US 5,435,344 AGrant
Flow Through Fuel Pressure Regulator
Issue Date:1995-07-25
•3 Claims
•3 Drawing Sheets
Abstract
An in-tank fuel pressure regulator having a through-passage member on the moveable wall for controlling the flow of fuel from the inlet to the outlet chambers of the regulator. The through-passage member has a central through-hole in which is positioned a valve seat that mates with a valve closure member that is in the inlet chamber. The valve closure member is a truncated sphere that is swivel mounted to maintain seal tight alignment with the valve seat.
Metadata
Assignee
- Siemens Automotive L.P.
Inventors
- Barry S. Robinson
- Michael J. Hornby
Application Information
Application Number:US 2396653
Filing Date:1994-05-09
Priority Date:1993-07-14
Art Unit:347
Classifications
IPC:
G05D 1608
Field of Search:
137123251508;507;574;576509;514;46286
Patent Drawings (3 sheets)
Description
Field of the Invention
This invention relates to fuel pressure regulators that are used in fuel injection systems of internal combustion engines that power automotive vehicles.
Background and Summary of the Invention
From prior patents, including commonly assigned U.S. Pat. Nos. 4,928,729; 4,991,556; 5,002,030; and 5,076,320; it is known to mount a fuel pressure regulator on a fuel rail assembly for the purpose of regulating the pressure of the fuel that is supplied to fuel injectors mounted on the fuel rail. The pressurized fuel that is delivered to the fuel rail is pumped from a fuel tank through a fuel supply conduit, and excess fuel is returned from the fuel pressure regulator's return port through a fuel return conduit to the tank. This type of system is sometimes called a return type system. A typical fuel pressure regulator used in such a system comprises a housing having a movable wall that divides the housing into a fuel chamber and a control, or reference, chamber. The reference chamber's interior is referenced to engine intake manifold vacuum so that the regulated pressure across the fuel injectors is essentially insensitive to changes in manifold vacuum.
Another type of fuel injection system does not have a fuel return conduit and is sometimes called a non-return, returnless, or dead-headed system. In such a system, the fuel pressure is regulated at the tank, with the fuel pressure regulator being part of a pump module that is assembled into the tank and contains, inter alia, a fuel pump. If a fuel pressure regulator like the one in the above-described return system were to be used in a non-return system, a vacuum conduit from the engine intake manifold would have to be connected to its reference chamber if vacuum compensation were to be retained in the same way, and the fuel pressure regulator would simply spill excess fuel into the tank through its return port. On the other hand, if the reference chamber were exposed to the headspace of the tank, either intake manifold vacuum compensation would not be used or else it would have to be provided in some other way.
The present invention relates in one respect to an improvement in a fuel pressure regulator for a non-return system, and in another respect to an improvement in the mounting of such a fuel pressure regulator. The invention arises through the recognition that certain features of the prior fuel pressure regulator used in a return type system are unnecessary when used in a non-return system. As a result, the invention provides a novel and unique configuration for a non-return type fuel pressure regulator that uses fewer parts than its return type predecessor, and is therefore more cost-effective than simply moving the prior regulator into the tank. Several embodiments of the inventive fuel pressure regulator are disclosed.
The foregoing, along with other features, advantages, and benefits of the invention may be garnered from the ensuing detailed description of a presently preferred embodiment of the invention. Drawings accompany this disclosure and illustrate the best mode contemplated at this time for carrying out the invention.
Brief Description of the Drawings
FIG. 1 is a view of a representative fuel system for an I.C. engine, with portions shown schematically and portions broken away.
FIG. 2 is an enlarged cross-sectional view of a portion of FIG. 1 for showing the fuel pressure regulator and its mounting in greater detail.
FIG. 3 is a view similar to FIG. 2 showing a second embodiment.
FIG. 4 is an enlarged fragmentary view of a portion of FIG. 3, but showing a different operative condition.
FIG. 5 is a view similar to FIG. 2 showing a third embodiment.
FIG. 6 is an enlarged fragmentary view of a portion of FIG. 5 but showing a different operative condition.
FIG. 7 is an enlarged top plan view of one of the elements of the third embodiment shown by itself.
FIG. 8 is a top plan view of another element of the third embodiment shown by itself.
FIG. 9 is an elevational view of FIG. 8.
