U.S. patent application number 09/738535 was filed with the patent office on 2001-12-06 for reformate control valve assembly for a fuel cell.
Invention is credited to Bircann, Raul A., Mieney, Harry R., Palmer, Dwight O..
Application Number | 20010049043 09/738535 |
Document ID | / |
Family ID | 26893970 |
Filed Date | 2001-12-06 |
United States Patent
Application |
20010049043 |
Kind Code |
A1 |
Bircann, Raul A. ; et
al. |
December 6, 2001 |
Reformate control valve assembly for a fuel cell
Abstract
A three-way gas control valve assembly for selectively
controlling gas flow from one inlet port into two outlet ports or
vice-versa, such as may be required for flow control of
hydrogen-containing reformate in fuel cell applications. The valve
assembly comprises three subassemblies: a metering subassembly
disposable within the high-temperature environment in the fuel cell
for mechanically regulating reformate flow; an actuating
subassembly disposable outside the fuel cell and connected to the
metering subassembly for actuating a pintle shaft and valve head in
the metering subassembly; and a coupling tube subassembly
extendable through an insulative shroud to mechanically couple and
thermally isolate the metering and actuating subassemblies.
Inventors: |
Bircann, Raul A.; (Penfield,
NY) ; Palmer, Dwight O.; (Rochester, NY) ;
Mieney, Harry R.; (Byron, NY) |
Correspondence
Address: |
Delphi Technologies, Inc.
P.O. Box 5052
Mail Code 480414420
Troy
MI
48007
US
|
Family ID: |
26893970 |
Appl. No.: |
09/738535 |
Filed: |
December 15, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60198607 |
Apr 19, 2000 |
|
|
|
Current U.S.
Class: |
429/439 ;
251/304; 251/88 |
Current CPC
Class: |
H01M 8/04089 20130101;
F16K 11/044 20130101; Y02E 60/50 20130101; F16K 31/0627
20130101 |
Class at
Publication: |
429/34 ; 251/88;
251/304 |
International
Class: |
H01M 008/02; F16K
005/00; F16K 025/00 |
Claims
What is claimed is:
1. A three-way valve assembly for selectively dividing and
regulating the flow of a fluid entering the assembly through a
non-regulating port and exiting the assembly through first and
second regulated ports, comprising: a) a metering subassembly
having a valve body including a first chamber including said
non-regulating port and first and second regulated ports, said
first and second regulated ports being provided with first and
second valve seats, said valve body having a second chamber in
communication with said first chamber via said second regulated
port, said subassembly further having a valve head disposed within
said first chamber for selectively mating with said first and
second valve seats to regulate flows through said first and second
regulated ports, said head having a pintle shaft connected thereto
and extending through a wall of said valve body for displacing said
head between said first and second valve seats; b) a coupling tube
subassembly mounted on said metering subassembly and surrounding
said pintle shaft; and c) an actuating subassembly mounted on said
coupling tube subassembly and operative of said pintle shaft for
controllably displacing said head to vary the amount of fluid
flowing through said first and second regulated ports.
2. A three-way valve assembly in accordance with claim 1 wherein
said metering subassembly is formed of materials suitable for
sustained operation at temperatures in excess of 800.degree. C.
3. A three-way valve assembly in accordance with claim 2 wherein
said valve body is formed of an inconel alloy.
4. A three-way valve assembly in accordance with claim 2 wherein
said actuating subassembly is capable of sustained operation at
temperatures up to 150.degree. C.
5. A three-way valve assembly in accordance with claim 1 wherein
said fluid comprises gaseous reformed hydrocarbon.
6. A three-way valve assembly in accordance with claim 5 wherein
said gaseous reformed hydrocarbon includes hydrogen.
7. A three-way valve assembly in accordance with claim I further
comprising spring means for biasing said head toward one of said
first and second valve seats.
8. A three-way valve assembly in accordance with claim 1 further
comprising seal means for preventing leakage of fluid from said
metering is subassembly through said coupling tube subassembly.
