Disc Inflator Gas Cooling Offset Ejection
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Solution Overview
Problem
Conventional disc inflators face challenges in reducing size and weight while maintaining gas cooling and mist removal functions, as they require additional parts like gas flow path forming members, leading to increased size and weight.
Innovation Solution
The design incorporates a gas flow path within the inflator case and a holding member, with a gas ejection hole offset from the combustion chamber's central position, and a separation wall with communication holes to promote heat exchange and mist removal without using a filter, allowing for compact and lightweight construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a coolant filter is disposed at an inner peripheral portion of the upper case to remove combustion residue and cool gas, then gas cooling and mist removal functions are improved, but the inflator increases in radial size and weight
Solution Approach 1:
The invention extracts and eliminates the coolant filter component from the inflator structure. Instead of using a separate filter component, the patent utilizes the inner peripheral surface of the upper case itself as the cooling and mist removal surface, thereby removing the need for additional parts and reducing overall weight.
Solution Approach 2:
The upper case serves multiple functions: it contains the combustion chamber, provides structural support, and acts as a cooling surface for gas and mist removal. By making the upper case multi-functional, the invention eliminates the need for separate coolant filter components, reducing both weight and radial size.
2Temperature
If a gas flow path forming member is disposed concentrically to form an L-shaped gas flow path for cooling gas and removing mist, then gas cooling and mist removal functions are improved, but the inflator increases in radial size and weight
Solution Approach 1:
The invention extracts and eliminates the separate gas flow path forming member. Instead, the gas flow path is formed by the spatial arrangement of the combustion chamber and the inner peripheral surface of the upper case, removing the need for additional components and reducing radial size.
Solution Approach 2:
The invention merges the functions of the gas flow path forming member with the upper case structure. The upper case both contains the combustion chamber and provides the cooling surface, combining multiple functions into a single structural element and reducing radial dimensions.
3Object-generated harmful factors
If a gas flow path forming member is disposed concentrically to form an L-shaped gas flow path for cooling gas and removing mist, then gas cooling and mist removal functions are improved, but the weight of the inflator increases due to the installed member
Solution Approach 1:
The invention extracts and eliminates the gas flow path forming member that would otherwise be needed to achieve mist removal. The mist removal function is achieved through the gas flowing along the inner peripheral surface of the upper case, eliminating the need for additional components and reducing weight.
Solution Approach 2:
The upper case serves itself by providing both structural containment and the cooling/mist removal surface. The structure that contains the combustion chamber also provides the surface along which gas flows for cooling and mist removal, eliminating the need for separate components.
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 cools the gas and removes mist without additional parts, reducing the inflator's radial size and weight, making it suitable for compact vehicle airbag devices.
Implementation Method 1
a gas generating agent filled at an outer peripheral portion of the squib combusts, and a large amount of gas is generated
Implementation Method 2
the gas that flows into the airbag is also cooled
Implementation Method 3
mist of the gas generating agent adheres to a wall surface and is removed
Implementation Method 4
mist of the gas generating agent adheres to a wall surface
Data Source
AI summary
A disc inflator having gas cooling and mist removal functions, and reduced in weight and in size in a radial direction. An inflator case (40) has an upper case (36) at an occupant side and a lower case (38) at a side opposite an occupant. A tubular holding member (60) having a separation wall (64) at a base portion thereof is provided in the inflator case. A gas flow path (74) is formed at a periphery of the holding member (60), and communication holes (80) communicating with the gas flow path (74) are formed in the separation wall (64). At a peripheral wall portion (36B) of the upper case (36) is formed a gas ejection hole (76) at a position offset towards an occupant side only by a distance δ from a central position P of a combustion chamber (68). Accordingly, a length (L1) of a flow path from the starting end of the flow path to the gas ejection hole (76) increases, enabling effective heat exchange of a high temperature gas and removal of mist (82). Thereby, a conventionally used filter may be disposed of.