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REFERENCE TO RELATED APPLICATIONS  
         [0001]    The present invention claims priority to French Patent Application No. 02 07 566, filed Jun. 19, 2002.  
           [0002]    1. Technical Field  
           [0003]    The present invention relates to a window lifter, and more particularly to a vehicle door having such a window lifter.  
           [0004]    2. Background of the Invention  
           [0005]    Window lifters in vehicle doors are often difficult to mount. Several solutions have been proposed for mounting the window lifter in the door.  
           [0006]    French patent 2,761,104 discloses a window lifter having two substantially parallel rails with cables in an X-configuration between the rails and sliding thereon. The window lifter also includes an X-shaped support joining the upper ends and enveloping the cables. The support provides rigidity for the window lifter, which can be mounted in a modular fashion in a large opening in the door. This window lifter suffers from the disadvantage of requiring large amounts of material for enveloping the cable over the whole length thereof between the rails, making the window lifter expensive to manufacture. Additionally, this type of window lifter cannot be installed into every type of vehicle door. Indeed, this type of window lifter must be installed via a large opening in the door, but certain doors may have small openings that limit access to the inside of the door. Additionally, the X-shaped crossing arrangement occupies a lot space inside the door, preventing other items of equipment being incorporated into the door.  
           [0007]    U.S. Pat. No. 5,617,675 discloses a collapsible window lifter that is installed through openings that limit access to the inside of the door. This is achieved by incorporating a U-shape in the window lifter. The vertical arms of the slider-guiding U pivot at one of their ends on the base of the U. To introduce the window lifter through the opening, the vertical arms are folded down against the base of the U. Once the window lifter is in place, the vertical arms are unfolded inside the door and then secured thereto.  
           [0008]    This window lifter nevertheless has the disadvantage of being highly complex and expensive to produce because of the pivoting arrangements. Unfolding the arms becomes increasingly complex as the opening in the door becomes narrower. Additionally, folding and unfolding the arms may degrade cable tension in the window lifter. Further, rigidity at the free end of the vertical arms is decreased, leading to the arms bending which is prejudicial to the securing of the window lifter. Also, when the door has a concave shape, the radius of curvature applied to the window lifter for matching the shape of the door prevents a complete folding of the window lifter; thus, introducing a window lifter into the door opening becomes more complex.  
           [0009]    There is consequently a need for a window lifter that is less expensive to manufacture and that is flexible enough to be readily mounted on a vehicle door while still providing adequate protection for the cable.  
         SUMMARY OF THE INVENTION  
         [0010]    The invention according to one embodiment is a window lifter comprising a first and a second parallel guide rail, a connecting arm rigidly connecting the said rails, the connecting arm being connected to the guide rails at a point along the rails between their ends, cable returns defining a cable path along the said rails and said connecting arm.  
           [0011]    According to one embodiment, the connecting arm extends at least in part outside a surface defined by the guide rails. Other embodiments incorporate details such as forming an angle of between 45° and 135° with respect to the connecting arm and one of the rails, and/or locating the connecting arm substantially at a half-way point along said rails.  
           [0012]    According to one embodiment, the first and second guide rails carry a cable return at each of their ends and in that said connecting arm has a cable return at each one of its ends. One of the cable returns of the connecting arm may carry a motor and speed reduction gear.  
           [0013]    According to one embodiment, the guide rails are of metal and the connecting arm is of plastic material. According to a further embodiment the guide rails each carry a projecting part extending towards the other rail, each of said projecting parts carrying a cable return directing the cable path along the connecting arm. The guide rails and the connecting arm may have supports for automobile fixtures.  
           [0014]    The invention is also directed to a vehicle door having an inventive window lifter is also provided. According to one embodiment, the door includes a hollow section and openings for introducing the window lifter into the hollow section, the first and second rails extending inside the hollow section and the connecting arm being outside the hollow section.  
           [0015]    In other embodiments of the vehicle door, the connecting arm supports a window lifter motor and speed reduction gear and/or the vehicle door includes automobile fixtures secured on the connecting arm  
           [0016]    Further characteristics and advantages of the invention will become clearer from the following description of some embodiments of the invention provided by way of non- and limiting example, and with reference to the attached drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1 shows a window lifter according to one embodiment of the invention.  
         [0018]    [0018]FIG. 2 shows a window lifter of FIG. 1 according to another embodiment.  
         [0019]    [0019]FIG. 3 is a section through the window lifter of FIG. 1 along line A-A.  
