There is a lot of information on the Intenet- a basic search on African American Inventors will yield great results with most search engines - while it is true that many of us do not hold patents, there is still a lot of data out there. There are two that we use with our Delta Academy on a regular basis:
www.inventorsmuseum.com/africanam.htm and
www.inventions-express.com
You might also want to check with a local college or university, especially if they have a minority engineering or science office. Those staff people tend to be advocates for the field and have tons of info.
Good Luck!