Seat Belt Pretensioner Sealing With Ball-Driven Spool Retraction
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Solution Overview
Problem
Existing cable-driven seat belt pretensioners in vehicles suffer from gas leakage due to tolerances, reducing their effectiveness and releasing hot, pressurized gas into the vehicle environment during emergencies.
Innovation Solution
A push-type pretensioner system utilizing spherical-shaped power transmission members driven by a gas generator to rotate a spool, with a seal member to prevent gas leakage and a ratchet mechanism to ensure one-way rotation of the spool, enhancing occupant restraint performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cable-driven pretensioner mechanism is used, then the seat belt can be tensioned during emergency, but gas leaks due to tolerances reducing effectiveness and releasing hot pressurized gas into the vehicle environment
Solution Approach 1:
The patent extracts the harmful gas leakage issue by introducing a seal member that isolates the high-pressure gas within the pretensioner mechanism, preventing it from escaping into the vehicle environment. The seal member is positioned between the cable and the housing to block gas escape paths.
Solution Approach 2:
The seal member acts as an intermediary element between the high-pressure gas environment and the vehicle interior, blocking the harmful gas from reaching the passenger compartment while allowing the mechanical function to proceed.
2Reliability
If a cable-driven pretensioner mechanism is used, then the seat belt can be tensioned during emergency, but gas leaks reducing effectiveness
Solution Approach 1:
The patent extracts the harmful gas leakage issue by introducing a seal member that isolates the high-pressure gas within the pretensioner mechanism, preventing it from escaping into the vehicle environment. The seal member is positioned between the cable and the housing to block gas escape paths.
Solution Approach 2:
The seal member acts as an intermediary element between the high-pressure gas environment and the vehicle interior, blocking the harmful gas from reaching the passenger compartment while allowing the mechanical function to proceed.
3Object-generated harmful factors
If a push-type pretensioner with spherical members is used, then gas sealing is improved, but the mechanism complexity increases
Solution Approach 1:
The patent employs spherical power transmission members instead of traditional cable-pulley mechanisms. These spherical members travel along a curved ramp surface within the housing, converting linear gas pressure into rotational motion of the spool. The spherical geometry provides inherent rolling contact that improves gas sealing while maintaining mechanical efficiency.
Solution Approach 2:
The patent uses high-pressure gas generated during collision to directly drive the spherical members along the ramp, converting pneumatic energy into mechanical work for spool rotation. This pneumatic actuation eliminates the need for complex mechanical linkages while improving gas sealing through the enclosed chamber design.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively tensions the seat belt immediately upon impact, improving occupant restraint by preventing gas leakage and ensuring reliable operation during emergencies.
Implementation Method 1
a gas generator disposed at one end of the pretensioner pipe... a hot, high-pressure operating gas is supplied from the gas generator to the inside of the pretensioner pipe
Implementation Method 2
The operating gas forces a piston to slide along the inside of the pretensioner pipe
Implementation Method 3
the piston presses against one of the spherical shaped members forcing one or more of the spherical shaped members to engage teeth of a drive wheel thereby rotating the spool
Implementation Method 4
The seal member is located between the at least one power transmission element and the gas generator
Implementation Method 5
A ratchet ring is disposed adjacent to the ball housing and connected to the spool... The ratchet ring is configured to engage the ball housing when the webbing is pulled in an engagement direction so that the spool is prevented from rotating
Data Source
AI summary
A seat belt pretensioner for a seat belt device in a vehicle, the pretensioner including a frame, a ball housing attached to the frame and a drive wheel located within the ball housing. A spool is connected to the drive wheel and is fixed to one end of a seat belt webbing so that the webbing may be wound around the spool. The pretensioner further includes a pipe connected to the ball housing and a gas generator connected to the pipe. At least one power transmission element is carried in the pipe and is driven by gas provided from the gas generator to contact the drive wheel and rotate the spool to retract the seat belt. A seal member is located between the at least one power transmission element and the gas generator. The seal member is sized to plug the pipe at an inlet to the ball housing.