Abstract:

The electro-hydraulic servo mechanism bears external force and generates passive motion under the non-working condition after being installed into a launch vehicle. A thorough analysis of the motion characteristics of a servo mechanism under the action of external force in the non-working state is presented. The results show that the zero position characteristic of the servo valve and the sealing performance of the high-pressure loop of a servo mechanism are the main factors affecting the motion characteristics of the servo mechanism under the non-working condition. When the motion occurs under the action of external force, one side of the cylinder is often in the state of vacuum pumping. The servo valve with good zero position characteristics, and the servo mechanism with small leakage in the high-pressure loop will be in bidirectional immobility or unidirectional movability state under the action of external force. The validity of the conclusion is verified by the physical test of typical products.

Key words:  Electro-hydraulic servo mechanism, Electro-hydraulic servo valve, Thrust vector control, Launch vehicle, Kinematic analysis