in a tope view; 
           [0032]      FIG. 404  illustrates the sub assembly according to  FIG. 402  in a first side view; 
           [0033]      FIG. 405  illustrates the sub assembly according to  FIG. 402  in a second side view; 
           [0034]      FIG. 406  illustrates the representation according to  FIG. 403  in an assembled configuration; 
           [0035]      FIG. 407  illustrates a sectional view according to the sectional line A-A in  FIG. 406 ; 
           [0036]      FIG. 408  illustrates a representation of the sub assembly according to  FIG. 402  in an assembled configuration a perspective view with a schematic representation of a plier head; 
           [0037]      FIG. 409  illustrates the representation according to  FIG. 404  of the sub assembly in an assembled configuration; and 
           [0038]      FIG. 410  illustrates a sectional view according to the sectional line B-B in  FIG. 409 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0039]    A fastening element according to the invention is designated overall with the reference numeral  4110 . 
         [0040]    The fastening element  4110  includes a retaining bracket  4111  which includes a shaft  4112  which is formed by two shaft lobes  4113 . The shaft lobes  4113  include a free end  4114  and are respectively attached at a shaft head  4116  with a joined end  4115 . 
         [0041]    The shaft lobes  4113  are offset from each other and include an intermediary space  4117  between each other. The free ends  4114  taper and form insertion trunks  4118  this way wherein the fastening element  4110  has to be assembled with the insertion trunks forward. Behind the insertion trunks  4118  in a direction towards the shaft head  4116  each shaft lobe  4113  forms support elements  4119  which are embodied as interlocking hooks  4120  which are oriented in outward direction, this means away from the intermediary space  4117 . A shaft neck  4121  arranged thereafter in a direction of the shaft head  4116  transitions into a shaft disengagement section  4122  into which an engagement cam  4123  is embossed that is also oriented in an outward direction. 
         [0042]    The shaft head  4116  is configured substantially disc shaped and defines a plane relative to which the shaft lobes  4113  are essentially oriented orthogonal. An imaginary inner radius r of the shaft head  4116  corresponds approximately to a radius of a pass through opening  4138  in a first component  4113  and a recess  4139  in a second component  4134  into which the shaft  4112  of the fastening element  4110  is insertable. Therefore the shaft lobes  4113  are arranged on this radius r. 
         [0043]    In a portion of the connection of the shaft lobes  4113  at the shaft head  4116  the shaft head  4116  therefore includes recesses which are configured as engagement recesses  4124 . In these portions the shaft head tapers from an outer radius R down to an inner radius r. 
         [0044]    A portion of the fastening element  4110  is therefore formed by an insulating element  4130 . The insulating element  4130  is configured approximately annular or annular disc shaped in the first embodiment described herein. The inner ring cavity is configured as a pass through opening  4143 . 
         [0045]    As apparent in particular from  FIGS. 402, 404 and 405  the insulating element  4130  is provided to be arranged under the shaft head  4116 . Thus, the shaft lobes  4113  are slid through the pass through opening  4143  until the insulating element  4130  contacts a bottom side of the shaft head  4116 . 
         [0046]    As apparent from  FIGS. 403, 404 and 405  a bottom side of the shaft head  4116  contacts a top side of the insulating element  4130 , whereas a bottom side of the insulating element  4130  is provided for a contact on the first component  4133  ( FIG. 407 ).  FIG. 405  furthermore illustrates that the shaft lobes  4113  are deformed inward at their free ends  4114  and respectively include support elements  4126  that are oriented towards each other and supported at each other. The support elements  4126  support the shaft lobes  4113  in a rigid manner in their normal position in which the interlocking hooks  4120  protrude beyond the inner radius r in a circumferential expanding manner. 
         [0047]    Eventually it is appreciated that the retaining bracket  4111  is advantageously made from a piece of sheet metal through a stamping and crimping process. The insulating element  4130  is made from an electrically non-conductive and spring elastic material. According to an advantageous embodiment the insulating element  4130  is mad from silicone. Other spring elastic plastic materials, however, are suited as well. 
         [0048]      FIG. 407  illustrates a sectional view of the fastening element  4110  in an installed condition according to the sectional line A-A in  FIG. 406 . A first component  4133  is initially illustrated which contacts a second component  4134 . The first component  4133  typically is a circuit board  4135 , the second component  4134  typically is a lamp element  4136 . The circuit board  4135  is provided with conductive paths  4137  which are used for electricity or signal supply for LEDs that are not illustrated which are arranged on the circuit board  4135 . The circuit board  4135  is provided with a pass through opening  4138 , the lamp element  4136  includes a recess  4139 . it is appreciated that the pass through opening  4138  in the first component  4133  has to be configured as a pass through opening  4138  over the entire material thickness. The recess  4139  of the second component  4134  in the illustrated embodiment is also configured as a bore hole penetrating the material over the entire thickness. The recess  4139  of the second component  4134  however can also be configured as a dead hole. The pass through opening  4138  and the recess  4139  are aligned with each other. 
         [0049]    In order to connect the first component  4133  and the second component  4134  with each other both components as illustrated in  FIG. 407  are arranged on top of each other so that the pass through opening  4138  and  4139  are aligned with each other. Then the subassembly put together according to  FIG. 402  to form the fastening element  4110  including a retaining bracket  4111  and an insulating element  4130  are inserted in the insertion direction X through the pass through opening  4138  into the recess  4139 . Thus, the fastening element  4110  is inserted into the pass through opening  4138  and the recess  4139  with the free end  4114  of the shaft  4112 , in particular with the insertion trunks  4118  of the shaft lobes  4113  forward. Eventually the insulating element  4130  contacts the surface of the circuit board  4135  with conductive paths  4137 . 
