Abstract:
A mounting structure including: an outer housing having a first locking portion; a ceiling including a lamp opening portion in a central portion thereof; an inner housing including: a first locking facing portion which is locked in the first locking portion of the outer housing; and a second locking portion on and directly attached to the inner housing; and a reinforcement having a second locking facing portion which is locked on the second locking portion of the inner housing. The ceiling is fixed between the outer housing and the inner housing by locking the first locking facing portion of the inner housing in the first locking portion of the outer housing via the lamp opening portion in the ceiling. A bracket portion shaped so as to follow a shape of an upper side of the ceiling is provided along an outer circumference of the inner housing.

Description:
TECHNICAL FIELD 
     The present invention relates to a mounting structure for an automotive room lamp and particularly to a mounting structure for the automotive room lamp which is made lighter in weight. 
     BACKGROUND ART 
     Conventionally, a conventional mounting structure for use in mounting a room lamp in a ceiling of a passenger compartment has been known. In the conventional mounting structure, a head lining constituting a ceiling is installed onto an inner side of a roof panel, and an room lamp is installed in a lamp installation hole provided in the head lining from below (refer to Patent Documents 1 and 2). 
     CITATION LIST 
     Patent Document 
     [Patent Document 1] JP-A-2002-36948 
     [Patent Document 2] JP-A-2001-213233 
       FIGS. 6A to 6C  shows exploded perspective views depicting a conventional mounting structure for an automotive room lamp.  FIG. 6A  is an overall perspective view of a conventional mounting structure that has been fabricated  FIG. 6B  is an exploded perspective view of the mounting structure shown in  FIG. 6A .  FIG. 6C  is an exploded perspective view of a lamp assembly which is shown in a lowest position in  FIG. 6B . 
     In  FIGS. 6A to 6C , reference numeral  60  ( FIG. 6A ) denotes a conventional mounting structure for the automotive room lamp. This mounting structure for the automotive room lamp  60  is disassembled into, as is shown in  FIG. 6B , a reinforcement  65 , a bracket  64 , a ceiling  63  and a lamp assembly  66  sequentially in that order from top. 
     Further, the lamp assembly  66  is disassembled into an inner housing  62  and an outer housing  61  as is seen in  FIG. 6C . 
     Hereinafter, the individual constituent elements of the conventional mounting structure for the automotive room lamp will be described. 
     &lt;Conventional Outer Housing  61 &gt; 
     The outer housing  61  is a resin member which performs as a lens which transmits lamp light from a lamp function portion of the inner housing  62 . This outer housing  61  includes erected members  61   v  which include lock locking holes  61   g  which lock therein lock claws on the inner housing  62 . 
     &lt;Conventional Inner Housing  62 &gt; 
     The inner housing  62  is configured as a hollow rectangular parallelepiped body having no bottom in an interior of which the lamp function portion is accommodated. This inner housing  62  includes in the interior thereof the lock claws which are locked in the corresponding locking holes  61   g  in the outer housing  61 . In addition, a plurality of (two in the figure) lock claws  62   h,  which are brought into engagement with lock locking holes  65   h  (which will be described later) in the reinforcement  65 , are provided on an upper outer side of the inner housing  62  in positions which correspond to the lock locking holes  65   h  in the reinforcement  65 . 
     &lt;Conventional Ceiling  63 &gt; 
     The ceiling  63  is made up of a resin member having a rectangular shape when viewed from thereabove which constitutes literally a ceiling portion when an automotive room lamp is mounted to an upper portion in the passenger compartment. This ceiling  63  includes a flat bottom surface portion  63   p  at a central portion, a wall surface portion  63   v  which is erected around a circumference of the bottom surface portion and a flange portion  63   f  which extends outwards horizontally from the wall surface portion  63   v.  A lamp opening portion  63   a,  through which the inner housing  62  having the rectangular parallelepiped configuration is passed, is opened in a center of the bottom surface portion  63   p.    
     &lt;Conventional Bracket  64 &gt; 
     The bracket  64  is a reinforcement member which increases the strength of the ceiling  63  when the ceiling  63  is installed onto the reinforcement  65 . This bracket  64  has partially the same configuration as a back-side configuration of the ceiling  63 . Therefore, the bracket  64  can firmly be fixed to a back side of the ceiling  63  with an adhesive for example. A lamp opening portion  64   a,  which has the same size as the lamp opening portion  63   a,  is opened in a center of the bracket  64  so as to allow the inner housing  62  having the rectangular parallelepiped configuration to pass therethrough. 
