Engine fuel systems

Details Engine fuel systems Engine fuel systems

2000-03-13

2001-04-24

Moulis, Thomas N. (Department: 3747)

Internal-combustion engines

Charge forming device

Fuel flow regulation between the pump and the charge-forming...

C123S516000, C123S514000

Reexamination Certificate

active

06220228

ABSTRACT:

The invention relates to engine fuel systems and to engine assemblies incorporating such systems.
An engine fuel system provides fuel from a source to an engine. Since the fuel may include entrained air, and since such air is undesirable in the fuel fed to the engine, it is customary to provide a device for removing such air before it reaches the engine.
It has previously been proposed to use for this purpose manually operated bleed valves, float control valves or restrictor orifices. A manually operated bleed valve opens an air vent when operated to allow the release of accumulated air. A float valve has a chamber containing the fuel which, as the chamber fills with air, causes the float to open an air vent to release accumulated air until the float once again reaches a position where the air outlet is closed. A restrictor orifice is a small aperture intended to allow the passage of air but halt the passage of fuel. A typical orifice diameter might be 0.25 to 0.35 mm.
All of these proposals have problems. Manual valves are difficult to operate and, if they are not closed as the last air exits, they can cause the spillage of fuel. In addition, they cannot be operated during the time the engine is running if it is installed in a vehicle.
Float valves are expensive and can be orientation-sensitive when the engine forms part of a vehicle. They are also sensitive to vibration and shock.
The problem with restrictor orifices is that they are easily blocked by a single large particle. In addition, when the system is initially filled from dry, the flow rate through the orifice is not sufficiently high. In order to overcome this, some systems using orifices incorporate other systems for removing the initial air in the system. These can involve the application of vacuum or manual venting. If the restrictor orifice is made larger, for example in excess of 0.5 mm in diameter, the blockage and air flow problems are reduced but there is significant flow of fuel through the orifice. While this fuel can be returned to the source, the engine can become starved of fuel as the filter blocks or the returning fuel can transmit so much heat to the source that the engine never becomes warm. In a vehicle, this can cause the passenger compartment heater to become inoperative.
In view of these difficulties, restrictor orifices and float valves are normally avoided. Engines in vehicles are normally provided with manual valves with instructions to users on how to start the vehicle if the vehicle runs out of fuel.
According to a first aspect of the invention, there is provided an engine fuel system comprising a passage for conveying fuel from a source to an engine, the passage including an air vent, an oleophobic filter medium being provided in said vent through which air is vented but which resists the passage of fuel without wetting out.
The term “oleophobic”, as used in this specification in relation to a filter medium, defines a filter medium which yields a minimum contact angle of between 100° and 140°, preferably about 100°, with mineral oil when measured by the Sessile Drop Method. This known method involves the measurement of the tangent angle of a stationary drop of oil resting on a flat surface of the filter medium, the angle being measured by a microscope.
The invention also includes within its scope an engine assembly comprising an internal combustion engine and a source of fuel and an engine fuel system according to the first aspect of the invention, connected between the fuel source and the engine.
The use of an oleophobic filter medium allows the venting of large volumes of air but minimal volumes of fuel.


REFERENCES:
patent: 4079717 (1978-03-01), Shirose
patent: 4117817 (1978-10-01), Nishida
patent: 4298358 (1981-11-01), Ruschke
patent: 4314539 (1982-02-01), Schade
patent: 4589395 (1986-05-01), Timms et al.
patent: 4658797 (1987-04-01), Brand
patent: 5115784 (1992-05-01), Mito et al.
patent: 5468388 (1995-11-01), Goddard et al.
patent: 5730106 (1998-03-01), Gonzalez
patent: 5740784 (1998-04-01), McKinney
patent: 5832902 (1998-11-01), Davis et al.
patent: 5863317 (1999-01-01), Smith et al.
patent: 5894833 (1999-04-01), Kikuchi et al.
patent: 6063152 (2000-05-01), Teter
patent: 307 739 (1989-03-01), None
patent: 90 11444 (1990-10-01), None
patent: 2 140 706 (1984-04-01), None

Affiliated with

Also associated with

Rating

Engine fuel systems does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Engine fuel systems, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Engine fuel systems will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2536154