Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
2000-04-25
2001-11-13
Moulis, Thomas N. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C138S028000
Reexamination Certificate
active
06314942
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to pressure dampers for use in fuel delivery systems for engines for motor vehicles.
BACKGROUND OF THE INVENTION
In fuel rails for injector-based fuel injection systems, the various devices associated with the fuel system cause pressure waves in the fuel to propagate through the fuel rails. Such pressure waves, if occurring at the wrong time, may have a small amount of fuel leaving the fuel rail and being injected into the engine at the time the injector is pulsed open. In addition, such pressure waves cause noise in the system that may be objectionable. Pressure pulses will give false readings to fuel pressure regulators by operating the regulator with a false indication of fuel pressure, which may result in fuel being bypassed and returned to the fuel tank.
A known pressure dampening system uses elastic walls forming the fuel supply line. As pressure pulses occur, the elastic walls function to dampen the pressure pulsations. Other pressure dampening systems use a pressure damper plugged in the end of a fuel rail with a pressure regulator at the other end. Still other pressure dampening systems use a compliant member operable to reduce peak pressure during injector firing events. The member is positioned in the fuel rail so as to not adversely affect the flow of fuel to an injector opening in the rail. The member is not free to rotate in the rail and the pressure pulses are dampened by the member, which is a pair of welded together shell halves with an enclosed airspace. Other pressure dampening systems use an in-line fuel pressure damper from the outlet of the fuel filter to the fuel rail. The damper is a pressure accumulator which operative to reduce transient pressure fluctuations induced by the fuel pump and the opening and closing of the fuel injectors.
Another dampening system utilizes an integral pressure damper that is attached to the fuel rail. The return tube is brazed to the rail and then at a convenient time in the assembly process the damper, which is a diaphragm, is attached to the return tube and crimped into position. The diaphragm operates to reduce audible operating noise produced by the injector pressure pulsations.
Still another dampening system uses a pulse damper in the fuel pump comprising a hollow body formed of a thin walled tube of flexible and resilient plastic material with heat sealed ends forming at least one chamber. The chamber carries a compressible gas to dampen pressure pulsations. Another dampening system uses a bellows modulator inside a gear rotor fuel pump for reducing pump noise by reducing the amplitude of fuel pressure pulses. Yet another system uses a bellows-like device at the junction of the lines of the flow path of the fluid from a fuel feed pump thereby forming a discontinuity in the flow path to reduce compressional vibrations of fuel being conveyed.
It would be beneficial to develop a dampening element that is relatively compact and inexpensive to manufacture and install.
BRIEF SUMMARY OF THE INVENTION
Briefly, the present invention provides a fuel rail assembly. The fuel rail assembly comprises a generally hollow fuel rail having a longitudinal rail axis extending therethrough and a fuel damper element having a wall and a longitudinal damper element axis extending therethrough. The fuel damper element is located within the fuel rail. The damper element axis is generally parallel with the rail axis.
The present invention also provides a dampening element for a fluid conduit. The dampening element comprises an elongated member adapted to be inserted into the fluid conduit. The elongated member has at least one generally rounded portion extending along a length of the member.
Additionally, the present invention provides a method of reducing pressure pulsations in a fluid conduit. The method comprises providing a fluid conduit with a dampening element located therein, the dampening element having an elongated member having at least one generally rounded portion extending along a length of the member; and flowing pressurized fluid through the fluid conduit.
Additionally, the present invention provides a method of forming a fuel rail assembly. The method comprises compressing a wall of an elongated member toward a longitudinal axis of the element in at least two locations along a length of the member, forming at least one generally rounded portion; and inserting the elongated member into a fuel rail.
REFERENCES:
patent: 2409304 (1946-10-01), Morrison
patent: 4651781 (1987-03-01), Kandelman
patent: 4823844 (1989-04-01), Bartholomew
patent: 5575262 (1996-11-01), Rohde
patent: 5617827 (1997-04-01), Eshleman
patent: 5709248 (1998-01-01), Goloff
patent: 5845621 (1998-12-01), Robinson et al.
patent: 5896843 (1999-04-01), Lorraine
Kilgore Jason T.
Robinson Barry S.
Moulis Thomas N.
Siemens Automotive Corporation
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