         [0020]    [0020]FIG. 4 shows a vehicle door incorporating the window lifter of FIG. 2. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0021]    A window lifter according to one embodiment of the invention comprises two parallel guide rails which are rigidly connected by a connecting arm. Generally, the connecting arm is connected to the guide rails between their ends, along the rails. Cable returns define a cable path along the rails and arm. This window lifter is more rigid at the free ends of the guide rails since the connecting arm is connected remotely from the ends of the rails. Moreover, because the rigidity of the window lifter is simply provided by one single connecting arm extending from one guide rail to the other, the window lifter saves on material while simultaneously ensuring the cable is protected as it runs along the rails.  
         [0022]    [0022]FIG. 1 shows one embodiment of the window lifter of the invention. The window lifter  10  comprises a first guide rail  12  and a second guide rail  14 . The rails  12 ,  14  respectively guide linear movement of sliders  11   a  and  11 b. The sliders  11   a  and  11   b  are secured to a window glass (not shown) of the vehicle. Incorporating two guide rails allows movement of the window glass at two points, ensuring that the glass will not swing while it is moving. The guide rails are rigidly connected together by a connecting arm  16 .  
         [0023]    The connecting arm  16  has two ends  16   a  and  16   b  through which the connecting arm  16  is joined to the guide rails  12 ,  14  at a point between the ends of the rails  12 ,  14 . Cable returns  18 ,  20 ,  22 ,  24 ,  26 ,  28  define a cable path along the rails  12 ,  14  and the arm  16 . A cable  13  drives the sliders  11   a  and  11   b  while being protected from deterioration as the cable  13  runs close to the rigid rails  12 ,  14  and arm  16 .  
         [0024]    The guide rails  12 ,  14  may be made of, for example, metal or plastic material. The rails  12 ,  14  can be manufactured by pressing or by molding. The rails  12 ,  14  are preferably mutually parallel so that the sliders  11   a,    11   b  are driven in parallel directions to allow the window glass to move without encumbrance. The guide rails  12 ,  14  include fixing lugs  30   a,    30   b,    30   c,    30   d  for securing the window lifter  10  onto the vehicle door. For driving sliders  11   a,    11   b  via the cable, the guide rails  12  and  14  have respective cable returns  18 ,  20  and  26 ,  28  at each end. The cable returns can be, for example, pulleys. Cable tensioners can be provided on the pulleys, spreading the pulleys apart to lengthen the cable path.  
         [0025]    In one embodiment, the connecting arm  16  is made of a metal or plastic material formed by pressing or molding. It can either be a member that is secured onto the guide rails or be integrally constructed with the guide rails. In the latter case, the connecting arm  16  can be obtained by cutting a metal plate which is then pressed, or it can be obtained by molding a complete rail and arm assembly.  
         [0026]    In one embodiment, the rails  12 ,  14  are made of metal and connecting arm  16  is made of plastic material. This allows cost and weight savings in the assembly. In one embodiment, the rails  12 ,  14  each have a projecting part extending towards the other rail, and each projecting part carries a cable return  22 ,  24  directing the cable path along the connecting arm  16 . The advantage is that the stresses set up by operation of the cable returns  22 ,  24  are taken up by the rails  12 ,  14 . The connecting arm  16  is then preferably secured between these two projecting parts  22 ,  24 .  
         [0027]    The connecting arm  16  rigidly connects the rails  12 ,  14  allowing the cable to be tensioned while the window lifter is being assembled. Cable tension is thus preserved during handling and transport of the window lifter. Additionally, the rigidity of the window lifter allows more readily assembly on the vehicle door. Indeed, the upper ends of the rails  12 ,  14  are firstly secured to the door. The rigidity of the window lifter then allows the lower ends of the rails  12 , 14  to come in blind fashion to the designed securing position on the door.  
         [0028]    The connecting arm  16  is connected to the guide rails  12 ,  14  between their ends, along the rails. For example, for a rail which is  450  cm long, connecting arm  16  can be connected to the rails  12 ,  14  at a point at least  30  cm from the end of a rail  12 ,  14 . Compared to a U-shaped window lifter, the advantage of the connecting arm according to the invention is that the rails  12 ,  14  are kept rigid, particularly at the free ends of the rails. The guide rails  12 ,  14  of the invention are therefore connected together at regions that are closer to the center of the rails rather than at the ends of the rails, as is the case in a U-shaped window lifter. By connecting the middle portions, and not the ends, of the guide rails  12 ,  14 , the invention limits deflection at each of the free ends of guide rails  12 ,  14 .  
