Information
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Patent Grant
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6182637
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Patent Number
6,182,637
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Date Filed
Friday, November 12, 199924 years ago
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Date Issued
Tuesday, February 6, 200123 years ago
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Inventors
-
Original Assignees
-
Examiners
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CPC
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US Classifications
Field of Search
US
- 123 467
- 251 355
- 138 30
- 137 510
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International Classifications
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Abstract
The present invention provides a damper for a fuel system. The damper includes a first chamber with an interior surface, and a second chamber with a fuel receiving opening. A diaphragm separates the first chamber and the second chamber. A device is disposed within the first chamber that biases the diaphragm toward the fuel receiving opening. A retainer, which supports the device proximate the diaphragm, is located in the first chamber. The retainer has a surface exposed to the interior surface of the first chamber. A lubricant is disposed on at least one of the interior surface of the first chamber and the surface of the retainer.
Description
FIELD OF INVENTION
This invention relates to a damper for automotive fuel systems, and more particularly, a damper for minimizing fuel pressure pulsations in a fuel rail.
BACKGROUND OF INVENTION
Existing fuel delivery systems which use an in-tank fuel pressure regulator usually employ an energy absorbing device mounted on or near the fuel rail. The energy absorbing device serves to compensate for fuel pressure pulsations created in the fuel rail that occur as a result of sequential firing of fuel injectors operatively connected to the fuel rail. A known energy absorbing device is a damper mounted on the fuel rail. A damper of this type is disclosed in commonly-assigned, co-pending U.S. patent application Ser. No. 09/086,084, entitled “Fuel Rail Damper”, filed May 28, 1998, which is incorporated herein in its entirety by reference. This known damper has an upper chamber and a lower chamber separated by a solid, flexible diaphragm. The upper chamber contains a spring that biases the diaphragm toward the lower chamber. The spring is retained in a spring seat, which engages the diaphragm. The lower chamber has an opening which allows fuel to enter from the fuel rail and contact the diaphragm. Changes in fuel pressure cause the diaphragm to adjust the volumetric capacity of the lower chamber to damp the fuel pressure changes.
Applicants have discover that over prolonged periods of operation, the known damper can exhibit reduced operative capacity. As the diaphragm adjusts the volume of the lower chamber, the spring seat reciprocates within the upper chamber. While reciprocating in the upper chamber, the spring seat can become galled from contacting the upper chamber, even though the spring seat is sized to minimize contact with the upper chamber. It is believed that a spring seat with galled surfaces can reduce operability of the damper. Thus, a damper arrangement is needed which can, under prolonged operative conditions, maintain a stable damping coefficient.
SUMMARY OF THE INVENTION
The present invention provides a damper for a fuel system. The damper includes a first chamber with an interior surface, and a second chamber with a fuel receiving opening. A diaphragm separates the first chamber and the second chamber. A device is disposed within the first chamber that biases the diaphragm toward the fuel receiving opening. A retainer, which supports the device proximate the diaphragm, is located in the first chamber. The retainer has a surface exposed to the interior surface of the first chamber. A lubricant is disposed on at least one of the interior surface of the first chamber and the surface of the retainer.
In a preferred embodiment, the retainer is a spring seat and the device biasing the diaphragm is a spring. The seat is a cup-shaped member having a lateral side surface exposed to the interior surface of the first chamber. The lubricant is disposed on the lateral side surface, and is, preferably, disposed on the lateral side surface by a lubricity additive of a plating disposed on the lateral side surface.
The present invention also provides a method of damping pressure pulsations in a fuel system. The method is accomplished by separating a housing into a first chamber and a second chamber with a diaphragm; providing the second chamber having a fuel receiving opening; disposing a device in the first chamber that biases the diaphragm toward the fuel receiving opening; supporting the device proximate the diaphragm with a retainer; and providing lubricant between the retainer and the first chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawing, which is incorporated herein and constitutes part of this specification, illustrates a presently preferred embodiment of the invention, and, together with the general description given above and the detailed description given below, serve to explain features of the invention.
