Abstract:
A convertible vehicle top stack mechanism includes a moveable rearmost roof bow and an actuator. In an other aspect of the present invention, a linkage assembly couples a rearmost roof bow to a side rail. A further aspect of the present invention employs a rotatable member or crank to drive a set of buggy links in order to raise and lower an active number five roof bow.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
   The present invention relates generally to automotive vehicle convertible roofs and more particularly to a convertible vehicle top stack mechanism having an active rearmost roof bow. 
   Some traditional convertible roofs for automotive vehicles employ an active number five bow which can be selectively rotated from a nominal and generally horizontal position to a raised and generally vertical position in order to allow clearance for a moveable, rigid tonneau cover. Such a tonneau cover needs to be opened to allow convertible roof access for retraction into a storage compartment or boot well, and the tonneau cover is closed so the number five roof bow can sit on top of it when the convertible roof is fully raised. One such example is disclosed in U.S. Pat. No. 6,039,382 entitled “Folding Top for a Motor Vehicle” which issued to Mather et al., on Mar. 21, 2000, and is incorporated by reference herein. 
   Hydraulically driven buggy links have been used to move active number five roof bows in various of these conventional roof systems. Some exemplary U.S. patents disclosing these conventional constructions are: U.S. Pat. No. 5,816,644 entitled “Folding Top for a Convertible” which issued to Rothe et al. on Oct. 6, 1998; and U.S. Pat. No. 5,749,619 entitled “Motor Vehicle with Foldable Roof, and Foldable Roof for Such a Motor Vehicle” which issued to Mentink on May 12, 1998; both of these are incorporated by reference herein. It is noteworthy, however, that many traditional number five bow actuation systems have required undesirably high forces to operate which necessitates difficult to package, large and expensive hydraulic cylinders while increasing the chance of premature part failure. Furthermore, many of these traditional systems disadvantageously create undesirably fast acceleration of the number five bow during movement which can lead to premature part failure. 
   In accordance with the present invention, a convertible vehicle top stack mechanism includes a moveable rearmost roof bow and an actuator. In an other aspect of the present invention, a linkage assembly couples a rearmost roof bow to a side rail. A further aspect of the present invention employs a rotatable member or crank to drive a set of buggy links in order to raise and lower an active number five roof bow. Yet another aspect of the present invention employs an automatic actuator which has an elongated dimension generally parallel to a rear side rail of a top stack mechanism. 
   The convertible vehicle top stack mechanism of the present invention is advantageous over traditional constructions in that the present invention reduces the activation forces required to move a rearmost roof bow relative to a side rail while also reducing acceleration spikes during movement of the rearmost roof bow. The present invention is further advantageous by providing a more modularized and integrated package for the top stack mechanism to facilitate and ease assembly of same into an automotive vehicle body. For example, the automatic actuator is preassembled to the top stack mechanism prior to shipment to the customer&#39;s final assembly plant such that a portion of the actuator does not need to be subsequently fastened to the automotive vehicle body. Accordingly, the present invention reduces part failure during usage, is easier to control, and is simpler to package and install in the vehicle. Additional advantages and features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view showing the preferred embodiment of an automotive vehicle convertible roof of the present invention, in a fully raised position; 
       FIG. 2  is a fragmentary perspective view showing the preferred embodiment automotive vehicle convertible roof, in a fully raised position; 
       FIG. 3  is a side elevational view showing a portion of the preferred embodiment automotive vehicle convertible roof; 
       FIG. 4  is an enlarged and fragmentary, perspective view showing a portion of the preferred embodiment automotive vehicle convertible roof, with a number five roof bow in a raised position; 
       FIG. 5  is a fragmentary perspective view showing the preferred embodiment automotive vehicle convertible roof with the number five roof bow in a raised position and the remainder of a top stack mechanism in a partially retracted position; 
       FIG. 6  is a perspective view showing a portion of the preferred embodiment automotive vehicle convertible roof; and 
       FIG. 7  is an exploded, perspective view showing a portion of the preferred embodiment automotive vehicle convertible roof. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The preferred embodiment of a convertible roof  21  attached to an automotive vehicle body  23  of the present invention is shown in  FIGS. 1 and 2 . Only one side of convertible roof  21  will be discussed herein since the other side is essentially a mirrored image of the one discussed and illustrated. Convertible roof  21  includes a top stack mechanism  25  which is covered by a pliable or flexible fabric cover  27  which has a solid glass back window or backlite  29 , or alternately a flexible PVC window, attached thereto. 