         [0029]    [0029]FIG. 2 shows a window lifter according to another embodiment of the invention. This embodiment maximizes the rigidity in the window lifter. The amount of deflection at a point on the guide rail is proportional to the distance between this point and another point at which the guide rail and the connecting arm join. Thus, the smallest simultaneous deflection at the free ends  12   a,    12   b,    14   a,    14   b  of the rails  12 ,  14  is obtained when the connecting arm is substantially at half the length of the guide rails and substantially perpendicular to the guide rails  12 ,  14 . In this embodiment, the window lifter generally has an H-shape.  
         [0030]    In one embodiment, the connecting arm  16  and guide rails  12 ,  14  can include supports for automobile fixtures. For example, the supports may be designed to carry a loudspeaker, door lock, armrest, or other fixtures. The rigidity of the window lifter provides support for the fixtures as well as forces occurring during use of the door. For example, when a passenger closes the door using the armrest, the window lifter can take up the forces resulting from the door closing. The window lifter can therefore help limit sagging of the door.  
         [0031]    The inclination and position of fixing the connecting arm along the guide rails allows the window lifter to be adapted to securing automobile fixtures. The connecting arm offers numerous possible positions for fastening the fixtures, depending on the height and length of the door. Thus, the connecting arm can form an angle a between 45° and 135° with respect to one of rails  12 ,  14 . In FIG. 1, the connecting arm  16  makes an angle a of about 45° with respect to guide rail  14 . Thus, the connecting arm  16  passes through a central region of the door allowing, for example, the handle for closing the door to be secured to points  32  and  34  on the connecting arm  16 , along with the armrest in the region identified by reference numeral  36  (FIG. 1).  
         [0032]    Another advantage of the connecting arm  16  is that it can be adapted as a function of door geometry to allow components of the door to be fitted. Currently known X-shaped window lifters cannot be adapted to door geometry.  
         [0033]    The cable  13  returns  18 ,  20 ,  22 ,  24 ,  26 ,  28  define a cable path along the rails  12 ,  14  and the connecting arm  16 . The cable  13  follows the rigid rails  12 ,  14 , and the connecting arm  16 , allowing it to be protected from deterioration. Further, the connecting arm  16  reduces the amount of material needed to protect the cable  13 , particularly when compared to an X-shaped window lifter.  
         [0034]    In the embodiment shown in FIG. 1, the first rail  12  and the second rail  14  have a cable return  18 ,  20 ,  26 ,  28  at each of their free ends allowing the cable to extend along the rails for driving the sliders  11   a  and  11   b.  The cable returns can be, for example, pulleys. The connecting arm  16  also has cable returns  22 ,  24 , which allow the cable to be guided and protected along arm  16 .  
         [0035]    [0035]FIG. 3 is a section view of the window lifter of FIG. 2 taken along line A-A. The cable return  22  can be seen more clearly in FIG. 2. In FIG. 3, it can be seen that cable return  22  has two parts  22   a  and  22   b  to drive cable  13  twice, as can be seen in FIG. 2. In FIG. 3, the two parts  22   a  and  22   b  of the cable return  22  are rotatably mounted independently of each other so that the cable  13  is rotatably driven in two different directions. The cable return  22  is, for example, composed of two pulleys  22   a  and  22   b  sharing a common axis of rotation. The pulleys may also be arranged side by side with non-common axes of rotation. The cable return  24  has the same structure as cable return  22 .  
         [0036]    [0036]FIG. 3 shows a guide rail  12  having a curved shape to allow it to be adapted to a vehicle door having a curved profile. Of course, the other guide rail  14  (not shown in FIG. 3) will also have a curved shape to accommodate the profile of the door.  
         [0037]    The cable  13  is driven by a motor having a speed reduction gear (not shown), which can be secured at any point along the cable path except on the path of the sliders.  
         [0038]    In one alternative embodiment, one of the cable returns  22 ,  24  guiding the cable  13  along the connecting arm  16  carries the motor and speed reduction gear. As shown in FIG. 3, one of the cable returns  22 ,  24  of the connecting arm  16  carries a motor and speed reduction gear. The speed reduction gear can take the place of the cable return  22   b  and have a part  22   a  fixed thereon, using a common axis with the speed reduction gear. This reduces the number of cable returns in the system and allows the stresses on the motor and speed reduction gear and cable return  22   a  to be taken up on a common axis.  
         [0039]    The window lifter can be secured inside a door having openings that limit access to the inside of the door. For this purpose, the connecting arm  16  is offset with respect to the guide rails  12 ,  14 . In FIG. 3, the connecting arm  16  extends at least partially outside the surface defined by the guide rails  12 ,  14 . The central portion  16   a  of the connecting arm  16  (visible in FIG. 2) lies in a surface that is offset with respect to the surface defined by the guide rails. The central portion  16   a  supports the cable returns  22  and  24 .  
