Underwater actuator and underwater vehicle including the same

1. An underwater actuator comprising:

a housing configured to be immersed under water;

a cylinder chamber formed in the housing;

a piston disposed in the cylinder chamber such that the piston is movable in a sliding manner in the cylinder chamber, the piston dividing the cylinder chamber into a first pressure receiving chamber and a second pressure receiving chamber;

a rod extending from the piston towards the first pressure receiving chamber, the rod penetrating the housing;

a release chamber formed in the housing, the release chamber having an internal pressure kept lower than a water pressure of an outside of the housing;

a first passage formed in the housing, the first passage transferring water from the outside of the housing to the second pressure receiving chamber;

a second passage formed in the housing, the second passage transferring water from the second pressure receiving chamber to the release chamber, wherein the first passage and the second passage include a shared passage shared at the second pressure receiving chamber;

a switching mechanism including:

a single spool;

a first switcher disposed in the first passage and configured to switch a communication state either to allow or to block a communication between the second pressure receiving chamber and the outside of the housing; and

a second switcher disposed in the second passage and configured to switch a communication state either to allow or to block a communication between the second pressure receiving chamber and the release chamber; and

a sliding chamber formed in the housing and connected to the second pressure receiving chamber via the shared passage, the single spool being configured to slide in the sliding chamber.

2. The underwater actuator according to claim 1 , wherein the shared passage includes a restricting mechanism.

3. An underwater actuator comprising:

a housing configured to be immersed under water;

a cylinder chamber formed in the housing;

a piston disposed in the cylinder chamber such that the piston is movable in a sliding manner in the cylinder chamber, the piston dividing the cylinder chamber into a first pressure receiving chamber and a second pressure receiving chamber;

a rod extending from the piston towards the first pressure receiving chamber, the rod penetrating the housing;

a release chamber formed in the housing, the release chamber having an internal pressure kept lower than a water pressure of an outside of the housing;

a first passage formed in the housing, the first passage transferring water from the outside of the housing to the second pressure receiving chamber;

a second passage formed in the housing, the second passage transferring water from the second pressure receiving chamber to the release chamber, wherein the first passage and the second passage include a shared passage shared at the second pressure receiving chamber; and

a switching mechanism including:

a single spool configured to slide in a sliding chamber;

a first switcher disposed in the first passage and configured to switch a communication state either to allow or to block a communication between the second pressure receiving chamber and the outside of the housing;

a second switcher disposed in the second passage and configured to switch a communication state either to allow or to block a communication between the second pressure receiving chamber and the release chamber; and

a third switcher configured to switch a communication state either to allow or to block a communication between the release chamber and the outside of the housing.

4. The underwater actuator according to claim 1 , wherein:

the spool is configured to move in the sliding chamber from a first end of the sliding chamber toward a second end of the sliding chamber such that a position of the spool shifts in a sequential order from a first position to a second position and to a third position,

when the spool is in the first position, the first switcher blocks communication between the second pressure receiving chamber and the outside of the housing, and the second switcher blocks communication between the second pressure receiving chamber and the release chamber,

when the spool moves from the first position to the second position, the first switcher allows communication between the second pressure receiving chamber and the outside of the housing, and the second switcher continues to block communication between the second pressure receiving chamber and the release chamber, and

when the spool moves from the second position to the third position, the first switcher blocks communication between the second pressure receiving chamber and the outside of the housing, and the second switcher allows communication between the second pressure receiving chamber and the release chamber.

5. An underwater vehicle comprising:

the underwater actuator according to claim 4 ; and

an electric actuator including a drive shaft configured to push the spool, wherein the spool is not coupled to the drive shaft.

6. The underwater actuator according to claim 1 , wherein

the switching mechanism further includes a third switcher configured to switch a communication state either to allow or to block a communication between the release chamber and the outside of the housing,

the spool is configured to move in the sliding chamber from a first end of the sliding chamber toward a second end of the sliding chamber such that a position of the spool shifts in sequential order from a first position to a second position, to a third position, and to a fourth position,

when the spool is in the first position, the first switcher blocks communication between the second pressure receiving chamber and the outside of the housing, the second switcher blocks communication between the second pressure receiving chamber and the release chamber, and the third switcher blocks communication between the release chamber and the outside of the housing,

when the spool moves from the first position to the second position, the first switcher allows communication between the second pressure receiving chamber the outside of the housing, the second switcher continues to block communication between the second pressure receiving chamber and the release chamber, and the third switcher continues to block communication between the release chamber and the outside of the housing,

when the spool moves from the second position to the third position, the first switcher blocks communication between the second pressure receiving chamber and the outside of the housing, the second switcher allows communication between the second pressure receiving chamber and the release chamber, and the third switcher continues to block communication between the release chamber and the outside of the housing, and

when the spool moves from the third position to the fourth position, the first switcher continues to block communication between the second pressure receiving chamber and the outside of the housing, the second switcher blocks communication between the second pressure receiving chamber and the release chamber, and the third switcher allows communication between the release chamber and the outside of the housing.

7. The underwater actuator according to claim 1 , wherein

a compressible fluid is encapsulated in the first pressure receiving chamber,

the cylinder chamber includes:

a movement region, in which the piston is configured to move between a rod-expanded position and a rod-retreated position, the movement region forming the second pressure receiving chamber and a part of the first pressure receiving chamber; and

an auxiliary region, into which the compressible fluid of the movement region flows when the piston moves from the rod-retreated position to the rod-expanded position, the auxiliary region forming a remaining part of the first pressure receiving chamber, and

a pressure in the auxiliary region is lower than the water pressure of the outside of the housing when the piston moves from the rod-retreated position to the rod-expanded position.

8. The underwater actuator according to claim 1 , wherein

the piston moves between a rod-expanded position and a rod-retreated position, and

cushioning that contacts with the piston when the piston is in the rod-expanded position or cushioning that contacts with the piston when the piston is in the rod-retreated position is provided in the cylinder chamber.

9. An underwater vehicle comprising:

the underwater actuator according to claim 1 ; and

a drive device configured to move the spool in the sliding manner.