Patent Publication Number: US-6216394-B1

Title: Window lift mechanism

Description:
TECHNICAL FIELD 
     The subject invention generally relates to an apparatus for moving a closure member, such as a window, into an open or closed position. 
     BACKGROUND ART 
     All modem automobiles include a window lift assembly for raising and lowering windows in the door of the vehicle. The most common type of window lift assembly incorporates a “scissor mechanism.” As shown in FIG. 1, a scissor-type system includes a door  10 , a window  12  vertically moveable within the door  10 , a horizontal support bracket  14  on the window  12 , and a scissor mechanism  16  supported on the door  10  and engaged with a track  17  on the support bracket  14 . A sector rack  18  is supported on the scissor mechanism  16 , and a pinion gear  20  supported on the door  10  is engaged with the sector rack  18 . In vehicles with power windows, a worm gear  22  driven by a motor  24  is engaged with a driven gear  26  which, in turn, is operatively joined to the pinion gear  20 . The motor  24 , worm gear  22 , and driven gear  26  are all mounted to the door  10  of the vehicle. In vehicles without power windows (not shown), the pinion gear is driven by a manual hand-crank. 
     Unfortunately, the scissor-type mechanism includes many drawbacks such as the large amount of space and numerous parts required. The scissor-type mechanism is also mechanically inefficient, prohibiting the use of light-weight materials and requiring the use of relatively large motors to drive the system. The large motors necessarily require increased space and electrical power and also increase the weight of the system. With the limited space in a scissor-type system it is also necessary, in order to provide the required torque transfer efficiency and acceptable up and down times (3-4 seconds), to have a small diameter pinion gear, typically 0.5 to 0.75 inches, and relatively large driven gear, typically 1.8 to 2.5 inches in diameter, with gear ratios of 9 to 16 and 80 to 90, respectively. This results in excessive worm gear speed in the range of 3000 to 4000 RPM which causes excessive driven gear tooth shock and armature noise. The combination of high torque, typically 80 to 125 inch-pounds at stall, and shock due to high worm speeds mandates that either expensive multiple gears and/or single driven gears with integral shock absorbers be utilized. 
     In U.S. Pat. No. 4,167,834 to Pickles, a more mechanically efficient vertical rack and pinion window lift system is disclosed. This type of system is represented in FIGS. 2 and 3 and includes a door  28 , a window  30  vertically moveable within the door  28 , a support bracket  32  on the window  30 , a vertical rack  34  supported on the door  28 , and a pinion gear  36  supported on the support bracket  32  in engagement with the rack  34 . A motor  38  is supported on the support bracket  32  on the same side of the window  30  as the rack  34  and pinion gear  36  and drives the pinion gear  36  through a worm gear/driven gear transmission (not shown) engaged with the pinion gear  36 . The pinion gear  36  is continually meshed with the rack  34  to drive the window  30  up and down. Obvious advantages of this system are the mechanical efficiency, fewer parts and, hence, reduced weight, and reduced motor size. The system is also more simple to install than the scissor-type system. 
     The Pickles window lift assembly, while theoretically plausible, does not function adequately due to the complex method and arrangement used to adapt the support bracket  32 , motor  38 , worm gear, and driven gear to the window  30 . As discussed in United States Patent No.  4 , 967 , 510  to Torii et al., in window lift systems of the type shown in FIGS. 2 and 3 (such as the Pickles system) a larger torque than necessary is required to drive the system due to the angular moment set up by the weight of motor  38  and related structure acting upon moment arm L 1 . In addition, more space than necessary is required due to the “superimposed sequential” stacking of components in the thickness direction of the door resulting in an overall width W 1 . 
