Electronically controlled throttle valve with limp home mechanism

Abstract

The subject invention is a linkage assembly for an electronically controlled throttle (ETC) that provides for the precise setting of a limp home engine speed for a vehicle. Essentially a controlled amount of movement is attained between a closed position and a limp home throttle position. A throttle valve is attached to a first shaft and rotates to regulate air intake. The first shaft is attached to a sector gear. The sector gear is driven by the ETC. A stop bracket limits the amount that the sector gear can close the throttle valve. The stop bracket defines an opening, and a cam is disposed within the opening. A spring biases the stop bracket against the cam. Normally, the ETC can overcome the spring and the stop bracket is forced against the cam such that stop bracket contacts the cam to define a closed throttle position. Of course, when operational the ETC can drive the valve to open position as demanded by the vehicle. The limp home engine speed is set by a preset by the difference between the length of the opening of the stop bracket and a width of the cam. If the ETC becomes disabled, there is not enough force to overcome the spring and move the sector gear to the closed throttle position, instead the sector gear remains at the second stop position to provide the limp home engine idle speed that allows a driver to sufficiently maneuver the vehicle.