U.S. patent application number 10/657874 was filed with the patent office on 2004-03-11 for chemical-specific sensor for monitoring amounts of volatile solvent during a drying cycle of a dry cleaning process.
This patent application is currently assigned to General Electric Company. Invention is credited to Carnahan, James Claude, Fyvie, Thomas Joseph, Hallman, Darren Lee, Mani, Vanita.
Application Number | 20040045096 10/657874 |
Document ID | / |
Family ID | 46299913 |
Filed Date | 2004-03-11 |
United States Patent
Application |
20040045096 |
Kind Code |
A1 |
Mani, Vanita ; et
al. |
March 11, 2004 |
Chemical-specific sensor for monitoring amounts of volatile solvent
during a drying cycle of a dry cleaning process
Abstract
A solvent vapor sensor for determining amounts of solvent vapor
flowing during a solvent dry cleaning process is provided. The
solvent cleaning process utilizes a solvent based cleaning fluid
primarily made up of cyclic siloxane solvent. The solvent vapor
sensor, i.e., a chemical specific sensor, may be configured in
various forms, such as a spectroscopic sensor, a piezo-based
sensor, a strain-gauge based sensor, and a capacitive sensor.
Inventors: |
Mani, Vanita; (Clifton Park,
NY) ; Hallman, Darren Lee; (Clifton Park, NY)
; Fyvie, Thomas Joseph; (Schenectady, NY) ;
Carnahan, James Claude; (Niskayuna, NY) |
Correspondence
Address: |
General Electric Company
CRD Patent Docket Rm 4A59
P.O. Box 8, Bldg. K-1
Schenectady
NY
12301
US
|
Assignee: |
General Electric Company
|
Family ID: |
46299913 |
Appl. No.: |
10/657874 |
Filed: |
September 8, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10657874 |
Sep 8, 2003 |
|
|
|
10127001 |
Apr 22, 2002 |
|
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Current U.S.
Class: |
8/142 |
Current CPC
Class: |
D06F 43/086 20130101;
D06F 43/08 20130101 |
Class at
Publication: |
008/142 |
International
Class: |
D06F 001/00 |
Claims
What is claimed is:
1. An article cleaning apparatus comprising: an air management
mechanism; a cleaning basket assembly; a fluid regeneration device;
a working fluid device coupled to said fluid regeneration device,
said cleaning basket assembly, and said air management mechanism, a
clean fluid device coupled to said cleaning basket assembly and
said fluid regeneration device; a controller coupled to said air
management mechanism, said cleaning basket assembly, said working
fluid device, said regeneration device, and said clean fluid
device; wherein said controller is configured to control a cleaning
process, including at least a solvent cleaning process, wherein
said solvent cleaning process utilizes a solvent based cleaning
fluid comprising cyclic siloxane solvent; and a solvent vapor
sensor coupled to the controller to determine amounts of solvent
vapor that may flow during said solvent cleaning process.
2. The article cleaning apparatus of claim 1 wherein said solvent
vapor sensor is selected from the group consisting of a
spectroscopic sensor; a piezo-based sensor; a strain-gauge based
sensor; and a capacitive sensor.
3. The article cleaning apparatus of claim 1 wherein said solvent
vapor sensor comprises an infrared sensor responsive to siloxane
absorbance of infrared radiation.
4. The article cleaning apparatus of claim 1 wherein said solvent
vapor sensor comprises an infrared sensor selectively responsive to
infrared radiation absorbance of siloxane and water vapor.
5. The article cleaning apparatus of claim 1 wherein said solvent
vapor sensor comprises a quartz crystal microbalance sensor
including a transducer film.
6. The article cleaning apparatus of claim 5 wherein said
transducer film comprises a non-polar polymer.
7. The article cleaning apparatus of claim 6 wherein said
transducer film comprises a hydrocarbon chain.
8. The article cleaning apparatus of claim 1 wherein said solvent
vapor sensor comprises a strain gauge sensor including a transducer
film.
9. The article cleaning apparatus of claim 8 wherein said
transducer film comprises a non-polar polymer.
