Sensors are an important part of a car, which can transmit signals and be used to detect various parameters of the car. According to the classification of physical quantities, it can be divided into displacement, force, speed, temperature, flow, gas composition and other sensors, and according to the working principle, it can be divided into resistance, capacitance, inductance, voltage, Hall, photoelectric, grating, thermocouple and other sensors. Sensors commonly used in automobiles include air flow sensors, odometer sensors, oil pressure sensors, and water temperature sensors.
The air flow sensor converts the inhaled air into an electrical signal that is sent to the electronic control unit (ECU) as one of the basic signals to determine fuel injection. According to the different measuring principles, it can be divided into four types: rotary fin type air flow sensor, Carmen vortex type air flow sensor, hot wire type air flow sensor and hot film type air flow sensor. The first two are volumetric flow types, and the latter two are mass flow types. There are two main types of hot wire air flow sensor and hot film air flow sensor.
The odometer sensor is usually mounted on a differential or half shaft to sense the number of revolutions, and generally uses Hall and photoelectric methods to detect the signal. The odometer sensor calculates the car's driving speed and mileage by detecting the signal. The design of two bearings on the transmission shaft reduces the force distance in operation, reduces friction and enhances service life.
Oil pressure sensor is a miniature electromechanical system that integrates miniature sensors, actuators, signal processing and control circuits, interface circuits, communication and power supplies. Commonly used are silicon piezoresistive and silicon capacitive, both of which are micromechanical and electronic sensors generated on silicon wafers. The oil pressure sensor is used to detect how much oil is still in the car's oil, and converts the detected signal into a signal that we can understand, reminding us how much oil we still have, or how far we can go, or even reminding the car that it needs to be refueled.
Inside the water temperature sensor is a semiconductor thermistor that is mounted on the water jacket of the engine block or cylinder head, in direct contact with the cooling water. The electronic control unit measures the temperature of the engine cooling water based on the change in the thermistor, which is used as a correction number for fuel injection and ignition timing. We can know the state of the car through the temperature of the engine water temperature, whether it is stopped or moving, or how long it has been moving.
