Seatbelt Tensioner Piston Guide Section Diameter
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Solution Overview
Problem
Existing seatbelt tensioners experience uneven force transmission to the tensioner drive wheel, particularly after long periods and with temperature fluctuations, due to radial deformation of the piston during installation.
Innovation Solution
A seatbelt tensioner design with a pipe having a receiving section and a guide section, where the second inner diameter of the guide section is smaller than the first inner diameter and the initial-state outer diameter of the piston, minimizing plastic deformation and ensuring reliable sealing and even force transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the piston is pressed into the receiving section during installation to seal against the inner surface, then sealing is achieved, but radial deformation occurs causing uneven force transmission
Solution Approach 1:
The pipe is divided into two functional sections: a receiving section with a first inner diameter for installation, and a guide section with a second inner diameter for operation. This segmentation allows the piston to be installed without excessive deformation while ensuring proper sealing during operation.
Solution Approach 2:
Different sections of the pipe have different inner diameters optimized for different functions. The receiving section has a larger diameter to facilitate installation with minimal deformation, while the guide section has a smaller diameter to ensure tight sealing during operation.
2Reliability
If the piston outer diameter is made larger than the first inner diameter for sealing, then sealing is improved, but plastic deformation increases causing uneven force transmission
Solution Approach 1:
The pipe is divided into two functional sections: a receiving section with a first inner diameter for installation, and a guide section with a second inner diameter for operation. This segmentation allows the piston to be installed without excessive deformation while ensuring proper sealing during operation.
Solution Approach 2:
The inner diameter parameter of the pipe is changed along its length, with the receiving section having a larger diameter and the guide section having a smaller diameter. This parameter change allows the piston to maintain its shape during installation while achieving tight sealing during operation.
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 design ensures uniform force transmission to the tensioner drive wheel, preventing gas escape and maintaining sealing, thus enhancing the reliability and efficiency of the seatbelt tensioning process.
Implementation Method 1
the at least one mass body is drivable by the pressure generable by the gas generator and acting on the piston arranged between the gas generator and a mass body
Implementation Method 2
the piston is pressed into the receiving section of the pipe, thus radially deforming the piston both elastically and plastically
Implementation Method 3
the piston bears in the guide section more reliably against the inner wall of the pipe
Data Source
AI summary
A seatbelt tensioner for a seat belt retractor, having a pipe (1) with a tensioner drive wheel, a gas generator (10), a piston (3), and at least one mass body (4). The mass body (4) is drivable by gas from the gas generator (10) acting on the piston (3) between the gas generator (10) and a mass body (4). The mass body drives the tensioner drive wheel. The pipe (1) has a receiving section (5) with a first inner diameter (2), in which the piston (3) in its initial state is arranged with an initial-state outer diameter (8). The pipe (1) has a guide section (6) which adjoins the receiving section (5) and which has a second inner diameter (7). The second inner diameter (7) is smaller than the first inner diameter (2) and smaller than the initial-state outer diameter (8) of the piston (3).