Internal-combustion engines – Charge forming device – Fuel flow regulation between the pump and the charge-forming...
Reexamination Certificate
1999-05-14
2001-09-25
Miller, Carl S. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel flow regulation between the pump and the charge-forming...
C123S457000, C137S539000
Reexamination Certificate
active
06293259
ABSTRACT:
TECHNICAL FIELD
The present invention relates to automotive fuel systems for supplying fuels at a regulated pressure to an automotive engine and particularly relates to a pressure regulator for supplying fuel at a predetermined pressure wherein the regulator does not contain a movable diaphragm as the pressure control mechanism.
BACKGROUND
In typical pressure regulators for automotive fuel systems, there is often provided a pressure regulator having a movable wall or diaphragm dividing the regulator into chambers on opposite sides thereof at different pressures. The difference in pressure determines the position of the diaphragm, which in turn determines the size of a flow passage through the regulator. Thus, depending upon the difference in pressure on opposite sides of the diaphragm, the flow through the regulator is regulated to a predetermined pressure. In returnless fuel systems, for example, as illustrated in U.S. Pat. No. 5,413,077 of common assignee herewith, the disclosure of which is incorporated herein by reference, the diaphragm controls the position of a ball valve which is spring-biased toward a valve seat. Fuel flows past the spring and normally opened ball valve into a compartment on one side of the diaphragm for flow to a fuel rail. The opposite side of the diaphragm may have a vacuum reference. It will be appreciated that the difference in pressure between the chambers on the opposite sides of the diaphragm displaces the diaphragm, which in turn mounts a post for moving the ball valve away from the seat or permitting the ball valve to move toward the seat under the spring bias.
Such systems are eminently satisfactory for use in providing fuel to a fuel rail at a predetermined regulated pressure. It is well recognized that fuel systems with pressure regulators using diaphragms or movable walls have excellent performance characteristics. One of the advantages of the pressure regulator containing a diaphragm or movable wall is that a substantially constant pressure of fuel is supplied to the fuel rail over a full range of fuel flow. Varying pressure in the fuel rail would degrade engine performance. While such pressure regulators have been proven satisfactory, they require a substantial number of diverse parts, complicating assembly and causing increased associated costs. There has thus developed a need in a mechanical fuel system for a pressure regulator without a diaphragm or movable wall which provides the desired engine performance characteristics of substantially constant regulated fuel pressure over a wide range of flow conditions and which is relatively simple and inexpensive to manufacture.
DISCLOSURE OF THE INVENTION
In accordance with the present invention, there is provided a fuel system having a fuel pressure regulator without a movable diaphragm. Hence, the regulator of the present invention has a reduced number of parts, is inexpensive and simple to manufacture, and yet provides a substantially constant pressure of fuel over a wide range of fuel flow conditions suitable for an automotive engine without the use of a diaphragm. Particularly, the present invention provides a fuel system having a fuel rail for supplying fuel to the fuel injectors, a fuel tank for containing the fuel and a fuel pump for supplying the fuel at a certain pressure in the fuel system. The fuel pressure regulator hereof is provided in the fuel line or in the fuel tank and regulates the pressure of the fuel supplied to the fuel rail to a predetermined pressure without use of the movable diaphragm or wall. The present invention is particularly useful in an automotive returnless fuel system where the regulator hereof is mounted close to or in the fuel tank and supplies a regulated higher pressure fuel from the fuel tank for regulation to a lower substantially constant fuel rail pressure by an integrated returnless fuel regulator and without return of fuel to the tank.
To accomplish this, the pressure regulator hereof includes a ball valve movable toward and away from a valve seat which also forms a fuel inlet for the pressure regulator. On the opposite side of the ball from the valve seat is a flow channel director which is particularly sized to enable fuel flow through the pressure regulator at a substantially constant pressure over the full range of flow rates for automotive engine usage. It has been discovered that by manipulating certain of the geometries of the flow channel director and particularly the flow outlet passage, a pressure regulator suitable for use in an automotive fuel system is provided without the necessity of a diaphragm or movable wall. Moreover, the pressure regulator hereof controls the pressure sufficiently accurately over the range of flow rates to enable elimination of the diaphragm or movable wall typical of most pressure regulators. The pressure regulator, in accordance with the present invention, is sized according to the output of particular pumps. For example, for large automobiles with large engines, different sizes of pressure regulators would be required in comparison with smaller automobiles with smaller engines. That is, the flow characteristics of the pressure regulator hereof is dependent upon the flow from the pump outlet. However, for a given fuel pump size, a substantially constant regulated pressure is provided over the desired range of fuel flow. For example, employing the pressure regulator hereof without a diaphragm or movable wall and using the properly sized flow channel director, a substantially constant regulated pressure over a full range of 20-150 kg/hr is achieved. As a general proposition, the foregoing is achieved where the flow channel director passage is in relation to the mass flow of fuel according to the following equation:
d=
(0.52±0.02){square root over (
m
+L )}
where d is the diameter of the channel in mm. and m is the mass flow rate in grams per second. By following this equation within the range indicated, substantially constant fuel pressure is provided over the desired fuel flow range.
In a preferred embodiment according to the present invention, there is provided a fuel system for an internal combustion engine comprising a fuel rail for supplying fuel to fuel injectors, a fuel tank for containing fuel, a fuel pump for supplying fuel from the fuel tank under pressure to the fuel rail, a fuel pressure regulator for regulating the pressure of the fuel supplied to the fuel rail to a predetermined pressure, the regulator including a housing and a valve seat in the housing having a fuel inlet, a valve element movable toward and away from the valve seat, a flow channel director mounting the valve element on an opposite side thereof from the seat and a spring for biasing the flow channel director and the valve element toward the valve seat, the flow channel director having a plurality of passages therethrough, the valve element being movable toward and away from the seat, enabling flow of fuel through the inlet between the valve element and seat and through the flow channel passages for regulating the fuel pressure to a substantially constant value over a predetermined range of flow.
In a further preferred embodiment according to the present invention, there is provided a fuel system for an internal combustion engine comprising a fuel rail for supplying fuel to fuel injectors, a fuel tank for containing fuel, a fuel pump for supplying fuel from the fuel tank under pressure to the fuel rail, a fuel pressure regulator for regulating the pressure of the fuel supplied to the fuel rail to a predetermined pressure, the pressure regulator being sized to provide a substantially constant regulated pressure over a flow range of 20-150 kg/hr and without a movable diaphragm dividing the regulator into flow and non-flow chambers on opposite sides thereof.
In a still further preferred embodiment according to the present invention, there is provided in a returnless fuel system for an internal combustion engine having a fuel rail for supplying fuel to fuel injectors, a fuel tank for containing fuel, a fuel pump
Bennett Jan L.
Kilgore Jason T.
Robinson Barry S.
Miller Carl S.
Siemens Automotive Corporation
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