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The electronic throttle body can automatically open or close the throttle according to the driver’s will to apply the accelerator pedal to let the engine work under the corresponding operating mode. The electronic throttle has cancelled the conventional throttle guy and the opening of throttle is controlled by ECU based on the signal from accelerator pedal and other signals (such as A/C, power assisted steering, back and gearshift etc.) through an electronic step motor inside the electronic throttle body. In addition to cancel of conventional idle speed by-pass and idle speed step motor, there are also throttle position sensors on the electronic throttle body to feed back the opening of the throttle. This suite of throttle position sensor is different from the common one; totally two suites of throttle position sensors are installed inside the electronic throttle body to monitor rationality of the signals from the latter; when any problem occurs in a certain signal, ECU can still use the other suite of signals to work on. 6.2 Working principle: The throttle driving motor is a micro motor, which is composed of multi steel stators in a circle and a rotor, with one coil on each steel stator. The rotor is a permanent magnet with a nut at its center. All stators coils are constantly power on. As long as the direction of current of one coil is changed, the rotor will turn a certain angle. When the directions of current of all stator coils is changed in a proper order, a rotating magnetic field is formed, which will drive the rotor made from permanent magnet rotate along a certain direction. Its principle is just that of a micro direct current motor. This motor drives a suite of special gear reducing mechanism and a bidirectional spring; when the system is under power off condition, this mechanism can ensure that the opening of throttle valve plate maintains at a safe position where is bigger than that for idle speed but not too high, so that the vehicle can continue to run; if engine ECU has entered this failure mode, when applying the accelerator pedal, the valve plate of the electronic throttle body will no longer act. 电子节气门
6.3 Failure diagnosis: ECU can monitor short-circuit and break of coil of the throttle driving motor, and light the engine failure light in case of such failure to let the engine enter failure mode, when the engine fails to accelerate, has very poor driving performance and needs maintenance immediately.
7. Oxygen Sensor 7.1 Function of the sensor: Oxygen sensor is one of the principal sensors on modern autos; it can feed back the mixture strength by detecting oxygen content in exhaust gas. ECU will correct the mixed gas based on the Electronic throttle |