10. The article cleaning apparatus of claim 8 wherein said
transducer film comprises a hydrocarbon chain.
11. A solvent vapor sensor for determining amounts of solvent vapor
flowing during a solvent dry cleaning process, wherein said solvent
cleaning process utilizes a solvent based cleaning fluid comprising
cyclic siloxane solvent.
12. The solvent vapor sensor of claim 11 wherein said solvent vapor
sensor is selected from the group consisting of a spectroscopic
sensor, a piezo-based sensor, a strain gauge based sensor, and a
capacitive sensor.
13. The solvent vapor sensor of claim 11 wherein said solvent vapor
sensor comprises an infrared sensor responsive to siloxane
absorbance of infrared radiation.
14. The solvent vapor sensor of claim 11 wherein said solvent vapor
sensor comprises an infrared sensor selectively responsive to
infrared radiation absorbance of siloxane and water vapor.
15. The solvent vapor sensor of claim 11 wherein said solvent vapor
sensor comprises a quartz crystal microbalance sensor including a
transducer film.
16. The solvent vapor sensor of claim 15 wherein said transducer
film comprises a non-polar polymer.
17. The solvent vapor sensor of claim 16 wherein said transducer
film comprises a hydrocarbon chain.
18. The solvent vapor sensor of claim 11 wherein said solvent vapor
sensor comprises a strain gauge sensor including a transducer
film.
19. The solvent vapor sensor of claim 18 wherein said transducer
film comprises a non-polar polymer.
20. The solvent vapor sensor of claim 18 wherein said transducer
film comprises a hydrocarbon chain.
21. An article cleaning apparatus comprising: a controller
configured to control a cleaning process, including at least a
solvent cleaning process, wherein said solvent cleaning process
utilizes a solvent based volatile cleaning fluid comprising cyclic
siloxane solvent; and a chemical-specific sensor configured to
monitor amounts of the volatile solvent fluid, and coupled to the
controller to control a drying cycle for extracting a desired level
of moisture from the articles.
Description
[0001] This application is a continuation-in-part of co-pending and
commonly assigned U.S. patent application Ser. No. 10/127,001 filed
Apr. 22, 2002.
BACKGROUND OF THE INVENTION
[0002] The present invention is generally related to a laundering
appliance, and, more particularly, to a dry cleaning appliance that
uses a volatile solvent for cleansing the articles and, even more
particularly, to sensing devices for monitoring amounts of the
volatile solvent present during a drying cycle of a dry cleaning
process.
[0003] Conventional household clothing washers use anywhere from
about 60 liters to about 190 liters of water to wash a typical load
of clothing articles. The spent water and cleaning agents are then
dumped into sewage. Furthermore, the water is frequently heated to
improve wash effectiveness and usually requires a large amount of
energy to be put into the articles as heat in order to vaporize the
retained water and dry the articles. The combination of high water
usage, high-energy usage and disposal of cleaning additives in the
detergent can put a large strain on the environment.
[0004] Conventional professional dry cleaning perchloroethylene
(PERC) solvent has been shown to be hazardous to human health as
well as to the environment. Use of a cyclic siloxane composition,
more specifically decamethylcyclopentasiloxane (or simply siloxane,
also commercially referred to as D5), as a replacement for PERC is
known. The use of a siloxane solvent in laundering has been shown
to result in reduced wrinkling, superior article care, and better
finish than water washing. Furthermore, the siloxane solvent has a
lower heat of vaporization than water. Compared to water, the
siloxane solvent can be more easily dried out of the article. If a
washing machine contained a solvent based cleaning cycle, the
solvent cycle could replace some or all of the washing currently
being done in water, which would result in a significant reduction
in energy and water use.
