U.S. patent application number 09/867889 was filed with the patent office on 2001-09-27 for combination pressure sensor and regulator for direct injection engine fuel system.
Invention is credited to Beuger, Paul P.M., Wade, Richard A..
Application Number | 20010023616 09/867889 |
Document ID | / |
Family ID | 23486668 |
Filed Date | 2001-09-27 |
United States Patent
Application |
20010023616 |
Kind Code |
A1 |
Wade, Richard A. ; et
al. |
September 27, 2001 |
Combination pressure sensor and regulator for direct injection
engine fuel system
Abstract
A pressure regulating device for high pressure fuel systems
includes a pressure sensing element attached directly to a pressure
chamber. The pressure sensing element includes a semiconductor
element that deflects in response to a deflection of a portion of
the pressure caused by fuel pressure within the pressure chamber. A
coil is electrically connected with the pressure sensing element
and is configured to generate a magnetic field that moves a
magnetic armature to control fuel pressure.
Inventors: |
Wade, Richard A.; (Shelby,
NC) ; Beuger, Paul P.M.; (Shelby, NC) |
Correspondence
Address: |
MYERS BIGEL SIBLEY & SAJOVEC
PO BOX 37428
RALEIGH
NC
27627
US
|
Family ID: |
23486668 |
Appl. No.: |
09/867889 |
Filed: |
May 30, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09867889 |
May 30, 2001 |
|
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|
09376823 |
Aug 18, 1999 |
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Current U.S.
Class: |
73/756 |
Current CPC
Class: |
F02B 2075/125 20130101;
Y02T 10/123 20130101; F02M 63/0225 20130101; Y10T 137/7761
20150401; Y02T 10/12 20130101 |
Class at
Publication: |
73/756 |
International
Class: |
G01L 007/00 |
Claims
That which is claimed is:
1. A pressure sensing and pressure regulating apparatus for a fluid
system, comprising: a housing; a pressure chamber within the
housing comprising a wall configured to deflect responsive to fluid
pressure within the pressure chamber; a pressure sensing device
attached to the wall within the housing, wherein the pressure
sensing device is configured to generate electrical signals
responsive to deflection of the pressure chamber caused by fluid
pressure within the pressure chamber; and a pressure regulating
device within the housing comprising a valve member that is
configured to relieve fluid pressure in the pressure chamber by
allowing fluid to exit from the pressure chamber, wherein movement
of the valve member is responsive to electrical signals generated
by the pressure sensing device.
2. A pressure sensing and pressure regulating apparatus according
to claim 1 wherein the pressure sensing device comprises a
semiconductor element.
3. A pressure sensing and pressure regulating apparatus according
to claim 1 wherein the valve member comprises a magnetic
armature.
4. A pressure sensing and pressure regulating apparatus according
to claim 3 further comprising a coil disposed within the housing,
wherein the coil is electrically connected with the pressure
sensing device, and wherein the coil is configured to generate a
magnetic field responsive to electrical signals from the pressure
sensing device that moves the magnetic armature to control fluid
pressure within the pressure chamber by allowing fluid to exit from
the pressure chamber.
5. A pressure sensing and pressure regulating apparatus according
to claim 1 further comprising a controller electrically connected
with the pressure sensing device and configured to maintain fluid
pressure in the pressure chamber within a predetermined range of
pressures, and wherein the controller is selected from the group
consisting of proportional controllers, derivative controllers,
integral controllers, proportional-derivative controllers,
proportional-integral controllers, and
proportional-integral-derivative controllers.
6. A pressure sensing and pressure regulating apparatus according
to claim 1 wherein the fluid system comprises a fuel system.
7. A pressure regulating apparatus for a fluid system, comprising:
a housing having an axial bore extending therethrough that defines
a longitudinal direction, wherein the housing includes a fluid
inlet passageway and a fluid outlet passageway; a sense tube
assembly disposed within the axial bore, comprising: a
longitudinally extending outer tube, comprising: a tubular body
having an inner surface and an outer surface and having an open end
and an opposite closed end; and a longitudinally extending channel
formed along the inner surface of the outer tube body from the
outer tube open end toward the outer tube closed end; and a
longitudinally extending inner tube disposed within the outer tube,
comprising: a tubular body having an inner surface and an outer
surface and having an open end and an opposite closed end; wherein
the inner tube closed end includes an aperture formed therethrough;
wherein the outer surface of the inner tube body is in contacting
relationship with the inner surface of the outer tube body to
define a pressure chamber between the outer tube closed end and the
inner tube closed end; and wherein the longitudinally extending
channel is in fluid communication with the fluid inlet passageway
and forms a fluid flow path between the inner tube and the outer
tube from the fluid inlet passageway to the pressure chamber; a
magnetic pole piece disposed within the inner tube, comprising:
opposite first and second ends; and an internal bore that
terminates at the magnetic pole piece first and second ends,
wherein the internal bore is in fluid communication with the fluid
outlet passageway; a magnetic armature slidably secured within the
inner tube between the magnetic pole piece and the inner tube
closed end, comprising: a body having an outer surface and
terminating at opposite first and second ends, wherein the magnetic
armature second end is configured to matingly engage the aperture
in the inner tube closed end; and a longitudinally extending
passageway that terminates at the magnetic armature first and
second ends and that is in fluid communication with the magnetic
pole piece internal bore; biasing means configured to bias the
magnetic armature away from the magnetic pole piece and to cause
the magnetic armature second end to matingly engage the aperture in
the inner tube closed end; a pressure sensing element attached to
the outer tube closed end, wherein the pressure sensing element is
configured to measure fluid pressure within the pressure chamber;
and a coil disposed within the housing, wherein the coil is
configured to generate a magnetic field responsive to electrical
signals from the pressure sensing element that moves the magnetic
armature axially within the inner tube to control fluid pressure by
allowing fluid entering the pressure chamber via the fluid inlet
passageway to exit via the fluid outlet passageway.
8. A pressure regulating apparatus according to claim 7 wherein the
inner tube further comprises: a radially extending flange adjacent
the inner tube open end; and an aperture formed through a portion
of the flange, wherein the longitudinally extending channel in the
outer tube is in fluid communication with the fluid inlet
passageway via the flange aperture and forms a fluid flow path
between the inner tube and the outer tube from the fluid inlet
passageway to the pressure chamber.
9. A pressure regulating apparatus according to claim 7 wherein the
inner tube second end has an annular configuration.
10. A pressure regulating apparatus according to claim 7 wherein
the longitudinally extending passageway in the magnetic armature
comprises a longitudinally extending slot formed in the outer
surface of the magnetic armature body.
11. A pressure regulating apparatus according to claim 7 wherein
the magnetic armature comprises a pair of diametrically opposed
longitudinally extending slots formed in the outer surface of the
magnetic armature body.
