Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
2000-01-19
2001-09-11
Moulis, Thomas N. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C251S127000
Reexamination Certificate
active
06286486
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a fuel system for an internal combustion engine, and more particularly to a fuel system including a pressure regulator for a vehicle powered by a fuel injected internal combustion engine.
BACKGROUND OF THE INVENTION
Most modem automotive vehicles are powered by an internal combustion engine that is connected with a source of fuel, e.g., gasoline, diesel, natural gas, alcohol, hydrogen, etc. The fuel is stored on-board the vehicle and supplied to the engine in a precisely controlled manner.
According to a conventional fuel system, as shown in
FIG. 11
, gasoline is stored in a tank on-board a vehicle. The gasoline is withdrawn from the tank by a pump and fed through a filter to fuel injectors, which deliver the gasoline to combustion cylinders in the engine. The fuel injectors are mounted on a fuel rail to which fuel is supplied by the pump. The pressure at which the fuel is supplied to the fuel rail must be metered to ensure the proper operation of the fuel injectors. Metering is carried out using pressure regulators which control the pressure of the fuel in the system at all levels of engine speed.
Known pressure regulators, as shown in
FIG. 12
, employ a spring biased valve seat with a longitudinal flow passage. A detailed view of a known valve seat is shown in FIG.
13
. The valve seat is biased to a closed position to prevent the flow of fuel through the pressure regulator at low fuel pressures. As fuel pressure builds in the system, the pressure against the valve seat overcomes the biasing force of the spring, allowing fuel to flow through the valve seat, thereby controlling the fuel pressure in the system.
Fuel flow rate, measured in liters per hour, through known pressure regulators tends to be low at high engine speed, measured in revolutions per minute, as large quantities of fuel are consumed in the combustion process. At low engine speeds, less fuel is consumed in combustion and flow rates through the pressure regulators are high. These high fuel flow rates through known pressure regulator valve seats produce unacceptably high noise and pressure levels. A valve seat is needed that maintains flow-related noise and pressure within acceptable levels, even at high fuel flow rates.
SUMMARY OF THE INVENTION
The present invention provides a fuel system that comprises a tank, a pump, a flow-through pressure regulator, and piping connecting these components and an internal combustion engine. The flow-through pressure regulator maintains a substantially constant noise output from low fuel flow rates to high fuel flow rates. Further, the pressure of fuel in the regulator remains substantially constant or decreases slightly as the fuel flow rate increases from a low fuel flow rate to a high fuel flow rate. The flow-through pressure regulator includes a housing having an inlet and an outlet offset along a longitudinal axis. The housing is separated by a divider into a first chamber and a second chamber. The divider has a passage that communicates the first chamber with the second chamber. The passage includes a first section extending along the longitudinal axis and a second section extending transverse to the longitudinal axis. The first section provides a first communication path between the first chamber and the second chamber. The second section provides a second communication path between the first section and the second chamber. A closure member permits or inhibits flow through the passage.
The divider can include a valve seat that is suspended by the divider in the housing and provides the passage. The valve seat has a first seat portion and a second seat portion disposed along the longitudinal axis on opposite sides of the divider such that the first seat portion is disposed the first chamber and the second seat portion is disposed in the second chamber. The first section of the passage extends along the longitudinal axis through the first portion and into the second portion of the seat. The second section of the passage extends transverse to the longitudinal axis in the second portion of the seat.
The valve seat can comprise a first surface disposed in the first chamber, a second surface disposed in the second chamber, and a side surface disposed between the first surface and the second surface. The first section of the passage communicates with the first surface and the second surface. The second section communicates with the first section and the side surface. The first section has a first wall extending from the first surface to the second surface. The second section has a second wall and a third wall, each communicating with the first section and the side surface. Each of the first wall, second wall, and third wall can comprise a cylindrical configuration. The first wall can have a first diameter, second diameter, and third diameter, where the first diameter comprises a selected value. The second diameter is proximate the second wall and the third wall. The diameter of the second wall and the third wall comprise a value approximately equal to the square root of the selected value. In the preferred embodiment, each of the second wall and the third wall extends through the first wall to diametrically opposed locations on the side surface. The first wall, the second wall, and the third wall comprise, respectively, a first central axis, a second central axis and a third central axis that intersect at a common point located within the second portion of the seat.
In a preferred embodiment, the divider is a diaphragm, and a first biasing element is located in the second chamber. The closure member includes a ball disposed in a retainer. The housing includes a first cup-shaped member and a second cup-shaped member. In a preferred embodiment, the flow-through pressure regulator of the present invention has a sound rating in Sones that remains substantially constant from a low fuel flow rate to a high fuel flow rate. The pressure of fuel in the regulator of the present invention remains substantially constant or decreases slightly as the fuel flow rate through the regulator increases from a minimum fuel flow rate to a maximum fuel flow rate.
The present invention also provides a low noise valve seat for a flow-through regulator. The valve seat has an exit geometry which reduces output noise and pressure levels at high fuel flow rates. The valve seat includes a first seat portion having a first surface disposed about a central axis, a second seat portion having a second surface offset from the first surface along the central axis, a side surface disposed between the first surface and the second surface and a passage extending from the first chamber through the first portion and the second portion to the second chamber. The passage has a first section and a second section. The first section of the passage extends along the central axis in both the first portion and the second portion of the valve seat. The second section of the passage extends transverse to the longitudinal axis in the second portion of the valve seat. The first section communicates with the first surface and the second surface, and the second section communicates with the first section and the side surface.
The present invention also provides a method of inversely correlating maximum pressure and flow values of a flow-through regulator while stabilizing noise generation of the flow-through regulator. The flow-through regulator includes a housing with an inlet and an outlet offset along a longitudinal axis, a divider separating the housing into a first chamber and a second chamber, a passage through the divider that provides communication between the first chamber and the second chamber, and a closure member that permits or inhibits flow through the passage. The method is achieved by establishing a first communication path between the first chamber and the second chamber with a first section of the passage extending along the longitudinal axis, and establishing a second communication path between the first section and the second chamber with a second section of
Hem Bunnareth
Kilgore Jason T.
Robinson Barry S.
Moulis Thomas N.
Siemens Automotive Corporation
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