9. A three-way valve assembly in accordance with claim 8 wherein
said seal means includes a convoluted diaphragm disposed between
said pintle shaft and said coupling tube subassembly.
10. A three-way valve assembly in accordance with claim 1 further
comprising means for cooling said coupling tube subassembly.
11. A three-way valve assembly in accordance with claim 10 wherein
said means for cooling includes a grooved shaft bearing disposed in
said coupling tube subassembly at a first end thereof, and at least
one port near a second end thereof, said grooves and port
communicating between the exterior and interior of said tube
subassembly to define a pathway for passage of cooling air into and
out of said coupling tube assembly.
12. A fuel cell, comprising: a) a housing having an aperture
therethrough; and b) a three-way valve assembly disposed in said
aperture for regulating flow of fluid reformate in said fuel cell,
said assembly including i) a metering subassembly, including a
valve body, head, and pintle shaft, disposed within said housing
and extending through said aperture; ii) a coupling tube
subassembly mounted on said metering subassembly outside said
housing and surrounding said pintle shaft; and iii) an actuating
subassembly mounted on said coupling tube subassembly and operative
of said pintle shaft for controllably displacing said head within
said valve body to vary the volumes of first and second flows from
said valve body.
13. A fuel cell in accordance with claim 12 further comprising an
insulative layer surrounding said housing, said coupling tube
subassembly extending through said layer.
14. A fuel cell in accordance with claim 12 wherein said valve body
has a first chamber including a non-regulating port and first and
second regulated ports, said first and second regulated ports being
provided with first and second valve seats, said valve body having
a second chamber in communication with said first chamber via said
second regulated port, said metering subassembly further having
said valve head disposed within said first chamber for selectively
mating with said first and second valve seats to regulate flows
through said first and second regulated ports, said pintle shaft
being connected to said head and extending through a wall of said
valve body for displacing said head between s said first and second
valve seats.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. No. 60/198,607, filed Apr. 19, 2000.
TECHNICAL FIELD
[0002] The present invention relates to pintle-type valves; more
particularly, to such valves for variably regulating the flow of
fluids, and especially gases, among three ports; and most
particularly, to a control valve assembly for controllably varying
the flow of gas from one inlet port into two outlet ports
(three-way valve), such as may be required for reformate flow
control in fuel cell applications.
BACKGROUND OF THE INVENTION
[0003] Pintle-type valves are well known in the art for variably
controlling flow of fluids, including gases. The advent of fuel
cells as alternative propulsion systems or auxiliary power units
for automotive and other similar applications, has created a need
for improved, highly specialized gas flow control valves. Such fuel
cells are known to use hydrogen gas as an energetic fuel for
exothermic combination with oxygen at high temperature. Hydrogen
may be supplied continuously to a fuel cell as a "reformate"
product of catalytic degradation of hydrocarbons such as gasoline
or methanol. At start-up of the reformer, however, the reformer
operating temperature typically is too low for production of a
satisfactory percentage of hydrogen in the reformate. Therefore,
until the reformer achieves a sufficiently high temperature, the
fuel cell cannot be started 5 and the reformate output is diverted
to a waste burner rather than being simply discharged to the
atmosphere. As the percentage of hydrogen in the reformate
increases, the reformate output stream is gradually diverted by a
three-way valve away from the burner and to the fuel cell.
Sensitive control of such diversion is highly important to
satisfactory operation of the fuel cell.
[0004] The requirements of such valves, including material
properties, operating at very high temperatures (800.degree. C. or
greater), operating in corrosive environments, and minimum
tolerance for leakage, are difficult or impossible for prior art
valves to meet. Degradation of materials resulting from sustained
exposure to such conditions can diminish valve performance
significantly, leading ultimately to valve and fuel cell failure.
Some components of prior art valves, such as force-balancing
springs, may experience appreciable set or relaxation at high
temperatures, rendering them useless, or their working lifetimes
may be significantly shortened. Operating at such high temperatures
can cause excessive linear expansion in critical elements,
rendering gas metering inaccurate or impossible. Plastic parts can
melt or become deformed, thereby rendering the valve permanently
inoperative.