12. A pressure regulating apparatus according to claim 7 wherein
the body of the inner tube and the body of the outer tube each have
respective cylindrical configurations.
13. A pressure regulating apparatus according to claim 7 wherein
the pressure sensing element comprises a semiconductor element that
deflects in response to a deflection of the outer tube second end
caused by pressure within the pressure chamber.
14. A pressure regulating apparatus according to claim 13 wherein
the semiconductor element comprises an embedded Wheatstone
bridge.
15. A pressure regulating apparatus according to claim 7 further
comprising means for adjusting axial movement of the magnetic
armature within the inner tube relative to a magnetic field
produced by the coil.
16. A pressure regulating apparatus according to claim 7 further
comprising a controller electrically connected with the pressure
sensing element and configured to maintain fluid pressure within a
prescribed range of pressures, and wherein the controller is
selected from the group consisting of proportional controllers,
derivative controllers, integral controllers,
proportional-derivative controllers, proportional-integral
controllers, and proportional-integral-derivative controllers.
17. A pressure sensing and pressure regulating apparatus according
to claim 7 wherein the fluid system comprises a fuel system.
18. A pressure regulating apparatus for a fuel system, comprising:
a housing having an axial bore extending therethrough that defines
a longitudinal direction, wherein the housing includes a fuel inlet
passageway and a fuel outlet passageway; a sense tube assembly
disposed within the axial bore, comprising: a longitudinally
extending outer tube, comprising: a tubular body having an inner
surface and an outer surface and having an open end and an opposite
closed end; and a longitudinally extending channel formed along the
inner surface of the outer tube body from the outer tube open end
toward the outer tube closed end; and a longitudinally extending
inner tube disposed within the outer tube, comprising: a tubular
body having an inner surface and an outer surface and having an
open end and an opposite closed end; a radially extending flange
adjacent the inner tube open end, wherein a first aperture is
formed through a portion of the flange; wherein the inner tube
closed end includes a second aperture formed therethrough; wherein
the outer surface of the inner tube body is in contacting
relationship with the inner surface of the outer tube body to
define a pressure chamber between the outer tube closed end and the
inner tube closed end; and wherein the longitudinally extending
channel is in fluid communication with the fuel inlet passageway
via the first aperture and forms a fuel flow path between the inner
tube and the outer tube from the fuel inlet passageway to the
pressure chamber; a magnetic pole piece disposed within the inner
tube, comprising: opposite first and second ends; and an internal
bore that terminates at the magnetic pole piece first and second
ends, wherein the internal bore is in fluid communication with the
fuel outlet passageway; a magnetic armature slidably secured within
the inner tube between the magnetic pole piece and the inner tube
closed end, comprising: a body having an outer surface and
terminating at opposite first and second ends, wherein the magnetic
armature second end is configured to matingly engage the second
aperture in the inner tube closed end; and a pair of diametrically
opposed longitudinally extending slots formed in an outer surface
of the magnetic armature body; a longitudinally extending
passageway that terminates at the magnetic armature first and
second ends and that is in fluid communication with the magnetic
pole piece internal bore; biasing means configured to bias the
magnetic armature away from the magnetic pole piece and to cause
the magnetic armature second end to matingly engage the second
aperture in the inner tube closed end; a pressure sensing element
attached to the outer tube closed end, wherein the pressure sensing
element comprises a semiconductor element that deflects when the
outer tube closed end deflects as a result of pressure within the
pressure chamber; and a coil disposed within the housing, wherein
the coil is configured to generate a magnetic field responsive to
electrical signals from the pressure sensing element that moves the
magnetic armature axially within the inner tube to control fuel
pressure by allowing fuel entering the pressure chamber via the
fuel inlet passageway to exit via the fuel outlet passageway.
19. A pressure regulating apparatus according to claim 18 wherein
the inner tube second end has an annular configuration.
20. A pressure regulating apparatus according to claim 18 wherein
the longitudinally extending passageway in the magnetic armature
comprises a longitudinally extending slot formed in an outer
surface of the magnetic armature body.
21. A pressure regulating apparatus according to claim 18 wherein
the body of the inner tube and the body of the outer tube each have
respective cylindrical configurations.
22. A pressure regulating apparatus according to claim 18 wherein
the semiconductor element comprises an embedded Wheatstone
bridge.
23. A pressure regulating apparatus according to claim 18 further
comprising means for adjusting axial movement of the magnetic
armature within the inner tube relative to a magnetic field
produced by the coil.
24. A pressure regulating apparatus according to claim 18 further
comprising a controller electrically connected with the pressure
sensing element and configured to maintain fuel pressure within a
prescribed range of pressures, and wherein the controller is
selected from the group consisting of proportional controllers,
derivative controllers, integral controllers,
proportional-derivative controllers, proportional-integral
controllers, and proportional-integral-derivative controllers.
25. A direct injection fuel system for an internal combustion
engine, comprising: a fuel tank; a fuel rail; a fuel supply line
connecting the fuel tank and the fuel rail; a pump for pumping fuel
from the fuel tank to the fuel rail via the fuel supply line; a
plurality of fuel injectors in fluid communication with the fuel
rail, wherein each fuel injector is configured to directly inject
fuel from the fuel rail into a respective combustion chamber within
the internal combustion engine; a pressure sensing and pressure
regulating unit that senses and regulates fuel pressure within the
fuel rail, comprising: a housing; a pressure chamber within the
housing comprising a wall configured to deflect responsive to fuel
pressure within the pressure chamber, wherein the pressure chamber
is in fluid communication with-the fuel rail; a pressure sensing
device attached to the wall within the housing, wherein the
pressure sensing device is configured to generate electrical
signals responsive to deflection of the pressure chamber cause by
fuel pressure within the pressure chamber; and a pressure
regulating device within the housing comprising a valve member that
is configured to relieve fuel pressure in the pressure chamber by
allowing fuel to exit from the pressure chamber to the fuel tank,
wherein movement of the valve member is responsive to electrical
signals generated by the pressure sensing device.
26. A direct injection fuel system according to claim 25 wherein
the pressure sensing device comprises a semiconductor element.
27. A direct injection fuel system according to claim 25 wherein
the valve member comprises a magnetic armature.
28. A direct injection fuel system according to claim 27 further
comprising a coil disposed within the housing, wherein the coil is
electrically connected with the pressure sensing device, and
wherein the coil is configured to generate a magnetic field
responsive to electrical signals from the pressure sensing device
that moves the magnetic armature to control fuel pressure within
the pressure chamber by allowing fuel to exit from the pressure
chamber to the fuel tank.