     In the present invention, an inner housing is devised so as to eliminate the use of this bracket  64 . Therefore, the step of fixing the bracket  64  with the adhesive can be omitted. 
     &lt;Conventional Reinforcement  65 &gt; 
     The reinforcement  65  is a member which supports the automotive room lamp in whole. Because of this, the reinforcement  65  is installed onto a frame of the motor vehicle which lies on the back side of the ceiling. The reinforcement  65  is a bent plate having a flat bottom surface  65   p  at a bottom thereof which is formed by bending a piece of rectangular sheet metal in such a way as to bend it from a side  65 L sequentially externally (M 1 ), internally (V 2 ), internally (V 3 ), and externally (M 4 ) every time the sheet metal extends a predetermined distance from the side  65 L towards the other side and in parallel with the side  65 L. A plurality of lock locking holes  65   h  (two locations in the figure) are opened in the bottom surface  65   p.  The automotive room lamp mounting structure  60  is built up completely by the lock claws  62   h  on the inner housing  62  being locked in the lock locking holes  65   h.    
     As described above, the lamp assembly  66  is formed by locking the lock claws of the inner housing  62  in the lock locking holes  61   g  in the outer housing  61 , and the ceiling assembly is formed by bonding the bracket  64  to the back side of the ceiling  63  with the adhesive. 
     In this way, the conventional automotive room lamp mounting structure  60  is made up of the outer housing  61 , the inner housing  62 , the ceiling  63 , the bracket  64  and the reinforcement  65  which are arranged sequentially in that order from the bottom. 
     SUMMARY OF INVENTION 
     Technical Problem 
     &lt;Problems of Conventional Mounting structure for Automotive Room Lamp&gt; 
     The applicant of this patent application notices that in the component members making up the conventional mounting structure for the automotive room lamp  60 , the bracket  64  as the reinforcement member constitutes a factor which increases the fabrication cost of the same construction. Moreover, the bracket  64  also constitutes a factor which increases the weight of the same construction. Further, one step is added in which the ceiling assembly is formed by bonding the bracket  64  to the back side of the ceiling  63  with the adhesive, which affects the productivity of the same construction. 
     The present invention is made for solving the problems. An object of the invention is to provide amounting structure for an automotive room lamp which reduces the fabrication cost and weight thereof and provides good productivity by being devised so as not to use the bracket  64 . 
     Solution to Problem 
     With a view to attaining the object, according to a first invention, there is provided an automotive room lamp mounting structure, comprising sequentially in the following order from bottom: 
     an outer housing having a first locking portion; 
     a ceiling including a lamp opening portion in a central portion thereof; 
     an inner housing having a first locking facing portion which is locked in the first locking portion of the outer housing and a second locking portion; and 
     a reinforcement having a second locking facing portion which is locked on the second locking portion of the inner housing, 
     wherein the ceiling is fixed between the outer housing and the inner housing by locking the first locking facing portion of the inner housing in the first locking portion of the outer housing via the lamp opening portion in the ceiling, and 
     wherein a bracket portion shaped so as to follow a shape of an upper side of the ceiling is provided along an outer circumference of the inner housing. 
     By configuring the mounting structure for the automotive room lamp in the way described above, the bracket used as the independent member in the conventional construction is eliminated. Instead, the bracket portion is formed along the outer circumference of the inner housing, whereby the step can be eliminated in which the conventional bracket as the independent member is bonded to the back side of the ceiling with the adhesive, thereby making it possible to contribute to reduction in fabrication cost and increase in productivity. 
     Further, since the bracket portion of the inner housing is shaped so as to follow the shape of the upper side of the ceiling, the bracket portion is brought into abutment with the upper side of the ceiling, whereby not only is bagginess in the ceiling prevented, but also the strength of the ceiling is increased. 
     According to a second invention, there is provided the mounting structure for the automotive room lamp as set forth in the first invention, wherein the ceiling includes a bottom surface portion which connects to the lamp opening portion in the central portion so as to extend outwards therefrom, a wall surface portion erected along an outer circumference of the bottom surface portion, and a flange portion which extends outwards horizontally from the wall surface portion. 