[0005] There are currently commercial dry cleaning machines, which
use a cyclic siloxane dry cleaning process, but these machines
present several barriers to in-home use. Known commercial dry
cleaning machines are generally much larger than typical home
washing machines, and would not fit within typical washrooms. These
commercial dry cleaning machines typically require high voltage
power (>250V) and often require separate steam systems,
compressed air systems, and chilling systems to be attached
externally. The solvent amount generally stored in the commercial
dry cleaning machines is usually more than about 190 liters, even
for the smallest capacity commercial machines. The typical dry
cleaning facility has both solvent cleaning and water cleaning
machines on the premises and uses each machine for their separate
functions. Known commercial dry cleaning machines are typically
designed to be operated by a skilled employee and do not contain
appropriate safety systems for either in-home locations or for
general use. In many states, the use of commercial dry cleaning
machines by the general public is forbidden.
[0006] U.S. patent application Ser. No. 10/127,001, titled
"Apparatus and Method for Article Cleaning", filed on Apr. 22,
2002, (Attorney Docket No. RD-29557), commonly assigned to the same
assignee of the present invention, and herein incorporated by
reference in its entirety, represents one innovative implementation
of an appliance that provides solvent, or water-based cleaning (or
combination thereof). As set forth in the foregoing patent
application, this appliance may be advantageously accommodated
either in an in-home or in a coin-operable laundry setting. That
is, an appliance that may be used not just for commercial dry
cleaning applications, but also having the appropriate small size,
cost, and user-interface considerations for a home-based laundry
system.
[0007] In order to reduce usage costs and improve safety of
commercial coin-operable versions and in-home versions of waterless
or very low water washers employing a solvent, such as volatile
cyclic siloxane, as the primary wash fluid, it is desirable to
provide a "dry-to-dry" cleansing operation and be able to sense the
state of dryness of the clothes during a drying cycle. To that end,
a relatively low-cost chemical-specific sensor that accurately and
reliably senses amounts of the volatile siloxane solvent is
desirable.
BRIEF DESCRIPTION OF THE INVENTION
[0008] Generally, the present invention fulfills the foregoing
needs by providing in one aspect thereof, a solvent vapor sensor
for determining amounts of solvent vapor flowing during a solvent
dry cleaning process, e.g., during a drying cycle of the dry
cleaning process. The solvent cleaning process utilizes a solvent
based cleaning fluid comprising cyclic siloxane solvent.
[0009] In another aspect thereof, the present invention further
fulfills the foregoing needs by providing an article cleaning
apparatus including an air management mechanism, a cleaning basket
assembly, and a fluid regeneration device. A working fluid device
is coupled to the fluid regeneration device, the cleaning basket
assembly, and the air management mechanism. A clean fluid device is
coupled to the cleaning basket assembly and the fluid regeneration
device. A controller is coupled to the air management mechanism,
the cleaning basket assembly, the working fluid device, the
regeneration device, and the clean fluid device. The controller may
be configured to control a cleaning process including at least a
solvent cleaning process that utilizes a solvent based cleaning
fluid comprising cyclic siloxane solvent. A solvent vapor sensor is
coupled to the controller to determine amounts of solvent vapor
flowing during the solvent cleaning process, e.g., during a drying
cycle of the dry cleaning process.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The features and advantages of the present invention will
become apparent from the following detailed description of the
invention when read with the accompanying drawings in which:
[0011] FIG. 1 is a block diagram of the article cleaning apparatus
in accordance with one embodiment of the present invention;
[0012] FIG. 2 is a schematic diagram of the fluid processing
mechanism in accordance with one embodiment of the present
invention;
[0013] FIG. 3 is a schematic diagram of a filter arrangement in
accordance with one embodiment of the present invention;
[0014] FIG. 4 is a schematic diagram of a filter arrangement in
accordance with another embodiment of the present invention;
[0015] FIG. 5 is a schematic diagram of the air management
mechanism and the cleaning basket assembly in accordance with one
embodiment of the present invention;
