U.S. patent application number 12/008185 was filed with the patent office on 2008-07-24 for inlet pressure attenuator for single plunger fuel pump.
This patent application is currently assigned to Stanadyne Corporation. Invention is credited to Ilija Djordjevic, Robert Lucas.
Application Number | 20080175735 12/008185 |
Document ID | / |
Family ID | 39609012 |
Filed Date | 2008-07-24 |
United States Patent
Application |
20080175735 |
Kind Code |
A1 |
Lucas; Robert ; et
al. |
July 24, 2008 |
Inlet pressure attenuator for single plunger fuel pump
Abstract
An attenuator diaphragm assembly for a fuel injection pump,
comprising a diaphragm formed of two half-shells, having mated flat
rims that are welded together along their peripheral edges and a
compression joint formed at inward, unwelded portions of the rims,
and a carrier that captures the joined and welded rims.
Inventors: |
Lucas; Robert; (Ellington,
CT) ; Djordjevic; Ilija; (East Granby, CT) |
Correspondence
Address: |
ALIX YALE & RISTAS LLP
750 MAIN STREET, SUITE 1400
HARTFORD
CT
06103
US
|
Assignee: |
Stanadyne Corporation
|
Family ID: |
39609012 |
Appl. No.: |
12/008185 |
Filed: |
January 9, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60879738 |
Jan 10, 2007 |
|
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Current U.S.
Class: |
417/540 ;
417/254 |
Current CPC
Class: |
F02M 37/0041
20130101 |
Class at
Publication: |
417/540 ;
417/254 |
International
Class: |
F04B 11/00 20060101
F04B011/00 |
Claims
1. In a fuel pump having single plunger that reciprocates into and
out of a pumping chamber situated within a pump housing; a
pressurized inlet line through the housing to an inlet valve that
feeds the pumping chamber; a damping chamber integrated with the
housing, in which fuel passes around at least one gas filled and
sealed attenuator diaphragm along a flow path to the inlet valve;
each diaphragm being formed of two half-shells, having central
convex bulges and mated flat rims which are supported in a
diaphragm carrier within the damping chamber; wherein the
improvement comprises that the rims are welded together along their
outer edges and a compression joint is formed at inward, unwelded
portions of the rims to reduce stresses transmitted to the welded
edges.
2. The fuel pump of claim 1, wherein the rims are bent over at a
bend line that forms said compression joint.
3. The fuel pump of claim 1, wherein each half-shell is
substantially circular and each rim circumscribes a respective
convex bulge.
4. The fuel pump of claim 3, wherein the rims are bent over at a
circumferential bend line that forms said compression joint.
5. The fuel pump of claim 4, wherein the bent over portion of the
rims forms a circumferential ridge that is substantially coaxial
with the axis of the diaphragm.
6. The fuel pump of claim 4, wherein the circumferential bend line
is located within the radially inward 75 percent of the radial
dimension of the rim.
7. The fuel pump of claim 3, wherein the diaphragm carrier has a
radial slot including upper and lower walls that closely confront
the inner radial portion of the rim but not the circumferential
weld.
8. The fuel pump of claim 7, wherein the radial slot
circumferentially surrounds said weld.
9. The fuel pump of claim 8, wherein the slot has a radially inner
portion where the walls are clamped against the rim and a radially
outer portion forming a space surrounding said weld.
10. The fuel pump of claim 7, wherein the radial slot is one of a
plurality of said slots circumferentially spaced apart around the
rim.
11. The fuel pump of claim 10, wherein each slot has a radially
inner portion where the walls are clamped against the rim and a
radially outer portion forming a space surrounding said weld.
12. The fuel pump of claim 1, wherein each half-shell is
substantially circular; each rim circumscribes a respective convex
bulge; the rims are bent over at a circumferential bend line that
forms said compression joint; the bent over portion of the rims
forms a circumferential ridge that is substantially coaxial with
the axis of the diaphragm; the diaphragm carrier has a radial slot
including upper and lower walls; and the ridge is captured between
the upper and lower walls.
13. The fuel pump of claim 12, wherein each rim has a flat portion
radially inward of the bend line; the upper wall extends closely
over said flat portions of the rims; and the welded outer edges are
supported by the lower wall.
14. An attenuator diaphragm assembly for a fuel injection pump,
comprising: a diaphragm formed of two half-shells, having mated
flat rims that are welded together along their peripheral edges and
a compression joint formed at inward, unwelded portions of the
rims; and a carrier that captures the joined and welded rims.