29. A direct injection fuel system according to claim 25 further
comprising a controller electrically connected with the pressure
sensing device and configured to maintain fuel pressure within the
fuel rail within a predetermined range of pressures, and wherein
the controller is selected from the group consisting of
proportional controllers, derivative controllers, integral
controllers, proportional-derivative controllers,
proportional-integral controllers, and
proportional-integral-derivative controllers.
30. A direct injection fuel system for an internal combustion
engine, comprising: a fuel tank; a fuel rail; a fuel supply line
connecting the fuel tank and the fuel rail; a pump for pumping fuel
from the fuel tank to the fuel rail via the fuel supply line; a
plurality of fuel injectors in fluid communication with the fuel
rail, wherein each fuel injector is configured to directly inject
fuel from the fuel rail into a respective combustion chamber within
the internal combustion engine; a pressure regulating apparatus,
comprising: a housing having an axial bore extending therethrough
that defines a longitudinal direction, wherein the housing includes
a fuel inlet passageway in fluid communication with the fuel rail
and a fuel outlet passageway; a sense tube assembly disposed within
the axial bore, comprising: a longitudinally extending outer tube,
comprising: a tubular body having an inner surface and an outer
surface and having an open end and an opposite closed end; and a
longitudinally extending channel formed along the inner surface of
the outer tube body from the outer tube open end toward the outer
tube closed end; and a longitudinally extending inner tube disposed
within the outer tube, comprising: a tubular body having an inner
surface and an outer surface and having an open end and an opposite
closed end; wherein the inner tube closed end includes an aperture
formed therethrough; wherein the outer surface of the inner tube
body is in contacting relationship with the inner surface of the
outer tube body to define a pressure chamber between the outer tube
closed end and the inner tube closed end; and wherein the
longitudinally extending channel is in fluid communication with the
fuel inlet passageway and forms a fuel flow path between the inner
tube and the outer tube from the fuel inlet passageway to the
pressure chamber; a magnetic pole piece disposed within the inner
tube, comprising: opposite first and second ends; and an internal
bore that terminates at the magnetic pole piece first and second
ends, wherein the internal bore is in fluid communication with the
fuel outlet passageway; a magnetic armature slidably secured within
the inner tube between the magnetic pole piece and the inner tube
closed end, comprising: a body having an outer surface and
terminating at opposite first and second ends, wherein the magnetic
armature second end is configured to matingly engage the aperture
in the inner tube closed end; and a longitudinally extending
passageway that terminates at the magnetic armature first and
second ends and that is in fluid communication with the magnetic
pole piece internal bore; biasing means configured to bias the
magnetic armature away from the magnetic pole piece and to cause
the magnetic armature second end to matingly engage the aperture in
the inner tube closed end; a pressure sensing element attached to
the outer tube closed end, wherein the pressure sensing-element is
configured to measure fuel pressure within the pressure chamber;
and a coil disposed within the housing, wherein the coil is
electrically connected with the pressure sensor, and wherein the
coil is configured to generate a magnetic field responsive to
electrical signals from the pressure sensing element that moves the
magnetic armature axially within the inner tube to control fuel
pressure by allowing fuel entering the pressure chamber via the
fuel inlet passageway to exit via the fuel outlet passageway; and a
fuel return line connecting the pressure regulating apparatus and
the fuel tank, wherein the fuel return line is configured return
fuel exiting from the pressure regulating apparatus via the fuel
outlet passageway to the fuel tank.
31. A direct injection fuel system according to claim 30 wherein
the inner tube further comprises: a radially extending flange
adjacent the inner tube open end; and an aperture formed through a
portion of the flange, wherein the longitudinally extending channel
in the outer tube is in fluid communication with the fuel inlet
passageway via the flange aperture and forms a fuel flow path
between the inner tube and the outer tube from the fuel inlet
passageway to the pressure chamber.
32. A direct injection fuel system according to claim 31 wherein
the fuel is pumped to a pressure of between about 0 psi and about
1,500 psi.
33. A direct injection fuel system according to claim 30 wherein
the inner tube second end has an annular configuration.
34. A direct injection fuel system according to claim 30 wherein
the longitudinally extending passageway in the magnetic armature
comprises a longitudinally extending slot formed in the outer
surface of the magnetic armature body.
35. A direct injection fuel system according to claim 30 wherein
the magnetic armature comprises a pair of diametrically opposed
longitudinally extending slots formed in the outer surface of the
magnetic armature body.
36. A direct injection fuel system according to claim 30 wherein
the body of the inner tube and the body of the outer tube each have
respective cylindrical configurations.
37. A direct injection fuel system according to claim 30 wherein
the pressure sensing element comprises a semiconductor element that
deflects in response to a deflection of the outer tube second end
caused by fuel pressure within the pressure chamber.
38. A direct injection fuel system according to claim 37 wherein
the semiconductor element comprises an embedded Wheatstone
bridge.
39. A direct injection fuel system according to claim 30 further
comprising means for adjusting axial movement of the magnetic
armature within the inner tube relative to a magnetic field
produced by the coil.
40. A direct injection fuel system according to claim 30 further
comprising a controller electrically connected with the pressure
sensing element and configured to maintain fuel pressure within a
prescribed range of pressures, and wherein the controller is
selected from the group consisting of proportional controllers,
derivative controllers, integral controllers,
proportional-derivative controllers, proportional-integral
controllers, and proportional-integral-derivative controllers.
41. A method of calibrating a pressure sensing element within a
pressure regulating apparatus for a fuel system to compensate for
mechanical strain imposed on the pressure sensing element during
assembly of the pressure regulating apparatus, wherein the pressure
regulating apparatus includes a pressure chamber and a pressure
sensing element attached to the pressure chamber, and wherein the
pressure sensing element is configured to measure fuel pressure
within the pressure chamber, the method comprising the steps of:
enclosing the pressure chamber and pressure sensing element
attached thereto within a housing, wherein the pressure sensing
element is electrically connected to an electrical terminal located
external to the housing; detecting an electrical signal generated
by the pressure sensing element; and transmitting electrical
signals to the pressure sensing element via the electrical
terminal.
42. A method according to claim 41 wherein the pressure chamber
comprises: a longitudinally extending outer tube, comprising: a
tubular body having an inner surface and an outer surface and
having an open end and an opposite closed end; and a longitudinally
extending channel formed along the inner surface of the outer tube
body from the outer tube open end toward the outer tube closed end;
and a longitudinally extending inner tube disposed within the outer
tube, comprising: a tubular body having an inner surface and an
outer surface and having an open end and an opposite closed end;
wherein the inner tube closed end includes an aperture formed
therethrough; wherein the outer surface of the inner tube body is
in contacting relationship with the inner surface of the outer tube
body to define a pressure chamber between the outer tube closed end
and the inner tube closed end; and wherein the longitudinally
extending channel forms a fuel flow path between the inner tube and
the outer tube from a fuel source to the pressure chamber.