     The system disclosed in the patent to Torii et al. improved substantially over Pickles in its functional adaptability. The Torii system is represented in FIG.  4  and includes a window  40 , a support bracket  42  on the window  40 , a motor  44 , a pinion gear  46 , and a rack  48 . To eliminate the angular moment on the window  40  caused by the weight of the motor  44 , the Torii system positioned the motor  44  such that the center of gravity of the motor  44  was substantially aligned with the plane of movement of the window  40 . However, as shown in FIG. 4, this arrangement prevents the rack  48  from being positioned as close as possible to the window  40 , resulting in an increased angular moment on the window  40  caused by the torque generated at the rack/pinion gear interface acting upon a larger than necessary moment arm L 2  (due to the larger than necessary overall width W 2 ). The angular moment can cause the window to “pull in” in the direction shown by the arrow labeled P. Further, although not shown in FIG. 4, the Torii system includes a support bracket for supporting the window  40  and motor  44 . Similar to the Pickles system, the support bracket is “sequentially stacked” with respect to the motor, unnecessarily increasing the overall width of the system. 
     In co-pending U.S. patent application Ser. No. 08/762,447, now U.S. Pat. No. 6,073,395 filed Dec. 9, 1996 by Fenelon, the inventor of the present application, the restrictive and rigid systems presented by Pickles and Torii et al. were vastly improved upon by incorporating controlled flexibility into the rack system, hence providing for smooth operation as the window is raised and lowered. The system also reduced the number of components by “modularizing” the support bracket and minimizing the torque placed on the window by altering the “stacking arrangement” of the motor plus transmission, support bracket, and rack plus driven gear. This improved arrangement is shown in FIGS. 5 and 6 where reference numeral  52  is the window,  64  is the motor attached to the inside of support bracket  61 , and  62  is the pinion gear intermeshed with rack  56 . Note that W 3  is the total width of the stacked arrangement and L 3  is the moment which produces torque on window  52 . Similar to Pickles and Torii et al., Fenelon&#39;s improved arrangement “sequentially stacks” the components, unnecessarily increasing the overall width of the system. 
     Therefore, it is desirable to provide a window lift system which includes the benefits of a rack and pinion system, allows for smooth operation as the window is raised and lowered, and minimizes the torque placed on the window. Additionally, it is desirable to minimize the space occupied by the various components in all dimensions and particularly in the thickness direction of the door, and further to minimize the total number of components and hence the overall weight of the system. 
     SUMMARY OF THE INVENTION AND ADVANTAGES 
     In one embodiment of the present invention, a closure assembly is provided including a closure member, a support bracket joined to the closure member, a first pinion gear supported by the support bracket, and a first rack operatively engaged with the first pinion gear. A driven gear is supported for rotation by the support bracket and is operatively joined with the pinion gear. A motor is supported by the support bracket and includes an output shaft engaged with the driven gear. The support bracket fulfills a dual function by simultaneously acting as a transmission housing. The motor defines a profile in a width-wise direction, and the support bracket is positioned substantially within the width-wise profile of the motor. In this manner, the space occupied by the motor and support bracket can be minimized while further reducing the number of individual components required. 
     In another embodiment of the present invention, a closure assembly is provided including a closure member, a support bracket joined to the closure member, a first pinion gear supported by the support bracket, and a first rack operatively engaged with the first pinion gear. A driven gear is supported for rotation by the support bracket and is operatively joined with the pinion gear. A motor is provided including an output shaft having a worm gear engaged with a driven gear. The motor is supported at a first distal end of the support bracket wherein the output shaft extends toward a second distal end of the support bracket. In this embodiment as well, the space occupied by the motor and support bracket can be minimized together with minimizing the total number of components. 
