| 摘要 |
A throttle body for a fuel injection system of an internal combustion engine, comprising an air valve and a throttle valve which are arranged in series in an intake bore defined in the throttle body, and a fuel injection nozzle which is adapted to inject fuel into the intake bore. The air valve is biased by a spring towards its closing direction and can be opened by the air flow hitting the air valve and/or by a vacuum actuator which tends to increase the opening angle of the air valve according the magnitude of the negative pressure existing in the intake bore between the air valve and the throttle valve. The throttle body further comprises for instance a solenoid valve which prohibits the action of the actuator when the engine has not been warmed up, when the rotational speed of the engine is not sufficiently high, or when the opening angle of the throttle valve is not sufficiently great. A timer prevents abrupt opening of the air valve even when all the conditions for opening the air valve have been met for the purpose of preventing the air/fuel mixture from becoming over lean.
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