Clock Spring Assembly With Rupture Pin for Overwind Detection
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Solution Overview
Problem
Existing clock springs in automobiles can be improperly mounted, leading to faulty electrical connections and potential airbag deployment due to ribbon cable damage when rotated in one direction, which may not trigger warning signals.
Innovation Solution
A clock spring assembly with a rupture pin on the ribbon cable that blocks further unwinding in the opposite direction, ensuring the ribbon cable is torn off to trigger a warning signal when improperly mounted, preventing conductor path damage and ensuring reliable electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the clock spring is mounted without centering alignment, then installation speed is improved, but the ribbon cable may be overwound causing conductor path damage and faulty electrical signals
Solution Approach 1:
The rupture pin is pre-positioned on the ribbon cable at a location that will engage with the slot if overwinding occurs. This preliminary arrangement allows the safety mechanism to automatically activate without requiring complex real-time monitoring systems, enabling fast installation while protecting against mounting errors.
Solution Approach 2:
The rupture pin acts as an intermediary element between the ribbon cable and the housing slot. It provides a simple mechanical interface that translates excessive rotation into a visible failure mode (ribbon cable rupture), thereby protecting the conductor paths without adding complexity to the installation process.
2Ease of operation
If the ribbon cable is allowed to unwind freely in both directions, then ease of operation is improved, but conductor paths may be damaged due to overwinding in one direction
Solution Approach 1:
The rupture pin and slot combination creates a preliminary protective barrier against overwinding damage. Before the conductor paths can be damaged by excessive rotation in one direction, the rupture pin engages the slot to prevent further unwinding, thereby preemptively blocking the harmful effect while allowing normal bidirectional operation.
Solution Approach 2:
The potential harm of overwinding is converted into a beneficial safety feature. When the rupture pin engages the slot, it transforms the harmful excessive rotation into a controlled failure mode that visibly indicates improper mounting, thereby preventing conductor path damage while maintaining ease of normal operation.
3Device complexity
If no mounting alignment feature is provided, then device complexity is reduced, but improper mounting cannot be detected leading to silent failures
Solution Approach 1:
The complex active alignment and detection systems are extracted and replaced with a simple passive mechanical indicator. The rupture pin-slot mechanism extracts the essential function of detecting improper mounting without requiring sensors, electronics, or complex mechanical alignment features, thereby reducing overall device complexity while improving detectability.
Data Source
AI summary
A clock spring assembly includes a stationary housing and a rotor. The stationary housing and the rotor cooperatively define a chamber that accommodates at least one flexible ribbon cable (501) that is wound in a first rotational direction onto the rotor and fixed at one end to the rotor and at the other end to the stationary housing. The flexible ribbon cable is wound around the rotor (601) and establishes an electrical connection between the rotor and the stationary housing. A rupture pin (502) is attached to the at least one ribbon cable. A slot (605) is provided in the housing and captures the rupture pin if the rotor is overwound in the second rotational direction opposite to the first rotational direction such that the rupture pin blocks the ribbon cable (501) from unwinding any further.