Take you to understand the automotive electronic control unit and its function

Blog | news | Apr 12,2023

Powertrain Electronic Control System

Electronically controlled automatic transmission (ECAT)

Generally speaking, the speed and torque required by the driving wheels of the car are quite different from the speed and torque that the engine can provide, so the transmission system is required to change the transmission ratio from the engine to the driving wheels, and the engine’s Power is transmitted to the drive wheels so that it can adapt to changes in external loads and road conditions.

In addition, parking, reversing, etc. are also realized by the transmission system. It is the fundamental task of the transmission control system to coordinate the working conditions of the engine and the transmission system in a timely manner, give full play to the potential of the power transmission system, and achieve the best match.

ECAT can automatically change the position of the gear lever after calculation and judgment according to the engine load, rotational speed, vehicle speed, brake working status, and various parameters controlled by the driver, and precisely control the gear ratio according to the gear shifting characteristics, so as to realize the gear shifting of the transmission The best control, the best gear and the best shift time.

The device has the advantages of high transmission efficiency, low fuel consumption, good gear-shifting comfort, good driving stability, and long service life of the transmission. Using electronic technology, especially microelectronic technology to control the transmission system, has become the main method for the current automobile to realize the automatic transmission function.

Electronically controlled four-wheel drive technology (4WD)

The driving force of the car comes from the adhesion of the tires to the ground. The four-wheel drive makes full use of the adhesion of the wheels to the ground, and of course, it will obtain good driving performance. But because the turning radius of each wheel is different when turning, the speed of the wheel rotation is also different (inside and outside, front and rear).

The four wheels cannot be connected through a rigid transmission system, and a differential must be installed between the left and right wheels and between the front and rear drive shafts. The problem caused is that the driving force of the four wheels is limited by the wheel with the least friction with the ground, and a differential lock needs to be set.

Electronically controlled four-wheel drive technology senses the situation of the four wheels on the road through sensors, analyzes and judges them through microcomputers, drives through solenoid valves, changes the characteristics of the viscous coupler, and distributes the driving force between the front and rear drive shafts and on the left and right wheels.

Brake Control System

Electronic brakeforce distribution (EBD)

When the car brakes, if the four tires attach to the ground under different conditions, and the friction between the four wheels and the ground is different, slipping, tilting and rollover will easily occur during braking (the braking force of the four wheels is the same).

The function of EBD is to calculate the friction value of the four tires at high speed due to the different adhesion at the moment of braking, and then adjust the braking device so that it can be adjusted at high speed according to the set program to achieve the braking force and The friction (traction) is matched to ensure the stability and safety of the vehicle.

This system works in conjunction with ABS to greatly improve braking performance.

Drive anti-skid system (ASR)

The functional completion and expansion of the anti-lock brake system of the car is the anti-skid system (ASR), and the two systems have many common components. The system uses the speed sensor on the driving wheel to sense whether the driving wheel is slipping. When slipping, the control element will reduce the speed by braking or through the accelerator to make it no longer slip.

It is essentially a speed regulator, which can improve the longitudinal adhesion between the wheel and the road surface when the speed changes sharply at the start and in the curve, provide the maximum driving force, improve its safety, and maintain the directional stability of the car.

Body electronic stability system (ESP)

This is an anti-skid system. ESP can identify the unstable state of the vehicle and control the braking system, engine management system, and transmission management system to compensate for vehicle slippage in a targeted manner to prevent the vehicle from slipping out of the lane.

This system refers to a technology that integrates temporary braking during driving and long-term braking after parking and realizes parking braking by electronic control.

EPB is a technology that realizes parking braking by electronic control. Its working principle is the same as that of mechanical parking brakes, and both use cables to tighten the brake shoes of the rear wheels for braking. The other is to use electromechanical calipers to control the parking brake by using the electric motor to clamp the brake pads to generate braking force.

EPB extends from the basic parking function to the automatic parking function (AUTO HOLD). The application of automatic parking function technology makes the driver not need to brake for a long time when the vehicle is stopped and can avoid unnecessary sliding of the vehicle when the automatic electronic parking brake is activated. Simply put, the vehicle does not slip after the meeting.

Steering Control System

Electronically controlled four-wheel steering technology (4WS)

When the car turns while driving, the front wheels tend to understeer and the rear wheels tend to oversteer due to the lateral force. The latter will cause the car to lose the stability of the steering. The faster the speed, the more obvious the problem, and even a side slip and roll over.

The solution is generally to compensate by turning the rear wheels at an angle of 1° to 2° in the same direction as the front wheels. The electronically controlled four-wheel steering technology senses the speed of the front wheels, the angle of the steering wheel, and the deflection of the vehicle body through sensors, and is processed by a microcomputer. The servo motor drives the steering of the rear wheels, and the response time is within tens of milliseconds.

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