Pretensioner Clutch Plate Axial Offset Prevention
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Solution Overview
Problem
Existing pretensioner devices for vehicle occupant restraint systems face issues with positional offset of the clutch plate with respect to the rotating body, which can lead to ineffective engagement and potential interference during rapid deceleration events.
Innovation Solution
The design incorporates a clutch plate with meshing claws that deform and engage with the rotating body's engaging teeth, featuring first and second projections to restrict movement and ensure proper alignment, preventing positional offset and ensuring reliable engagement during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the clutch plate is supported by the pinion with meshing claws fitting into valley portions of engaging teeth, then the clutch mechanism can be compact and simple, but the clutch plate may become offset from the pinion under external force
Solution Approach 1:
The patent applies preliminary action by pre-positioning the clutch plate at a predetermined position relative to the pinion using protrusions and recesses. The clutch plate has a first protrusion that fits into a first recess on the pinion, and a second protrusion that fits into a second recess, establishing the correct alignment before operation. This preliminary positioning prevents offset during subsequent operation while maintaining a compact structure.
2Reliability
If the meshing claws are allowed to deform outwardly to engage the cylindrical portion, then the clutch can connect reliably during rapid deceleration, but the clutch plate may move axially with respect to the pinion
Solution Approach 1:
The patent establishes preliminary action by pre-positioning the clutch plate at a predetermined position relative to the pinion using protrusions and recesses. The clutch plate has a first protrusion that fits into a first recess on the pinion, and a second protrusion that fits into a second recess, establishing the correct alignment before operation. This preliminary positioning prevents offset during subsequent operation while maintaining a compact structure.
Solution Approach 2:
The patent applies local quality by providing different functional features at different locations on the clutch plate and pinion. The meshing claws have localized protrusions that engage with corresponding recesses on the pinion to prevent axial movement, while other portions of the clutch plate are designed to deform outwardly for radial engagement with the cylindrical portion. This localized differentiation allows simultaneous achievement of positional stability and engagement reliability.
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
This configuration effectively prevents positional offset of the clutch plate, ensuring reliable rotation of the take-up shaft and webbing tensioning, even under external forces, thereby maintaining the integrity of the pretensioning mechanism.
Implementation Method 1
a piston (74) provided at one side in the axial direction of the cylindrical portion (62), and moving due to operation of a gas generating means (70) at a predetermined time
Implementation Method 2
when the rotating body rotates relatively in the webbing take-up direction, the plurality of meshing claws are guided by the plurality of engaging teeth, and deform outwardly, and engage an inner peripheral surface of the cylindrical portion
Implementation Method 3
the engaging teeth of the rotating body have first projections (118) which project-out in a peripheral direction of the rotating body, the meshing claws of the clutch plate have second projections (130) which project-out in the peripheral direction of the rotating body... due to the second projections engaging with the first projections, movement of the clutch plate in an axial direction with respect to the rotating body is restricted
Implementation Method 4
a take-up shaft (18) at which a webbing (20) for restraining a vehicle occupant is taken-up and pulled-out
Data Source
AI summary
In a pretensioner device, engaging teeth of a pinion (rotating body) have first projections which project-out toward the other side in the peripheral direction of a cam portion. Meshing claws of a clutch plate have second projections which project-out toward a one side in the peripheral direction of the cam portion, and whose gear portion side end surfaces face the first projections. In a state before operation of the pretensioner device, movement of the clutch plate toward one side in the axial direction with respect to the pinion is restricted due to the second projections engaging with the first projections. Accordingly, in the pretensioner device, in the state before operation, even if some type of external force is applied to the clutch plate, positional offset of the clutch plate toward the one side in the axial direction with respect to the pinion can be prevented.