         [0050]    A diameter of the pass through opening  4138  corresponds at least to an inner radius r and is smaller than an outer radius R of the shaft head  4116 . The recess  4139  corresponds approximately to the inner radius r in order to provide safe anchoring of the interlocking hooks  4120 . 
         [0051]    When inserting the fastening element  4110  in the direction X the interlocking hooks  4120  protruding beyond the inner radius r in a diameter expanding manner extend at the edges from the pass through opening  4138  and the recess  4139 . Since the interlocking lobes  4113  are supported at each other in a rigid manner the interlocking hooks  4120  are moved in a spring elastic manner in a direction towards the inner cavity  4117 . 
         [0052]    When the insulating element  4130  contacts the surface of the circuit board  4135  an insertion movement in a direction X that is required for anchoring both components  4133 / 4134  at each other is not yet completed. The interlocking hooks  4120  have at least not completely penetrated the recess  4139  of the second component  4134 . Thus, a continuation of the insertion movement in a direction X is required wherein an insertion pressure is imparted onto the shaft head  4116  which compresses the insulating element  4130 . Thus, the reset elastic insulating element  4130  builds up reset forces against the insertion pressure. Now the interlocking hooks  4120  penetrate the recess  4139  and interlock at its bottom side in that the reset forces move the interlocking hooks  4120  backward. 
         [0053]    The reset forces of the insulating element  4130  acting against the insertion pressure, however, are maintained and lead to a clamping of the components  4133  and  4134  against each other, wherein the interlocking hooks  4120  on one side and the shaft head  4116  on the other side are used as reactive bearings against which the reset forces of the insulating element  4130  act. This way an exactly definable contact pressure or an exactly definable contact force is generated between the surfaces of the first component and of the second component  4133 / 4134  precisely contacting each other. Thus, it has become apparent from the preceding functional description that the insulating element  4130  is also used as a clamping element  4130 . 
         [0054]    Generating a defined contact pressure between the first component  4133  and the second component  4134  is particularly significant for a function of the fastening element  4110  according to the invention since the fastening element  4110  is provided in particular for attaching circuit boards provided with LEDs at heat dissipating lamp elements  4136 . The heat dissipation of the circuit board  4135  to the lamp element  4136  which significantly influences service life of the LED and which is therefore necessary is influenced in a significant manner by a correct contact pressure between the first component  4113  and the second component  4134 . 
         [0055]    However, it is also provided to be able to disengage the fastening element  4110  again in order to separate the components  4133  and  4134  from each other. For this purpose the support bracket  4111  includes the engagement recesses  4124  that are visible quite well in  FIG. 401  and  FIG. 403  and which are briefly described supra wherein the engagement recesses provide space for a pair of vices.  FIG. 408  illustrates a perspective view of a mounted fastening element  4110  which connects the component  4133  and  4134  with each other. A vice head  4141  is schematically illustrated, whose vice jaws  4142  in a portion of the engagement recesses  4124  are arranged at open sections of the insulating element  4130 .  FIG. 410  illustrates a sectional view of the fastening element  4110  fixating the components  4133  and  4134  at each other according to the sectional line B-B in  FIG. 409 .  FIG. 410  furthermore illustrates the vice jaws  4142  which are omitted in  FIG. 409  for clarity purposes. 
         [0056]    In  FIG. 410  it is clearly visible that the interlocking hooks  420  reach under a bottom side of the second component  4134  so that both components  4133 / 4134  are arranged connected with each between the insulating element  4130  and the interlocking hook  4120 . The vice jaws  4142  with their operating surfaces oriented towards each other contact the exposed sections of the insulating element  4130 . Closing the vice causes the vice jaws  4142  to move towards each other. Therefore a force is imparted to the disengagement cams  4123  through the intermediary positioning the insulating element  4130  which leads to a displacement of the shaft lobes  4113  in the portion of the interlocking hooks  4120  into the intermediary cavity  4117 . The shaft lobes  4113  are thus deformed in a reset elastic manner and in turn built up reset forces which act against the dislocation direction of the shaft lobes  4113 . As soon as the shaft lobes  4113  have been moved towards each other sufficiently the fastening element  4110  can be pulled out of the recess  4139  and the pass through opening  4138  against the insertion direction X using the vice, so that the first component  4113  and the second component are separable from each other. 
         [0057]    It is furthermore appreciated at the retaining bracket  4111  is made from metal in an advantageous embodiment. The insulating element  4130  is advantageously made from a reset elastic silicone material. Selecting a metal as a material for the retaining bracket  4111  has the essential advantage that it sustains the reset forces imparted by the insulating element  4130 , whereas a plastic material typically bears the risk that it yields to the reset forces over time. This can lead to a disengagement of the connection between the first component  4133  and the second component  4134  and has the consequence that the contact force between both components  4133 / 4134  is reduced which leads to a reduced heat transfer. 
       REFERENCE NUMERALS AND DESIGNATIONS 
       [0000]    
       
           4110  fastening element 
           4111  retaining bracket 
           4112  shaft 
           4113  shaft lobe 
           4114  free end 
           4115  connected end 
           4116  shaft head 
           4117  intermediary cavity 
           4118  insertion tip 
           4119  support element 
           4120  interlocking hook 
           4121  shaft neck 
           4122  shaft disengagement section 
           4123  disengagement cam 
           4124  disengagement recess 
           4126  spring arm/spring bar 
           4130  insulating and clamping element 
           4133  first component 
           4134  second component 
           4135  circuit board 
           4136  lamp element 
           4137  conductive path 
           4138  pass through opening 
           4139  recess 
           4141  vice head 
           4142  vice jaws 
           4143  pass through opening 
         X insertion direction 
         r inner radius 
         R outer radius