Abstract:
In a sunroof system ( 3 ) for a vehicle using a push-pull cable ( 22 ) for actuating a sunroof panel ( 4 ), the push-pull cable is received in a drive pipe ( 25 ), and a sunroof frame ( 12 ) is provided with a drive pipe retaining feature ( 16, 18 ). Therefore, the drive pipe may be made of flexible material, and firmly held in place by the pipe retaining feature even when the push-pull cable is subjected to significant tensile and compressive load. The pipe retaining feature may include a pipe retaining groove ( 16 ) for receiving the drive pipe and clips ( 18 ) for resiliently retaining the drive pipes in the pipe retaining groove.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to a drive system for a closure member configured to selectively close an opening of a vehicle roof, and in particular to an automotive sunroof system. 
         [0002]    In a typical automotive sunroof system, a pair of side frames each fitted with a guide rail extend in a fore-and-aft direction on either side of a roof opening. Each side frame has a front end adjacent to a front edge of the roof opening and a rear end extending further rearward from a rear edge of the roof opening. A pair of sliders supporting a slide panel are slidably supported by the corresponding guide rails, and to each slider is connected an end of a Bowden or push-pull cable which is configured to be pushed and pulled as required by an electric motor located centrally in a front frame extending along the front edge of the roof opening. Thereby, the slide panel can be moved in a fore-and-aft direction between a closed position fully closing the roof opening and an open position fully exposing the roof opening. 
         [0003]    The push-pull cable typically comprises an inner wire including a steel core wire and an additional outer wire wrapped spirally around the core wire, and, optionally, a sheath pipe or a housing that slidably receives the inner wire. The push-pull cable is normally held in position to the corresponding side frame by using cable guides integrally formed in the side frame, and extends substantially linearly along the length of the side frame. A relatively rigid drive pipe made of steel extends from the front end of each side from to a drive gear of the electric motor, and an idle pipe extends from the drive gear away from the drive pipe so that the section of the push-pull cable extending from the front end of the side panel past the drive gear of the electric motor may be guided without any significant deflection in spite of the significant tension and compression that is required to be transmitted by the push-pull cable. 
         [0004]    Such a drive pipe and idle pipe are required to be bent in a complex configuration, and this contributed to an increase in the cost of the sunroof system. Japanese patent No. 3043589 (patent document 1) discloses an automotive sunroof system including a pair of drive pipes that are disposed on a common plane and a pair of idle pipes that are made of relatively flexible plastic material. Thereby, the work required for bending the drive pipes can be simplified, and the generation of noises due to the collision between the drive pipes and idle pipes that can be caused by the vibrations of the vehicle can be avoided. 
         [0005]    Japanese patent No. 3994815 (patent document 2) discloses an automotive sunroof system in which a front frame made of plastic material is integrally molded with guide pipe portions for receiving the push-pull cable therein. This prior invention allows the number of component parts to be reduced. 
         [0006]    According to the invention disclosed in patent document 1, the drive pipes are made of steel, and the need for bending steel pipes prevents the reduction in the manufacturing cost and weight. Because each drive pipe is required to protrude ahead of the front frame for the purpose of avoiding a sharp bending of the drive pipe, the protruding parts of the drive pipes are prone to inadvertent deformation during the handling of the sunroof assembly, and any deformation of the drive pipes may ruin the whole drive system of a sunroof system. 
         [0007]    In the case of the sunroof system disclosed in patent document 2, the number of component parts can be reduced owing to the elimination of the drive pipes, but a highly complex die assembly is required for molding the front frame, and this increases the manufacturing cost. Furthermore, because the guide pipe portions cannot be molded so as to entirely surround the push-pull cables, a measure is required to prevent grease from dripping from the guide pipe portions. It is also difficult to entirely eliminate noises that are caused by the sliding contact between the cable and guide pipe portions. 
         [0008]    The guide pipe portions are typically given with a highly complex configuration, and this tends to cause poor dimensional and geometrical precision. If there are burrs in the guide pipe portions, the sliding engagement between the burrs and cables cause noises. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    In view of such problems of the prior art, a primary object of the present invention is to provide a sunroof system in which a push-pull cable is smoothly guided by a guide pipe (drive pipe and/or idle pipe) while eliminating the need for precise bending work for the guide pipe. 