FIG. 1
is a cross-sectional view of an embodiment of the damper of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1
illustrates a preferred embodiment of the damper
10
that attenuates pressure pulsations in a fuel system. The damper
10
is, preferably, an assembly of components operatively attached to a fuel rail (not shown) by a fuel rail cup
20
. The damper
10
includes an upper chamber
30
, a first chamber, and the lower chamber
40
, a second chamber. The upper chamber
30
and the lower chamber
40
are separated by a flexible diaphragm
50
within the damper assembly. The diaphragm
50
is secured in place between the upper chamber
30
and lower chamber
40
. The upper chamber
30
is formed by a first member of the assembly, which is, preferably, a cover
32
that creates a sealed chamber with the diaphragm
50
. A biasing device, which is, preferably, a spring
60
and, a retainer for the biasing device, which is, preferably, a spring seat
62
, are disposed in the upper chamber
30
. The spring seat
62
engages the diaphragm
50
so that the spring
60
biases the diaphragm
50
toward the lower chamber
40
.
The lower chamber
40
is formed by a second member of the damper assembly, which is preferably, a housing
70
. Although the damper assembly in the preferred embodiment is provided by two separate members, cover
32
and housing
70
, a unitary member could be provided. The lower end of the housing
70
has an opening
72
, a fuel receiving opening, which allows fuel to enter the damper
10
from the fuel system. The upper end of the housing
70
has a flange
74
that supports the diaphragm
50
. The flange
74
is surrounded by a flange
34
of cover
32
. A portion of the flange
74
projects inwardly to provide a radial shoulder
76
. The radial shoulder
76
allows for a maximum effective area of the diaphragm
50
to be exposed to fuel in the lower chamber
40
.
A spacer
80
is disposed in the lower chamber
40
and contacts a seat
78
formed in the housing
70
. The seat
78
limits axial movement of the spacer
80
toward the opening
72
. The force of spring
60
limits axial movement of the spacer
80
toward the cover
32
. The height of the spacer
80
, in the axial direction along the longitudinal axis A, is greater than the distance between the seat
78
and an inner edge of the radial shoulder
76
, and, preferably, is greater than the distance between the seat
78
and the flange
74
. The spacer
80
, therefore, prevents contact between the diaphragm
50
and the radial shoulder
76
. Because contact is prevented between the diaphragm
50
and the radial shoulder
76
, the diaphragm
50
does not adhere to the radial shoulder
76
, even after prolonged exposure to heat and fuel. By avoiding contact with the radial shoulder
76
, a maximum effective area of the diaphragm
50
is continually exposed to the lower chamber
40
. Further details of the spacer
80
, and its operative performance within the damper
10
, is explained in co-pending application U.S. patent application Ser. No. 09/438,291 entitled “Pressure Pulsation Damper with Free Floating Spacer,” filed on even date, which is hereby incorporated in its entirety by reference.
The damper
10
is attached to the fuel cup
20
by a clip
90
comprising a support portion
92
on an outer diameter and a plurality of retention members
94
on an inner diameter. Further details of this clip are disclosed in commonly-assigned, co-pending U.S. patent application Ser. No. 09/342,589 entitled “A Self-Tightening Clip”, filed Jun. 29, 1999, which is also hereby incorporated in its entirety by reference. The support portion
92
of the clip
90
is disposed between the flange
74
of the housing
70
and the flange
34
of the cover
32
. The clip retention members
94
extend over a lip on the fuel cup
20
to maintain the damper
10
in place on the fuel cup
20
. An O-ring
100
, disposed on the housing
70
, provides a seal between the damper
10
and the fuel cup
20
.