43. A method according to claim 42 wherein the pressure sensing
element comprises a semiconductor element that deflects in response
to a deflection of the outer tube closed end caused by pressure
within the pressure chamber.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to pressure
regulating devices and, more particularly, to pressure regulating
devices for fuel systems.
BACKGROUND OF THE INVENTION
[0002] To help meet consumer demand for more fuel efficient
vehicles, automotive companies have begun investigating the use of
direct injection fuel systems for internal combustion engines. In a
direct injection fuel system, a fuel injector injects highly
pressurized fuel directly into an engine cylinder combustion
chamber during the compression stroke. Direct fuel injection can
facilitate efficient fuel combustion, thereby improving fuel
economy.
[0003] Because fuel is injected during a compression stroke, the
fuel must be at a high pressure (e.g., about 200 Bar or 2,900 psi)
in order to enter the cylinder. High fuel pressure is typically
achieved by using a high-pressure booster pump in conjunction with
a low pressure fuel tank pump.
[0004] FIG. 1 is a schematic illustration of a conventional direct
injection fuel system 5 for an internal combustion engine. Fuel,
such as gasoline, is pumped from a tank 10 via a low pressure tank
pump 12 to a high pressure booster pump 14. The high pressure
booster pump 14 raises the pressure of the fuel so that the fuel
can enter a combustion chamber against the compression pressure in
the cylinder. Typically, a high pressure booster pump is mounted to
an engine and is operated directly from a cam (or crank) shaft
within the engine. As illustrated in FIG. 1, the high pressure fuel
discharged from the high pressure booster pump 14 flows through a
fuel rail 42 and to each injector 18 via a respective fuel
passageway 20. Each injector 18 is configured to deliver a
controlled amount of fuel into a respective cylinder 22 when
activated by an engine control unit (ECU) 24. Conventionally, fuel
pressure in a fuel rail 42 is controlled via a fuel rail pressure
regulator 26 and a fuel rail pressure sensor 28. Typically, the
pressure sensor 28 and pressure regulator 26 communicate with each
other via an ECU 24.
[0005] Because two separate components (i.e., a pressure regulator
and a pressure sensor) are typically used to control fuel pressure
in conventional direct injection fuel systems, multiple connections
in a fuel rail are typically necessary. Unfortunately, each
connection in a high pressure fuel rail is a potential source of
fuel leakage. Because fuel rails are typically mounted near hot
exhaust manifolds, the potential for fire caused by a fuel leak
from a high pressure fuel rail can be substantial.
SUMMARY OF THE INVENTION
[0006] In view of the above discussion, it is an object of the
present invention to facilitate reducing the potential for fire
caused by fuel leaks in high pressure direct injection fuel systems
for internal combustion engines.
[0007] It is another object of the present invention to provide
fuel pressure monitoring and control for high pressure direct
injection fuel systems wherein only a single connection in a fuel
rail is required.
[0008] These and other objects of the present invention are
provided by pressure regulating devices for high pressure fluid
systems, such as fuel systems, wherein a pressure sensing element
is attached directly to a pressure chamber within a pressure
regulating device. According to one embodiment of the present
invention, a sense tube assembly is disposed within an axial bore
of a housing. The sense tube assembly includes a longitudinally
extending outer tube having a longitudinally extending inner tube
disposed within the outer tube to define a fuel pressure
chamber.
[0009] The outer tube has a tubular body terminating at an open end
and at an opposite closed end. A longitudinally extending channel
is formed along the inner surface of the outer tube body from the
outer tube open end toward the outer tube closed end.
[0010] The inner tube has a tubular body terminating at an open end
and at an opposite closed end. The inner tube closed end includes
an aperture formed therethrough. A radially extending flange is
positioned adjacent the inner tube open end and has an aperture
formed through a portion thereof. The longitudinally extending
channel in the outer tube is in fluid communication with a fuel
inlet passageway in the housing via the flange aperture. The
longitudinally extending channel in the outer tube forms a fuel
flow path between the inner tube and the outer tube from the fuel
inlet passageway to the fuel pressure chamber.
[0011] A magnetic pole piece is disposed within the inner tube and
includes opposite first and second ends and an internal bore that
terminates at the magnetic pole piece first and second ends. The
magnetic pole piece internal bore is in fluid communication with a
fuel outlet passageway in the housing.
[0012] A magnetic armature is slidably secured within the inner
tube between the magnetic pole piece and the inner tube closed end.
The magnetic armature includes a body having a pair of slots formed
in the outer surface thereof and terminating at opposite first and
second ends. The magnetic armature second end is configured to
matingly engage the aperture in the inner tube closed end. The
slots formed in the armature are in fluid communication with the
magnetic pole piece internal bore. A spring, located between the
magnetic armature and magnetic pole piece, is configured to bias
the magnetic armature away from the magnetic pole piece and to
cause the magnetic armature second end to matingly engage the
aperture in the inner tube closed end.
[0013] A pressure sensing element is attached to the outer tube
closed end and is configured to measure fuel pressure within the
pressure chamber. The pressure sensing element includes a
semiconductor element that deflects in response to a deflection of
the outer tube second end caused by pressure within the pressure
chamber. A coil disposed within the housing is electrically
connected with the pressure sensing element and is configured to
generate a magnetic field responsive to electrical signals from the
pressure sensing element. The magnetic field moves the magnetic
armature axially within the inner tube to control fuel pressure by
allowing fuel entering-the pressure chamber via the fuel inlet
passageway to exit via a fuel outlet passageway.
[0014] Because the present invention combines a pressure sensing
element and pressure regulator within a single device, only a
single connection in a fuel rail is required. Accordingly, the
number of potential sources of fuel leaks is reduced by the present
invention.
[0015] According to another embodiment of the present invention, a
controller, such as a proportional-integral-derivative (PID)
controller, may be electrically connected with the pressure sensing
element to create a "smart solenoid" whereby fuel pressure can be
maintained within a prescribed range of pressures. The controller
closes the loop around the sensed pressure via the pressure sensing
element and adjusts the voltage to the coil which controls the
axial movement of the magnetic armature within the inner tube in
order to maintain fuel pressure within a predetermined range.
[0016] According to another embodiment of the present invention, a
post-assembly calibration method is provided to compensate for
mechanical strain imposed on pressure sensing elements during
assembly of pressure regulating devices. A pressure sensing element
attached to a pressure chamber within a pressure regulating device
housing is electrically connected to an electrical terminal located
external to the housing. The pressure sensing element is then
calibrated to compensate for mechanical strain imposed on the
pressure sensing element during assembly by transmitting electrical
signals to the pressure sensing element via the electrical
terminal.
[0017] The present invention may be utilized with various high
pressure fluid systems, and is not limited to high pressure fuel
systems.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a schematic illustration of a conventional direct
injection fuel system for an internal combustion engine.