         [0010]    A second object of the present invention is to provide a sunroof system which allows a push-pull cable and guide pipe to be assembled to a frame with ease. 
         [0011]    A third object of the present invention is to provide a sunroof system which is protected from inadvertent deformation of the guide pipe. 
         [0012]    A fourth object of the present invention is to provide a sunroof system provided with a plastic frame which is easy to mold. 
         [0013]    According to the present invention, such an object can be accomplished by providing a sunroof system for selectively closing an opening formed in a roof of a vehicle, comprising: a pair of side frames attached to the roof of the vehicle and extending on either side of the opening in a first direction; a cross frame extending between the side frames; a slider slidably engaged by each side frame for sliding movement in the first direction and supporting a part of a closure member configured to close the opening formed in the roof; a push-pull cable formed with a driven gear along a length thereof and having one end connected to each slider; a drive gear rotatably supported by the cross frame and meshing with the driven gear of the push-pull cable; a drive pipe extending at least along a length of the cross frame and receiving a corresponding part of the push-pull cable therein; wherein the drive pipe is made of plastic material and the cross frame is provided with a pipe retaining feature therein. 
         [0014]    Because the drive pipe is made of plastic material, the drive pipe may be readily conformed to the required shape, and has an additional advantage of being light weight. As opposed to the conventional steel or other metal drive pipe, the plastic drive pipe does not require precise bending work so that the manufacturing cost can be reduced. In particular, because the drive pipe can be retained by the cross frame in a desired configuration by using the pipe retaining feature, the assembly work can be simplified. 
         [0015]    The plastic drive pipe provides an additional advantage of reducing noises that may be caused by the friction between the drive pipe and push-pull cable. Even though the push-pull cable is subjected to a significant compressive and tensile load, the drive pipe combined with the pipe retaining feature effectively prevents the deflection of the push-pull cable, and this contributes to the reliable operation of the actuating mechanism. Because the drive pipe can be freely bent and kept in position by the pipe retaining feature, the drive pipe can be easily confined within the profile of the cross frame, and is protected from external forces during the handling thereof. Also, the plastic drive pipe is highly resilient, and resistant to permanent deformation. 
         [0016]    The pipe retaining feature typically comprises a pipe retaining groove formed along a length of the cross frame. Preferably, the cross frame comprises a main planar section formed by a wall extending substantially horizontally, and the pipe retaining groove is given with such a depth that at least part of the drive pipe retained in the pipe retaining groove overlaps with the horizontal wall of the main planar section. 
         [0017]    Thereby, the load acting upon the drive pipe is directly transmitted to the horizontal wall of the main planar section along the major plane thereof so that the load acting on the drive pipe can be effectively supported, and the deflection of the push-pull cable can be positively prevented. This also minimizes the required rigidity of the cross frame. 
         [0018]    According to a preferred embodiment of the present invention, the side frames extend in a fore-and-aft direction of a vehicle body, and the cross frame comprises a front frame extending along a front edge of the opening between front ends of the side frames. 
         [0019]    According to another embodiment of the present invention, the side frames extend in a fore-and-aft direction of a vehicle body, and the cross frame comprises a rear frame extending along a rear edge of the opening between rear ends or intermediate parts of the side frames. 
         [0020]    According to a particularly preferred embodiment of the present invention, the pipe retaining feature comprises a plurality of clips arranged along a length of the pipe retaining groove, each configured to resiliently engage the drive pipe in the pipe retaining groove. The resilient clips simplifies the assembly of the drive pipe, and allows the drive pipe to be removed from the pipe retaining groove when required while the drive pipe can be firmly held in position when in use. 
         [0021]    If the pipe retaining groove at least partly comprises a bottom wall while parts of the pipe retaining groove corresponding to the clips are provided with an open bottom end, the cross frame can be molded from plastic material without requiring any complex die assembly. The use of molded plastic material for the cross frame reduces the manufacturing cost, and the weight of the sunroof system. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    Now the present invention is described in the following with reference to the appended drawings, in which: 
           [0023]      FIG. 1  is a simplified plan view of a sunroof system embodying the present invention; 
           [0024]      FIG. 2  is a plan view of a front frame of the sunroof system; 
           [0025]      FIG. 3  is a sectional view taken along line III-III of  FIG. 2 ; and 
           [0026]      FIG. 4  is an enlarged fragmentary sectional view taken along line IV-IV of  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]      FIG. 1  generally shows a roof of an automobile incorporated with an automotive sunroof system  3  embodying the present invention. In the following description, numerals denoting some of the parts of the sunroof system  3  may be accompanied by a suffix “l” or “r” to indicate that the particular components are located on which side of the vehicle body, and such parts may be collectively denoted with the corresponding numerals without the suffix. 
