Propeller guard and unmanned aerial vehicle

1. A propeller guard for an unmanned aerial vehicle including a main body part and a propeller part, the propeller guard comprising:

an encircling part that extends around the propeller part and protects the propeller part; and

a connection part that connects the main body part and the encircling part,

wherein:

the encircling part has a buoyant force for maintaining at least a part of the main body part and the propeller part above water,

the connection part has a raising and lowering mechanism, and

the raising and lowering mechanism moves the encircling part to a first position where the encircling part externally surrounds at least a part of the propeller part when the unmanned aerial vehicle is in flight and lowers the encircling part from the first position to a second position where at least a part of the main body part and the propeller part is maintainable above water when the unmanned aerial vehicle lands on water.

2. The propeller guard according to claim 1 , wherein;

the encircling part includes a material having a specific gravity less than that of water.

3. The propeller guard according to claim 1 , wherein;

the raising and lowering mechanism includes a telescopic mechanism.

4. The propeller guard according to claim 1 , wherein;

the raising and lowering mechanism includes a chain.

5. The propeller guard according to claim 1 , wherein:

the encircling part extends from a height of the propeller part to at least a height of a bottom surface of the main body part of the unmanned aerial vehicle.

6. An unmanned aerial vehicle comprising:

a propeller guard according to claim 1 ; and

a water landing sensor that is disposed on a lower portion of the main body part and detects that the main body part comes into contact with a water surface.

7. The unmanned aerial vehicle according to claim 6 , wherein;

the water landing sensor performs a detection by detecting electrical conduction in water.

8. A vehicle, comprising:

a main body;

a propeller; and

a propeller guard including:

an encircling structure that extends around the propeller and protects the propeller;

a connection that connects the main body and the encircling structure; and

an actuator to raise and lower the encircling structure,

wherein:

the encircling structure has a buoyant force for maintaining at least a part of the main body and the propeller above water, and

the actuator moves the encircling structure to a first position where the encircling structure externally surrounds at least a part of the propeller when the vehicle is in flight and lowers the encircling structure from the first position to a second position where at least a part of the main body and the propeller is maintainable above water when the vehicle lands on water.

9. The vehicle according to claim 8 , wherein:

the encircling structure includes a material having a specific gravity less than that of water.

10. The vehicle according to claim 8 , further comprising:

a telescopic support connected to the actuator and the encircling structure which telescopes when the actuator moves.

11. The vehicle according to claim 8 , further comprising:

a chain connected to the actuator.

12. The vehicle according to claim 8 , wherein:

the encircling structure extends from a height of the propeller to at least a height of a bottom surface of the main body of the aerial vehicle.

13. The vehicle according to claim 8 , further comprising:

a propeller guard according to claim 1 ; and

a water landing sensor that is disposed on a lower portion of the main body and detects that the main body comes into contact with a water surface.

14. The vehicle according to claim 13 , wherein:

the water landing sensor performs a detection by detecting electrical conduction in water.