Searching for patents is not always easy, but Google Patents does what it can to help.
What is Google Patents (patents.google.com)?
Google Patents includes a million + patents from 100+ patent offices around the world. Results may also include technical documents, books indexed in Google Books and Google Scholar as well as documents from the Prior Art Archive.
(What is Prior Art? It's any evidence that your invention is already known. Source and more: EPO.org)