Fluid handling – Line condition change responsive valves – Thermal responsive
Reexamination Certificate
1999-01-12
2001-10-02
Hepperle, Stephen M. (Department: 3753)
Fluid handling
Line condition change responsive valves
Thermal responsive
C123S460000, C123S464000, C137S505140, C137S505420
Reexamination Certificate
active
06296012
ABSTRACT:
TECHNICAL FIELD
The invention relates generally to a fuel system for an internal combustion engine for use, for example, in an automobile, and particularly to a fuel pressure regulator employing a shape memory device for altering the calibration pressure in response to a predetermined temperature of the fuel within the pressure regulator.
BACKGROUND OF THE INVENTION
In U.S. Pat. No. 5,413,077 of common assignee herewith, there is disclosed a returnless fuel pressure regulator which can be mounted on or adjacent the fuel rail assembly close to the fuel injectors and which regulator avoids any need for a return line to the fuel tank. The regulator disclosed in that patent also includes an intake manifold vacuum reference which essentially alters the calibration pressure of the regulator dependent upon throttle position.
A further modification of the pressure regulator illustrated in that patent is described and illustrated in U.S. patent application Ser. No. 09/056,044, filed Apr. 6, 1998 (Attorney Docket No. 98P7662). In that application, the check valve spring is formed of a shape memory alloy. The spring is responsive to a predetermined temperature to alter the fuel flow and/or pressure characteristics of the regulator and functions as a switch for providing regulated pressure or non-regulated pressure.
BRIEF SUMMARY OF THE INVENTION
In accordance with the present invention, a temperature responsive shape memory device is used in the diaphragm assembly of a returnless regulator of the type disclosed in U.S. Pat. No. 5,413,077 to alter the calibration pressure of the pressure regulator and particularly to increase the regulation pressure during a hot soak and to facilitate a hot start of the combustion engine. Particularly, the shape memory device preferably comprises a spring carried by the diaphragm assembly of the returnless regulator and engageable with a movable member, also carried by the diaphragm assembly. The member is mounted for movement with and relative to the diaphragm assembly. Particularly, the member is movable relative to the diaphragm assembly toward and away from the movable valve element of the check valve in response to a predetermined temperature of fuel within the regulator. Depending on whether the fuel temperature increases or decreases to the predetermined temperature, the member will displace the valve element away from or toward the valve seat, respectively. Preferably, the member comprises a post, which bears against the valve element throughout the range of movement of the valve element between its fully open and closed positions.
For example, when the fuel in the fuel rail and, consequently, within the pressure regulator increases in temperature during a hot soak, i.e., when the engine is off and heat concentrates in the fuel rail, it is important to prevent vaporization of the fuel within the fuel rail and hence vapor lock, which would preclude restarting of the engine. As the temperature of the fuel within the pressure regulator increases, the pressure of the fuel line causes the diaphragm to move away from the check valve, causing the valve to move toward a valve-closed position. Should the valve close, a vapor lock may occur. With the shape memory device carried by the diaphragm assembly, the shape memory device responds to a predetermined temperature and elongates to displace the post and hence the valve element in a direction opening the valve, thereby equalizing the system pressure and preventing vapor lock and the fuel rail from being over-pressurized. At temperatures above the predetermined activation temperature of the shape memory device, the member maintains the check valve in an open position enabling high pressure fuel to flow from the fuel tank to the fuel rail, thereby maintaining the fuel in liquid form and avoiding vapor lock in the fuel rail whereby a hot restart of the engine can be accomplished.
The temperature responsive shape memory device in effect causes a change in the calibration pressure of the pressure regulator. That is, the calibration pressure is set by a calibration spring within the control chamber of the regulator housing. The shape memory device, however, when actuated at a predetermined fuel temperature, increases the calibration pressure. This tends to maintain the fuel in the fuel rail in liquid form at system pressure and avoids the hot restart problem by preventing vapor lock and over-pressurization of the fuel in the fuel rail.
In a preferred embodiment according to the present invention, there is provided a fuel pressure regulator comprising a housing, a movable diaphragm dividing the housing into a fuel chamber and a control chamber, the housing having a fuel inlet port for flowing pressurized fuel toward the fuel chamber and a fuel outlet port for flowing pressure regulated fuel from the housing, a valve between the fuel inlet port and the fuel outlet port and including a valve seat, a valve element movable toward and away from the valve seat and a spring for biasing the valve element toward the valve seat, the diaphragm including a member movable with and relative to the diaphragm toward and away from the valve element and a device carried by the diaphragm engaging the member and formed of a temperature responsive shape memory material for displacing the valve element relative to the seat in response to a predetermined temperature of the fuel within the pressure regulator.
In a further preferred embodiment according to the present invention, there is provided a fuel pressure regulator comprising a housing, a movable diaphragm dividing the housing into a fuel chamber and a control chamber, the housing having a fuel inlet port for flowing pressurized fuel toward the fuel chamber and a fuel outlet port for flowing pressure regulated fuel from the housing, a valve between the fuel inlet port and the fuel outlet port and including a valve seat, a valve element movable toward and away from the valve seat and a spring for biasing the valve element toward the valve seat, a calibration spring carried by the housing for calibrating the pressure regulator to a predetermined regulation pressure and a device responsive to a predetermined temperature of the fuel in the regulator for changing the calibration of the pressure regulator from the predetermined regulation pressure to a second calibration pressure.
Accordingly, it is a primary object of the present invention to provide a fuel pressure regulator having a temperature responsive shape memory device which avoids problems associated with high fuel temperatures, facilitates a hot restart of the engine and alters the calibration pressure when the temperature of the fuel lies at or above a predetermined temperature.
REFERENCES:
patent: 4778104 (1988-10-01), Fisher
patent: 5174326 (1992-12-01), Steinert et al.
patent: 5413077 (1995-05-01), Hornby et al.
patent: 5509390 (1996-04-01), Tuckey
Kilgore Jason T.
Robinson Barry S.
Hepperle Stephen M.
Siemens Automotive Corporation
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