[0005] Some prior art specialized industrial gas control valves may
meet some of the individual requirements, such as leakage, flow
capacity, or operating temperature. However, they are impractical
for automotive applications because of excessive size, prohibitive
cost, slow response, and required actuation force. The cost of some
prior art valves can approach or exceed the targeted cost of the
entire vehicle for which a flow-control valve is intended. For
these reasons, prior art valves are not suitable.
[0006] What is needed is a three-way gas flow control valve
assembly having valving components which can stand extremely high
operating temperatures (greater than 800.degree. C.), actuating
components which can operate in moderately high temperatures
(100-150.degree. C.), and means for thermally isolating the valving
components from the actuating components. Such a valve assembly
must be relatively small and lightweight, inexpensive to
manufacture, highly reliable, and virtually leak-proof.
[0007] It is the primary object of the invention to provide an
improved three-way valve assembly meeting these criteria for use in
selectively controlling the flow of reformate from a hydrocarbon
reformer to a waste burner and to a fuel cell.
SUMMARY OF THE INVENTION
[0008] The invention is directed to a three-way gas control valve
assembly for selectively controlling gas flow from one inlet
conduit into two outlet conduits or vice-versa, such as may be
required for flow control of reformate in fuel cell applications.
The valve assembly comprises three subassemblies: a metering
subassembly disposable within the high-temperature environment in
the fuel cell for mechanically regulating reformate flow; an
actuating subassembly disposable outside the fuel cell and
connectable to the metering subassembly for actuating a pintle
shaft and valve head in the metering subassembly; and a coupling
tube subassembly extending through an insulative zone to
mechanically couple and thermally isolate the metering and
actuating subassemblies.
[0009] The metering subassembly comprises a valve body having first
and second chambers. The first chamber is provided with first and
second opposed valve seats surrounding opposed first and second
regulated ports. The first regulated port leads outside the valve,
and the second regulated port leads to the second chamber. A
dual-faced valve head disposed in the first chamber between the
opposed valve seats is connected to a pintle shaft extending
through the second regulated port by which the valve head can be
axially translated to selectively occlude either the first or
second seat but not both simultaneously. The first chamber is
provided with a first non-regulating port and the second chamber is
provided with a second non-regulating port, each non regulating
port leading outside the valve to serve as either a gas inlet or
gas outlet to the first and second chambers, respectively.
[0010] The actuating subassembly comprises a solenoid actuator
having an internal armature and armature shaft for engaging the
outer end of the pintle extending through an inner bearing disposed
in a wall of the metering subassembly. Armature travel is
controlled by computer and an axial position sensor attached to the
armature.
[0011] The coupling tube subassembly comprises a cylindrical
element which surrounds the pintle shaft where it extends through
the insulative covering of the fuel cell, supports an outer bearing
for the pintle shaft, and connects the valve body to the
actuator.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The foregoing and other objects, features, and advantages of
the invention, as well as presently preferred embodiments thereof,
will become more apparent from a reading of the following
description in connection with the accompanying drawings, in
which:
[0013] FIG. 1 is a cross-sectional elevational view of a first
embodiment of a to three-way reformate control valve assembly in
accordance with the invention;
[0014] FIG. 2 is a view like that shown in FIG. 1, showing a
portion of a second embodiment having a coupling tube subassembly
wherein vents are provided in the outer bearing and coupling tube
for forced-air cooling of the coupling tube assembly and to provide
an engineered leak path which prevents higher pressure in the tube
from leaking through the lower bushing and into the upper chamber,
by bleeding off this higher pressure above the bushing;
[0015] FIG. 3 is a view like that shown in FIG. 1, showing a
portion of a third embodiment having a coupling tube subassembly
wherein a convoluted diaphragm seal is incorporated at the outer
end of the coupling tube and pintle shaft to form a positive,
flexible barrier against leakage of gas out of the metering
subassembly through the coupling tube subassembly; and
[0016] FIG. 4 is a graph showing amount of gas flow through the
first and second ports independently as a function of percent
travel of the valve head between the complete closure of each of
the ports.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0017] Referring to FIG. 1, a first embodiment 10 of a three-way
reformate control valve assembly for a fuel cell comprises an
actuating subassembly 12 including an actuator 14 which may be of
any suitable type such as a stepper motor or DC motor but
preferably is a solenoid having an armature subassembly 16
including an armature shaft 18. Armature subassembly 16 is disposed
conventionally within the windings 20 such that its travel
authority is defined by the axial clearance 22 between the armature
23 and a guiding sleeve 24. Armature travel is precisely controlled
by PWM logic in a controller (not shown) operatively connected to
an armature position sensor 17.