         [0040]    The offset is, for example, provided by giving connecting arm  16  a U-shape, the central portion of the U being the portion  16   a  of the connecting arm  16 . The connecting arm is for example obtained by pressing or molding. The connecting arm  16  then carries lugs  16 d, shown in FIG. 3, at both sides of the central region  16   a,  allowing the central portion  16   a  to be joined to the guide rails  12 ,  14 . In another embodiment, the central portion  16   a  is joined to the rails  12 ,  14  by bracing members  16   b  to which, for example, central portion  16   a  is welded.  
         [0041]    [0041]FIG. 4 shows a door  23  of the vehicle carrying the window lifter of FIG. 2 and exhibiting offset of the connecting arm  16 . The door shown in FIG. 4 can incorporate a window lifter either with or without cable returns. To reinforce vehicle door rigidity, automobile manufacturers limit access to the inside of the door. The openings provided in the door allow equipment and fixtures to be introduced inside the door. In FIG. 4, the door  23  has a hollow section  37  and openings  38 ,  40  that allow equipment and fixtures to be introduced into the door  23 . The openings  38 ,  40  allow the window lifter  10  to be placed into the hollow section  37 . The openings  38 ,  40  are separated by a support portion  39  ensuring rigidity of the door  23 . The hollow section  37  delimits a damp and dry region, one inside the hollow section and the other outside, towards the inside of the vehicle.  
         [0042]    As shown in FIG. 4, the first guide rail  12  and second guide rail  14  are inside the hollow section  37  and the connecting arm  16  is the outside hollow section  37 . The window lifter  10  can be arranged in the door by, for example, first introducing the upper ends  12   a  and  14   a  of the guide rails  12 ,  14  into the openings  38 ,  40 . The ends  12   a  and  14   a  are then inserted more deeply into hollow section  37  toward the top of the door until the lower ends  12   b,    14   b  of rails  12 ,  14  can be introduced via openings  38 ,  40  into hollow section  37 . The connection between the connecting arm  16  and the rails  12 ,  14  at a point between their ends allows such a maneuver.  
         [0043]    The window lifter  10  is then lowered towards the bottom of the door and then secured in position by, for example, using the fixing lugs  30   a  and  30   d  (FIG. 1). Securing the window lifter may be conducted by, for example, first fixing the upper ends  12   a,    14   a  to the door  23 . The rigidity of the window lifter  10  will allow the lower ends  12   b,    14   b,  to move into position. Note that the order in which the ends of the window lifter  10  are introduced into the door  23  is not limited to the discussion above.  
         [0044]    The shape of the connecting arm  16  outside the surface defined by the rails  12 ,  14  allows the connecting arm to rest on the support portion  39 , outside the hollow section  37 , while the guide rails  12 ,  14  remain inside the hollow section. Having the connecting arm  16  outside the hollow section  37  allows the motor and speed reduction gear to be arranged on the arm  16  and kept in the dry region of the door.  
         [0045]    According to another embodiment, the support portion  39  of the door  23  has a concave shape, which is pushed in toward the inside of hollow section  37 . This allows the window lifter  10  to be arranged inside the hollow section  37  without any portion of the connecting arm  16  being disposed outside the surface defined by the guide rails. This facilitates manufacture of window lifter  10 . The invention also concerns the door  23  of the vehicle carrying the window lifter described.  
         [0046]    Obviously, the present invention is not limited to the embodiments described above by way of example. For example, the embodiment where at least one part of the connecting arm  16  is disposed outside the surface defined by guide rails  12  and  14  is not limited to a window lifter  10  with an H-shape and the connecting arm inclined with respect to the guide rails; the offset can also be obtained with a window lifter  10  having generally a U-shape. Further, the invention is not limited to a door having two openings  38 ,  40  as shown in FIG. 4; the door can, for example, have a longitudinal opening running in the direction of movement of the vehicle, or with a length slightly greater than the width of the window lifter. It can also be arranged to provide the window lifter described in the bodywork of a hatchback vehicle, at the height of the rear seat passengers.  
         [0047]    It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that the method and apparatus within the scope of these claims and their equivalents be covered thereby.

Summary:
A vehicle window lifter includes first and second parallel guide rails, a connecting arm rigidly connecting the guide rails at a point along the rails between their ends, and cable returns defining a cable path along the rails and connecting arm. The connecting arm and guide rails form a cable path for a cable, protecting the cable while providing high rigidity and simple mounting on a vehicle door.