During operation of the damper
10
, the spring seat
62
reciprocates along the longitudinal axis A. The spring seat
62
, which serves as the preferred retainer, is a cup-shaped member having a diaphragm engagement face
64
. The engagement face
64
is connected to a lateral side surface
66
by a rounded outer edge
68
. The engagement face
64
of the spring seat
62
and a surface of the spacer
80
provide opposing structural members that apply opposite axial loads along longitudinal axis A to the diaphragm
50
. The engagement face
64
has a contact area less than the effective contact area of the diaphragm
50
, due to the rounded outer edge
68
. By providing the engagement face
64
with this configuration, the spring seat
62
biases the diaphragm
50
without biasing the spring seat
62
against the radial shoulder.
Reciprocation of the spring seat
62
, reciprocates lateral side surface
66
of the spring seat
62
relative to an interior surface
36
of the cover
32
. The lateral side surface
66
of the spring seat
62
and the interior surface
36
of the cover
32
are, preferably, planar surfaces that extend substantially parallel to the longitudinal axis A. In the preferred embodiment, the lateral side surface
66
and the interior surface
36
have a corresponding circumferential configuration, which is, preferably, circular, although other corresponding circumferential configuration could be employed. The corresponding circumferential configuration of the lateral side surface
66
and the interior surface
36
allows for a compact damper assembly. Even though the spring seat
62
is sized so that the lateral side surface
66
should avoid contact with the interior surface
36
of the cover
32
, applicants have discover that under particular operative conditions, the damper
10
can demonstrate a reduced damping capacity because of frictional forces developed when the lateral side surface
66
contacts the interior surface
36
. Prolonged contact between the lateral side surface
66
and the interior surface
36
cause frictional forces that can gall the metallic material employed selected for these surfaces, which can result in a permanent reduction in the operative capacity of the damper
10
.
In order to minimize the frictional contact between the lateral side surface
66
and the interior surface
36
, a method of lubricating at least one of these internal surfaces is provided. For example, a lubricant is provided on at least one of the lateral side surface
66
or the interior surface
36
. In addition to providing an arrangement that minimizes frictional contact between the lateral side surface
66
and the interior surface
36
, and, thus, prevents galling of the lateral side surface
66
and the interior surface
36
, lubrication of at least one of these surfaces within the damper, also, advantageously, improves the performance of the damper
10
during various operative conditions. Time interval performance tests have demonstrated at least a twenty percent increase in the damping coefficient of the damper of the preferred embodiment with internal surface lubrication as compared to a damper of the preferred embodiment without internal surface lubrication.
The selected method of lubricating the lateral side surface
66
or the internal surface
36
provides for internal surface lubrication of the damper assembly. The internal surface lubrication of the damper assembly can be achieved by various arrangements, each of which provides alternative embodiments of the damper
10
. It is to be understood that each of the various arrangements that provide a method of internal surface lubrication could be employed singularly or in a combination thereof. To provide lubrication of the specified surfaces, the lateral side surface
66
and the interior surface
36
, any medium that reduces frictional forces between the specified surfaces can be employed. The medium could be, for example, oil, grease, or a lubricity additive in an appropriate material exposed to at least one of the specified surfaces. The medium should at least provide a thin layer of a lubricating substance on at least one of the specified surfaces. That is, if an oil or grease is used as the medium, a thin layer of the selected oil or grease is applied to at least one of the lateral side surface
66
and the interior surface
36
, and, in particular, the lateral side surface
66
. If a material with the lubricity additive is employed as the medium, the material that contains the lubricity additive could be the material employed to form at least one of the spring seat
62
and the cover
32
, or a plating applied to at least one of the specified surfaces, the lateral side surface
66
or the interior surface
36
, as long as during relative movement of the specified surfaces, the selected material provides a thin layer of a lubricating substance to at least one of the specified surface. An example of such a material, which could be used as the material to form one of the spring seat
62
or the cover
32
and provide a lubricating substance to at least one of the specified surfaces, is an oil impregnated steel. In the preferred embodiment, the medium is a plating of electroless nickel with Teflon, polytetrafluoroethylene, additives. The plating
68
is applied to spring seat
62
so that the at least lateral side surface
66
is covered. The nickel plated spring seat
62
is, preferably, formed from a stainless steel.
