JPS6463627A - Throttle valve device - Google Patents

Abstract

PURPOSE:To prevent the runaway of an engine when abnormality occurs in it by providing the first throttle valve which is manually controlled and small in its diameter and the second throttle valve which is electrically controlled and large in its diameter in parellel with each other, and moreover a means for fully closing the second throttle valve when the abnormality occurs in a driving part of the second throttle valve. CONSTITUTION:When a driver steps down on the accelerator pedal 7 during the normal operation of an engine, a controller 19 computes the desired opening of a throttle valve 12 on a detecting signal issued from an accelerator sensor 8, and then a motor 16 is controlably driven to remove deviation between the above-mentioned desired opening and an actual opening obtained through a throttle opening sensor 21. On the other hand, when abnormality occurs in the motor 16, the controller 19 disengages a clutch 15, end energizing force of a returning spring 18 therefore makes the throttle valve 12 return to its fully closing position. In this case, the first throttle valve 11 is operated by stepping on the accelerator pedal 7 to make the controlling of an engine up to about 20% of the maximum air volume required for the engine possible, and the self-running of a car therefore becomes possible.