     By configuring the mounting structure for the automotive room lamp in the way described above, since irregularities are formed, the strength of the ceiling can be increased, and similarly the strength of the bracket of the inner housing can also be increased. 
     According to a third invention, there is provided the mounting structure for the automotive room lamp as set forth in the first invention, wherein a lock protection member having a height higher than the first locking portion of the outer housing is erected in proximity to the first locking portion. 
     By configuring the mounting structure for the automotive room lamp in the way described above, there is made no damage to the erected member, which can largely contribute to increasing productivity. 
     According to a fourth invention, there is provided the mounting structure for the automotive room lamp as set forth in the third invention, wherein the lock protection member has a thickness which is thicker than the first locking portion. 
     By configuring the mounting structure for the automotive room lamp in the way described above, the strength of the lock protection member can be increased and hence the possibility of occurrence of damage to the erected member is reduced further, which can largely contribute to increasing productivity. 
     According to a fifth invention, there is provided the mounting structure for the automotive room lamp as set forth in the third invention, wherein the lock protection member comprises a reinforcement rib. 
     By configuring the mounting structure for the automotive room lamp in the way described above, the strength of the lock protection member can be increased and hence the possibility of occurrence of damage to the erected member is reduced further, which can largely contribute to increasing productivity. 
     Advantageous Effects of Invention 
     Thus, as described above, according to the invention, the bracket used as the independent member in the conventional construction is eliminated. Instead, the bracket portion is formed along the outer circumference of the inner housing, whereby the step can be eliminated in which the conventional bracket as the independent member is bonded to the back side of the ceiling with the adhesive, thereby making it possible to contribute to reduction in fabrication cost and increase in productivity. 
     Further, not only can bagginess in the ceiling be prevented, but also the strength of the ceiling can be increased. 
     In addition, no damage is made to the erected member by providing the lock protection member, which can largely contribute to increasing productivity. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view showing an inner housing of a mounting structure for an automotive room lamp according to Embodiment 1 of the invention. 
         FIGS. 2A and 2B  show exploded perspective views of the mounting structure for the automotive room lamp according to the invention.  FIG. 2A  is a perspective view of a reinforcement, and  FIG. 2B  is an exploded perspective view of the mounting structure for the automotive room lamp which is mounted onto the reinforcement. 
         FIG. 3  is an overall perspective view of the automotive room lamp according to the invention which is built up by assembling together all the constituent members shown in  FIGS. 2A and 2B . 
         FIG. 4  shows sectional views showing a procedure of assembling the constituent members shown in  FIG. 2B , according to which assemblage is progressed in the order from  FIG. 4C  to  FIG. 4A . 
         FIGS. 5A to 5D  show perspective views depicting individually an inner housing and an outer housing according to Embodiment 2.  FIG. 5A  is a perspective view of the inner housing as viewed in one direction, and  FIG. 5B  is a perspective view of the inner housing as viewed by turning it upside down.  FIG. 5C  is a perspective view of the outer housing as viewed from one direction, and  FIG. 5D  is a perspective view of the outer housing as viewed from the other side. 
         FIGS. 6A to 6C  show an exploded perspective views depicting a conventional mounting structure for an automotive room lamp.  FIG. 6A  is an overall perspective view of the conventional mounting structure for the automotive room lamp which has been fabricated.  FIG. 6B  is an exploded perspective view of the mounting structure for the automotive room lamp in  FIG. 6A .  FIG. 6C  is an exploded perspective view of a lamp assembly in  FIG. 6B . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, a mounting structure for an automotive room lamp according to the present invention will be described. 
       FIG. 1  is a perspective view showing an inner housing of a mounting structure for an automotive room lamp according to Embodiment 1 of the present invention. 
     &lt;Embodiment 1: Configuration of Inner Housing&gt; 
       FIG. 1  is a perspective view showing the configuration of an inner housing. In  FIG. 1 , reference numeral  12  denotes an inner housing according to Embodiment 1 of the invention. This inner housing  12  is a resin member made up of a main body portion  12   m  having a hollow rectangular parallelepiped shape which accommodates a lamp function portion in an interior thereof and a bracket portion  12   b  which surrounds an outer circumference of the main body portion  12   m.    