[0019] FIG. 2 is a side, section view of a fuel pressure regulating
apparatus according to an embodiment of the present invention.
[0020] FIG. 3A is a side, section view of the inner tube of the
sense tube assembly within the pressure regulating apparatus of
FIG. 2.
[0021] FIG. 3B is an end view of the inner tube of FIG. 3A
illustrating an aperture formed in the flange that permits fuel to
flow from the fuel inlet passageway into the fuel flow path between
the inner tube and the outer tube.
[0022] FIG. 4A is a side, section view of the outer tube of the
sense tube assembly within the pressure regulating apparatus of
FIG. 2.
[0023] FIG. 4B is a section view of the outer tube of FIG. 4A
illustrating a longitudinally extending channel which forms a fuel
flow path between the inner tube and outer tube of the sense tube
assembly.
[0024] FIG. 5A is an enlarged section view of the magnetic armature
in the pressure regulating apparatus of FIG. 2.
[0025] FIG. 5B is an enlarged end view of the magnetic armature of
FIG. 5A taken along lines 5B-5B.
[0026] FIG. 6A is an enlarged section view of the magnetic pole
piece in the pressure regulating apparatus of FIG. 2.
[0027] FIG. 6B is an enlarged end view of the magnetic pole piece
of FIG. 6A taken along lines 6B-6B.
[0028] FIG. 7 is an enlarged side, section view of the pressure
regulating apparatus of FIG. 2 illustrating the pressure sensing
element that is attached to the outer surface of the outer tube
second end.
[0029] FIG. 8 is a bottom plan view of the electrical connector
socket of the pressure regulating apparatus of FIG. 2 illustrating
the electrical terminals contained therein.
[0030] FIG. 9 is a schematic illustration of operations for
calibrating a pressure sensing element within a pressure regulating
apparatus according to the present invention to compensate for
mechanical strain imposed on the pressure sensing element during
assembly.
[0031] FIG. 10 is a schematic illustration of a direct injection
fuel system incorporating various aspects of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0032] The present invention now will be described more fully
hereinafter with reference to the accompanying drawings, in which
preferred embodiments of the invention are shown. This invention
may, however, be embodied in many different forms and should not be
construed as limited to the embodiments set forth herein; rather,
these embodiments are provided so that this disclosure will be
thorough and complete, and will fully convey the scope of the
invention to those skilled in the art. Like numbers refer to like
elements throughout.
[0033] Referring now to FIG. 2, a pressure regulating apparatus 40
according to an embodiment of the present invention is illustrated.
The pressure regulating apparatus 40, which is in fluid
communication with a fuel rail 42, includes an annular first
housing portion 43 and an annular magnetic flux housing 44 which
are collectively referred to herein as a "housing" that has an
axial bore 45 extending therethrough. The axial bore 45 defines a
longitudinally extending axial direction, indicated by reference
letter A, and is configured to receive a flow plug 46, sense tube
assembly 47 and pressure sensing element 48 as will be described in
detail below.
[0034] The illustrated fuel rail 42 includes a first end portion
42a that is configured to receive an end portion 46a of a flow plug
46. In the illustrated embodiment, a filter 17 is attached to the
flow plug end portion 46a to prevent foreign materials entrained
within fuel from entering the pressure regulating apparatus 40. The
fuel rail 42 is in fluid communication with a fuel inlet passageway
54a and a fuel outlet passageway 54b in the flow plug 46.
[0035] The illustrated fuel rail 42 also includes a second end
portion 42b that is threadingly engaged with a first end portion
43a of the annular first housing portion 43. An O-ring 49 is
configured to maintain a sealed engagement between the fuel rail 42
and the annular first housing portion 43 as would be understood by
one skilled in the art.
[0036] The annular flux housing 44 has opposite first and second
end portions 44a, 44b. The annular flux housing 44 is configured to
enclose an insulating bobbin 50 disposed therewithin and having
conductive wire 51 coiled therearound to define a coil 52 for
generating a magnetic field when electrical current flow is induced
therein. The coil 52 generates a magnetic field which causes
magnetic flux to flow through the flux housing 44, into the upper
flux washer 55, into a magnetic armature 80, into a magnetic pole
piece 84, into a lower flux washer 56, and then back to the flux
housing 44. The flow of magnetic flux causes the magnetic armature
80 to move axially within the sense tube assembly 47. This magnetic
force is assisted by the fuel pressure force pushing on the
magnetic armature 80 at the poppet seat 72. Opposing these two
forces is the force of the armature spring 82. The balancing of
these forces is what allows for pressure regulation of fuel within
the fuel rail 42. Coils for moving magnetic armatures (or
solenoids) are well understood by those skilled in this art and
need not be described further herein.
[0037] The flow plug 46 is positioned within the axial bore 45 as
illustrated. The flow plug 46 has a first end 46a secured within
the fuel rail 42. The flow plug 46 includes a fuel inlet passageway
54a and a fuel outlet passageway 54b. The fuel inlet passageway 54a
is in fluid communication with the fuel rail 42. The flow plug 46
has an opposite second end portion 46b secured within an inner tube
60 of the sense tube assembly 47. An O-ring 53a is configured to
prevent fuel leakage between the flow plug first end 46a and the
fuel rail 42, and an O-ring 53b is configured to prevent fuel
leakage between the flow plug second end 46b and the inner tube 60
as would be understood by one skilled in the art. Fuel enters the
pressure regulating apparatus 40 from the fuel rail 42 via the fuel
inlet passageway 54a and exits from the pressure regulating
apparatus 40 via the fuel outlet passageway 54b, as will be
described in detail below.
[0038] The illustrated sense tube assembly 47 disposed within the
axial bore 45 includes a longitudinally extending inner tube 60
disposed within a longitudinally extending outer tube 66. The inner
tube 60 and outer tube 66 will now be described in detail with
reference to FIGS. 3A-3B and FIGS. 4A-4B, respectively.
[0039] Referring to FIG. 3A, a side, section view of the inner tube
60 is illustrated. The illustrated inner tube 60 includes a tubular
(preferably cylindrical) body 61a with an open end 61b and a closed
end 61c, and inner and outer surfaces 61d, 61e. The inner tube 60
defines an elongated, cylindrical chamber 64 extending between the
open and closed ends 61b, 61c that is configured to receive the
magnetic armature 80 and a pole piece 84 as described below.
[0040] The inner tube closed end 61c has an annular configuration
that defines an aperture 71. As will be described below, the
aperture 71 defines a poppet seat 72 for receiving the armature
first end 80a (FIG. 2) in mating relationship. A radially extending
flange 62 is positioned adjacent the inner tube open end 61b, as
illustrated. An aperture 63 is formed through a portion of the
flange 62, as illustrated. FIG. 3B is an end view of the inner tube
60 illustrating the flange 62 and the aperture 63 formed
therein.
