28 Electronic Control Systems in Vehicles and Their Functions

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1. Engine Electronic Control System

The Engine Electronic Control System (EECS) electronically controls the engine’s ignition, fuel injection, air-fuel ratio, and exhaust emissions, allowing the engine to operate under optimal conditions to improve overall vehicle performance, save energy, and reduce exhaust emissions.

Electronic Ignition System (ESA)

The electronic ignition system consists of a microprocessor, sensors and their interfaces, and actuators. The system calculates and determines the ignition timing based on engine parameters measured by sensors, ensuring the engine operates at the optimal ignition advance angle under different speeds and air intake conditions, maximizing power output and torque while reducing fuel consumption and emissions, thus conserving fuel and reducing air pollution.

Electronic Fuel Injection (EFI)

The electronic fuel injection system has gradually replaced mechanical or electromechanical mixed fuel injection systems due to its superior performance. When the engine is running, this system calculates based on parameters such as air flow, intake temperature, engine speed, and operating temperature measured by various sensors, compares this with the optimal fuel control parameters stored in memory, and adjusts the fuel supply amount timely to ensure the engine operates at its best state, thus improving overall performance while delivering a certain power output.

Exhaust Gas Recirculation Control (EGR)

The exhaust gas recirculation control system is an effective measure currently used to reduce NOx emissions in exhaust gases. Its main component is the CNC EGR valve, which accurately controls the amount of exhaust gas recirculated to the engine. The ECU adjusts the recirculation rate based on engine operating conditions, opening the EGR valve when the engine is under load to mix a portion of the exhaust with fresh intake air for combustion, thereby achieving recirculation and optimal control of exhaust gases entering the intake system to suppress the formation of harmful NOx gases and reduce their emissions. However, excessive recirculation of exhaust gases can affect the ignition performance of the air-fuel mixture, impacting engine power, especially at idle, low speed, light load, and cold start conditions, where recirculated exhaust can significantly affect engine performance.

Idle Speed Control (ISC)

The idle speed control system regulates the airflow to control intake flow by adjusting the area of the air passage. The main component is the idle speed control valve (ISC). The ECU compares the target speed determined from input signals from various sensors with the actual engine speed, and based on the difference, determines the control amount corresponding to the target speed to drive the actuator controlling the air quantity, keeping the idle speed near optimal levels.

In addition to the above control devices, electronic technologies utilized in the engine include throttle timing, secondary air injection, engine boosting, evaporative emissions, combustion chamber volume, and compression ratio, which have been applied in some vehicle models.

2. Power Transmission Electronic Control System

Electronic Control Automatic Transmission (ECAT)

Generally, the required speed and torque of the vehicle’s drive wheels differ significantly from what the engine can provide, necessitating a transmission system to alter the gear ratio between the engine and the drive wheels to transmit engine power to the drive wheels, adapting to changes in external loads and road conditions. Moreover, parking and reversing also rely on the transmission system, which coordinates the operation of the engine and transmission system to fully utilize the potential of the power transmission system, achieving optimal matching, which is the fundamental task of the transmission control system.

ECAT can automatically change the gear lever position based on calculations of engine load, speed, vehicle speed, brake status, and various parameters controlled by the driver, accurately controlling the gear ratio according to shift characteristics to achieve optimal shift control, obtaining the best gear and shift timing. This device boasts high transmission efficiency, low fuel consumption, good shifting comfort, stable driving, and a long transmission lifespan. Utilizing electronic technology, especially microelectronics, to control the transmission system has become the primary method for achieving automatic transmission functionality in modern vehicles.