15. The attenuator diaphragm of claim 14, wherein each half-shell
is substantially circular; each rim circumscribes a respective
convex bulge; the rims are bent over at a circumferential bend line
that forms said compression joint; the bent over portion of the
rims forms a circumferential ridge that is substantially coaxial
with the axis of the diaphragm; the diaphragm carrier has a radial
slot including upper and lower walls; and the ridge is captured
between the upper and lower walls.
16. The attenuator diaphragm of claim 15, wherein each rim has a
flat portion radially inward of the bend line; the upper wall
extends closely over said flat portions of the rims; and the welded
outer edges are supported by the lower wall.
Description
RELATED APPLICATION
[0001] This application claims priority under 35 U.S.C. 119(e) from
U.S. Provisional Application No. 60/879,738 filed Jan. 10, 2007 for
"Inlet Pressure Attenuator for Single Plunger Fuel Pump", the
entire disclosure of which is hereby incorporated by reference.
BACKGROUND
[0002] The present disclosure relates generally to fuel pumps, and
is more particularly concerned with a new and improved single
plunger fuel pump.
[0003] Practitioners in the field of fuel pump design and
development for vehicles readily understand the main components of
a typical single plunger pump and their function and operation. The
engine drive shaft carries a lobed cam that reciprocates the
pumping plunger within a pumping sleeve secured to the housing,
between charging (intake) and discharging (output) phases. The
pumping end of the plunger is situated in the pumping chamber,
which fills with fuel at a feed pressure of up to about 4 bar
during the charging phase and, preferably subject to initial spill
control, pressurizes the fuel in the pumping chamber up to about
200 bar for delivery to, e.g., a common rail.
[0004] The feed fuel is fed directly to the pumping chamber through
an inlet valve, which receives flow from an inlet damping chamber.
The fuel passes one or more attenuator diaphragms in the damping
chamber along the flow path to the pumping chamber. The diaphragms
encapsulate fixed masses of gas, such as helium at two bars. The
flexibility of the diaphragms can adjust the volumes of the gas in
response to pressure variations in the feed line and thereby
maintain a substantially constant feed pressure to the inlet
valve.
[0005] A problem encountered with known welded diaphragms, is that
the substantially continual accommodation of normal pressure
fluctuations and the occasional attenuation of spurious pressure
transients, stresses the welds and causes leakage, with resulting
deterioration of performance or even failure.
SUMMARY
[0006] It is an object of the present invention to provide an
improved technique for stress relieving the junction of juxtaposed
thin rims of a pressurized bellows type diaphragm attenuator that
is integrated with the inlet feed train of a single plunger fuel
pump.
[0007] One embodiment is directed to an attenuator diaphragm
assembly for a fuel injection pump. The diaphragm assembly includes
a diaphragm formed of two half-shells, having mated flat rims that
are welded together along their peripheral edges. A compression
joint is formed at inward, unwelded portions of the rims and a
carrier or frame captures the joined and welded rims.
[0008] Another embodiment is directed to a fuel pump having a
single plunger that reciprocates into and out of a pumping chamber
situated within a pump housing. The pump features a pressurized
inlet line through the housing to an inlet valve that feeds the
pumping chamber. A damping chamber is integrated with the housing,
in which fuel passes around at least one gas filled and sealed
attenuator diaphragm along a flow path to the inlet valve. Each
diaphragm is formed of two half-shells, having central convex
bulges and mated flat rims which are supported in a diaphragm
carrier within the damping chamber. The rims are welded together
along their outer edges and a compression joint is formed at
inward, unwelded portions of the rims to reduce stresses
transmitted to the welded edges.
[0009] Preferably, each half-shell is substantially circular and
each rim circumscribes a respective convex bulge. The rims are bent
over at a circumferential bend line that forms the compression
joint. The bent over portion of the rims forms a circumferential
ridge that is substantially coaxial with the axis of the diaphragm.
The diaphragm carrier has a radial slot including upper and lower
walls between which the ridge is captured. Each rim has a flat
portion radially inward of the bend line. The upper wall extends
closely over said flat portions of the rims and the welded outer
edges are supported by the lower wall.
