| 摘要 |
A variable Venturi slide includes a beveled edge at an oblique angle to lower surface of the slide and air flow, and an auxiliary hole having an opening on the beveled edge communicating between the air flow and the interior of the variable Venturi slide. By being located on the beveled edge, the opening of the auxiliary hole is effectively kept out of the high velocity low air pressure air stream at lower air velocities during partial throttle conditions. The auxiliary hole bleeds vacuum from the interior of the variable Venturi slide, picked up by the other lift hole located on the bottom of the slide, and slows the slide lift rate. The slide stays down or rises very slowly under conditions in which a conventional prior art slide would be starting to rise at a linear rate. At higher air velocities, when the throttle plate is opened quickly or operated at near wide open conditions, the opening of the auxiliary hole adds vacuum to the interior of the slide, and increases the slide lift rate. In such manner, the lift rate of the slide is reduced at lower air pressure and velocity, while at the same time, the lift rate of the slide is increased at higher air pressure and velocity. The resulting non-linear lift rate keeps the fuel mixture lean under partial throttle conditions when driving conditions require it, yet provides a ratio of air to fuel mixture that represents the optimum value for the prevailing conditions of engine speed and load throughout a broad range, thereby effecting an improvement in fuel economy and reducing the emission of pollutants.
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