Description of the Preferred Embodiment
FIG. 1 shows a portion of a fuel injection system of an I.C. engine powered automotive vehicle. A pump module 10 is disposed in association with a fuel tank 12, and a portion thereof that is relevant to the present invention comprises a fuel pump 14, which is typically electrically operated. Pump 14 has a suction port 16 via which it sucks fuel from tank 12 when operated. The pressurized fuel is pumped via a pressure port 18 of pump 14 through a supply conduit 20 to an engine-mounted fuel rail 22 that comprises a gallery for serving pressurized fuel to fuel injectors 24 at selected locations on the fuel rail. The fuel injectors are individually selectively operated by an engine management ECU (not shown) to cause individual fuel injections of appropriate duration to sequentially charge individual engine cylinders. A portion of supply conduit 20 is a pipe 26 that is in module 10 and that comprises a cup-shaped receptacle 28 that is teed into the pipe. This receptacle provides for the mounting of a fuel pressure regulator 30. FIG. 2 shows greater detail.
Receptacle 28 comprises a circular sidewall having a circular flange 32 extending around its open outer end and an internal shoulder 34 spaced inwardly of flange 32 short of the receptacle's bottom wall 36. Fuel pressure regulator 30 comprises a circular housing 38 having a lower end portion received in receptacle 28. Housing 38 has an external shoulder 40 that is complementary to shoulder 34 so that the two define a space for an O-ring seal 42 that seals between them when the fuel pressure regulator is received in the receptacle as shown. This seal forms an upper boundary of an ensealed zone 44 that is cooperatively defined by the portions of receptacle 28 and housing 38 that are below seal 42. It is this zone that is teed into supply conduit 20 by a suitable passage 46 between them. Housing 38 also comprises a circular flange 48 that seats on flange 32 when fuel pressure regulator 30 is associated with receptacle 28 as shown. A bracket, or some other form of known retention means, (not shown) is used to hold the two flanges together and thereby retain the fuel pressure regulator in the receptacle mounting.
Housing 38 comprises two drawn metal shells 50 and 52 that are joined together at flange 48 to clamp the outer margin of a diaphragm 54 in a sealed manner thereby dividing the interior of the housing into a fuel inlet chamber 56 defined by the diaphragm and shell 50 and a fuel outlet chamber 58 defined by the diaphragm and shell 52. The central region of diaphragm 54 contains a circular through-hole within which a circular annular element 60 is disposed. Element 60 has a circular flange 62 extending around its O.D., and this flange bears against one side of the margin of the diaphragm surrounding its central circular through-hole. An annular retainer 64 is fitted over element 60 and against the opposite side of the margin of the central circular through-hole in the diaphragm. These parts are joined to form an assembly in which the O.D. of element 60 is sealed to the diaphragm through-hole. Element 60 itself contains a central circular through-hole 66 that provides a path of communication between the two chambers 56 and 58. At the end of element 60 that is toward chamber 56, a raised sealing lip 68 forms a seat that circumscribes through-hole 66.
Fuel inlet chamber 56 contains a closure 70 disposed for coaction with lip 68 in performance of the pressure regulating function. Closure 70 is a truncated sphere greater than a hemisphere and having a flat circular surface 72 at the truncation. Lip 68 and surface 72 are mutually confronting. Sphere 70 is captured in a spring-loaded swivel mounting which comprises a post 74 and a small helical compression spring 76. The base, or proximal end, of post 74 comprises a shoulder 78 that allows the post to be stood upright and seated on the margin of a circular hole in the bottom wall of shell 50 and joined in a sealed manner to that wall around the hole's margin. The distal end of post 74 contains a socket within which sphere 70 can swivel without too much looseness. The socket's rim 80 is turned slightly inwardly after the sphere has been received in the socket so as to thereby retain the sphere in the socket while still permitting swiveling. Prior to placement of the sphere in the socket, spring 76 is placed in a small blind hole at the bottom of the socket, and in the completed mounting of the sphere, this spring exerts a bias force resiliently urging the sphere against the socket's slightly inwardly turned rim 80.
A large helical coiled compression spring 82 is contained in outlet chamber 58. One end of spring 82 is seated on a spring seat that is integrally formed with the end wall of shell 52. The other end of spring 82 is seated on flange 62 around the outside of element 60. Spring 82 is substantially coaxial with the central region of diaphragm 54 and element 60, serving to resiliently bias the central region of diaphragm 54, including element 60, toward fuel inlet chamber 56, and hence bias sealing lip 68 toward seating on surface 72.