     The main body portion  12   m  includes in an interior thereof lock claws  12   g  (refer to  FIG. 4C ) which are locked in locking holes  11   g  (refer to  FIG. 2B ) in an outer housing  11  (refer to  FIG. 2B ) and a plurality of (two in  FIG. 1 ) lock claws  12   n  which are brought into engagement with lock locking holes  15   h  in a reinforcement  15  in positions which correspond to the lock locking holes  15   h  in the reinforcement  15  on an upper outer side thereof. The configuration of the main body portion  12   m  is the same as that of the conventional inner housing  62  (refer to  FIG. 6C ). 
     In addition, the invention is characterized in that the bracket portion  12   b  is formed integrally with the outer circumference of the inner housing  12 . The bracket portion  12   b  includes a horizontal portion  12   h  which extends horizontally from side walls  12   w  on four sides of the main body portion  12   m  and a U-shaped groove  12   u  which is situated at a distal end of the horizontal portion  12   h.  The horizontal portion  12   h  and the U-shaped groove  12   u  are brought into abutment with a bottom surface portion  13   p  of a ceiling  13  to thereby prevent the occurrence of bagginess in the ceiling  13 . This contributes to increasing the strength of the ceiling. 
     &lt;Installing Position of Inner Housing  12 &gt; 
     Next, where in the mounting structure for the automotive room lamp and how the inner housing  12  according to Embodiment 1 is installed will be described. 
       FIGS. 2A and 2B  show exploded perspective views of the mounting structure for the automotive room lamp according to the invention.  FIG. 2A  is a perspective view of the reinforcement having the same configuration as that of the conventional reinforcement.  FIG. 2B  is an exploded perspective view of the mounting structure for the automotive room lamp that is mounted onto the reinforcement. 
     Shown in  FIGS. 2A and 2B  sequentially from bottom are the outer housing  11 , the ceiling  13 , the inner housing  12  according to the invention, and the reinforcement  15 . 
     When comparing  FIGS. 2A and 2B  with  FIGS. 6A to 6C  which show the conventional mounting structure, it is found that the bracket  64  which is used in the conventional mounting structure is not shown in  FIGS. 2A and 2B . Further, it is found that in  FIG. 2B , the inner housing  12  is positioned above the ceiling  13  and the flange portion  12   b  of the inner housing  11  is in abutment with the ceiling  13 , whereas in  FIGS. 6A to 6C , the inner housing is positioned below the ceiling. The flange portion  12   b  of the inner housing  12  shown in  FIG. 2B  reinforces the ceiling  13  to thereby prevent the occurrence of bagginess in the ceiling  13 . 
     The outer housing  11 , the ceiling  13  and the reinforcement  15  will be described as follows. 
     &lt;Outer Housing  11 &gt; 
     The outer housing  11  is a resin member having a rectangular shape when viewed from thereabove which performs as a lens which transmits lamp light from the lamp function portion of the inner housing  12 . Elongate rectangular erected members  11   v  are erected at central portions of two sides so as to face each other. The lock locking holes  11   g,  which lock therein the lock claws  12   g  (refer to  FIG. 4C ) of the inner housing  12 , are provided in upper portions of the erected members  11   v.    
     &lt;Ceiling  13 &gt; 
     The ceiling  13  is made up of a resin member having a rectangular shape when viewed from thereabove which constitutes literally a ceiling portion when an automotive room lamp is mounted in an upper portion in a passenger compartment. The ceiling  13  includes the flat bottom surface portion  13   p  at a central portion, a wall surface portion  13   v  which is erected around a circumference of the bottom surface portion  13   p  and a flange portion  13   f  which extends outwards horizontally from the wall surface portion  13   v.  A lamp opening portion  13   a,  through which the inner housing  12  having the rectangular parallelepiped shape is passed, is opened in a center of the bottom surface portion  13   p.  The bottom surface portion  13   p,  the wall surface portion  13   v  and the flange portion  13   f  are formed light in weight and thin in thickness and extend outwards over a wide range and therefore are not strong in terms of strength. 
     &lt;Reinforcement  15 &gt; 
     The reinforcement  15  is such as to support a lamp apparatus in whole. The reinforcement  15  is installed onto a frame of the motor vehicle which lies on a back side of the ceiling. The reinforcement  15  is a bent plate having a bottom surface  15   p  at a bottom thereof which is formed by bending a piece of rectangular sheet metal in such a way as to bend it from a side  15 L sequentially externally (M 1 ), internally (V 2 ), internally (V 3 ), and externally (M 4 ) every time the sheet metal extends a predetermined distance from the side  15 L towards the other side and in parallel with the side  15 L. A plurality of lock locking holes  15   h  (two locations in  FIG. 2 ) are opened in the protruding bottom surface  15   p.  The automotive room lamp mounting structure  10  is completed when the lock claws  12   n  on the inner housing  12  are locked in the lock locking holes  15   h.    