         [0028]    Referring to  FIG. 1 , the roof  1  of the automobile comprises a roof panel  2  having a rectangular opening  2   a  formed in a front part thereof and a sunroof system  3  configured to selectively close the opening  2   a . The sunroof system  3  comprises a sunroof panel (closure member)  4  configured to slide in a fore-and-aft direction and tilt up and down to open and close the opening  2   a  in a per se known manner, a sunroof frame  10  attached to the part of the roof  1  surrounding the opening  2   a  and an actuator  20  for actuating the sunroof panel  4 . 
         [0029]    The sunroof frame  10  comprises a pair of side frames  11  ( 11   l  and  11   r ) extending in the fore-and-aft direction on either lateral side of the opening  2   a , a front frame  12  extending along the front edge of the opening  2   a  and joining the front ends of the side frames  11  and a center frame  13  extending along the rear edge of the opening  2   a  and joining intermediate parts of the side frames  11 . Each side frame  11  is formed with a cable guide  14  for guiding a push-pull cable  22  as will be described hereinafter. 
         [0030]    A pair of panel brackets  5   l  and  5   r  are attached to a lower surface of the sunroof panel  4  and extend along either side edge thereof in the fore-and-aft direction. Each panel bracket  5  is slidably supported by the corresponding side frame  11  (or a guide rail incorporated in the side frame and not shown in the drawings) via a front slider  6  and a rear slider  7 . Each rear slider  7  is connected to the panel bracket  5  via a cam and link mechanism so that a rear part of the sunroof panel  4  may be guided not only for a fore-and-aft movement but also for a vertical movement that is required for the tilting movement of the sunroof panel  4 . 
         [0031]    The actuator  20  comprises a pair of push-pull cables  22  each made of a flexible steel core wire and a spirally wound steel wire wrapped around the core wire so as to form a rack gear extending along the length of the cable. This rack gear serves as a driven gear  21  which meshes with a corresponding drive gear  23  rotatably supported by the front frame  12  via a shaft extending vertically upwardly or downwardly and rotatively actuated by an electric motor  24  via a reduction gear unit not shown in the drawings. Each push-pull cable  22  is guided by a cable guide  14  provided on the corresponding side frame  11  and extends linearly. The part of each cable  22  extending from a front end of the side frame  11  to the drive gear  23  is guided by a drive pipe  25  which is fixedly attached to the front frame  12 . 
         [0032]    The part of each cable  22  extending beyond the drive gear  23  is guided by an idle pipe  26  also fixedly attached to the front frame  12 . These guide pipes (drive pipes  25  and idle pipes  26 ) not only protect the push-pull cable  22  from dust and moisture but also restrict the deflection of the cable  22  when the cable  22  is being pushed and pulled so that the rear sliders  7  may be displaced in precise correspondence with the rotation of the drive gear  23 . The two push-pull cables  22  extend in parallel to each other in the parts thereof meshing with the drive gear  23  so that the displacement of the rear sliders  7  may be accurately synchronized with the rotation of the drive gear  23 . In  FIGS. 1 and 2 , the idle pipe  27   r  connected to the right slider  7   r  has the suffix “r” and is called as the “right” idle pipe even though it is located on the left hand side of the vehicle roof. The same is true with the “left” idle pipe  27   l  with an appropriate commutation. 
         [0033]    In the illustrated embodiment, the left drive pipe  25   l  crosses the right idle pipe  26   r  only once as the left drive pipe  25   l  extends from the electric motor  24  to the front end of the left side frame  11   l  as seen in plan view. On the other hand, the right drive pipe  25   r  crosses the left idle pipe  26   l  twice as the left drive pipe  25   l  extends from the electric motor  24  to the front end of the right side frame  11   r  as seen in plan view. Thereby, the drive pipe, in particular the right drive pipe  25   r  is allowed to extend to from the electric motor  24  to the right slider  7   r  guided along the right side frame  11   r  without being sharply bent and, at the same time, without protruding excessively in the fore-and-aft direction. It is important that the drive pipe extends into the front end of the side frame in the fore-and-aft direction and minimize curvature as much as possible so as to avoid under stress to the push-pull cable  22  and the drive pipe  25 . It is also important to confine the fore-and-aft extent of the drive pipe  25  so that the required space for the sunroof system may be minimized. 