[0041] Referring to FIG. 4A, a side, section view of the outer tube
66 is illustrated. The outer tube 66 includes a tubular body 67a
having an open end 67b and an opposite closed end 67c, and having
inner and outer surfaces 67d, 67e. A longitudinally extending
channel 68 is formed along the inner surface 67d of the outer tube
body 67a from the outer tube open end 67b toward the outer tube
closed end 67c. FIG. 4B is a section view of the outer tube 62 that
illustrates the cross-sectional contour of the longitudinally
extending channel 68.
[0042] The outer tube 66 defines an elongated, cylindrical chamber
70 extending between the open and closed ends 67b, 67c that is
configured to receive the inner tube 60 therewithin. The outer tube
open end 67b includes a radially extending flange 74 adjacent
thereto as illustrated. The flange 74 abuts the flange 62 of the
inner tube 60 when the inner tube 60 is assembled within the outer
tube chamber 70 (as illustrated in FIG. 2).
[0043] The outer tube second end 67c has an outer surface 75 to
which the pressure sensing element 48 (FIG. 2) is attached. In the
illustrated embodiment, a slot 76 circumferentially extends around
the outer tube 66 adjacent the second end 67c as illustrated in
FIG. 4A. The slot 76 is configured to receive an O-ring (77, FIG.
2) that is configured to seal the outer tube 66 within the axial
bore 45 as would be understood by one skilled in the art.
[0044] When the inner and outer tubes 60, 66 are assembled to form
the sense tube assembly 47, the outer surface 61e of the inner tube
body 61a is in contacting relationship with the inner surface 67d
of the outer tube body 67a to define a pressure chamber 65 between
the outer tube closed end and the inner tube closed end, as
illustrated in FIG. 2. The fit between the inner tube 60 and the
outer tube 62 is sufficiently snug such that fuel within a pressure
range of between about 0 pounds per square inch (psi) and about
3,000 psi is prevented from leaking therebetween.
[0045] Preferably, the inner tube 60 is formed from non-magnetic
material including, but not limited to, non-magnetic stainless
steel having a thickness of between about 0.012 inches and about
0.018 inches. Preferably, the outer tube 66 is formed from
nonmagnetic material including, but not limited to, nonmagnetic
stainless steel having a thickness of between about 0.012 inches
and about 0.018 inches.
[0046] In addition, the longitudinally extending channel 68 in the
outer tube 66 forms a fuel flow path 69 located between the inner
tube 60 and the outer tube 66. The aperture 63 in the inner tube
flange 62 is aligned with an annular ring on the outer tube. This
annular ring creates a cavity 67e which feeds the fuel flow path 69
so that the fuel inlet passageway 54a is in fluid communication
with the fuel flow path 69. Accordingly, fuel can flow from the
fuel inlet passageway 54a into the pressure chamber 65 via the fuel
flow path 69.
[0047] Referring back to FIG. 2, the magnetic armature 80, a spring
82 and the magnetic pole piece 84 are disposed within the inner
tube chamber 64, as illustrated. The magnetic armature 80 includes
opposite first and second ends 80a, 80b and is slidably secured
within the inner tube chamber 64. The magnetic armature 80 is
configured to move along the axial direction A in response to a
magnetic field generated by the coil 52. The magnetic pole piece 84
is fixed within the inner tube chamber 64 adjacent the magnetic
armature first end 80a and includes opposite first and second ends
84a, 84b, as illustrated.
[0048] The magnetic armature 80 is biased via the spring 82 along
the axial direction A away from the pole piece second end 84b and
toward the inner tube second end 61c. The magnetic armature second
end 80b is configured to matingly engage with the poppet seat 72
formed in the inner tube second end 61c to prevent passage of fuel
into the inner tube chamber 64. In the illustrated embodiment, the
magnetic armature 80 is mechanically loaded to a closed position
when current is not induced within the coil 52. However, it is
understood that the magnetic armature 80 may be mechanically loaded
to an open position via the spring 82 when current is not induced
within the coil 52.
[0049] Still referring to FIG. 2, the magnetic pole piece 84
includes an axial bore 85 extending along the axial direction A
between the opposite first and second ends 84a, 84b, as
illustrated. A portion of the magnetic pole piece axial bore
adjacent the pole piece second end 84a is threaded and configured
to receive a correspondingly-threaded adjusting screw 86 therein as
illustrated. The adjusting screw 86 is configured to adjust or
calibrate the position of the magnetic armature second end 80b with
respect to the poppet seat 72 at the inner tube second end 61c by
compressing or expanding the spring 82, as would be understood by
one of skill in the art.
[0050] The annular flux housing 44, magnetic armature 80, upper and
lower flux washers 55, 56 and magnetic pole piece 84 form a
magnetic flux circuit such that flow of electrical current within
the coil 52 produces a magnetic field that causes the magnetic
armature first end 80a to move in the axial direction A within the
inner tube 60 toward the pole piece second end 84b. The spring 82
biases against the magnetic armature first end 80a to counter the
magnetic force attracting the magnetic armature 80 towards the pole
piece 84. As would be understood by one of skill in the art, the
amount of movement of the magnetic armature 80 may be controlled by
controlling the amount of electrical current applied to the coil 52
and/or by selecting a spring that has a desired spring rate. Fuel
pressure exerted on the magnetic armature is typically between
about 0 psi and about 1,500 psi.
[0051] Referring now to FIGS. 5A-5B, the configuration of the
magnetic armature 80 illustrated in FIG. 2 is shown in enlarged
detail. The second end 80b has a conical-shaped projection 80c that
is configured to matingly engage with the poppet seat 72 formed in
the inner tube second end 61c. The magnetic armature 80 includes a
pair of diametrically opposed slots 88a, 88b that extend between
the opposite first and second ends 80a, 80b. Slots 88a, 88b allow
fuel passing through the inner tube aperture 71 from the pressure
chamber 65 to flow past the magnetic armature 80 and into the axial
bore 85 of the magnetic pole piece 84. It is understood that the
magnetic armature 80 may have various shapes and configurations and
is not limited to the illustrated embodiment. For example, the
magnetic armature 80 may have a "D" shape (in lieu of slots 88a,
88b) which allows fuel to flow past the magnetic armature 80 and
into the axial bore 85 of the magnetic pole piece 84.
[0052] The magnetic armature 80 also includes a bore 89 that
extends partially into the magnetic armature from the first end
80a. The bore 89 is configured to receive the spring (82, FIG. 2)
therein for biasing the magnetic armature away from the magnetic
pole piece second end 84b.
