Make your search more relevant by using the following criteria-
AND A AND B -Search content which contain both A and B.
For Example: chocolate AND engine
OR A OR B -Search content which contain either A or B or both.
For Example: chocolate OR engine
! !A -Search content which does not contain A.
For Example: !chocolate
* A* -Search content which contain words starting with A.
For Example: choco* (returns "choco", "chocolate", "chocoholic"...)
? A? -Search for content which contain words starting with A and followed by a single character.
For Example: engine? (returns "engine", "engines", "engined")
~ A~ -Search for content with similar spelling for A.
For Example: roam~ (returns "roam", "roams", "foam")
~N "A B"~N -Search for content which contain A within N words of B.
For Example: "chocolate engine"~5 (returns "chocolate engine", "chocolate processing engine"...)
The following query terms may be used to search for a word or phrase within a specific patent field:
pn: -Publication Number
an: -Application Number
For Example: ttl:chocolate