1. Principle of electronic throttle and cable throttle
Due to various reasons such as environmental protection, economy and reliability, electronic accelerator is now widely used in newer models. The so-called electronic accelerator is for the former cable accelerator. The traditional cable accelerator directly connects the accelerator pedal with the throttle with thin steel rope, and the depth of the accelerator pedal is directly corresponding to the opening and closing of the throttle.
There is no cable in the electronic accelerator
. By installing a potentiometer (variable resistance) in the pedal, the depth of the accelerator is converted into the resistance value of the resistance. The electronic system of the car indirectly determines the depth of the accelerator pedal by sampling the resistance value.
Finally, the ECU drives the stepper motor to control the throttle opening. It is not difficult to find through the principle comparison that the characteristics of the cable throttle are simple system, direct control, the throttle pedal and the throttle opening is 1:1; the characteristics of the electronic throttle
is that the throttle pedal only represents the driver's operation intention, and the final throttle control is given to the ECU.
2. Features of ECU control throttle in electronic throttle vehicle
In the model of electronic throttle, when ECU controls the throttle, it will analyze the depth of the throttle and the vehicle condition, and finally calculate the appropriate throttle opening.When the driver starts to accelerate abruptly (press the pedal to the bottom), the ECU will analyze according to the current speed, throttle size, etc. from the perspective of fuel economy and reasonable emissions, it will appropriately limit the throttle opening range, and control the fuel injection system to limit the maximum fuel injection of the fuel injection nozzle.
In this way, the driver feels that there is obviously a delay when the accelerator is depressed before the car starts to work. This is called the accelerator hysteresis. Therefore, the throttle hysteresis is actually formed by the ECU by limiting the instantaneous power output of the engine. Of course, it also brings benefits - fuel saving and environmental protection.
However, the electronic accelerator
is not used to limit the power output of the engine. When the car runs, if you quickly press / release the accelerator pedal 1 / 3 of the depth, you can feel the obvious refueling / fuel collection of the car, and its effect is almost equivalent to the situation of completely pressing / releasing the accelerator. What's the matter? This is the case that ECU assists the driver to speed up / slow down quickly according to the current vehicle condition.
Therefore, the ECU will help the driver to achieve the desired acceleration / deceleration operation according to the vehicle conditions during the driving of the electronic accelerator model, making it easier for the driver to operate the accelerator pedal.
3. Principle of power booster
Power booster is developed to improve the throttle hysteresis. According to the characteristics of electronic throttle
, this product has the following characteristics:
(1) Accelerating the throttle opening and improving the static response is achieved by improving the sensitivity of throttle response. When the system finds that the driver has the desire to accelerate, it will drive the throttle to open as soon as possible through the circuit, so that the sensitivity of throttle response is improved. The accelerator pedal signal is still stepless.
(2) Amplify the acceleration of the throttle signal and improve the dynamic response. When the accelerator pedal is depressed, the accelerator will calculate the change rate of the throttle signal according to the amplitude and time of pressing. The faster the change is, the stronger the acceleration requirements are, and the power boost will increase the change rate. The final effect is that the acceleration dynamic response is better and faster.