Along with rapid development of auto industry, auto manufacturers in America, Germany, Japan and other countries successively adopted electronic throttle control system early in 1990s. Electronic throttle control system mainly consists of throttle pedal, pedal displacement sensor, ECU (electronic control unit), data bus wire, servomotor and choker executing mechanism. Electronic throttle is generally adopted in fairly new models. Electronic throttle is named in comparison with fly-by-wire throttle which features direct connection between throttle pedal and choker with thin steel wire. The treading depth of throttle pedal directly corresponds to the opening width of choker. Electronic throttle is free of wire. Treading depth of throttle will be converted into resistance value after a potentiometer (with variable resistance) is mounted in pedal. Electronic system of automobile indirectly determines the depth of pedal through sampling of resistance value. Finally, ECU will activate stepping motor to control the opening width of choker. It can be easily found through principle comparison that fly-by-wire throttle features simple system and direct control, with the proportion of the opening width of throttle and choker being 1:1. Characteristics of electronic throttle are as follows: throttle pedal only indicates driver’s operating intention, while the final right to control choker belongs to ECU.
2. Characteristics of Electronic Throttle Control System and ECU(ECU)
In models with electronic throttle control system, ECU will analyze the treading depth of throttle in combination with auto conditions when controlling electronic choker, and then calculate appropriate opening width of choker at the current time. When diver speeds up suddenly at the time of startup (tread the pedal to the utmost), ECU will perform analysis according to the current auto speed, opening width of choker and other factors, appropriately restrict the opening width of choker from the perspective of fuel saving and reasonable exhaust emission, and control fuel spray system to restrict maximum spray of fuel injection nozzle at the same time. In this way, driver will feel that automobile begins to start after throttle is treaded for a while, which is the so-called throttle lagging. Therefore, throttle lagging is actually the result of ECU operation through restricting instant output of engine, which can make automobile more environmental-friendly and energy-saving.
Operating Principle of Strong booster
(1) Accelerating choker opening and improving static response
“Acceleration” of Strong booster is realized mainly through improving the responding sensitivity of choker. When ECU finds that driver has the intention for acceleration, it will activate rapid opening of choker via circuit signals to improve the responding
sensitivity of throttle.
(2) Speeding up throttle signals and improving dynamic response
When accelerator treads on throttle pedal, Strong booster will calculate the alteration rate of throttle signals according to treading depth and time. Alteration rate is in proportion to accelerating requirements. Strong booster will enhance such alteration rate and finally realize maximum dynamic response of auto acceleration.
(3) Providing false driving style for ECU’s adjustment of engine parameters
ECU of modern engine generally has the capacity of self-adapting driving style. If driver often treads on throttle quickly to a considerable depth (also known as pulling speed), ECU will gradually consider that the driver’s style tends to be “violent”. In this way, engine will slowly adjust choker and fuel spray system, etc. to obtain optimal adjusting parameters of engine under this style. After Strong booster is used for a long time, even if the driver drives the car with previous “mile” driving style, engine will still acquire experience of “violent” driving, which is equivalent to the adjustment of ECU parameters. At the long last, engine will automatically amend its parameters to adapt to such driving style.