[0018] Screws 26 and hollow spacers 28 secure actuating subassembly
12 to a coupling tube assembly 30 by engaging bores in flange 32 of
upper flanged tube 34. Circumferential ribs 36 are provided on
flange 32 for dissipating heat from the fuel cell to the
environment and reducing unwanted heating of actuator 14.
[0019] Upper flanged tube 34 includes an axial bore 38 interrupted
by an annular boss 40 forming a shelf 42 and narrowed axial bore 44
for receiving a radially compliant shaft bearing 46. Preferably,
the diameter of bore 44 is slightly greater than the diameter of
the portion of upper bearing 46 disposed in bore 44, so that upper
bearing 46 may be radially compliant in response to any axial
misalignments within valve assembly 10. Upper flanged tube 34
extends through an insulative shroud 35 around the fuel cell and is
sealingly disposed as by welding, threading, or slip fit and set
screws, at the lower end 48 in a socket 50 in lower receptacle 52
which is provided with a partial flange 54 having throughbores for
receiving bolts 56 to secure coupling tube subassembly 30 to valve
body 58 of metering subassembly 60. Preferably, fuel cell housing
or mounting plate 62 is sandwiched therebetween to secure valve
assembly 10 to the fuel cell.
[0020] Valve body 58 has first and second chambers 64 and 66,
respectively. First chamber 64 contains first and second opposed
valve seats 68,70 surrounding opposed first and second regulated
ports 72,74. First regulated port 72 leads outside the valve, and
second regulated port 74 leads to second chamber 66. A valve head
76 disposed in first chamber 64 between the opposed valve seats is
provided with first and second sealing faces 78, 80 for mating with
first and second seats 68,70, respectively, to open and close
access to first and second regulated ports 72,74, respectively.
Valve head 76 is connected to a pintle shaft 82 extending through
second regulated port 74 and second chamber 66 by which means the
valve head may be axially moved to selectively and progressively
occlude either the first or second seat but not both
simultaneously. First chamber 64 is provided with a first
non-regulating port 84 and second chamber 66 is provided with a
second non-regulating port 86, each non-regulating port leading
outside the valve to serve as either a gas inlet from the reformer
(not shown) or gas outlet to the first and second chambers 64,66,
respectively, between the waste burner (not shown) and the fuel
cell reaction chamber (not shown).
[0021] Metering subassembly 60 must be formed of material which is
highly resistant to corrosion or deformation at high temperatures
inside the fuel cell. Preferably, valve body 58, seats 68,70, and
head 76 are formed of an Inconel alloy, which has the added
advantage that all components have identical coefficients of
thermal expansion.
[0022] Stepped bore 88 in a wall of valve body 58 is receivable of
a stepped lower bearing 90 coaxially disposed with seats 68,70 and
head 76, which bearing is preferably pressed into bore 88 without
provision for radial compliance as in upper bearing 46. Bearing 90
is clamped into bore 88 by the just-described bolting of lower
receptacle 52 to valve body 58 and provides primary guidance for
pintle shaft 82 in axial motion. Preferably, the diametral
clearance between bearing 90 and pintle shaft 82 is held to the
smallest possible value that still allows free axial motion of
shaft 82. To ensure that this relationship remains invariant over
the range of anticipated operating conditions, the press fit,
bearing diameter, shaft diameter, and surface finish of all these
components are carefully selected and matched. The materials
preferably are superalloys which are alumina or chromia formers,
for example, Haynes 230, 214, and 242; Inconel 625 or 718;
Hastelloy X; Incoloy MA 956; Numonic 105; and other similar similar
materials which are dimensionally stable and corrosion-resistant at
high temperatures.
