Patent ID: 7404323

Claim:
A concentration detector for detecting a concentration of a liquid fuel in a container, the concentration detector comprising: a rotating means positioned underneath a level of a liquid fuel, having a rotational center, and being rotatable at an angle on an X-Y plane, the rotating means comprising: at least three floating objects connected with each other, each floating object has a specific gravity less than a specific gravity of the liquid fuel ρ, and the floating objects are balanced according to a torque equation, F(θ,ρ)=0, such that the rotating means is still under the level of the liquid fuel, wherein while a concentration of the liquid fuel is changed and the angle θ of the rotating means is detected, the specific gravity of the liquid fuel ρ is obtained from the torque equation, F(θ,ρ)=0, and thereby computing the concentration of the liquid fuel.