     In another embodiment of the present invention, a closure assembly is provided including a closure member, a support bracket joined to the closure member, and a rack. The rack comprises a longitudinal rail including teeth on first and second opposing sides of the rail. A first pinion gear is supported by the support bracket and engaged with the teeth on a first side of the rack, and a second pinion gear is supported by the support bracket and engaged with the teeth on a second side of the rack. In this embodiment, the rack is adapted to engage dual pinion gears without requiring the expense and space of two separate racks. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other advantages of the present invention will be readily appreciated from the following detailed description of the invention when considered in connection with the accompanying drawings wherein: 
     FIG. 1 is a perspective view of a prior art scissor-type window lift assembly; 
     FIG. 2 is a perspective view of a first prior art rack-and-pinion window lift assembly; 
     FIG. 3 is a cross-sectional view of a first prior art rack-and-pinion window lift assembly; 
     FIG. 4 is a cross-sectional view of a second prior art rack-and-pinion window lift assembly; 
     FIG. 5 is a cross-sectional side-view of a third rack and pinion window lift assembly; 
     FIG. 6 is a cross-sectional view illustrating the motor assembly shown in FIG. 5; 
     FIG. 7 is a front perspective view of a first embodiment of the invention in which the pinion gears are engaged; 
     FIG. 8 is a rear perspective view of the first embodiment of the invention in which the driven gears are engaged; 
     FIG. 9 is a side view of the first embodiment of the invention; 
     FIG. 10 is a front perspective view of the first embodiment of the invention illustrating resilient shock absorbers engaged with each pinion gear; 
     FIG. 11 is a rear perspective view of the first embodiment of the invention in which the driven gears are not engaged; 
     FIG. 12 is a front perspective view of the first embodiment of the invention in which the pinion gears are not engaged; 
     FIG. 13 is a side view of a second embodiment of the invention; 
     FIG. 14 is a rear perspective view of the second embodiment of the invention; 
     FIG. 15 is a front perspective view of the second embodiment of the invention; 
     FIG. 16 is rear perspective view of the second embodiment of the invention in which the driven gears are disposed between the racks; 
     FIG. 17 is a rear perspective view of a third embodiment of the invention; 
     FIG. 18 is a front perspective view of the third embodiment of the invention; 
     FIG. 19 is a rear perspective view of a fourth embodiment of the invention; and 
     FIG. 20 is a front perspective view of the fourth embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A first embodiment of the invention is shown in FIGS. 7-9 and comprises a closure assembly  50  for moving a closure member, such as a window  52 , into an open or closed position. Referring to FIGS. 7 and 8, the closure assembly  50  includes first and second parallel racks  170 , 172 . The first rack  170  includes a row of teeth  174  which faces a row of teeth  176  on the second rack  172 . As shown in FIG. 7, first and second pinion gears  302 ,  304  are provided which include teeth  306  in engagement with the teeth  174 , 176  on the first and second racks  170 , 172 . The first and second pinion gears  302 , 304  are also in engagement with one another. 
     As shown in FIGS. 7 and 8, a plastic support bracket  308  supports the window  52 . The support bracket  308  is a longitudinal member including first and second distal ends  309 , 311 . Two mounting feet  310  join the window  52  to the support bracket  308  and permit limited side-to-side movement of the window  52 . Referring to FIG. 9, the mounting feet  310  each comprise a bracket  312  joined to a lower edge  68  of the window  52  and a base member  314  joined to the support bracket  308 . Each bracket  312  includes a lower C-shaped channel  316  which surrounds a flange  318  on the base member  314  and permits the bracket  312  to slide relative to the base member  314 . The lower edge  68  of the window  52  is received within a U-shaped channel  320  on each mounting foot  310 . 
     As the assembly is installed, the mounting feet  310  are first permanently attached to the bottom edge  68  of the window  52 . The window  52  is then dropped into place relative to the support bracket  308  such that the base member  314  of each mounting foot  310  will be bolted, riveted, or otherwise attached to the support bracket  308 . As shown in FIG. 9, the window is installed as close as possible to the racks  170 , 172  without contacting the racks  170 , 172 . 
     Referring to FIGS. 7 and 9, guide members  240  are provided on the support bracket  308  adjacent the first and second racks  170 , 172 . The guide members  240  ensure that the first and second racks  170 , 172  remain in engagement with the first and second pinion gears  302 , 304 . As shown in FIG. 9, the guide members  240  comprise spool shaped, plastic members having a cylindrical body  244  extending perpendicularly from the support bracket  308  and a circular flange  246  extending radially outwardly from a distal end of the body  244 . The guide members  240  are rotatably supported by cylindrical posts  248  (shown in phantom in FIG. 7) extending perpendicularly from the support bracket  308 . 