[0010] The compression joint isolates the weld from excessive
stresses associated with the expansion and contraction of the
diaphragm, thereby avoiding leakage of the gas and deterioration or
failure of pressure attenuating capability of the diaphragm.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] In the accompanying drawing, like elements are numbered
alike in the several Figures:
[0012] FIG. 1 is a perspective view of a one plunger fuel pump
having a substantially cubic housing or body, with the fuel inlet
connector projecting on the right, the single plunger actuation
assembly projecting from the left, and the inlet control valve
projecting from the top;
[0013] FIG. 2 is staggered section view of the pump of FIG. 1,
through the inlet connection with associated attenuator, and the
inlet control valve;
[0014] FIGS. 3A and 3B are enlarged plan and section views of the
split diaphragm carrier for the two pressurized diaphragms shown in
FIG. 2, with the section line indicated by A-A;
[0015] FIG. 4 is an enlarged view of the attenuator diaphragm,
showing the preferred bending at the rims for stress relief;
[0016] FIG. 5 is an enlarged view of an alternative technique for
reducing the stresses at the weld of the diaphragm rims;
DETAILED DESCRIPTION
[0017] FIG. 1 shows a one plunger fuel pump 10 having a
substantially cubic housing or body 12, with the fuel inlet
connector 14 projecting on the right, the single plunger actuation
assembly 16 projecting from the left, and the inlet control valve
18 projecting from the top. In FIG. 1, plunger 20 can be seen
projecting slightly from the single plunger actuation assembly
16.
[0018] With further reference to FIG. 2, the feed fuel is fed
directly to the pumping chamber 22 through the solenoid controlled
inlet valve 18, which receives flow through a first internal
passage 24 of the housing, from the inlet damping chamber 26. The
damping chamber receives feed fuel through an inlet fitting 28, and
the fuel passes around the attenuator diaphragms 30 on its way to
the first internal passage 24. The diaphragms encapsulate fixed
masses of gas, such as helium at two bars, but the flexibility of
the diaphragms can adjust the volumes of the gas in response to
pressure variations in the feed line and thereby maintain a
substantially constant feed pressure to the inlet valve 18.
[0019] The improvement with respect to the damping chamber 26 will
now be described in greater detail with reference to FIGS. 1, 2, 3
and 4. The substantially cylindrical chamber is in part defined by
a cup cover 32 welded to the inlet fitting 28 and to the wall of a
shallow bore in the housing 12. A diaphragm carrier 36 is annularly
disposed against the inside surface 36 of the cup cover 32. The
carrier has upper and lower annular grooves or slots 38, for
receiving the rims 40 of respective diaphragms 30. Each slot
includes upper and lower walls 42a and 42b that closely confront
the inner radial portion of each respective diaphragm rim. Each
diaphragm is formed of two substantially circular half-shells 44,
having central convex bulges 45 and mated flat rims 40. In an
environment at about two bar pressure, a helium balloon is placed
between the half-shells 44, the shells are urged together, and the
rims are TIG welded at the outer circumferences, as indicated by
reference numeral 46. This forms a central, substantially
cylindrical helium volume and a flat rim having a radial dimension
outside of the helium cylinder. While this embodiment features
upper and lower slots, it should be clear to those skilled in the
art that the object of the disclosure may be practiced with any
number of slots.
[0020] The improvement comprises that an annular compression joint
is formed on a radially inward, unwelded portion of the rim to
reduce stresses transmitted to the welded circumference.
[0021] In one embodiment, after welding along the outer edges of
the half-shells 44, the joined rims 40 are bent over to form a
circumferential ridge 48, preferably enough to nearly align the
bent over circumferential ridge with the axis of the cylinder,
shown by reference numeral 50. The bend line L forms the
compression joint 41. In general, the circumferential bend line is
located within the radially inward 75 percent of the radial
dimension of the rim. The joined rims have a flat portion 52
radially inward of the bend line. Generally, the circumferential
ridge 48 is captured between the upper and lower walls 42a and 42b
of a carrier annular groove 38 with the upper wall 42a extending
closely over the rim flat portion 52 while the lower wall 42b
supports the welded outer edges 46 of the rim.
[0022] This technique of forming the diaphragm avoids stress at the
weld 46 arising from the use environment, where a constant internal
pressure of about 2 bars acts in the direction of separating the
rims, and the diaphragm 30 undergoes continual contraction and
expansion, because the weld 46 is axially offset from the
separation plane between the rims.
[0023] Another embodiment is shown in FIG. 5, where the welded rims
are not bent over, but a different type of diaphragm carrier 34 has
a radial slot 38 such that the walls 42 of the slot along the
radially inner portion of the slot closely confront, or are
preferably clamped against, the inner radial portion of the rim 40.
This clamping is an alternative to the bend line of the embodiment
of FIG. 4, whereby the weld on the outer edges of the rim is
isolated from the forces associated with the pressure in and
flexing of the diaphragm 30, by the radially inner clamping. Such
clamping would typically leave a space or gap 54 along the radially
outer portion of the slot surrounding the weld 46.
[0024] While preferred embodiments have been set forth for purposes
of illustration, the foregoing description should not be deemed a
limitation of the disclosure herein, or of the scope of disclosure
or claims that may be presented in a regular application based on
the present application. Accordingly, various modifications,
adaptations and alternatives may occur to one skilled in the art
without departing from the spirit and scope of the present
disclosure.
* * * * *