So that fuel from zone 44 can be communicated to fuel inlet chamber 56, one or more fuel inlet holes 84 are provided through the wall of shell 50, and so that fuel can exit fuel outlet chamber 58, one or more fuel outlet holes 86 are provided through the wall of shell 52. With fuel module 10 disposed on tank 12, holes 86 serve to provide a path of communication between the interior of the fuel outlet chamber and the interior of the fuel tank.
The operation of fuel pressure regulator 30 will now be described. Pump 14 creates a supply of pressurized fuel in supply conduit 20 and zone 44. This pressurized fuel is also supplied to fuel inlet chamber 56 via holes 84 where it acts on the face of diaphragm 54 that is exposed to this chamber. This tends to move diaphragm 54 toward chamber 58 so that sealing lip 68 unseats from sphere 70 to allow fuel to flow from chamber 56 through hole 66 into chamber 58 and into tank 12 via holes 86. The movement of the diaphragm away from sphere 70 is resisted by the force exerted by spring 82. The spring characteristic is such relative to the diaphragm and fuel supply that a pressure regulation function is accomplished, causing the fuel supply pressure to be regulated to a certain nominal pressure. If the fuel supply pressure were to tend to rise, diaphragm 54 would move farther away from sphere 70 providing less restriction to flow between chambers 56 and 58 and allowing more excess fuel to be returned to tank. If fuel supply pressure were to tend to drop, diaphragm 54 would move closer to sphere 70 providing greater restriction to flow between the two chambers and allowing less excess fuel to be returned to tank. Thus, fuel flow from chamber 56 to chamber 58 is selectively restricted as a function of incipient fuel pressure fluctuations in chamber 56 and of the force of spring 82 to cause the fuel supply pressure to be pressure regulated to a nominal pressure. To the extent that there might be any slight cocking of the diaphragm, its consequences are rendered non-significant because sphere 70 can swivel to provide sealed closure of hole 66 when pump 14 ceases to operate.
The second embodiment shown in FIGS. 3 and 4 comprises a number of parts like those used in the first embodiment, and they will be referenced by the same numbers used in the first embodiment, sometimes without describing detail since similarities between the corresponding parts in the two embodiments will be readily perceived by the reader. The valve element in the second embodiment comprises a full sphere 70 that is carried by a circular annular element 60 whose shape is somewhat different from the corresponding element of the first embodiment. Element 60 of the second embodiment is annular in shape and contains a central through-hole 66. The valve seat 68 is provided at the radially inner edge of an internal shoulder of element 60. Sphere 70 is confined in a cage-like fashion by that portion of element 60 which is below seat 68 within fuel inlet chamber 56. Caging of sphere 70 is accomplished by means of a number of short curled fingers 90 that are circumferentially spaced around the lower rim of element 60 surrounding through-passage 66. These fingers curl slightly beyond an equator of sphere 70 so that greater than a hemisphere of the sphere is disposed within through passage 66. That portion of sphere 70 beyond through-passage 66 rests on a convex interior surface of a dome 92 that forms the central region of the end wall of shell 50. FIG. 3 shows spring 82 pushing element 60 and the central region of diaphragm 54 downwardly so that sphere 70 simultaneously rests on dome 92 and seats on seat 68 thereby closing through-passage 66 so that fuel cannot flow from fuel inlet chamber 56 to fuel outlet chamber 58.
The end wall of element 60 where through-passage 66 communicates with fuel outlet chamber 58 comprises an internal shoulder 94 which serves as a seat for the larger diameter end of a frustoconically shaped coil spring 96. The smaller diameter end of spring 96 bears against sphere 70. The force of spring 96 is less than that exerted by spring 82 so that the former is ineffective to unseat sphere 70 from seat 68 unless permitted to do so under certain conditions of operation occurring during use of the pressure regulator.
In use when pressurized fuel fills chamber 56 to create a net force on the movable wall that divides the two chambers 56 and 58, to displace the central region of that movable wall upwardly in the sense of increasing the volume of fuel inlet chamber 56 at the expense of decreasing that of fuel outlet chamber 58, spring 96 functions to maintain sphere 70 on dome 92 so that as a result sphere 70 unseats from seat 68. This allows excess fuel to pass from fuel inlet chamber 56 through the space created between sphere 70 and seat 68 and through through-passage 66 into fuel outlet chamber 58 where it can spill out through one of the openings 86 back into the tank. Having spring 96 of a frustoconical tapered shape as shown is advantageous because the location where it bears against sphere 70 is spaced inwardly from the opening that is created between seat 68 and sphere 70. When the pressure has been relieved, the central region of the movable wall moves downwardly causing seat 68 to close against sphere 70.
