Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
1999-11-12
2001-02-06
Moulis, Thomas N. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C138S030000
Reexamination Certificate
active
06182637
ABSTRACT:
FIELD OF INVENTION
This invention relates to a damper for automotive fuel systems, and more particularly, a damper for minimizing fuel pressure pulsations in a fuel rail.
BACKGROUND OF INVENTION
Existing fuel delivery systems which use an in-tank fuel pressure regulator usually employ an energy absorbing device mounted on or near the fuel rail. The energy absorbing device serves to compensate for fuel pressure pulsations created in the fuel rail that occur as a result of sequential firing of fuel injectors operatively connected to the fuel rail. A known energy absorbing device is a damper mounted on the fuel rail. A damper of this type is disclosed in commonly-assigned, co-pending U.S. patent application Ser. No. 09/086,084, entitled “Fuel Rail Damper”, filed May 28, 1998, which is incorporated herein in its entirety by reference. This known damper has an upper chamber and a lower chamber separated by a solid, flexible diaphragm. The upper chamber contains a spring that biases the diaphragm toward the lower chamber. The spring is retained in a spring seat, which engages the diaphragm. The lower chamber has an opening which allows fuel to enter from the fuel rail and contact the diaphragm. Changes in fuel pressure cause the diaphragm to adjust the volumetric capacity of the lower chamber to damp the fuel pressure changes.
Applicants have discover that over prolonged periods of operation, the known damper can exhibit reduced operative capacity. As the diaphragm adjusts the volume of the lower chamber, the spring seat reciprocates within the upper chamber. While reciprocating in the upper chamber, the spring seat can become galled from contacting the upper chamber, even though the spring seat is sized to minimize contact with the upper chamber. It is believed that a spring seat with galled surfaces can reduce operability of the damper. Thus, a damper arrangement is needed which can, under prolonged operative conditions, maintain a stable damping coefficient.
SUMMARY OF THE INVENTION
The present invention provides a damper for a fuel system. The damper includes a first chamber with an interior surface, and a second chamber with a fuel receiving opening. A diaphragm separates the first chamber and the second chamber. A device is disposed within the first chamber that biases the diaphragm toward the fuel receiving opening. A retainer, which supports the device proximate the diaphragm, is located in the first chamber. The retainer has a surface exposed to the interior surface of the first chamber. A lubricant is disposed on at least one of the interior surface of the first chamber and the surface of the retainer.
In a preferred embodiment, the retainer is a spring seat and the device biasing the diaphragm is a spring. The seat is a cup-shaped member having a lateral side surface exposed to the interior surface of the first chamber. The lubricant is disposed on the lateral side surface, and is, preferably, disposed on the lateral side surface by a lubricity additive of a plating disposed on the lateral side surface.
The present invention also provides a method of damping pressure pulsations in a fuel system. The method is accomplished by separating a housing into a first chamber and a second chamber with a diaphragm; providing the second chamber having a fuel receiving opening; disposing a device in the first chamber that biases the diaphragm toward the fuel receiving opening; supporting the device proximate the diaphragm with a retainer; and providing lubricant between the retainer and the first chamber.
REFERENCES:
patent: 3967363 (1976-07-01), Meyer
patent: 4051865 (1977-10-01), Cocking et al.
patent: 4089919 (1978-05-01), Sanson
patent: 4164954 (1979-08-01), Ballard
patent: 4685491 (1987-08-01), Fulmer et al.
patent: 5094433 (1992-03-01), Dan et al.
patent: 6032651 (2000-03-01), Field
Cecelic Joseph K.
Kilgore Jason T.
Moulis Thomas N.
Siemens Automotive Corporation
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