   Top stack mechanism  25  includes a rear side rail  31 , a center side rail  33  and a front side rail  35 . A forwardmost or number one roof bow  37  is attached to front side rail  35 , a number two roof bow  39  is pivotally coupled to center side rail  33 , a number three roof bow  41  is pivotally coupled to rear side rail  31  and a number four roof bow  43  is also pivotally coupled to rear side rail  31 . A rearmost or number five roof bow  45  has a mounting bracket  47  affixed thereto, thereby defining an assembly, which is pivotally coupled at a pivot  51  to an offset extension  49  rearwardly projecting from a lower portion of rear side rail  31 . Top stack mechanism  25  also includes various additional links  53  and  54 , and a primary top stack actuator  55 , such as a hydraulic cylinder or alternately, an electric motor. Primary actuator  55  moves the convertible roof between a fully raised and closed position covering a passenger compartment of the vehicle, to a fully retracted and open position within a roof storage compartment or boot well. 
   Referring now to  FIGS. 3 ,  6  and  7 , a five bow actuation assembly  81  includes a buggy link assembly  83 , a bell crank  85  and an automatic actuator  87 . Buggy link assembly  83  includes a front buggy link  91 , a rear buggy link  93  pivotally coupled to front buggy link  91  at a pivot joint  95 , and a driving, upper mini link  97 . Driving link  97  has a first end pivotally coupled to bell crank  85  at pivot  111  and an opposite, second end pivotally coupled at joint  95 . A forward end of front buggy link  91  is rotatably coupled to rear side rail  31  and a rearmost end of rear buggy link  93  is rotatably coupled to number five roof bow  45 . Bell crank  85  has a generally V-shape and is further attached to a set of flanges of rear side rail  31  at pivot  113 . 
   Actuator  87  includes a hydraulic fluid powered cylinder  101  within which is disposed a movable piston coupled to an elongated piston rod  103 . A ball receptacle  105  is affixed to an end of piston rod  103  for rotatable engagement journaled about a ball stud  107  which is mounted to arm of bell crank  85 . The opposite end of cylinder  101  is rotatably mounted within a pair of flanges  109  of rear side rail  31 . 
   Front and rear buggy links  91  and  93 , respectively, are located in an over-center and extended orientation when the convertible roof is fully raised and the number five roof bow is in its nominal position essentially at a belt line  121  of the vehicle where it is positioned on top of an exterior surface of a movable and rigid tonneau cover  123 . This orientation is best illustrated in  FIGS. 1 and 3 . Advancing of piston rod  103  relative to hydraulic cylinder  101  serves to rotate bell crank  85  toward number five roof bow  45  which, in turn, rotates and downwardly pulls driving link  97  in order to collapse buggy links  91  and  93  downward and away from their over-center condition. Accordingly, this actuation motion automatically rotates number five bow  45  in an upward direction toward a generally vertical and raised position as is shown in  FIGS. 4 and 5 . Tonneau cover  123  (see  FIG. 1 ) can simultaneously or subsequently be upwardly pivoted about a rear pivot axis, or alternately rearwardly slid above a trunk lid, to allow open access of the convertible roof for subsequent retraction and storage into the roof storage compartment. It is noteworthy that an elongated axis of actuator  87  is generally parallel to rear side rail  31  when the convertible top is fully raised and the number five bow is in its nominal position as shown in  FIG. 3 . This allows for more compact and aesthetically pleasing packaging of components, due in part, to the reduced size of the cylinder. 
   While the preferred embodiment of the convertible top stack mechanism has been disclosed, it should be appreciated that variations may be employed which fall within the scope of the present invention. For example, a movable trunk lid can be used in place of the disclosed tonneau cover. Furthermore, the top stack mechanism may be covered in whole or in part by multiple, substantially rigid, hard-top panel members in place of or in addition to a pliable cover, although all of the disclosed advantages may not be fully achieved. Moreover, additional linkages of varying shapes and locations may be employed with the present invention, although all of the disclosed advantages may not be fully achieved. It is also envisioned that electromagnetic devices can be used in place of the disclosed hydraulic actuator. Furthermore, the rearmost roof bow can be a number four, number six or other roof bow members depending upon the specific vehicle characteristics. While certain materials and shapes have been disclosed, it should be appreciated that various other shapes and materials and shapes can be employed. It is intended by the following claims to cover these and any other departures from the disclosed embodiments which fall within the true spirit of this invention.