In the third embodiment of FIGS. 5-9, the valve element is no longer a sphere 70 but rather a flat disk 70A. Disk 70A is caged on element 60 which once again has a somewhat different construction from the corresponding elements 60 of the first and second embodiments. Element 60 comprises a body having a cylindrical inserted sleeve 98 that defines that portion of through-passage 66 leading to fuel outlet chamber 58. The end of the insert 98 that confronts an imperforate central zone 100 of disk 70A is shaped to provide the valve seat 68 as a projection similar to the raised valve seat 68 in FIG. 2. The caging of disk 70A on element 60 occurs below valve seat 68 with the outer edge of element 60 being wrapped as a flange 101 around the outer margin of disk 70A, but allowing slight axial movement of the disk relative to element 60 within the confines of the cage. A wave spring washer 102 is disposed between a shoulder of the body of element 60 and the outer margin of disk 70A and functions to resiliently bias the disk in the direction of the flange 101.
FIG. 5 shows the closed position in which the dominant force of spring 82 is pushing the central region of the movable wall downwardly so that the lower face of the central imperforate zone 100 of disk 70A is forced against dome 92 and the upper surface of the zone is forced to seat against seat 68. When fuel introduced into fuel inlet chamber 56 reaches a pressure sufficiently high to displace the central region of the movable wall slightly upwardly from the position shown in FIG. 5, spring 102 will be effective to maintain the imperforate zone 100 of disk 70A against dome 92 while element 60, including insert 98, moves upwardly relative to disk 70A unseating seat 68 from the top surface of the zone 100 of disk 70A. Fuel can now flow through the three arcuate slots 104 that are provided in a radially intermediate portion of the disk and through the space that is created between the top surface of zone 100 and seat 58. This flow passes into fuel outlet chamber 68 from which it can spill out of one of the openings 86 back into the tank. When the pressure in inlet chamber 56 drops back to a level where excess fuel no longer needs to be spilled back to the tank, spring 82 forces the central region of the movable wall downwardly once again closing seat 68 against zone 100 of disk 70A.
The disclosed embodiments are advantageous because they use a smaller number of parts than would the fuel pressure regulator of U.S. Pat. No. 4,928,729 if it were to be used in a returnless system. While a presently preferred embodiment has been illustrated and described, it should be appreciated that principles of the invention are applicable to other embodiments.
Claims
What is claimed is:
1. A fuel system for an I.C. engine powered vehicle comprising a fuel tank for holding a supply of liquid fuel, a pump mounted on said tank for pumping fuel under pressure from an outlet of the pump, fuel conduit means for conveying fuel from said pump outlet to engine-mounted fuel injection means for injecting fuel into such an engine, and pressure regulating means for regulating the pressure of fuel that is pumped to said fuel injection means, characterized in that said fuel pressure regulating means comprises a housing divided by a movable wall into a fuel inlet chamber and a fuel outlet chamber, means via which fuel in said conduit means is communicated to said fuel inlet chamber, means via which said fuel outlet chamber is communicated to said tank, resilient bias spring means disposed in said fuel outlet chamber for resiliently biasing a central region of said movable wall toward said fuel inlet chamber in opposition to pressure exerted on said movable wall by fuel in said fuel inlet chamber, through-passage means on said central region of said movable wall having an annular member with a central through-hole that is mounted substantially coaxial with a central axis of said resilient bias spring means, valve means having a seat on said annular member that circumscribes said central through-hole and is raised from a surface of said annular member a valve closure member that coacts with said valve seat to selectively restrict said through-passage means disposed within said housing for coaction with said movable wall such that as said central region of said movable wall is selectively positioned within said housing as a function of the net sum of forces acting on it, said valve means selectively restricts said through passage means to selectively restrict the flow of excess fuel from said fuel inlet chamber to said fuel outlet chamber in a manner that as a consequence provides a desired pressure for fuel that is delivered to said fuel injection means.
2. A fuel system as set forth in claim 1 in which said valve closure member comprises a truncated sphere having a truncated surface toward said seat for coaction therewith.
3. A fuel system as set forth in claim 2 in which said truncated sphere is swivel mounted on one end of a post whose other end is mounted on said housing.