Convertible roof bow control mechanism

A vehicle convertible roof including a rearmost roof member, a side roof rail, an actuator and a link having a length that varies between a first length and a second as the rearmost roof member moves between a nominal and raised position. The adjustable length link is fixed at the second length during retraction and extension of the side roof rail of the vehicle convertible roof.

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. Moreover, many of these traditional systems also disadvantageously push the backlite or rear window into the rear passenger area of the vehicle thereby limiting the usable passenger space during the raising and retracting of the convertible roof.

In accordance with the present invention, a vehicle convertible roof includes a rearmost roof member, a side roof rail, an actuator, and a link having a length that varies as the rearmost roof member is moved between a nominal and raised position. In another aspect of the present invention, a convertible vehicle top stack mechanism includes a number five roof bow, an actuator and an adjustable length link that varies in length as the number five roof bow moves between a nominal and raised position. In still another aspect of the present invention, a method of operating a convertible roof includes changing a length of a link coupled to the rearmost roof member during movement from a nominal position to a raised position and maintaining the link at a fixed length during movement of a roof rail from a raised position to a retracted position.

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 movement of the convertible roof that limits the intrusion of the backlite into the passenger space during the retraction and raising operation thereby reducing the operating envelope of the convertible roof. Accordingly, the present invention reduces part failure during usage, is easier to control, and requires a smaller operating space. 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.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiment of a convertible roof21attached to an automotive vehicle body23of the present invention is shown inFIG. 1. Only one side of convertible roof21will be discussed herein since the other side is essentially a mirrored image of the one discussed and illustrated. Convertible roof21includes a top stack mechanism25which is covered by a pliable or flexible fabric cover27which has a solid glass back window or backlite29, or alternately a flexible PVC window, attached thereto.

Referring toFIGS. 2A–5B, top stack mechanism25includes a rear side rail31, a center side rail33and a front side rail35. A forwardmost or number one roof bow37is attached to front side rail35, a number two roof bow39is pivotally coupled to center side rail33, a number three roof bow41is pivotally coupled to rear side rail31and a number four roof bow43is also pivotally coupled to rear side rail31. A rearmost or number five roof bow45is pivotally coupled at a pivot51to a double clevis portion49of rear side rail31. Alternatively, number five roof bow45can include a mounting bracket (not shown) affixed thereto, thereby forming an assembly, which is pivotally coupled to double clevis portion49at pivot51. Top stack mechanism25also includes various additional links and linkage assemblies53and54, and a primary top stack actuator55, such as a hydraulic cylinder or alternately, an electric motor or rotary actuator. Primary actuator55moves convertible roof21between a fully raised and closed position covering a passenger compartment of the vehicle, as shown inFIGS. 1 and 2A, through intermediate positions, such as that shown inFIG. 4A, to a fully retracted and open position within a roof storage compartment or boot well, as shown inFIG. 5A.

A five bow actuation assembly81includes a buggy link assembly83, a bell crank85, an automatic actuator87, and an adjustable length link89. Link89can take a variety of forms as described below. Preferably, link89is in the form of an actuator having a varying length and operable to be locked at a given length, as described below. Buggy link assembly83includes a front buggy link91, a rear buggy link93pivotally coupled to front buggy link91at a pivot joint95, and a driving, upper mini link97. Driving link97has a first end pivotally coupled to bell crank85at pivot99and an opposite, second end pivotally coupled at joint95. A forward end of front buggy link91is rotatably coupled to rear side rail31and a rearmost end of rear buggy link93is rotatably coupled to number five roof bow45. Bell crank85has a generally V-shape and is further attached to a set of flanges of rear side rail31at pivot100.

Actuator87includes a hydraulic fluid powered cylinder101within which is disposed a movable piston coupled to an elongated piston rod103. A ball receptacle is affixed to an end of piston rod103for rotatable engagement journaled about a ball stud which is mounted to an arm of bell crank85. The opposite end of cylinder101is rotatably mounted within a pair of flanges of rear side rail31.

One end of adjustable length link89is rotatably coupled to a bracket105that is fixedly attached to vehicle body23. An opposite end of link89is rotatably coupled to a front offset portion107of number five roof bow45. The length of link89will vary between a first length L1when number five roof bow45is in its nominal position, as shown inFIGS. 2A and 2B, to a second elongated length L2when number five roof bow45is in its raised position, as shown inFIGS. 3A and 3B. Link89maintains second length L2during retraction and extension of top stack mechanism25, as shown inFIGS. 4Aand B and5A and B. Link89can take a variety of forms, as mentioned above. Preferably, link89is an actuator109that is adjustable between lengths L1and L2and lockable at length L2. Furthermore, the actuator109can be passive between lengths L1 and L2and lockable at length L2or actively driven between lengths L1and L2and locked at length L2. For example, link89/actuator109can include a hydraulic fluid-powered cylinder111within which is disposed a movable piston coupled to an elongated piston rod113. A ball receptacle115is affixed to an end of piston rod113for rotatable engagement journaled about a ball stud which is mounted to offset portion107of number five roof bow45. The opposite end of cylinder111is rotatably mounted to bracket105.

