Tether Release for Automotive Safety Device Actuation
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Solution Overview
Problem
Conventional initiators used in automotive safety devices, such as airbag assemblies, often produce gas and flames during actuation, which can be detrimental and cause the housing to burst open, compromising integrity and safety.
Innovation Solution
The development of flameless actuator assemblies that maintain integrity by using a tubular housing with a pyrotechnic material and a coolant to prevent burn-through, allowing for contained actuation without external ballistic events, and a tether release assembly to manage airbag deployment configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional initiators are used to actuate automotive safety devices, then the actuation function is achieved, but gas and flames are produced causing the housing to burst open and compromising integrity
Solution Approach 1:
The patent converts the harmful pyrotechnic combustion process into a beneficial contained pressure generation mechanism. The pyrotechnic material is enclosed within a cup that directs the combustion products to actuate the safety device without bursting the housing. The harmful flames and gas are contained and redirected to perform useful work (actuating the airbag or other safety device) while preventing external damage.
Solution Approach 2:
The cup acts as an intermediary component between the pyrotechnic material and the external environment. It contains the combustion process, directs the gas flow, and transmits the actuation force to the safety device mechanism. This intermediary structure prevents direct contact between the harmful combustion products and the housing, thereby maintaining integrity while achieving actuation.
2Reliability
If conventional initiators are used, then actuation function is achieved, but housing integrity is compromised due to burn-through
Solution Approach 1:
The patent converts the potentially harmful burn-through effect into a beneficial contained pressure actuation mechanism. The cup structure contains the combustion process and directs the force to actuate the safety device without compromising the housing. The heat and pressure that would normally cause burn-through are instead harnessed to reliably actuate the safety device through controlled mechanical action.
Solution Approach 2:
The cup serves as a protective intermediary between the pyrotechnic combustion process and the housing structure. It absorbs and contains the thermal and mechanical stresses, preventing direct transmission to the housing that would cause burn-through. The cup transmits only the necessary actuation force to the safety device mechanism while protecting the housing integrity.
3Reliability
If pyrotechnic material is contained with a cup and coolant, then housing integrity is maintained, but actuation time may increase
Solution Approach 1:
The patent modifies the combustion parameters by introducing a coolant that controls the burning rate and temperature of the pyrotechnic material. The coolant regulates the combustion process to maintain optimal pressure generation while preventing excessive heat that would compromise the housing. This parameter control ensures both integrity maintenance and efficient actuation timing.
Solution Approach 2:
The coolant undergoes phase transition (e.g., from liquid to vapor) during the combustion process, absorbing heat and regulating the temperature of the pyrotechnic material. This phase change helps control the combustion rate and pressure generation, ensuring that the actuation occurs within the required time frame while maintaining housing integrity through thermal management.
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 actuator assemblies ensure safe and reliable deployment of airbags by maintaining housing integrity and reducing actuation time, while the tether release mechanism allows for controlled deployment configurations, enhancing occupant safety in collision scenarios.
Implementation Method 1
a pyrotechnic material to produce gas
Implementation Method 2
using a tubular housing with a pyrotechnic material and a coolant to prevent burn-through
Data Source
AI summary
An actuator assembly that includes an actuator device. The actuator device includes a tubular housing with a first end and a second end, the tubular housing defining a storage chamber containing a pyrotechnic material to produce gas. At least one electrical connection is coupled to the first end, the electrical connection in reaction initiating communication with the pyrotechnic material. An actuator housing that partially encompasses the tubular housing, wherein an outer surface of the actuator housing comprises a hexagon shaped portion that extends along a longitudinal direction of the actuator housing. An assembly housing at least partially encompasses the actuator device, wherein an inner surface of the assembly housing comprises an engaging surface portion that extends along a longitudinal direction of the assembly housing that corresponds to and slidably engages with the hexagon shaped portion of the actuator housing.