Electric hydraulic actuator

An electric hydraulic actuator comprising:

• a motor providing a rotational force;
• a pump housing provided with a gear pump that converts the rotational force of the motor to a hydraulic pressure and thus forces a fluid to move and with a pilot check valve that changes a fluid flow path using the hydraulic pressure;
• a fluid tank disposed between the motor and the pump housing and providing a fluid storage space;
• a coupler extending through the fluid tank and connecting a rotary shaft of the motor and the gear pump to each other;
• a cylinder tube;
• a hollow rod disposed in the cylinder tube and connected to a piston so that a length of a portion of the cylinder tube exposed outside the cylinder tube varies according to a fluid supply path determined by operation of the gear pump;
• a cylinder housing coupled to one end of the cylinder tube and to the pump housing, the cylinder housing including two ports for transferring the fluid;
• and
• a return pipe having a first end coupled to the cylinder housing and a second end positioned within the hollow rod, thereby forming a flow path of the fluid between an internal space of the hollow rod and an internal space of the cylinder housing,
• wherein the two ports of the cylinder housing include a first port forming a flow path of the fluid supplied to a first side of the piston and a second port forming a flow path of the fluid returned to the return pipe, and
• the pump housing includes a third port corresponding to the first port and functioning to transfer the fluid to the gear pump and a fourth port corresponding to the second port and functioning to transfer the fluid to the gear pump.