SMA Valve Parallel Motion for Compact Seat Air Cell Control
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Solution Overview
Problem
Existing SMA valves for vehicle seat air cell pressurization are space-consuming due to the perpendicular movement of the valve element, making them less compact and more sensitive to component dimensions and tolerances, which affects the reliability of the end switch function.
Innovation Solution
A compact SMA valve design where the valve element moves parallel to the mounting plate, utilizing a parallelogram suspension and an actuator arm to pivot the conductor into contact with the mounting plate for reliable end switch functionality, reducing vertical space usage and dependency on component dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the valve element moves perpendicular to the mounting plate, then the valve can be actuated by SMA wire, but the valve becomes space-consuming and sensitive to component dimensions and tolerances
Solution Approach 1:
The valve element movement direction is changed from perpendicular to parallel relative to the mounting plate. This dimensional change allows the end switch contact to be reliably achieved through the conductor arm pivoting motion, reducing sensitivity to component tolerances while minimizing vertical space requirements.
Solution Approach 2:
Instead of moving the valve element perpendicular to the mounting plate as in conventional designs, the invention inverts the approach by moving the valve element parallel to the mounting plate. This inversion enables the conductor arm to pivot and reliably contact the mounting plate for end switch activation.
2Device complexity
If the valve element moves perpendicular to the mounting plate, then the valve structure is simplified, but the end switch function becomes sensitive to component dimensions and tolerances
Solution Approach 1:
A conductor arm is introduced as an intermediary element between the valve element and the end switch contact point. This conductor arm pivots to contact the mounting plate, providing a reliable electrical circuit closure that is less sensitive to component dimension variations and assembly tolerances.
Solution Approach 2:
The valve element movement is changed from perpendicular to parallel relative to the mounting plate. This dimensional change, combined with the conductor arm pivoting mechanism, reduces the system's sensitivity to manufacturing tolerances while maintaining structural simplicity.
3Volume of moving object
If the valve element moves parallel to the mounting plate, then vertical space is reduced and end switch reliability is improved, but the valve requires additional suspension mechanism
Solution Approach 1:
A parallelogram suspension mechanism is employed to enable the valve element to move parallel to the mounting plate. This dynamic suspension system maintains the valve element's orientation while allowing horizontal movement, achieving compact vertical space utilization without compromising functionality.
Solution Approach 2:
The parallelogram suspension mechanism serves multiple functions: it enables the valve element to move parallel to the mounting plate, maintains proper orientation of the valve components, and provides a stable platform for the conductor arm to pivot. This multi-functionality justifies the added structural complexity.
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 design achieves a compact and reliable end switch function, reducing vertical space usage and enhancing the reliability of the end switch operation by converting the valve element's movement into a parallel motion, thus minimizing the impact of component tolerances and dimensions.
Implementation Method 1
A SMA valve comprises a housing, a plunger as valve element, a spring urging the plunger to a closed position in a valve seat, and an actuator capable of acting on the plunger such that the actuator upon activation exerts a force on the plunger which moves the plunger away from the valve seat to an open position
Implementation Method 2
Actuation of the SMA valve is controlled by selectively supplying an electrical current to the SMA wire to heat it up to the threshold temperature
Data Source
AI summary
SMA valve for controlling pressurized air supply to an air cell in a vehicle seat comprising: a valve housing; a valve element (4) moveable between a closed position in which it is in sealing abutment with a valve seat, and an open position; a spring element urging the valve element to the closed position; a SMA wire (1) extending between a fixed point and the valve element (4), and which is arranged such that shortening of the SMA wire upon exceeding its threshold temperature exerts a force on the valve element (4) pulling it from the closed to the open position; a conductor (20) arranged to close an electrical circuit when the valve element reaches its open position; a control unit for supplying electrical power to the SMA wire for opening the valve and to detect closure of the electrical circuit, and arranged to reduce the electrical power supply to the SMA wire when detecting closure of the electrical circuit, wherein the suspension (8, 10, 10′, 12, 12′, 14, 14′) of the valve element is arranged such that the valve element moves parallel to the mounting plate (30) between the closed and open positions; and an actuator arm (16) fixed to and extending from the suspension is arranged such that it, upon movement of the valve element to the open position, pivots towards the mounting plate bringing the conductor (20) into contact with a contact area (34) on the mounting plate.