       FIG. 3  is an overall perspective view of an automotive room lamp according to the invention. Namely, when the constituent members shown in 
       FIGS. 2A and 2B  are assembled together, the automotive room lamp shown in  FIG. 3  is built up. 
     The mounting structure  10  for the automotive room lamp includes the outer housing  11 , the ceiling  13 , the inner housing  12  and the reinforcement  15  sequentially in that order from bottom. In this way, since the bracket  64  used in the conventional mounting structure is eliminated from  FIG. 3 , a step can be omitted of bonding the bracket portion to a back side of the ceiling  13  with an adhesive. Consequently, the invention contributes to reduction in fabrication cost and increase in productivity. Moreover, since the bracket portion  12   b  of the inner housing  12  includes the reinforcement function possessed by the conventional bracket  64  (refer to  FIGS. 6A and 6B ), the ceiling  13  can also be reinforced. 
     Next, a procedure of assembling together these constituent members will be described by use of  FIGS. 4A to 4C . 
     &lt;Assembling Procedure&gt; 
       FIGS. 4A to 4C  show sectional views showing a procedure of assembling the constituent members shown in  FIGS. 2A and 2B , according to which assemblage is progressed in the order from  FIG. 4C to 4A . 
       FIG. 4C  is a sectional view taken along the line A-A and viewed in a direction indicated by arrows A in  FIG. 2B . 
     When looking at a sectional shape of the ceiling  13  taken along the line A-A, the sectional shape of the ceiling  13  taken along the line A-A takes such a shape that the bottom surface portion  13   p  sinks from a circumferential edge portion  13   b  which forms the lamp opening portion  13   a  in the central portion to extend to the erected wall surface portion  13   v  and the flange portion  13   f  extends outwards horizontally from the wall surface portion  13   v.    
     On the other hand, the outer housing  11  includes the lock locking holes  11   g  which lock the lock claws  12   g  on the inner housing  12  in the erected members  11   v  and also includes erected walls  11   b  which are erected upwards from circumferential edge portions of four sides thereof. 
     Further, the inner housing  12  includes on an inner side of the main body portion  12   m  the lock claws  12   g  which each have a downward sloping surface portion so that the lock claws  12   g  can be locked in the lock locking holes  11   g  in the outer housing  11 . In addition, the inner housing  12  includes the two lock claws  12   n  on the upper outer side of the main body portion  12   m  so that the lock claws  12   n  can be brought into engagement with the lock locking holes  15   h  in the reinforcement  15 . 
     In addition, the bracket portion  12   b  along the outer circumference of the inner housing  12  includes the horizontal portion  12   h  and the U-shaped groove  12   u  at the distal end of the horizontal portion  12   h.  The sectional shape of the bracket portion  12   b  partially coincides with the configuration of the upper surface (the back side) of the ceiling  13 . 
       FIG. 4B  is the sectional view which corresponds to the perspective views of  FIGS. 2A and 2B . The reinforcement  15  is shown as a sectional view taken along the line B-B and viewed in a direction indicated by arrows B in  FIG. 2A . 
     In  FIG. 4C , when the ceiling  13  is held from therebelow by the outer housing  11  and from thereabove by the inner housing  12 , since the lock locking holes  11  g in the outer housing  11  lock therein the lock claws  12   g  on the inner housing  12 , the circumferential edge portion  13   b  of the ceiling  13  which is held therebetween is held and supported by head portions of the erected walls  11  b of the outer housing  11  and the horizontal portion  12   h  of the bracket portion  12   b  of the inner housing  12 . 
     Further, the bottom surface portion  13   p  and the wall surface portion  13   v  of the ceiling  13  are brought into abutment with the U-shaped groove  12   u  at the distal end of the horizontal portion  12   h  of the bracket portion  12   b  of the inner housing  12  which is provided according to the invention, whereby the occurrence of bagginess in the ceiling  13  is prevented so as to increase the strength of the ceiling. 
