Safety Belt Retractor Two-Spring Comfort Switching
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Solution Overview
Problem
Existing seat belt retractors with a 2-spring comfort function experience high forces during switching over, leading to discomfort, as the comfort spring is suddenly wound onto a block, and the functionality of one spring is dependent on the other, requiring both to provide the entire retraction force.
Innovation Solution
The solution involves independent operation of each return spring, with one spring acting constantly between the belt shaft and housing, and the other providing additional force when needed, using a switching device with a movable blocking part controlled by a linearly displaceable switching part to connect or disconnect the springs from the spool or housing, allowing for parallel operation and reduced forces during switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the comfort spring is suddenly wound onto a block during switching, then the retraction force is increased, but high forces act on the comfort spring and ratchet wheel causing discomfort
Solution Approach 1:
The patent applies the dynamics principle by making the connection between the coupling part and spool movable rather than fixed. The blocking part can pivot between blocking and non-blocking positions, allowing the system to dynamically transition between different spring configurations. This dynamic switching eliminates sudden force changes during the transition from one spring to another, as the springs can act in parallel during the switching process rather than requiring an abrupt transfer of load.
2Adaptability or versatility
If two return springs with different spring forces are used in series, then the 2-spring comfort function is achieved, but the functionality of one spring is dependent on the other
Solution Approach 1:
The patent applies segmentation by dividing the spring system into two independently connectable return springs (first and second return springs) that can be connected to the spool or housing through the coupling part and blocking part. This segmentation allows each spring to function independently - the first return spring can provide basic retraction force while the second return spring provides additional force when needed, without requiring the other spring to be functional. The blocking part enables selective engagement of each spring independently.
3Ease of operation
If the blocking part is used to connect the coupling part to the spool, then the switching function is achieved, but the structure becomes more complex
Solution Approach 1:
The patent applies merging by combining multiple functions into the blocking part: it serves as both the switching mechanism (blocking part) and the connector between the coupling part and spool. The blocking part integrates the switching function (pivoting between blocking and non-blocking positions) with the mechanical connection function, eliminating the need for separate switching and connection components. This integration simplifies the overall structure while maintaining the required switching functionality.
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 design eliminates sudden force changes, allows for adaptable spring characteristics, and reduces production costs by using identical springs, resulting in a more comfortable and efficient seat belt retraction mechanism with reduced installation space.
Implementation Method 1
one of the return springs (6) acts in parallel and is held with a first outer end (15) on a web (20) of a cover (5) and with a second inner end (19) in a rotationally fixed manner on a driving sleeve (12), so that the first return spring (6) acts practically constantly between the cover (5) and the driving sleeve (12)
Implementation Method 2
a second return spring (7) acts in parallel and is held with a first outer end (16) in a tension-resistant manner on an attachment of the housing (4) and with a second inner end (17) on a coupling part (8), whose connection to the spool (2) can be switched by a blocking part (11)
Implementation Method 3
the connection of the coupling part (8) to the spool (2) can be switched by a blocking part (11), whose pivoting movement can be controlled by a switching device (33)
Implementation Method 4
the swash plate (9) with external toothing (36), which can be recognized by internal toothing (35) in the receptacle (45), is rotatably mounted on an eccentric (42)
Data Source
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AI summary
The invention relates to a safety belt retractor that has a two-spring comfort function, comprising a belt shaft (2) which is rotatably mounted in a housing (1) and on which a safety belt can be wound, and at least two return springs (6, 7) that are spring-loaded in the winding direction of said safety belt and act between the housing (1) and the belt shaft (2), said return springs (6, 7) being arranged to act in parallel between the belt shaft (2) and the housing (1), and at least one of the return springs (6, 7) being able to be connected, by one end (15, 16, 17, 19), to the belt shaft (2) or the housing (1) by means of a shift device (33) that shifts as a function of the extraction length of said safety belt.