     The first and second pinion gears  302 , 304  (shown in FIG. 7) are operatively connected, respectively, to first and second driven gears  322 , 324  (shown in FIG.  8 ). The first and second driven gears  322 , 324  are engaged such that rotation of the first driven gear  322  produces corresponding rotation of the second driven gear  324 . Referring to FIG. 8, a central shaft  326  joins each pinion gear  302 , 304  to its respective driven gear  322 , 324 . The driven gears  322 , 324  are contained within an internal compartment  325  in the support bracket  308 . 
     Because the pinion gears  302 , 304  are engaged, it is not necessary to provide a second driven gear  324  engaged with the first driven gear  322  as shown in FIG.  7 . Instead, the second pinion gear  304  can be driven solely by the engagement with the first pinion gear  302 . Similarly, it is not necessary that the first and second pinion gears  302 , 304  be engaged (as shown in FIG. 8) as long as the first and second driven gears  322 , 324  are engaged. 
     Referring to FIG. 8, a motor  328  is supported on the support bracket  308  and includes a single output shaft  330  having a worm gear  332  formed at a distal end thereof. The worm gear  332  is helical and directly engages with teeth  334  on the first driven gear  322 . The motor  328  is mounted to the first distal end  309  of the support bracket  308  and the output shaft  330  extends toward the second distal end  311  within an internal passage  336 . As shown in FIG. 9, the motor  328  defines a profile W m , or “footprint”, in a width-wise direction generally perpendicular to the window  52 . The support bracket  308  has a width approximately equal to the width of the motor  328  and is positioned within the width-wise profile W m  of the motor  328 . In this manner, the combined width of the support bracket  308  and motor  328  can be minimized compared to other embodiments with which the support bracket  308  and motor  328  are “stacked” in a width-wise direction. Preferably, the motor  328  has a width of approximately 35 millimeters or less. The support bracket  308  integrally fulfills the dual function of supporting the window  52  as well as providing a transmission housing for the worm gear  332  and driven gears  322 , 324 . 
     As shown in FIG. 9, the motor  328  includes a center of gravity designated at  338  located on a first side of the window  52 . The racks  302 , 304  are located on a second side of the window  52 . This arrangement provides distinct advantages by permitting the racks  170 , 172  to be as close as possible to the window  52 . The center of gravity  338  of the motor  328  will remain close enough to the window  52 , however, to avoid excessive torque on the window  52  caused by the weight of the motor  328 . 
     Although not shown in the figures, an O-ring or other type of seal can be provided at the interface between the pinion gears  302 ,  304  and the support bracket  308  to prevent moisture from entering the internal components of the motor  308  and causing corrosion and premature failure of the motor  308 . 
     The pinion gears  302 , 304  shown in FIG. 7 do not include any form of internal shock absorber. However, depending upon the demands to be placed on the system, it may be desirable to place resilient shock absorbers  204  within one or both pinion gears  302 , 304  as shown in FIG.  10 . The resilient shock absorbers  204  are formed of an elastomeric material such as Santoprene  55 . The configuration of the shock absorbers  204  is discussed in detail in Applicant&#39;s co-pending application Ser. No. 08/762,447, now U.S. Pat. No. 6,073,395 filed Dec. 9, 1996. 
     FIGS. 11 and 12 illustrate an alternative configuration in which the output shaft  330  of the motor  328  includes dual worm gears  332  engaged with the first and second driven gears  322 , 324 . The first and second driven gears  322 , 324  (shown in FIG. 11) are not engaged because each is independently driven by the dual worm gears  332 . Similarly, the first and second pinion gears  302 , 304  (shown in FIG. 12) are not engaged because each receives torque from its respective driven gear  322 , 324 . In all other respects, this configuration is the same as discussed above with respect to FIGS. 7-10. 
     A second embodiment is shown in FIGS. 13-15 and is similar to the first embodiment discussed above. Unlike the first embodiment, however, the racks  170 , 172  include outwardly facing rows of teeth  174 , 176  which engage with the first and second pinion gears  302 , 304  (shown in FIG.  15 ). Guide wheels  341  (shown in phantom in FIGS. 14 and 15) engage the racks  170 , 172  to prevent the racks  170 , 172  from moving out of engagement with the pinion gears  302 , 304 . As shown in FIG. 13, the window  52  is positioned as close as possible to the racks  170 , 172  without physically touching the racks  170 , 172 . 
