US Patent RE39774 Fan guard structure for additional supercharging function

A fan guard has a function of supercharging a fan in addition to supporting a rotor device is disclosed. The fan guard is to be mounted beside the rotor device for supporting the rotor device, and additionally, the fan guard interacts with an airflow generated by the revolution of the rotor blades to supercharge the fan. The fan guard essentially includes a main frame, and a set of guard blades radially arranged inside the main frame and fixed onto an inner surface of the main frame by each one end thereof. Each of the guard blades is preferred to have a shape similar to the shape of the rotor blades, and the set of guard blades can be arranged either upstream or downstream of the rotor blades.