Pretensioner with gas escape mechanism

A pretensioner for rotating the take-up shaft of a seatbelt in the take-up direction in the event of an emergency to provide the belt with pretension, said pretensioner comprising:

• a gas generator;
• a driving member moved by the gas generated by the gas generator;
• a path for storing and guiding the driving member;
• a channel for guiding said gas to said path;
• a mechanical connection for converting the motion of the driving member into force for rotating said take-up shaft;
• and
• a gas bypass mechanism for discharging said gas out from said channel in the event that internal pressure exceeding a certain pressure is applied to said channel, including a hole provided to the side wall of said channel and a sleeve having a protrusion protruding into said hole disposed within said channel.

A pretensioner for rotating the take-up shaft of a seatbelt in the take-up direction in the event of an emergency to provide the belt with pretension, said pretensioner comprising:

• a gas generator;
• a driving member moved by the gas generated by the gas generator;
• a path for storing and guiding the driving member;
• a channel for guiding said gas to said path;
• a mechanical connection for converting the motion of the driving member into force for rotating said take-up shaft;
• and
• a gas bypass mechanism for discharging said gas out from said channel in the event that internal pressure exceeding a certain pressure is applied to said channel, including a tear line that tears in the event that said certain pressure is exceeded.

A pretensioner for rotating the take-up shaft of a seatbelt in the take-up direction in the event of an emergency to provide the belt with pretension, said pretensioner comprising:

• a gas generator;
• a driving member moved by the gas generated by the gas generator;
• a path for storing and guiding the driving member;
• a channel for guiding said gas to said path;
• a mechanical connection for converting the motion of the driving member into force for rotating said take-up shaft;
• and
• a gas bypass mechanism for discharging said gas out from said channel in the event that internal pressure exceeding a certain pressure is applied to said channel, including a keeper for fixing said gas generator at the end portion of said channel and configured such that a gap is created between said keeper and channel in the event that said certain pressure is exceeded, the keeper having a hole in a side wall normally covered by the surface of the gas generator.

A pretensioner for rotating the take-up shaft of a seatbelt in the take-up direction in the event of an emergency to provide the belt with pretension, said pretensioner comprising:

• a gas generator;
• a driving member moved by the gas generated by the gas generator;
• a path for storing and guiding the driving member;
• a channel for guiding said gas to said path;
• a mechanical connection for converting the motion of the driving member into force for rotating said take-up shaft;
• and
• a gas bypass mechanism for discharging said gas out from said channel in the event that internal pressure exceeding a certain pressure is applied to said channel;
• wherein said path is a channel and said driving member moves along the inner surface of said channel;
• and wherein a piston is further provided to the end of said driving member, and a small hole is opened in the side wall of the channel at the position where this piston passes in the initial stage of being moved;
• and wherein the diameter of said small hole is of a size which allows pressure necessary for normal operation to be maintained within the channel and also does not allow a pressure exceeding said certain pressure in the event that the movement of said piston is obstructed.