         [0034]    When fully closed, the sunroof panel  4  presents an upper surface flush with the adjacent part of the roof panel  2 . As the electric motor  24  actuates the drive gear  23  to pull the push-pull cables  22 , the cam mechanisms incorporated with the rear sliders  7  raises the rear end of the sun roof panel  4  upward, and thereby tilts up the sun roof panel  4 . When the cables  22  are pushed from this state, the sunroof panel  4  tilts down. When the cables  22  are pushed further from this state, the rear sliders  7  along with the sunroof panel  4  move rearward, and thereby full open the opening  2   a  in the roof panel  2 . 
         [0035]    The arrangement for mounting the drive pipes  25  and idle pipes  26  to the front frame  12  is described in the following with reference to  FIGS. 2 to 4 .  FIG. 2  is a plan view of the front frame  12 ,  FIG. 3  is a sectional view taken along line III-III of  FIG. 2 , and  FIG. 4  is an enlarged sectional view taken along line IV-IV of  FIG. 2 . As best shown in  FIG. 2 , the front frame  12  essentially consists of an injection molded planar member having the shape of letter C in plan view, and comprises a front planar section  12   a  extending substantially horizontally or in parallel with the roof panel  2  and defining a front edge of the front frame  12  when attached to the roof panel  2 , a rear planar section  12   b  extending substantially horizontally at a slightly lower level than the front planar section  12   a  defining a rear edge of the front frame  12  and a middle recess  12   c  disposed between the front planar section  12   a  and rear planar section  12   b  so as to define a laterally extending water drain groove. 
         [0036]    In a laterally middle part of the front planar section  12   a  is formed an opening  15  for passing the drive gear  23  or the shaft thereof from below or above depending on how the electric motor  24  is mounted on the front frame  12 , and a pair of pipe retaining grooves (drive pipe retaining groove  16  and idle pipe retaining groove  17 ) extend laterally, to the front and rear of the drive gear  23 , in a mutually parallel relationship. Of the pipe retaining grooves, the drive pipe retaining groove  16   l  for retaining a drive pipe  25   l  for the left push-pull cable  22   l  and the idle pipe retaining groove  17   l  for retaining an idle pipe  26   l  for the left push-pull cable  22   l  pass along the front side of the opening  15 . The drive pipe retaining groove  16   r  for retaining a drive pipe  25   r  for the right push-pull cable  22   r  and the idle pipe retaining groove  17   r  for retaining an idle pipe  26   r  for the right push-pull cable  22   r  pass along the rear side of the opening  15 . 
         [0037]    The drive pipe retaining grooves  16  extend halfway across the lateral width of the front planar section  12   a  at a substantially same elevation as the wall thereof, and have an upper side which is substantially entirely open. The idle pipe retaining grooves  17  likewise extend halfway across the lateral width of the front planar section  12   a , on the opposite lateral side, at a substantially same elevation as the wall thereof, and have an upper side which is substantially entirely open. As best shown in  FIG. 3 , at each lateral side end of the front planar section  12   a , the corresponding idle pipe retaining groove  17  is gradually curved downward so that the corresponding idle pipe  26  is allowed to cross and pass under the corresponding drive pipe retaining groove  16 . 
         [0038]    The front frame  12  is integrally molded with a pair of drain pipes  12   d  which communicate with a lower part of the middle recess  12   c  and pass under the corresponding drive pipes  25  and idle pipes  26 . The outer end of each drain pipe  12  may be connected to a rubber hose or the like not shown in the drawings to conduct the water drained from the middle recess  12   c  to the outside via the hollow interior of an A pillar or the like. 