     Next, the reinforcement  15  is locked. 
       FIG. 4A  is a sectional view taken along the line C-C and viewed in a direction indicated by arrows C in  FIG. 3 . 
     In  FIG. 4A , the lock claws  12   n  on the inner housing  12  are locked in the lock locking holes  15   h  in the reinforcement  15 , whereby the mounting structure  10  for the automotive room lamp ( FIG. 2A ) is completed. 
     &lt;Advantage of Embodiment 1&gt; 
     As is seen from  FIG. 4A , according to Embodiment 1 of the invention, the bracket  64  ( FIGS. 6A and 6B ) used as the independent member in the conventional mounting structure is eliminated and instead the bracket portion  12   b  is formed with the outer circumference of the inner housing  12 . Thus, the step can be omitted of bonding the conventional independent member to the back side of the ceiling with the adhesive. Consequently, the invention contributes to reduction in fabrication cost and increase in productivity. 
     In addition, since no abutment surface for positioning is required at the opening portion in the ceiling, there is no risk of damaging the opening portion in the ceiling. 
     Further, the bottom surface portion  13   p  and the wall surface portion  13   v  of the ceiling  13  are brought into abutment with the bracket portion  12   b  of the inner housing  12 , whereby the occurrence of bagginess in the ceiling  13  can be prevented so as to increase the strength of the ceiling. Although the art described in Patent Document 1 is also the art which eliminates the bracket, since the art concerned loses the function possessed by the conventional bracket, the occurrence of bagginess in the ceiling cannot be prevented. 
     In the present invention, the configuration described above is employed, therefore the bagginess in the ceiling  13  is prevented so as to increase the strength of the ceiling. 
     Nest, Embodiment 2 of the invention will be described. 
     &lt;Embodiment 2: Improvement in Outer Housing&gt; 
     Embodiment 2 relates to an improvement in the outer housing of Embodiment 1. 
       FIGS. 5A to 5D  show perspective views depicting individually an inner housing and an outer housing according to Embodiment 2.  FIG. 5A  is a perspective view of the inner housing as viewed in one direction, and  FIG. 5B  is a perspective view of the inner housing as viewed by turning it upside down.  FIG. 5C  is a perspective view of the outer housing as viewed from one direction, and  FIG. 5D  is a perspective view of the outer housing as viewed from the other side. 
     &lt;Configuration of Outer Housing  110 &gt; 
     An outer housing  110  is a resin member having a rectangular shape when viewed from thereabove. In the outer housing  110 , elongate erected members  110   v  are erected at central portions of two sides of a rectangular bottom surface  110   h  which performs as a lens which transmits lamp light from a lamp function portion of an inner housing  120 . Lock locking holes  110   g,  which are adapted to lock therein lock claws  120   g  ( FIG. 5B ) on the inner housing  120 , are provided in upper portions of the erected members  110 V. These configurations are the same as those of Embodiment 1. 
     The outer housing  110  of Embodiment 2 differs from that of Embodiment 1 in that lock protection members  110   s,  which will be described below, are provided in proximity to the erected members  110   v.  Namely, the protection member  110   s  is higher by A mm than a height of the erected member  110   v.  Moreover, vertically extending reinforcement ribs  110   r  are formed on the protection member  110   s,  and the thickness of the protection member  110   s  is made thicker than that of the erected member  110   v.  Thus, the protection member  110   s  is made more rigidly and strongly than the erected member  110   v  in whole. 
     &lt;Configuration of Inner Housing  120 &gt; 
     The inner housing  120  is, as is shown in  FIG. 1 , made up of a main body portion and a bracket portion lying along an outer circumference of the main body portion. In  FIGS. 5A to 5D , to make it easy to look at the inner housing according to Embodiment 2, only the main body portion  120   m  is shown with the bracket portion along the outer circumference of the inner housing omitted. In  FIGS. 5A and 5B , the inner housing  120  includes two lock claws  120   n,  which are adapted to be locked in lock locking holes  15   h  in a reinforcement  15  ( FIG. 2B ), on an upper outer side thereof in positions which correspond to the lock locking holes  15   h.  Further, the inner housing  120  includes lock claws  120   g,  adapted to be locked in the lock locking holes  110   g  formed in the erected members  110   v  on the outer housing  110 , which are formed on inner walls of recess portions  120   k  provided in a bottom portion  120   b  so as to be oriented inwards of the recess portions. 
