Pressure fluctuation damping for IC engine direct fuel injection system, comprises series or teed tubes, and/or absorbent inserts, added to injector delivery pipes, or to common rail

摘要

In the direct system, fuel injected directly (3) into each individual cylinder (6) is delivered from a common rail (1) supplied from an engine-driven high-pressure pump (7). Timing and duration of each injection is controlled by an electronic management unit. Injection pressures are subject to undesirable fluctuations attributable to the cyclic operation of the injectors themselves and to the pump characteristics In one proposal, a short tube (12) of greater diameter is inserted in the feed pipe (2). For an internal pipe diameter of 3mm, the insert might have diameter 9mm and length 25mm. Alternative devices described include -: a quarter wave resonator formed by a teed stub tube or by concentric interconnected sleeves: a 3-section stub progressively reducing in diameter: an interference device offering a parallel but longer alternative fuel path: a sealed cylinder fixed over a perforated section of the feed pipe. In this last case, and in the simple enlargement, the device is opt. filled with porous absorbent material attenuating through frictional effects: a similar effect may be produced by a porous absorbent liner in the common rail.