| 摘要 |
A gas-pressure actuator apparatus having a rotary actuator serving as a driving source for a pretensioner of a seatbelt system, and a gas generator for supplying a working gas to the actuator. The rotary actuator includes a cylinder block and a rotary piston. The cylinder block has a cylinder chamber, a preliminary chamber formed adjacent to the cylinder chamber, and a communicating hole for providing communication between the cylinder and preliminary chambers. The gas generator is attached to the cylinder block in such a manner that a gas outlet for releasing the generated gas opens into the preliminary chamber. The preliminary chamber functions as a gas pressure buffer space for the cylinder chamber and also serves as a capacity element as follows: In the early stage of the rotary piston operation where the volumetric capacity of the pressurizing chamber defined in the cylinder chamber is extremely small, the preliminary chamber lowers the gas pressure applied to the rotary piston. On the other hand, in a state where the volumetric capacity of the pressurizing chamber has become large at the end of the rotary piston operation, the preliminary chamber raises the gas pressure applied to the rotary piston. |