     &lt;Assemblage of Both Housings  110 ,  120 &gt; 
     When the erected members  110   v  and the protection members  110   s  on the outer housing  110  are inserted into the recess portions  120   k  provided in the bottom portion  120   b  of the inner housing  120 , the protection members  110   s  come into contact with constituent components within the inner housing  120  and proceeds further inwards to guide the erected members  110   v  while protecting the erected members  110   v.    
     Then, finally, the lock claws  120   g  on the inner housing  120  are locked in the lock locking holes  110   g  in the erected members  110   v  on the outer housing  110 , whereby the assemblage of both the housings is completed. 
     In this case, locking holes or lock claws are formed in or at distal ends of the protection members  110   s,  while mating locking mechanisms (lock claws or locking holes) are formed at corresponding portions within the inner housing  120 , whereby a double locking mechanism can be provided. 
     &lt;Advantage of Embodiment 2&gt; 
     According to Embodiment 2 configured in the way described above, since the lock protection members  110   s  which are made more rigidly and strongly than the erected members  110   v  are provided in proximity to the erected members  110   v,  even when the erected members  110   v  on the outer housing  110  are inserted into the recess portions  120   k  in the inner housing  120 , the protection members  110   s  bear all impacts produced when they come into contact with the constituent components within the inner housing  120 . Namely, since the protection members  110   s  play a role of a protector, the erected members  110   v  standing thereby proceed while being protected by the protection members  110   s.  Because of this, the lock claws  120   g  on the inner housing  120  can be locked in the lock locking holes  110   g  in the erected members  110   v  without damaging the erected members  110   v.  Thus, the assemblage of both the housings is completed with no problem. 
     In the conventional mounting structure and Embodiment 1, since these lock protection members  110   s  are not provided, when the erected members  110   v  are inserted into the inner housing  120 , the erected members  110   v  bear all impacts that are produced when they come into contact with the constituent members within the inner housing  120  since the lock protection members  110   s  are not provided. Consequently, there are fears that the erected members  110   v  are damaged before they fit into the inner housing  120 . However, according to Embodiment 2, since there are no fears that the erected members  110   v  are damaged, Embodiment 2 can largely contribute to increasing productivity. 
     The lock protection members  110   s  also perform to position the outer housing  110  with respect to the inner housing  120 . 
     Thus, according to the invention, the bracket  64  ( FIGS. 6A and 6B ) used as the independent member in the conventional mounting structure is eliminated, and instead the bracket portion  12   b  is formed along the outer circumference of the inner housing  12 , whereby the step can be omitted of bonding the bracket, which is the conventional independent member, to the back side of the ceiling with the adhesive. Thus, the invention contributes to reduction in fabrication cost and increase in productivity. 
     Further, by bringing the bottom surface portion  13   p  and the wall surface portion  13   v  of the ceiling  13  into abutment with the bracket portion  12   b  of the inner housing  12 , the occurrence of bagginess in the ceiling  13  can be prevented to thereby increase the strength of the ceiling. 
     In addition, since the damage to the erected members  110   v  can be prevented by providing the lock protection members  110   s,  the invention contributes largely to increasing productivity. 
     REFERENCE SIGNS LIST 
     
         
           10  mounting structure for automotive room lamp  11  outer housing 
           11   b  erected wall 
           11   g  lock locking hole 
           12   m  main body portion 
           11   v  erected member 
           12  inner housing 
           12   b  bracket portion 
           12   g  lock claw 
           12   h  horizontal portion 
           12   m  main body portion 
           12   n  lock claw 
           12   u  U-shaped groove 
           12   w  side wall 
           13  ceiling 
           13   a  lamp opening portion 
           13   f  flange portion 
           13   p  bottom surface portion 
           13   v  wall surface portion 
           15  reinforcement 
           15   h  lock locking hole 
           15   p  bottom surface 
           15 L side of metal sheet 
         M 1 , M 3  external bending 
         V 2 , V 4  internal bending 
           110  outer housing 
           110   g  lock locking hole 
           110   h  rectangular bottom surface 
           110   s  lock protection member 
           110   r  reinforcement rib 
           110   v  erected member 
           120  inner housing 
           120   b  bottom portion 
           120   k  recess portion 
           120   g  lock claw 
           120   n  lock claw