Valve actuator

1. A valve actuator comprising:

a housing comprising an upper plate and a lower plate that are spaced apart from each other in a vertical direction;

a motor disposed at the housing, the motor having a motor shaft;

a driving gear coupled to the motor shaft of the motor;

a transmission gear that is in contact with the driving gear, the transmission gear being configured to, based on rotation of the driving gear, rotate according to a predetermined gear ratio to the driving gear;

an output shaft comprising a main body and a plurality of protrusions, the plurality of protrusion radially protruding from the main body and being spaced apart from each other in a circumferential direction of the main body;

an output gear that is coupled to the output shaft and in contact with the transmission gear;

a stopper disposed in the housing and configured to limit a rotation angle of the output gear; and

an elastic member disposed between a lower portion of the plurality of protrusions and the lower plate of the housing, the elastic member being configured to push the main body and the plurality of protrusions through the upper plate of the housing to thereby release the output gear from the transmission gear based on the output shaft rotating by a predetermined angle,

wherein the upper plate of the housing defines:

a first hole configured to receive the main body in the vertical direction based on the output shaft rotating by the predetermined angle, and

a plurality of second holes that extend in a radial direction from the first hole and are configured to receive the plurality of protrusions in the vertical direction based on the output shaft rotating by the predetermined angle.

2. The valve actuator of claim 1 , wherein the plurality of protrusions include a first protrusion and a second protrusion that are spaced apart from each other in the circumferential direction and arranged about a center of the main body such that a first separation space and a second separation space are defined between the first protrusion and the second protrusion,

wherein each of the first protrusion and the second protrusion extends in the circumferential direction and has a circumferential length that corresponds to 90 degrees about the center of the main body, and

wherein each of the first separation space and the second separation space has a circumferential length that corresponds to 90 degrees about the center of the main body.

3. The valve actuator of claim 2 , wherein a circumferential length of each of the plurality of second holes corresponds to 90 degrees about the center of the main body, and

wherein a circumferential length of the first hole between the plurality of second holes corresponds to 90 degrees about the center of the main body.

4. The valve actuator of claim 1 , wherein the plurality of protrusions include a first protrusion, a second protrusion, a third protrusion, and a fourth protrusion that are spaced apart from one another in the circumferential direction and arranged about a center of the main body such that a first separation space, a second separation space, a third separation space, and a fourth separation space are defined between adjacent two protrusions among the first protrusion, the second protrusion, the third protrusion, and the fourth protrusion,

wherein each of the first protrusion, the second protrusion, the third protrusion, and the fourth protrusion extends in the circumferential direction and has a circumferential length corresponding to 45 degrees about the center of the main body, and

wherein each of the first separation space, the second separation space, the third separation space, and the fourth separation space has a circumferential length corresponding to 45 degrees about the center of the main body.

5. The valve actuator of claim 4 , wherein a circumferential length of each of the plurality of second holes is 135 degrees about the center of the main body, and

wherein a circumferential length of the first hole between the plurality of second holes corresponds to 45 degrees about the center of the main body.

6. The valve actuator of claim 1 , wherein the motor comprises a direct current (DC) motor.

7. The valve actuator of claim 1 , wherein the main body of the output shaft defines a groove at an upper end thereof.

8. The valve actuator of claim 1 , wherein at least a portion of upper ends of the plurality of protrusions has a tapered or curved shape.

9. The valve actuator of claim 1 , wherein the output gear has an upper region that is configured to contact the upper plate of the housing based on the output shaft rotating by the predetermined angle.

10. The valve actuator of claim 1 , wherein an upper end of the main body of the output shaft is disposed above an upper end of the plurality of protrusions.

11. A valve actuator comprising:

a housing comprising an upper plate and a lower plate that are spaced apart from each other in a vertical direction;

a motor disposed at the housing, the motor comprising a motor shaft;

a driving gear coupled to the motor shaft of the motor;

an output shaft comprising a main body and a plurality of protrusions, the plurality of protrusions radially protruding from the main body and being spaced apart from each other in a circumferential direction of the main body;

an output gear that is coupled to the output shaft and in contact with the driving gear;

a stopper disposed in the housing and configured to limit a rotation angle of the output gear; and

an elastic member disposed between a lower portion of the plurality of protrusions and the lower plate of the housing, the elastic member being configured to push the main body and the plurality of protrusions through the upper plate of the housing to thereby release the output gear from the driving gear based on the output shaft rotating by a predetermined angle,

wherein the upper plate of the housing defines:

a first hole configured to receive the main body in the vertical direction based on the output shaft rotating by the predetermined angle, and

a plurality of second holes that extend in a radial direction from the first hole and are configured to receive the plurality of protrusions based on the output shaft rotating by the predetermined angle.

12. The valve actuator of claim 11 , wherein the plurality of protrusions include a first protrusion and a second protrusion that are spaced apart from each other in the circumferential direction and arranged about a center of the main body such that a first separation space and a second separation space are defined between the first protrusion and the second protrusion,

wherein each of the first protrusion and the second protrusion extends in the circumferential direction and has a circumferential length that corresponds to 90 degrees about the center of the main body, and

wherein each of the first separation space and the second separation space has a circumferential length that corresponds to 90 degrees about the center of the main body.

13. The valve actuator of claim 12 , wherein a circumferential length of each of the plurality of second holes corresponds to 90 degrees about the center of the main body, and

wherein a circumferential length of the first hole between the plurality of second holes corresponds to 90 degrees about the center of the main body.

14. The valve actuator of claim 11 , wherein the plurality of protrusions include a first protrusion, a second protrusion, a third protrusion, and a fourth protrusion that are spaced apart from one another in the circumferential direction and arranged about a center of the main body such that a first separation space, a second separation space, a third separation space, and a fourth separation space are defined between adjacent two protrusions among the first protrusion, the second protrusion, the third protrusion, and the fourth protrusion,

wherein each of the first protrusion, the second protrusion, the third protrusion, and the fourth protrusion extends in the circumferential direction and has a circumferential length corresponding to 45 degrees about the center of the main body, and

wherein each of the first separation space, the second separation space, the third separation space, and the fourth separation space has a circumferential length corresponding to 45 degrees about the center of the main body.

15. The valve actuator of claim 14 , wherein a circumferential length of each of the plurality of second holes is 135 degrees about the center of the main body, and

wherein a circumferential length of the first hole between the plurality of second holes corresponds to 45 degrees about the center of the main body.

16. The valve actuator of claim 11 , wherein the motor comprises a direct current (DC) motor.

17. The valve actuator of claim 11 , wherein the main body of the output shaft defines a groove at an upper end thereof.

18. The valve actuator of claim 11 , wherein at least a portion of upper ends of the plurality of protrusions has a tapered or curved shape.

19. The valve actuator of claim 11 , wherein the output gear has an upper region that is configured to contact the upper plate of the housing based on the output shaft rotating by the predetermined angle.

20. The valve actuator of claim 11 , wherein an upper end of the main body of the output shaft is disposed above an upper end of the plurality of protrusions.