Patent ID: 7578121

Claim:
A thurst termination device for a rocket motor, which is constructed to close a plurality of thrust termination ports formed at a dome portion of a combustion tube mounted at the front of the rocket motor to communicate with a combustion chamber of the rocket motor in a sealing structure at a normal thrust state, and to open them respectively when a command of thrust termination is performed, wherein the thrust termination device comprises: a main cylinder opened at one end and supported by the thrust termination ports to close them, and formed with a vent opening at a bottom thereof; a primary piston inserted into the vent opening from the inside of the main cylinder, and transmitted with the pressure in the combustion chamber; a secondary piston mounted around the primary piston in the inside of the main cylinder, and transmitted with the pressure in the combustion chamber through the vent opening by the movement of the primary piston due to the pressure in the combustion chamber; a pressure load transmitting device mounted around a front end of the secondary piston and engaged with the secondary piston; a restriction pin for penetrating through the pressure load transmitting device, and the primary/secondary pistons to restrict them, and having a drawing wire connected at one end thereof and pulled to relieve the restriction state of them, when the command of thrust termination is performed; and a cross plate mounted at the front of the pressure load transmitting device and the main cylinder, and engaged with an inner peripheral surface of the thrust termination port at the edge thereof to restrict the pressure load transmitting device and the main cylinder.