While the invention has been disclosed with reference to certain preferred embodiments, numerous modifications, alterations, and changes to the described embodiments are possible without departing from the sphere and scope of the invention, as defined in the appended claims and their equivalents thereof. Accordingly, it is intended that the invention not be limited to the described embodiments, but that it have the full scope defined by the language of the following claims.
Claims
- 1. A damper for a fuel system, comprising:a first chamber having an interior surface; a second chamber having a fuel receiving opening; a diaphragm separating the first chamber and the second chamber; a device disposed within the first chamber that biases the diaphragm toward the fuel receiving opening; a retainer supporting the device proximate the diaphragm, the retainer having a surface exposed to the interior surface of the first chamber; and a lubricant disposed on at least one of the interior surface of the first chamber and the surface of the retainer.
- 2. The damper of claim 1, wherein the retainer comprises a seat.
- 3. The damper of claim 2, wherein the seat comprises a cup-shaped member having a lateral side surface exposed to the interior surface of the first chamber.
- 4. The damper of claim 3, wherein the lubricant is disposed on the lateral side surface of the seat.
- 5. The damper of claim 4, wherein the lubricant comprises an additive of a plating disposed on the lateral side surface.
- 6. The damper of claim 1, wherein the device that biases the diaphragm comprises a spring and; wherein the retainer comprises a spring seat having a face that engages the diaphragm and a lateral side surface, the face having a contact area less than an effective area of the diaphragm, the lateral side surface providing the surface of the retainer exposed to the interior surface.
- 7. The damper of claim 1, further comprising a spacer disposed in the second chamber that maintains a maximum effective area of the diaphragm.
- 8. The damper of claim 1, wherein the lubricant comprises at least one of an oil, grease, and a lubricity additive in a material.
- 9. The fuel injector of claim 1, further comprising a housing that provides the first chamber and the second chamber.
- 10. The damper of claim 9, wherein the housing includes a retention device, the retention device being configured to secure the damper to a fuel rail cup.
- 11. The damper of claim 10, wherein the retention device comprises a sheet metal clip integrally attached to the housing.
- 12. The damper of claim 11, wherein the housing comprises a first member that provides the first chamber and a second member that provides the fuel receiving opening, the first member including a first flange, the second member including a second flange; andwherein the clip includes a support portion and a plurality of retention members, the support portion being disposed between the first flange and the second flange, and the plurality of retention members extending from the support member toward the fuel receiving opening.
- 13. The damper of claim 12, wherein the second chamber comprises an inwardly angled radial shoulder adjacent the diaphragm.
- 14. A method of damping pressure pulsations in a fuel system comprising the steps of:separating a housing into a first chamber and a second chamber with a diaphragm; providing the second chamber having a fuel receiving opening; disposing a device in the first chamber that biases the diaphragm toward the fuel receiving opening; supporting the device proximate the diaphragm with a retainer; and providing lubricant between the retainer and the first chamber.
- 15. The method of damper of claim 14, further comprising the steps of:providing a cup-shaped member as the retainer, the cup-shaped member having a lateral side surface exposed to an interior surface of the first chamber.
- 16. The method of claim 15, further comprising the step of:providing a plating with a lubricity additive on the lateral side surface.
- 17. The method of claim 15, further comprising the step of:providing the retainer with a face that engages the diaphragm, the face having a contact area less than an effective area of the diaphragm.
- 18. The method of claim 14, further comprising the step of:disposing a spacer in the second chamber that maintains a maximum effective area of the diaphragm.
- 19. The method of claim 14, further comprising the step of:providing at least one of an oil, grease, and a lubricity additive in a material as the lubricant.
- 20. The method of claim 14, further comprising the steps of:providing for the first chamber with a first member of a housing; providing the second chamber with a second member of a housing; and disposing a support portion of a clip between a first flange of the first member and a second flange of the second member so that a plurality of retention members of the clip extend from a support member toward the fuel receiving opening.
US Referenced Citations (7)