         [0039]    As shown in  FIGS. 2 and 4 , the two side walls of each pipe retaining groove (drive pipe retaining groove  16  and idle pipe retaining groove  17 ) retain the corresponding drive pipe  25  or idle pipe  26 , and a plurality of clips  18  are provided at a regular interval along the length of the pipe retaining groove to resiliently engage the corresponding drive pipe  25  or idle pipe  26 , each clip  18  being provided with a barb  18   a  at a free end thereof so that the corresponding pipe may be forced into the pipe retaining groove from above (from the side of the upper surface  12   u  of the front frame  12 ). The part of the pipe retaining groove  16 ,  17  provided with each opposing pair of clips  18  has an open underside while the remaining part of the pipe retaining groove  16 ,  17  is provided with a bottom wall that supports the lower side of the drive pipe  17  or idle pipe  25 , as the case may be. Therefore, the pipe retaining grooves  16  and  17  can be integrally molded with the front frame member  12  without unduly complicating the structure of the molding die assembly. 
         [0040]    Each drive pipe  25  or idle pipe  26  is provided with an adequate flexibility to conform to the shape of the pipe retaining groove  16 ,  17 . Thus, the work involved in mounting the drive pipe  25  or idle pipe  26  is simplified but the pipe is securely retained therein once the pipe is fitted into the groove and clips. The removal of the drive pipe  25  or idle pipe  26  is similarly simplified as it can be effected simply by pulling the pipe out of the groove against the resilient force of the clips  19 . 
         [0041]    As shown in  FIG. 4 , each drive pipe retaining groove  16  is given with a depth such that the axial center  25 A of the drive pipe  25  overlaps with the thickness of the front planar section  12   a . Therefore, the load caused by the cable and acting on the drive pipe  25  is directly transmitted to the main body of the front planar section  12   a , and the direction of the application of the load is directed along the major plane of the front planar section  12   a  so that the load is efficiently supported by the front frame  12 , and the deflection of the drive pipe  25  can be positively prevented. The drive pipe  25  is not required to have the depth as discussed above over the entire length thereof, but may have the depth over a significant part of the entire length thereof. Also, the depth of each drive pipe  25  may be such that a part of the drive pipe  25 , instead of the axial center of the drive pipe  25 , overlaps with the thickness of the front planar section  12   a  as illustrated in  FIG. 3 . 
         [0042]    In the illustrated embodiment, the drive pipes  25  and idle pipes  26  are made of light plastic material so that the weight of the sunroof system  3  may be minimized. Because the drive pipes  25  and idle pipes  26  can be relatively freely bent without requiring any tool, the need for a precise forming process of the pipes is eliminated, and the drive pipes  25  and idle pipes  26  can be mounted on the front frame  12  simply by fitting them into the corresponding pipe retaining grooves  16  and  17 . When the electric motor  24  is actuated, and these pipes are subjected to a load from the push-pull cables  22 , because the pipes are firmly retained by the drive pipe retaining grooves  16 , the deflection of the push-pull cable  22  can be effectively prevented. 
         [0043]    In the foregoing embodiment, the electric motor  24  and drive gear  23  were located on the front frame  12 . However, it is also possible to place the electric motor  24 ′ and drive gear  23 ′ to the rear of the roof opening as indicated by the imaginary lines in  FIG. 1  without departing from the spirit of the present invention. They may be mounted on a rear frame that extends across the rear ends of the side frames  11  (as indicated by the imaginary lines in  FIG. 1 ) or on the center frame  13  (although not shown in the drawings). 
         [0044]    Although the present invention has been described in terms of a preferred embodiment thereof, it is obvious to a person skilled in the art that various alterations and modifications are possible without departing from the scope of the present invention which is set forth in the appended claims. For instance, the sunroof system of the illustrated embodiment was configured to effect both a sliding movement and tiling movement of the sunroof panel, but may also be configured to effect only one of the movements without departing from the spirit of the present invention. The electric motor and drive gear were installed in the front frame in the illustrated embodiment, but may also be mounted on a rear frame which may extend between rear ends or intermediate parts of the side frames. The sunroof may also be replaced with a sunshade. The kind of the push-pull cable is not limited to the one used in the illustrated embodiment, but may be freely selected from other forms of push-pull cables such as a cogged belt or a plastic rod having a rack gear formed on at least one side thereof. 
         [0045]    The contents of the original Japanese patent applications on which the Paris Convention priority claim is made for the present application are incorporated in this application by reference.