     As shown best in FIG. 14, a motor  340  is integrated within the support bracket  308  and has a dual-ended output shaft  342  including a worm gear  332  at each end of the output shaft  342 . The worm gears  332  engage with driven gears  322 , 324  which are, in turn, operatively connected with the pinion gears  302 , 304 . The worm gears  332  have opposite helical angles such that the pinion gears  302 ,  304  will rotate in opposing directions as is required to ensure that the pinion gears  302 , 304  cooperate during vertical movement of the window  52 . 
     Further, one or both pinion gears  302 , 304  can be provided with a resilient shock absorber  204  as shown in FIG. 10 with respect to the first embodiment. 
     As shown in FIG. 16, the racks  170 , 172  can alternatively be spaced farther apart such that the pinion gears  302 , 304 , motor  340 , and driven gears  322 , 324  are disposed between the racks  170 , 172 . In this configuration, the teeth  174 , 176  on the racks  170 , 172  are located on inwardly facing sides of the racks  170 , 172 . The motor  340  is mounted on the support bracket  308  by retaining straps  344 . The dual-ended output shaft  342  is supported for rotation by bearings  346  and includes a worm gear  332  at each end thereof. The worm gears  332  engage with driven gears  322 , 324  in the same manner as discussed above. Seal caps  348  are sonic welded to the support bracket  308  to cover the driven gears  322 , 324  and prevent entry of water or debris. 
     A third embodiment is shown in FIGS. 17 and 18 and includes parallel racks  170 , 172  engaged with dual pinion gears  302 , 304  similar to the first embodiment discussed above. Referring to FIG. 17, the motor  328  includes a single-ended output shaft  330  having worm gears  332  thereon engaged with first and second driven gears  322 , 324 . Unlike the first embodiment, however, the teeth  174  on the first rack  170  face the same direction as the teeth  176  on the second rack  172 . Thus, as shown in FIG. 18, the first pinion gear  302  is disposed between the first and second racks  170 , 172  while the second pinion gear  304  is engaged with the rack teeth  176  on an outwardly facing edge of the second rack  172 . In all other ways the third embodiment is identical to the first embodiment. 
     A fourth embodiment is shown in FIGS. 19 and 20 and includes a flexible rack  350  formed from a single, longitudinal rail having first and second rows of teeth  174 , 176  on opposing sides of the rack  350 . A motor  328  is provided having a single-ended output shaft  330  including a pair of worm gears  332  thereon. The worm gears  332  engage with driven gears  322 , 324  which are, in turn, operatively connected to pinion gears  302 , 304  by central shafts  326 . As shown in FIG. 20, the pinion gears  302 , 304  straddle the rack  350  and engage the rack teeth  174 , 176 . Guide members  240  are also provided and prevent the rack  350  from moving in a direction perpendicular to the window  52 . 
     As previously stated, the object of the present invention is to minimize the space occupied by the various components in all dimensions and, in particular, in the thickness direction of the door. Contrasting this dimension in FIG. 3 (Pickles), FIG. 4 (Torii et al.), FIG. 5 (Fenelon), and FIG. 13 (the present invention), we observe that the embodiment of FIG. 3 has the largest thickness, the embodiments of FIGS. 4 and 5 are approximately equal to one another (but smaller than shown in FIG.  3 ), and that the present invention shown in FIG. 13 has the smallest thickness. Indeed, the thickness of the embodiment of the present invention is only limited by the thickness of the motor required to drive the unit. It is estimated that a width less than 30 mm is readily achievable. This compares with an estimated 50 mm minimum for previous embodiments. Additionally, the total number of parts has been greatly reduced so that a total weight of less than 1.5 pounds is attainable. This compares favorably with existing weights of arm and sector systems of 6.0 pounds or more. 
     The invention has been described in illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. 
     Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.