1. Field of the Invention
The present invention relates to body panels suitable for use on motor vehicles, and more particularly to a tailgate for pickup trucks.
2. Discussion of Related Art
A tailgate as presently used in pickup trucks is a relatively heavy assembly, weighing about 50 pounds. The assembly is made from a number of stamped steel sheets that are joined together by resistance spot welding. Steel reinforcements are welded to the sheets, adding strength and rigidity at critical locations.
Pickup trucks are hard working vehicles wherein the tailgate is expected to perform reliably for many years. Pickup truck buyers demand that these closure panels be strong, reliable, and look good. Tailgates are expected to withstand people or heavy loads standing on them in an open position, as well as loads placed on a top edge when they are closed. They are also used to tie down payloads carried in the truck bed.
The tailgate needs to be as light as possible because many pickup truck users are small in stature. It is also desirable to reduce tailgate weight so that the truck's payload can be increased without sacrificing fuel economy. The presently available tailgates are heavy because they are made from steel. In addition, because they are assembled from many components, they are not as reliable, strong, or durable as desired. These steel panels are also subject to attack by moisture, road salt, and other chemical agents in the environment that are corrosive to steel and eventually detract from its structural integrity and appearance. Accordingly, there still remains a need to provide a lightweight, strong, durable panel for pickup truck tailgates that has minimal impact upon vehicle cost. It is also desirable to reduce tailgate weight in order to improve fuel efficiency and truck payload capacity.
In recent years, some vehicle body panels have been made from thermoplastic polymers. Such panels are lighter than steel. However, they generally provide reduced strength and rigidity compared with steel panels.
Some issued patents disclosing pickup truck tailgates include U.S. Pat. Nos. 4,861,093; 4,939,828; 5,328,225; 5,425,564; and 5,678,876. Although prior art pickup truck tailgates generally perform adequately, tailgates made from steel sheets detract from fuel economy and are cumbersome to lift manually because of their large weight. Accordingly, there still remains a need to provide a tailgate for pickup trucks that is light, has adequate strength and rigidity, and is an economical replacement for steel.
A principal objective of the present invention is to provide a tailgate assembly suitable for pickup trucks that is lighter than conventional tailgates made from sheet steel.
A related objective of the invention is to provide a tailgate assembly made from aluminum alloy and plastic components.
A further objective of our invention is to provide a tailgate assembly that can be manufactured economically.
These and other objectives and advantages of our invention will become readily apparent to persons skilled in the art from the following description of a particularly preferred embodiment.