The Physics Behind Bumper Sensors, Fuel Injection
Aug. 28, 2020—Sure, most mechanics know about fuel injectors and their functions. But how closely have you listened to them?
"As a physicist, what fascinates me with fuel-injection systems is that they rely on piezoelectric vibrations, in this case at frequencies of 1–5 kHz. That’s well within the range of human hearing, which extends up to about 20 kHz."
That's an excerpt from a fascinating article, written by David R. Andrews in PhysicsWorld, about the sonic and ultrasonic properties of vehicles. It's very detailed and covers longstanding vehicle functions like fuel injection, which uses an ultrasonic piezoelectric transducer to open and close valves using vibrations to make precise fuel mixtures.
More modern vehicles have those small discs fitted into bumpers. Those are electro-mechanical transducers that bounce signals off of nearby walls or objects to warn drivers of obstacles.
The article is, frankly, complex. But it is great information about the physics behind some of these common vehicle parts.