Airbag Pilot Valve With Differential Piston for Variable Filling
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Solution Overview
Problem
Conventional airbag systems for motor vehicles lack the ability to variably fill airbags based on the course of an accident or user-specific parameters, such as weight and size, which limits their effectiveness in providing tailored protection.
Innovation Solution
A valve system with a housing, electrically switchable pilot valve, and a piston that allows for controlled gas flow regulation, enabling variable filling of the airbag by adjusting the piston's diameter and using a spring for defined positioning, and an equalization line for pressure equalization, allowing for deliberate metering of gas flow based on accident dynamics and user characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional airbag system is used without a variable filling valve, then the airbag can be filled with gas in the event of a collision, but the filling cannot be adapted to the course of the accident or user-specific parameters
Solution Approach 1:
The valve system is segmented into distinct functional components: a pilot valve for control signal reception, a main valve for gas flow regulation, and a piston mechanism for variable positioning. This segmentation allows the complex function of adaptive filling to be achieved through coordinated simple components, resolving the contradiction between adaptability and complexity.
Solution Approach 2:
The piston acts as an intermediary element between the pilot valve control signal and the main gas flow. By positioning the piston at different locations within the valve body, it mediates the gas flow in a controlled manner, enabling variable filling without requiring a completely complex valve design.
2Ease of operation
If a valve system with variable piston positioning is implemented, then deliberate metering of gas flow is possible, but the device becomes more complex
Solution Approach 1:
The valve system utilizes the existing gas pressure from the gas generator to automatically position the piston and control the main valve opening. The gas pressure itself serves the dual purpose of both filling the airbag and controlling the valve mechanism, eliminating the need for additional complex control systems.
Solution Approach 2:
The valve system employs pneumatic principles where gas pressure differential forces the piston to specific positions. The pilot valve introduces control gas into a control chamber, creating pressure differential that moves the piston to regulate the main gas flow, achieving ease of operation through fluid pressure control rather than mechanical actuation.
3Quantity of substance
If the second diameter of the piston is made larger than the first diameter, then comparatively large mass flows can be controlled with a small pilot valve, but the piston design becomes more complex
Solution Approach 1:
The piston is designed with asymmetric diameters: a first diameter at one end and a larger second diameter at the other end. This asymmetric geometry allows the smaller pilot valve to control proportionally larger mass flows in the main valve, as the pressure differential acts on the larger surface area of the second diameter. The asymmetry resolves the contradiction by enabling high mass flow control capability without requiring a proportionally large pilot valve.
4Reliability
If a spring is added to exert force on the piston, then a defined position for the piston is realized, but the device complexity increases
Solution Approach 1:
A spring is introduced to exert a counteracting force on the piston, balancing the gas pressure forces. This spring force ensures the piston returns to a defined rest position when gas pressure is not applied, and works in conjunction with the pressure differential to achieve reliable, repeatable valve switching times. The spring acts as a mechanical counterweight to the pneumatic forces, providing stability and definition to the valve 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
Enables adaptive and controlled filling of airbags, ensuring optimal protection by allowing pre-filling before a collision and adjusting gas flow during the accident, while maintaining robustness and compactness, and ensuring reliable operation even in power supply failures.
Implementation Method 1
the valve has a spring in order to exert a force on the piston in the direction of the sealing seat
Implementation Method 2
The equalization line connects an inlet of the valve to the control chamber for fluid communication between the inlet and the control chamber
Implementation Method 3
The pilot valve selectively releases a pilot opening of the control chamber or seals the pilot opening
Implementation Method 4
The piston is moved away from the sealing seat due to the resulting forces and, consequently, releases a gas flow from the inlet to the outlet
Data Source
AI summary
Valve for an airbag system for a motor vehicle and airbag system for a motor vehicleThe invention relates to a valve for an airbag system for a motor vehicle, having:a housing (20) which extends along a longitudinal axis (21) and surrounds a cavity (22) having a taper (17) and surrounds a control chamber;an electrically switchable pilot valve (15) which selectively seals or releases a pilot opening (6) of the control chamber (5);a piston (3) which is arranged in the cavity (22) and can be displaced along the longitudinal axis (21) relative to the housing (20);an equalization line (4, 18) which connects an inlet (1) of the valve (100) to the control chamber (5) for fluid communication, wherein:a sealing seat (2) is formed at the taper (17) in order to block a gas flow from the inlet (1) to an outlet (14) of the valve (100) in a closed position, in which the piston (3) is in contact with the sealing seat (2), and to release said gas flow in further positions;the control chamber (5) is arranged on a first side (24) of the piston (3) facing away from the sealing seat (2); andthe piston (3) has a first diameter on a side (23) facing the sealing seat (2) and a second diameter (26) on the first side (24), the first diameter (25) being less than the second diameter (26).