Electronic Four-Wheel Drive Technology (4WD)

The driving force of a vehicle comes from the tires’ traction on the ground, and four-wheel drive fully utilizes the wheels’ traction for better driving performance. However, due to differing turning radii during steering, the wheels rotate at different speeds (inner and outer, front and rear), meaning the four wheels cannot be connected through a rigid transmission system, necessitating the installation of differentials between the left and right wheels as well as between the front and rear drive shafts. The resulting issue is that the driving force of the four wheels is limited by the wheel with the least ground friction, requiring the addition of a differential lock. The electronic four-wheel drive technology senses the conditions of all four wheels on the road through sensors, analyzes and judges this information through a microcomputer, and drives electromagnetic valves to alter the characteristics of the viscous coupling, distributing driving force between the front and rear drive shafts as well as between the left and right wheels.

3. Brake Control System

Anti-lock Braking System (ABS)

This system detects the speed of each wheel using speed sensors installed on each wheel or axle, calculates the wheel slip ratio, and compares it with the ideal slip ratio to determine whether to increase or decrease brake pressure, commanding actuators to adjust brake pressure in time to maintain the wheels in an ideal braking state, allowing the wheels to remain in a slightly slipping rolling state without locking up. This has become standard equipment in current passenger cars.

Electronic Brake-force Distribution System (EBD)

When braking, if the conditions of the four tires’ adhesion to the ground differ, the friction force between the four wheels and the ground will vary, leading to phenomena such as skidding, tilting, and rollover during braking (when the braking force of the four wheels is the same).

The function of EBD is to calculate the friction force values caused by different adhesion conditions of the four tires at the moment of braking, then adjust the braking device to quickly adapt according to a set program during motion, achieving a match between braking force and friction force (traction force) to ensure vehicle stability and safety. This system, when combined with ABS, can greatly enhance braking performance.

Drive Slip Control System (ASR)

The perfection and extension of the anti-lock braking system’s functions is the drive slip control system (ASR), which shares many components with ABS. This system uses speed sensors on the drive wheels to detect whether the drive wheels are slipping, and when slipping occurs, control elements reduce speed through braking or throttle control to eliminate the slip. Essentially, it acts as a speed regulator, improving longitudinal traction between the wheels and the road during sudden speed changes at startup and in turns, providing maximum driving force and enhancing safety, maintaining the vehicle’s directional stability.

Electronic Stability Program (ESP)

This is a slip prevention system that can detect vehicle instability and control the braking system, engine management system, and transmission management system to compensate for vehicle sliding, preventing the vehicle from leaving its lane.

Other similar products from various companies include:

Nissan: Vehicle Dynamics Control System (VDC).

Toyota: Vehicle Stability Control System (VSC).

Honda: Vehicle Stability Assist Control (VSA).

BMW: Dynamic Stability Control System (DSC).

Electronic Parking Brake System (EPB)

This system integrates temporary braking during driving and long-term parking braking after stopping, implemented through electronic control.

EPB operates similarly to mechanical parking brakes, tightening the rear brake shoes via a cable. Another method uses electronic mechanical calipers to generate braking force through an electric motor to achieve parking brake control.

EPB extends from basic parking functionality to automatic parking (AUTO HOLD). The application of automatic parking technology allows drivers to avoid prolonged braking when the vehicle stops and prevents unnecessary rolling when starting with automatic electronic parking brake engaged, simply put, the vehicle will not roll backward.

4. Steering Control System

Electric Power Steering System (EPS)

When turning the steering wheel, a torque sensor mounted on the steering shaft continuously measures the torque signal on the steering shaft. This signal, along with the vehicle speed signal, is input to the electronic control unit (ECU). The ECU determines the magnitude and direction of the assist torque based on these input signals, and the motor’s torque is applied to the vehicle’s steering mechanism through an electromagnetic clutch via a reduction mechanism, providing a steering force that is appropriate for the vehicle’s operating conditions.

Electronic Four-Wheel Steering Technology (4WS)

When a vehicle turns while driving, the front wheels tend to understeer due to lateral forces, while the rear wheels may oversteer, potentially destabilizing the vehicle’s steering stability, especially at higher speeds, which can even lead to skidding or rollover.