[0023] Pintle shaft 82 extends through coupling tube assembly 30
and terminates in an actuator-receiving element which preferably is
a flat-headed capnut 92 which threads onto the end of shaft 82 and
presents a broad upper surface for contact with armature shaft 18.
Shaft 18 engages capnut 92 as a pressure plate but is not
mechanically connected thereto, thus relaxing the alignment
requirements of actuator 14 with shaft 82.
[0024] Preferably, all components of the coupling tube subassembly
and the pintle shaft are formed of the same material, for example,
a stainless steel so that longitudinal thermal expansion of the
upper flanged coupling tube, which supports the actuator, is the
same as that of the pintle shaft, which interacts with the actuator
armature. Thus, calibration of the armature position sensor is
unaffected by thermal expansion of the coupling tube subassembly
and the pintle shaft.
[0025] A coil spring 96 is disposed in compression between capnut
92 and upper bearing 46 for urging valve head 76 toward second seat
70. In operation, actuator 14 operates against spring 96 to urge
head 76 toward first seat 68. Thus, in response to armature
position sensor 17, head 76 may be placed at any desired axial
location between seats 68 and 70 to divide and simultaneously
regulate the volume of first and second flows of gas through
regulated ports 72 and 74. Typical flow curves through regulated
ports 72 and 74 are shown in FIG. 4 as a function of valve head
travel, 0% being regulated port 72 fully open and regulated port 74
fully closed.
[0026] As noted above, an important consideration in providing
useful valves for some fuel cell applications is how to establish
and maintain a suitable thermal environment for the actuating
assembly which must be many hundreds of degrees cooler than the
environment for the metering assembly within the fuel cell.
Referring to FIG. 2, in a second embodiment 10' of a three-way
metering valve assembly, a ventilation system is provided for
cooling the coupling tube subassembly. Upper bearing 46' is
provided with a plurality of longitudinal passageways 98,
preferably as channels in the bore supporting pintle shaft 82,
communicating with the outside of valve 10' through spring 96 and
with the interior of upper flanged tube 34. A plurality of vent
ports 100 through tube 34 and lower receptacle 52 allow air to be
forced through tube 34 as shown in FIG. 2, thus cooling the
coupling tube assembly and preventing high pressure gas from
leaking from tube 34 through lower bearing 90 into second chamber
66.
[0027] In some fuel cell applications, active cooling as shown in
FIG. 2 is not practical because of a requirement for zero leakage
of gas from the coupling tube assembly, in which case the coupling
tube assembly may be made substantially longer to provide a longer
thermal path between the metering subassembly and the actuating
subassembly. Referring to FIG. 3, in a third embodiment 10" of a
three-way metering valve assembly, a positive seal is provided in
the form of a convoluted diaphragm 102, preferably formed of a
flexible metal. The convolutions in the diaphragm are selected such
that minimal parasitic axial friction loads are imposed on the
spring and actuator. Diaphragm 102 is retained at its inner
periphery between capscrew 92 and pintle shaft 82, and at its outer
periphery between a retaining plate 104 and flange 32 to which
plate 104 is bolted by bolts 106.
[0028] The foregoing description of the preferred embodiment of the
invention has been presented for the purpose of illustration and
description. It is not intended to be exhaustive nor is it intended
to limit the invention to the precise form disclosed. It will be
apparent to those skilled in the art that the disclosed embodiments
may be modified in light of the above teachings. The embodiments
described are chosen to provide an illustration of principles of
the invention and its practical application to enable thereby one
of ordinary skill in the art to utilize the invention in various
embodiments and with various modifications as are suited to the
particular use contemplated. Therefore, the foregoing description
is to be considered exemplary; rather than limiting, and the true
scope of the invention is that described in the following
claims.
* * * * *