[0053] Referring now to FIGS. 6A-6B, the configuration of the
magnetic pole piece 84 illustrated in FIG. 2 is shown in enlarged
detail. The magnetic pole piece 84 includes the axial bore 85 and a
pair of diametrically opposed slots 90a, 90b that extend between
opposite first and second ends 84a, 84b. The slots 90a, 90b are in
communication with the axial bore 85. The slots 84a, 84b and the
axial bore 85 allow fuel flowing around the magnetic armature 80 to
flow through the magnetic pole piece and into a chamber 92 within
the flow plug 46 that is in fluid communication with the fuel
outlet passageway 54b.
[0054] Referring back to FIG. 2, an air gap shim 87 is positioned
between the magnetic armature 80 and the magnetic pole piece 84 as
illustrated. The air gap shim 87 is formed from non-magnetic
material and prevents magnetic "latch" from occurring between the
magnetic armature 80 and the magnetic pole piece 84, as would be
understood by one of skill in the art.
[0055] Referring now to FIG. 7, the pressure sensing element 48
that is mounted directly to the outer surface 75 of the second end
67c of the outer tube 66 is illustrated in enlarged detail. The
pressure sensing element 48 preferably includes a semiconductor
element 100 having an embedded resistive element such as a
Wheatstone bridge. The semiconductor element 100 is preferably a
planar substrate formed from silicon. However, the semiconductor
element 100 may have various configurations and may be formed from
various materials. In the illustrated embodiment, the semiconductor
element 100 is surrounded by a protective covering or die cap
101.
[0056] As fuel pressure increases within the pressure chamber 65
(indicated by arrows P), the second end 67c of the outer tube 66
deflects toward the semiconductor element 100. The deflection of
the second end 67c of the outer tube 66 causes the semiconductor
element 100 to deflect which changes its resistance.
[0057] By applying a known voltage to the pressure sensing element
48 and monitoring the voltage drops across the pressure sensing
element 48, changes can be detected. By applying a plurality of
known pressures to the sense surface (i.e., the outer surface 75 of
the second end 67c of the outer tube 66) and monitoring the voltage
changes induced on the pressure sensing element 48 by these known
pressures, the pressure sensing element 48 can be accurately
calibrated to produce a pressure transducer.
[0058] As would be understood by one of skill in the art,
electrical resistive strain devices produce a varying resistance
when strained by a mechanical force. Accordingly, deflection of the
second end 67c of the outer tube 66 causes the semiconductor
element 100 to deflect and, thus, change resistance. By supplying a
voltage to the semiconductor element 100, a sensed voltage that is
proportional to the amount of fuel pressure within the pressure
chamber 65 can be generated. An exemplary pressure sensing element
48 is disclosed in co-pending and co-assigned U.S. patent
application Ser. No. 08/840,363, filed Apr. 28, 1997, which is
incorporated herein by reference in its entirety.
[0059] A flex circuit assembly 102 that includes electronics to
supply the resistive bridge with voltage and process the voltage
signals of the semiconductor element 100 is electrically connected
to the semiconductor element 100 via lead 102a. Lead 102b
electrically connects the flex circuit assembly 102 to an
electrical terminal 110a. Electrical terminal 110a is preferably
electrically connected with an ECU (24, FIG. 1) via an electrical
cable inserted within the socket 114. In the illustrated
embodiment, the flex circuit assembly 102 is embedded within a
dielectric material 103 such as KAPTON.RTM. flexible film (E. I. du
Pont de Nemours and Company, 1007 Market St., Wilmington, Del.).
Flexible dielectric films are well known by those having skill in
the art and need not be described further herein.
[0060] The output from the pressure sensing element 48 is typically
a 0.0-5.0 volt direct current (DC) analog signal. However, the
output from the pressure sensing element 48 may also be a digital
data stream. The output from the pressure sensing element 48 is
preferably generated internally via an application specific
integrated circuit (ASIC) which has a processor built therein. The
processor takes a voltage reading from the semiconductor element
100 and a voltage reading that is proportional to temperature and
generates the output voltage.
[0061] The flex circuit assembly 102 preferably includes a static
ground protection system and an electromagnetic interference (EMI)
circuit to dampen out background radiation. Static ground
protection systems and EMI circuits are well known by those of
skill in the art and need not be described further herein.
[0062] Preferably, additional terminals 110b-110e are housed within
the socket 114, as illustrated in FIG. 8. As would be understood by
one of skill in the art, terminals 110b-110e may be provided to
perform various functions, including: providing electrical power to
the coil 52; providing ground; providing an output line from the
pressure sensing element 48; providing power to the pressure
sensing element 48; and providing ground.
Pressure Sensing Element Calibration
[0063] Prior to final assembly of the pressure regulating apparatus
40, the electronic pressure sensing element 48 is typically
calibrated. However, assembly of the pressure regulating apparatus
40 may induce mechanical strain on the outer tube 66 and/or the
pressure sensing element 48 which may, in turn, negatively affect
any pre-assembly calibration efforts. According to another
embodiment of the present invention, calibration of a pressure
sensing element housed within a pressure regulating apparatus can
be performed after assembly is complete.
[0064] Referring now to FIG. 9, operations for calibrating a
pressure sensing element within a pressure regulating apparatus to
compensate for mechanical strain imposed on the pressure sensing
element during assembly of the pressure regulating apparatus are
illustrated. A pressure chamber and pressure sensing element
attached thereto is enclosed within a housing, such that the
pressure sensing element is electrically connected to an electrical
terminal located external to the housing (Block 200). Electrical
signals generated by the pressure sensing element are detected via
the electrical terminal (Block 202). Finally, the pressure sensing
element is then calibrated to compensate for mechanical strain
imposed thereon during assembly by transmitting electrical signals
to the pressure sensing element via the electrical terminal (Block
204).
[0065] Because actual changes in voltage generated by the pressure
sensing element 48 are small, temperature can play an important
role in calibration of the pressure sensing element 48. Calibration
is preferably performed by applying known pressures to the pressure
sensing element 48 while the pressure sensing element 48 is at
different temperatures and then monitoring the voltage signals
produced by the pressure sensing element 48. The output signal from
the pressure sensing element 48 can then be adjusted.
[0066] Preferably, an electrical terminal for transmitting the
output signal from the pressure sensing element 48 is utilized as a
digital input/output (I/O) port to program the ASIC. The ASIC has a
monitoring circuit that checks the electrical terminal for digital
communications. The electrical terminal thus allows the pressure
sensing element 48 to be calibrated after the pressure regulating
apparatus 40 has been assembled. By contrast, calibration of
conventional pressure sensors is performed prior to final
assembly.
