VEHICLE SENSORS: TYPES AND FUNCTIONS
In a way, sensors are the sensory organs of the vehicle. A fundamental component of electronic control systems, they must record physical or chemical variables and convert them into electrical signals…
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sensors in automobiles
EXAMPLES OF SENSORS FOR ENGINE CONTROL:
Pulse sensor, crankshaft
The crankshaft sensor captures engine speed and crankshaft position. The control unit uses these values to calculate the injection pulse and ignition pulse.
Camshaft position
The camshaft sensor is located in the cylinder head and checks a ring gear on the camshaft. This information is used, for example, to start the injection, for the signal to activate the solenoid valve of the pump/nozzle injection system and for cylinder-specific knock control.
Air mass meter
The air mass meter is installed between the air filter housing and the intake manifold. Measures the mass of air sucked in by the engine. This variable provides the basis for calculating the amount of fuel that must be supplied to the engine.
Intake air temperature/External temperature/Internal temperature
Air temperature sensors capture the ambient air temperature. The measured values are used to control various systems (e.g. the air conditioning system) or as correction values for the injection system. The installation location is determined by the air temperature to be measured. The sensor for the intake air temperature, for example, is located in the air duct for the intake air.
Coolant temperature
The coolant temperature sensor is screwed into the cooling system. The tip of the gauge projects into the coolant and records its temperature. The control unit uses this value to adapt the amount of fuel injected to the engine temperature.
Throttle position
The throttle valve sensors are connected to the throttle valve shaft. They monitor the opening angle of the butterfly valve. From the values, the engine electronics calculates the amount of fuel injected based on other factors.
Knock sensors
Knocking is an uncontrolled form of combustion in a gasoline engine. As continuous knocking can damage the engine, it must be checked and adjusted. The engine control unit evaluates voltage signals received from the knock sensor and regulates the ignition timing to a range just below what is known as the knock limit. Knock sensors are permanently monitored by the control unit.
Intake pipe pressure
The intake pipe pressure sensor measures the vacuum of the intake pipe downstream of the throttle valve and forwards this value to the engine control unit as an electrical signal. This is combined with the air temperature sensor value so that the air mass sucked in can be calculated.
oxygen sensors
The oxygen sensor measures the residual oxygen content in the exhaust gases to always ensure an ideal combustion mixture. Depending on the type of sensor, a chemical element (titanium dioxide/zirconium dioxide) and the residual oxygen content of the exhaust gases influence a voltage, which is then used by the control unit as a measured variable.
EXAMPLES OF BODY ELECTRONICS SENSORS:
Wheel speed
Wheel speed is used by driving safety systems such as ABS and ASR as a speed value, as well as by GPS systems to calculate the distance traveled. A failure will cause these systems to fail, significantly impairing security.
Speed, transmission
The transmission sensor captures the transmission speed. The speed signal is used by the control unit to precisely control the shift pressure during shifting and to decide which gear should be engaged and when.
Speed, distances covered
Distance sensors are used to capture driving speed. They are mounted on the transmission or rear axle. The information obtained is necessary for the speedometer, cruise control and converter slip control.
Engine oil level/coolant level
For operational safety reasons and for greater comfort, levels such as engine oil, coolant and washer fluid are monitored with level sensors. Level sensors send a signal to the engine control unit that activates an indicator lamp.
Brake lining wear
Brake wear sensors are located on the brake linings and are subject to the same wear. A visual signal informs the driver that the wear limit has been reached.
Security
Sensor information provides the basis for the operation of various active and passive safety systems. Thanks to significant progress in the development of new sensors, there has been a steady increase in the capabilities of safety and driver assistance systems in recent years. Sensors therefore have a fundamental role to play in increasing safety on our roads.
Some of the security systems are
1. Frontal collision avoidance system –
Alerts the driver when the vehicle approaches another vehicle in front of it. It employs various sensors such as cameras, RADAR or LIDAR to detect objects or other vehicles in front of the vehicle. A forward collision warning system equipped with autonomous braking can reduce vehicle speed, thereby mitigating the effect of the collision.
2. Adaptive cruise control –
Adaptive cruise control maintains the vehicle's preset speed. It automatically slows down the vehicle in heavy traffic to maintain a safe distance. Front-mounted sensors monitor the distance to the vehicle in front. The vehicle accelerates to maintain the preset cruising speed as traffic speeds up.
3. Lane departure warning and prevention system –
This system uses cameras to track the vehicle's position within the lane and alert the driver if the vehicle is in danger. Certain systems provide tactile warnings, such as seat or steering vibrations, while others provide audible and/or visual warnings.
4. Blind spot detection system –
This sensor network system monitors blind spots in the front, side and rear areas of the vehicle. Most systems provide visual alerts that appear in or near the side view mirrors when they detect the blind spot.
An audible alert is activated when the driver signals a turn and the vehicle heads towards the blind spot on the side of the turn.
Certain systems can also activate steering or braking controls to keep the vehicle in the lane.
5. Parking assistance and reversing prevention system –
Assists drivers with parking and backing up their vehicles. Rear object detection systems use sensors and cameras to allow the driver to look for objects at the rear of the vehicle while reversing.
6. Adaptive headlight
alerts drivers to better view objects on dark and curved roads. The headlight rotates in the direction of a moving vehicle to illuminate the road ahead based on the vehicle's speed and steering wheel movement.
7. Fatigue warning systems
it employs sophisticated algorithms to monitor steering control and other behaviors such as driver blink duration and rate. This system is designed to alert the driver if it detects drowsiness or inattention.
8. Curve speed warning system
it monitors the vehicle as it approaches curves in the road using a global positioning system and a digital map. Cornering speed sensors alert the driver if the system detects that the vehicle is approaching a curve at excessive speed.
Environmental Protection
Sensors make modern vehicles not only safer, but also cleaner. They provide the basic information for clean and efficient fuel combustion in the engine, thus allowing exhaust emission values and fuel consumption to be significantly reduced. Finally, they support the reliable operation of high-efficiency exhaust gas retreatment systems. Examples include the 3-way controlled catalytic converter, the diesel particulate filter or the DeNOx catalytic converter.
