Pressure sensors for Side Crash Detection (SAB)
How XENSIV™ safety crash detection sensors make cars safer - PSI5 PRO-SIL™ ready pressure sensors for side impact detection and pedestrian protection
Airbags are one of the most essential safety features in any vehicle. In order to protect car passengers as well as pedestrians, they and the crash impact sensors linked to them must work properly. Faulty car crash detection sensors can lead to severe consequences. Malfunctioning impact sensors can inhibit the function of other automotive safety features, such as the airbag pressure switch, which is responsible for deploying airbags during an accident. No automotive manufacturer can risk anything but the highest caliber of sensors in cars for maximum safety.
The Infineon XENSIV™ family of collision detection sensors for vehicles includes integrated impact pressure sensors that are long-lasting, accurate, and versatile, equipped with PSI5 peripheral interfaces that convert and send electric signals from sensors to electronic control units (ECUs). Our car crash detection sensors operate with cutting-edge safety systems that increase the protection of car occupants and pedestrians in the event of a collision. These applications, as well as our pedestrian protection and impact pressure sensors, meet the highest quality and accuracy standards, fully adhering to ISO 26262 compliance. Despite only needing two impact detection sensors, Infineon safety crash impact sensors deliver a reliable signal at an industry-leading reaction time.
Impact detection sensors used in cars for safety are generally located at the front of a vehicle, as this is the area where accidents most often occur. These sensors get alerted by a vehicle’s sudden deceleration. They measure collision intensity, and, if determining that airbags need to be released, send an electric signal to the SRS control system. Side impact sensors also measure collision intensity, but within the passenger doors on the sides of a car, measuring pressure changes that occur inside the doors due to external impact.
All front impact sensors for a car work in concert with its supplemental restraint system (SRS). The SRS is a passive system which controls the deployment of airbags and seatbelt restraints. When the front impact sensors sense a crash situation of the car, they send electric signals to the SRS. The SRS then compares this data with the car’s yaw rate and, if needed, sends a signal to deploy the necessary airbags via the airbag pressure switch and seatbelt restraints.
Front and side impact sensors interact similarly with the SRS system, but they measure different things. Whereas a front impact sensor in a car will react to the sudden deceleration of the vehicle, crash detection sensors in the side of a vehicle, like XENSIV’s KP 200 or 204, reacts to pressure changes that occur in the doors. One left front side impact sensor is located inside the driver door, and one right front impact sensor is located in the passenger door. Similarly, the left and right rear side impact sensor locations are inside the rear doors.
When a vehicle sustains lateral impact, the side impact pressure sensor in the affected door(s) observes the change of pressure that happens inside. Within these sensors, a microprocessor analyzes the pressure information and determines whether to send a collision signal to the SRS. If and when that signal reaches the SRS system, the SRS then determines which door(s) to deploy airbags from and sends the appropriate signal.
Data has shown car doors to be a significant cause of damage during auto accidents – particularly when pertaining to head injuries – even coming before outside objects like trees, signs, or light poles. By cushioning car occupants against the potential force of a vehicle’s doors, front and back side-impact sensors and their corresponding airbags not only increase passenger head safety, but also reduce the risk of injury to the neck, chest, and pelvic regions.
Vehicles typically have right and left front side impact sensors that lie within its “crush zone,” or the area along its front that is most likely to sustain damage in an accident. This proximity to the impact zone positions these front crash impact sensors to instantly deliver accurate signals to the SRS.
Additionally, there front impact sensors detecting the collision of a pedestrian with the front of a car. Two pedestrian protection front sensors sit at opposite ends of a tube along the inside of the car bumper. Pressure forced on the tube by the bumper activates these collision sensors in the car, which signal actuators to lift the hood of the vehicle. The hood’s impact angle minimizes the force of the collision and decreases the risk of serious harm that could stem from a pedestrian directly hitting the engine system.
The benefits of these front-facing impact sensors in a car are clear. They are instant, accurate, and durable; the XENSIV KP 201 sensor, for example, is specially designed to withstand high engine heat by being operational in temperatures up to 125 degrees Celsius. However, they do not present a catch-all solution to passenger or pedestrian safety. Auto manufacturers’ mounting need to address an increase in lateral accidents has brought about innovations in side-impact safety technology and equipment. More than ever before, it is now becoming standard that cars be fitted with right and left rear side impact sensor locations, in addition to front sensors.
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