Direct Injection Fuel System
[0067] Referring now to FIG. 10, a direct injection fuel system 5'
for an internal combustion engine incorporating a pressure
regulating apparatus according to various aspects of the present
invention is schematically illustrated. The illustrated direct
injection fuel system 5' includes a fuel tank 10, a fuel rail 42,
and a fuel supply line 17 connecting the fuel tank 10 and the fuel
rail 42. A high pressure booster pump 14 is provided for pumping
fuel from the fuel tank 10 to the fuel rail 42 via the fuel supply
line 17. As described above with respect to FIG. 1, a low pressure
fuel pump 12 may also be utilized, as would be understood by one
skilled in the art. A plurality of fuel injectors 18 are in fluid
communication with the fuel rail 42 and each fuel injector 18 is
configured to directly inject fuel from the fuel rail 42 into a
respective combustion chamber 22 within the internal combustion
engine.
[0068] A pressure regulating apparatus 40 as described above is in
fluid communication with the fuel rail 42. A fuel return line 19
connects the pressure regulating apparatus 40 and the fuel tank 10
and is configured to return fuel exiting from the pressure
regulating apparatus 40 to the fuel tank.
[0069] As will be described below, a controller 30 may be
electrically connected with a pressure sensing element within the
pressure regulating apparatus 40 and configured to maintain fuel
pressure within a prescribed range of pressures based upon the
requested input. The controller 30 may be a proportional
controller, a derivative controller, an integral controller, or
some combination thereof. For example, the controller 30 may be a
proportional-derivative controller, a proportional-integral
controller, or a proportional-integral-derivative (PID) controller.
Each of the above-mentioned types of controllers are well known to
those skilled in the art and need not be described further
herein.
Pressure Regulating Apparatus Operation
[0070] Referring back to FIG. 2, operation of the illustrated
pressure regulating apparatus 40 will now be described. High
pressure fuel enters the pressure regulating apparatus 40 from the
fuel rail 42 through the fuel inlet passageway 54a in the flow plug
46. The fuel passes through the aperture 63 in the flange 62 of the
inner tube 60 and into the fuel flow path 69 between the inner and
outer tubes 60, 66. The fuel flows through the fuel flow path 69
and into the pressure chamber 65 between the outer tube closed end
67c and the inner tube closed end 61c.
[0071] Fuel pressure within the pressure chamber 65 causes the
outer tube closed end 67c to deflect, which in turn causes the
semiconductor element 100 within the pressure sensing element 48 to
deflect. As would be understood by one of skill in the art, the
resistance in the Wheatstone bridge embedded within the
semiconductor element 100 changes with the deflection (strain) in
the strain in the semiconductor element 100 to produce an output
voltage when a constant current is applied via terminal 110a. The
output voltage is proportional to the deflection of the
semiconductor element 100 which is proportional to the fuel
pressure in pressure chamber 65. As would be understood by one of
skill in the art, the fuel pressure measured in the pressure
chamber 65 will be the same as the fuel pressure within the fuel
rail 42.
[0072] The pressure sensing element 48 reports fuel pressure in the
fuel rail 42 back to the vehicle ECU (24, FIG. 10). The pressurized
fuel also exerts positive pressure against the magnetic armature
second end 80b through aperture 71 in the inner tube second end
61c.
[0073] To regulate fuel pressure within the fuel rail 42, a vehicle
ECU reads the fuel pressure output signal from the pressure sensing
element 48 and determines what the proper fuel pressure should be
based upon various vehicle parameters including, but not limited
to, throttle position, engine speed (RPM), transmission gear, and
wheel slip. The ECU checks to see if the fuel pressure is where it
should be, and if not, adjusts the signal to the pressure
regulating apparatus 40 to change the fuel pressure to the desired
level. As described above, fuel pressure is adjusted by applying
electrical current to the coil 52. The generated magnetic field
causes the magnetic armature 80 to move along the axial direction A
toward the magnetic pole piece 84, which opens a leak path back to
the fuel tank (10, FIG. 10) in the vehicle, thereby reducing fuel
pressure in the fuel rail 42. The leak path is formed by the slots
88a, 88b in the magnetic armature 80, the axial bore 85 through the
magnetic pole piece 84, the chamber 92 within the flow plug 46, the
fuel outlet passageway 54b in the flow plug 46, and the fuel outlet
passageway 99 in the annular first housing 42.
[0074] The pressure regulating apparatus 40 can also act as a
pressure relief valve if fuel pressure exceeds a predetermined
pressure limit. Excessive fuel pressure applied to the magnetic
armature second end 80b can cause the spring 82 to compress, which
will allow flow through the leak path and, thus, a reduction in
fuel pressure.
[0075] According to another embodiment of the present invention,
the controller (30, FIG. 10) may be electrically connected with a
pressure sensing element 48 to create a "smart solenoid" (i.e., a
closed loop feedback control system is incorporated into the
pressure sensing electronics), whereby fuel pressure can be
maintained within a prescribed range of pressures. The controller
30 closes the loop around the sensed pressure via the pressure
sensing element 48 and adjusts, via current induced within the coil
52, axial movement of the magnetic armature 80 within the inner
tube 60 in order to maintain fuel pressure within a predetermined
range.
[0076] By reading the pressure sensing element 48, an ECU is able
to see the effects that its changes are having on fuel pressure and
can vary fuel pressure change requests. The control of how much
change an ECU asks the pressure sensing element 48 to make and how
quickly it should make that change is preferably controlled via
proportional-integral-derivative (PID) control. A PID controller
can allow a system to control the amount of overshoot that a fuel
rail sees from the pressure regulating apparatus 40 and also can
help insure that the pressure regulating apparatus 40 receives the
required value quickly.
[0077] A pressure regulating apparatus according to the present
invention provides a number of advantages. First, the number of
electrical terminals required by a pressure regulating apparatus
according to the present invention can be reduced from five to
three. Second, the output signal line from a pressure regulating
apparatus according to the present invention can change from analog
to digital. Third, a pressure regulating apparatus according to the
present invention can house the control electronics (e.g., a FET
transistor, resistor, and capacitor) required to drive the
coil.
[0078] The foregoing is illustrative of the present invention and
is not to be construed as limiting thereof. Although a few
exemplary embodiments of this invention have been described, those
skilled in the art will readily appreciate that many modifications
are possible in the exemplary embodiments without materially
departing from the novel teachings and advantages of this
invention. Accordingly, all such modifications are intended to be
included within the scope of this invention as defined in the
claims. In the claims, means-plus-function clauses are intended to
cover the structures described herein as performing the recited
function and not only structural equivalents but also equivalent
structures. Therefore, it is to be understood that the foregoing is
illustrative of the present invention and is not to be construed as
limited to the specific embodiments disclosed, and that
modifications to the disclosed embodiments, as well as other
embodiments, are intended to be included within the scope of the
appended claims. The invention is defined by the following claims,
with equivalents of the claims to be included therein.
* * * * *