A common solution is to have the rear wheels turn 1° to 2° in the same direction as the front wheels for compensation. Electronic four-wheel steering technology senses the front wheel speed, steering wheel angle, and body deflection through sensors, processes this information via a microcomputer, and drives a servo motor to steer the rear wheels, with a response time of just a few milliseconds.

5. Driving Control System

Adaptive Suspension System (ASS)

The adaptive suspension system automatically and timely adjusts the damping characteristics of the suspension and the stiffness of the suspension springs based on the instantaneous load on the suspension, maintaining the predetermined height of the suspension, significantly improving vehicle stability, maneuverability, and passenger comfort.

Cruise Control System (CCS)

Cruise control, also known as a constant speed driving system, allows the driver to maintain a fixed preset speed without operating the accelerator pedal. During long-distance driving, the cruise control system can be used so that the driver does not have to constantly press the accelerator, as the system automatically adjusts the throttle opening to maintain speed near the set speed based on driving resistance.

If the vehicle’s speed decreases when climbing, the microcomputer control system will automatically increase the throttle opening; conversely, it will decrease the throttle opening when descending to adjust engine power. This control system will automatically disconnect when the driver shifts to a lower gear or brakes.

This system reduces driver fatigue during long-distance driving, providing significant convenience while also achieving better fuel economy.

Tire Pressure Monitoring System (TPMS)

This system can automatically detect the tire pressure and temperature of the vehicle and alert the driver of any abnormal tire conditions.

The system can be divided into two types: one is the indirect tire pressure monitoring system, which determines abnormal tire conditions based on differences in tire rotation speed; the other is the direct tire pressure monitoring system, which installs four tire pressure monitoring sensors inside the tires to monitor tire pressure and temperature in real time during vehicle operation, providing timely alerts for high pressure, low pressure, or high temperature to prevent traffic accidents caused by tire failures, ensuring driving safety.

6. Safety Electronic Control System

Airbag System (SRS)

This system is a common passive safety device in vehicles both domestically and internationally. In the event of a collision, electronic components ignite the nitrogen compound in the airbag located in the steering wheel center (or in the dashboard, glove compartment, etc.), rapidly generating nitrogen to inflate the airbag. The airbag acts as a cushion between the driver and the steering wheel, and between front-seat occupants and the dashboard, preventing injury from hard impacts. This device must be used in conjunction with seat belts; otherwise, its effectiveness is greatly diminished.

Collision Warning and Prevention System (CWAS)

This system comes in various forms, with some alerting the driver automatically when the distance between two vehicles becomes dangerously close during driving, and if the vehicles continue to approach, it can automatically control the vehicle’s brakes to stop the vehicle just before a collision; others display the distance to obstacles when the vehicle is reversing, effectively preventing reversing accidents.

7. Comfort Electronic Control System

Automatic Air Conditioning System

The automatic temperature control system (ATC) for vehicle air conditioning, colloquially known as the constant temperature air conditioning system, automatically controls and adjusts to maintain the set temperature once the target temperature is established. The automatic air conditioning system consists of five parts: cooling system, heating system, ventilation (air distribution) system, automatic control system, and air purification system.

The fully automatic temperature control system comprises temperature sensors, control system ECU, and actuators. The temperature sensors include external air temperature sensors, internal air temperature sensors, sunlight sensors (solar intensity sensors), and evaporator temperature sensors.

Automatic Seat Adjustment System (AAS)

This device is a product of integrating ergonomic technology with electronic control technology, sensing the posture of passengers and adjusting the seat status accordingly to meet passengers’ comfort requirements.

Adaptive Front Lighting System (AFS)

The adaptive front lighting system can adjust the low beam of the headlights based on the vehicle’s dynamic changes and steering characteristics, effectively reducing driver fatigue when driving at night, allowing the driver to see the actual road conditions at turns, providing ample time to maneuver and respond to emergencies, thereby significantly enhancing nighttime driving safety. In Japan, some automakers have already equipped their high-end cars with AFS, such as Toyota, which uses a variable

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