Front and rear buggy links91and93, 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 line121(FIG. 1) of the vehicle where it is positioned on top of an exterior surface of a movable and rigid tonneau cover123. This orientation is best illustrated inFIGS. 1 and 2. Advancing of piston rod103relative to hydraulic cylinder101serves to rotate bell crank85toward number five roof bow45which, in turn, rotates and downwardly pulls driving link97in order to collapse buggy links91and93downward and away from their over-center condition and into an under-center position. Accordingly, this actuation motion automatically rotates number five roof bow45in an upward direction toward a generally vertical and raised position, as is shown inFIG. 3. Preferably, number five roof bow45is moved between 800–1000 relative to belt line121. Even more preferably, number five roof bow45is moved to a raised position that is substantially vertical.

During the movement of number five roof bow45from the nominal position to the raised position, link89/actuator109can be passive or active. Preferably, actuator109is active during this process and is driven from length L1to length L2simultaneously with the advancing of piston rod103relative to hydraulic cylinder101. The driving of actuators87,109is coordinated to provide a controlled movement of number five roof bow45from the nominal position to the raised position. Alternatively, when actuator109is passive, the movement of number five roof bow45from the nominal position to the raised position pulls on actuator109and causes actuator109to extend from length L1to length L2. When actuator109is passively operating, hydraulic fluid is free to flow into and out of cylinder111as rod113is moved relative to cylinder111. Regardless of actuator109being actively or passively driven, actuator109is locked or fixed at length L2for subsequent retraction of top stack mechanism25, as described below. To lock actuator109at length L2, the flow of hydraulic fluid into and out of cylinder111is prevented, such as by closing valves, so that rod113is fixed in position relative to cylinder111. Actuator109remains fixed at length L2during subsequent movement of top stack mechanism25between the extended and retracted positions, as shown inFIGS. 3Aand B,4A and B, and5A and B.

Simultaneously with or subsequently to the moving of number five roof bow45from the nominal position to the raised position, tonneau cover123(seeFIG. 1) can 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 actuator87is generally parallel to rear side rail31when the convertible top is fully raised and the number five bow is in its nominal position as shown inFIG. 2A. This allows for more compact and aesthetically pleasing packaging of components, due in part, to the reduced size of the cylinder. It is also noteworthy that number five roof bow45is substantially vertically oriented when in the raised position, as shown inFIG. 3A, as this position limits the intrusion of backlite29into the passenger compartment of the vehicle.

Primary actuator55is operated to cause top stack mechanism25to move from the raised position, shown inFIG. 3A, through intermediate positions, such as that shown inFIG. 4A, to the fully retracted position, as shown inFIG. 5A. During this movement, link89/actuator109remains fixed at length L2which causes number five roof bow45to approach rear side rail31, thereby providing for compact storage of convertible roof21within the roof storage compartment. Additionally, the length of actuator87is passively changed as number five roof bow45approaches rear side rail31. Tonneau cover123can then be moved to its closed position to cover an entirety or a portion of top stack mechanism25within the roof storage compartment.

To move convertible roof21from the stowed position to the raised position, tonneau cover123is moved to an open position and primary actuator55is operated to cause top stack mechanism25to move to the raised position shown inFIG. 3A. Actuator109is released from being fixed at length L2and can be either actively or passively driven back to length L1. When actively driven, actuators87and109operate in conjunction with one another to cause number five roof bow45to move from the raised position to the nominal position shown inFIGS. 2Aand B. When passively driven, actuator87is operated to cause number five roof bow45to move from the raised position to the nominal position, which imparts a compressive force on actuator109and causes rod113to retract into cylinder111. Front and rear buggy links91and93, respectively, move into an over-center and extended orientation thereby securing number five roof bow45in the nominal position. Tonneau cover123prior to or simultaneously with the movement of number five roof bow45from the raised position to the nominal position is moved from the open position to the closed position.

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, actuator109can take other forms. Actuator109can comprise a jack screw and drive nut having a length that varies based upon relative rotation between the jack screw and the drive nut. Another possible form of actuator109is a magneto-rheological damper wherein a magneto-rheological fluid is disposed within a cylinder within which is disposed a movable piston coupled to an elongated piston rod. The piston rod can move relative to the cylinder while allowing the fluid to flow through openings in the piston and can be locked in place by applying an electric field thereby causing the viscosity of the rheological fluid to increase and essentially fix the piston rod relative to the cylinder. Another possible actuator109is a gas strut that is biased to length L1and is lockable at length L2. It should be appreciated that still other types of actuators operable between lengths L1and L2and capable of being locked at length L2can be employed. Additionally, 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.