What is the brake priority system?
Brake priority system (BOS) refers to a system that allows the driver to stop the car by depressing the brake pedal even when the accelerator pedal is depressed and the accelerator is fully open (that is, the accelerator pedal is depressed to the bottom). That is to say, when the brake priority system detects that the driver tries to brake but fails, it will automatically switch the engine to idle speed. In other words, you should put on the brakes when the car slams on the accelerator or the accelerator is stuck. As long as the brake signal is received and the throttle signal voltage is high, the computer will reduce the engine fuel injection and throttle opening (non-throttle cable car) in a very short time, and reduce the engine speed to separate the clutch.
What is the brake priority system?
Working principle of brake priority system
Brake priority system? Its working principle is that it can only be started before braking when the accelerator is working, that is, when the vehicle is driving, first step on the accelerator pedal and keep the depth, and then step on the brake pedal with the left foot. At this time, the computer will send the signal to the accelerator sensor to minimize the fuel injection signal. This system can be divided into two types: mechanical throttle with cable and electronic throttle with electronic control. However, no matter how it is realized, the final effect is the same, avoiding the brake and throttle fighting, resulting in brake failure. Take the cable accelerator pedal as an example. There is a throttle switch at the top of the engine, which is pulled by a steel wire in a semicircle. This wire leads directly to the accelerator pedal. Step on the accelerator pedal, and the steel wire pulls the accelerator switch to open the accelerator. But it is actually two steel wires that connect the throttle switch. One of them leads to the accelerator pedal, and the other is pulled by the accelerator buffer. Because if there is no buffer, as soon as the foot releases the accelerator pedal, the accelerator will immediately return to idle speed, and then you will feel it in the car? Hit someone? Jumping around in the car greatly affects the comfort of the car. So when you release the throttle, the throttle will not come down at once, but will slow down because of the throttle buffer. The harder you step on the accelerator pedal, the more obvious the effect of throttle buffering is. So when you release the accelerator and step on the brake, you will not only bear the inertia of the car, but also the high-speed operation of the engine! Because the throttle hasn't completely returned to idle speed. The brake priority system can immediately restore the fuel supply system of the throttle to the idle position, even if the other foot steps on the throttle or the throttle is stuck, it will not refuel the engine. Even under normal braking conditions (not the extreme case of braking while stepping on the accelerator at the same time), compared with vehicles without this system, the braking distance of the braking priority system will be significantly shortened, so the safety performance of vehicles will be greatly improved.
Function of brake priority system
Braking priority is to stop the power output of the engine when the driver makes a wrong prediction, so as to reduce the car's continued acceleration, rather than braking at the first time. If the driver makes a mistake or the throttle is stuck, the experienced old driver will step on the brake at the first time. At this time, the signal will be transmitted to the driving computer, and at the same time when ABS takes effect, the brake will be given priority (the engine power will be switched to idle speed). In addition, the experience of old drivers should minimize the loss, rather than the system that everyone understands can shorten the braking distance. Just cut the engine power to idle speed, and the specific braking needs the accurate judgment of the driver and the start of ABS.
Matters needing attention
After the brake priority system is activated, the vehicle shall:
1, the throttle is immediately released to the minimum state (idle state), at which time the engine runs under the action of inertia, thus playing a certain deceleration role;
2. The gearbox upshifts first, and then gradually downshifts. This is because after the accelerator is stepped on the bottom, the ECU initially thinks that it needs to accelerate, and will first downshift, improve the acceleration and trigger? Brake priority? After that, it will upshift to the highest gear, reduce the engine driving force, and then gradually downshift according to the degree of vehicle speed reduction.
All the above are about what is the brake priority system and what is the function of the brake priority system. I hope it will help everyone.