I. Field of the Invention
The present invention relates generally to fuel injector assemblies and, more particularly, to a fuel injector assembly for a direct injection engine.
II. Description of Material Art
Many modern day automotive vehicles utilize direct fuel injection into a combustion engine to propel the vehicle. Such direct injection engines enjoy increased fuel economy as well as relatively lightweight and compact construction.
In a direct injection engine, bores are formed through the engine block to each of the cylinders contained in the engine. A fuel injector is then positioned within each fuel injector bore so that one end of the fuel injector is open to one of the combustion chambers for the engine. Consequently, upon activation, the fuel injectors inject the fuel directly into the combustion chamber rather than upstream from the combustion chamber as in the previously known multipoint fuel injection systems.
In order to supply fuel to the fuel injectors, a fuel rail extends along the side or top of the engine so that the fuel rail overlies the fuel injector bores to the combustion chambers. The fuel rail is secured to the engine block by a bracket and includes one fuel cup for each fuel injector for the engine. Thus, with a fuel inlet end of the fuel injector positioned in the cup and the fuel outlet end positioned in the fuel injector bore in the engine block, upon activation or opening of the fuel injector, pressurized fuel from the fuel rail passes through the fuel injector and directly into the combustion chamber. An engine control unit (ECU) provides electrical output signals to each of the fuel injectors to open the fuel injectors at the desired time and for the desired duration.
Because the fuel is injected directly into the combustion chamber, the fuel injection from the fuel injectors must necessarily be high pressure sufficient to overcome the pressure in the engine combustion chamber. This high pressure fuel injection thus necessarily exerts an outward force onto the fuel rail bracket each time the fuel injector is opened.
One disadvantage of these previously known direct injection engines is that the bracket for the fuel rail is typically attached to the side of the rail. However, during the operation of the engine, the force exerted by the fuel injectors onto the rail each time the fuel injector was opened or activated imposed a torsional load on the fuel rail. Indeed, in some cases, the torsional force on the fuel rail caused by activation of the fuel injectors even imparted a torsional force not only on the fuel rail bracket, but also on the fuel injectors themselves.
A still further disadvantage of direct injection internal combustion engines is that any vibration between the fuel bracket and the fuel rail creates noise from the engine. This noise, furthermore, is most noticeable, and thus most objectionable, when the engine is at slow or idle speeds.