[0016] FIG. 6 is a schematic diagram of the air management
mechanism and the cleaning basket assembly in accordance with
another embodiment of the present invention;
[0017] FIG. 7 is a schematic diagram of the devices coupled to the
controller in accordance with one embodiment of the present
invention;
[0018] FIG. 8 is a schematic cross sectional view of the cleaning
basket assembly in accordance with one embodiment of the present
invention;
[0019] FIG. 9 is a three-dimensional partial cross sectional view
of the article cleaning apparatus in accordance with one embodiment
of the present invention;
[0020] FIG. 10 is a plot of retained moisture content as a
percentage of an article's weight versus the relative humidity;
[0021] FIG. 11 is a block diagram of the process selection in
accordance with one embodiment of the present invention;
[0022] FIG. 12 is a flow diagram of a humidity sensing process in
accordance with one embodiment of the present invention;
[0023] FIG. 13 is a flow diagram of a solvent cleaning process in
accordance with one embodiment of the present invention;
[0024] FIG. 14 is a flow diagram of a water cleaning process in
accordance with one embodiment of the present invention;
[0025] FIG. 15 is a flow diagram of a basket drying process in
accordance with one embodiment of the present invention;
[0026] FIG. 16 is a flow diagram of a cycle interruption recovery
process in accordance with one embodiment of the present
invention;
[0027] FIG. 17 plots exemplary phase spectra of siloxane and water
vapor in the near IR region;
[0028] FIG. 18 plots exemplary phase spectra of siloxane and water
vapor in the mid IR region;
[0029] FIG. 19 shows a block diagram of an exemplary embodiment of
an spectral sensor for infrared detection of siloxane vapor;
[0030] FIG. 20 shows a block diagram of another exemplary
embodiment of an spectral sensor for infrared detection of both
siloxane and water vapor;
[0031] FIG. 21 shows a plot of an exemplary mid-IR sensor response
to saturated siloxane vapor;
[0032] FIG. 22 shows a plot of an exemplary mid-IR sensor response
saturated siloxane and water vapor;
[0033] FIG. 23 shows a schematic of an exemplary resonator, e.g., a
QCM resonator, including a transducer film for detecting volatile
siloxane; and
[0034] FIG. 24 shows a plot of an exemplary QCM resonator coated
with an exemplary transducer film, e.g., RTV-615 in the presence of
siloxane and water vapor.
DETAILED DESCRIPTION OF THE INVENTION
[0035] The present invention includes an apparatus and method for
the cleaning of articles at home or in a coin-op laundry setting.
As used herein, the term, "articles" is defined, for illustrative
purposes and without limitation, as fabrics, textiles, garments,
and linens and any combination thereof. As used herein, the term,
"solvent based cleaning fluid" is defined for illustrative purposes
and without limitation, as comprising a cyclic siloxane solvent
and, optionally, a cleaning agent. If water is present in a solvent
based cleaning fluid, the water is present in an amount in a range
from about 0.25 percent to about 10 percent of the total weight of
the solvent based cleaning fluid. In another embodiment of the
present invention, if water is present in the solvent based
cleaning fluid, the water is present in an amount in a range from
about 0.25 percent to about 2 percent of the total weight of the
solvent based cleaning fluid. As used herein, the term, "cleaning
agent" is defined for illustrative purposes and without limitation,
as being selected from the group consisting of sanitizing agents,
emulsifiers, surfactants, detergents, bleaches, softeners, and
combinations thereof. As used herein, the term, "water based
cleaning fluid" is defined for illustrative purposes and without
limitation, as comprising water and, optionally, a cleaning agent.
In the present invention, the article cleaning apparatus 1000 of
FIG. 1 is configured to perform a cleaning process 350 of FIG. 11.
As used herein, the term, "cleaning process" is defined, for
illustrative purposes and without limitation, as utilizing a
solvent cleaning process 375, a water cleaning process 600, and any
combination thereof. The solvent cleaning process 375 and the water
cleaning process 600 are presented in more detail after the article
description of the cleaning apparatus 1000 of FIG. 1. It is
recognized that alternative configurations of the article cleaning
apparatus 1000 are possible.
[0036] The article cleaning apparatus 1000 comprises the air
management mechanism 1, the cleaning basket assembly 2, and a fluid
regeneration device 7. The article cleaning apparatus 1000 further
comprises a working fluid device 6 that is coupled to the fluid
regeneration device 7, the cleaning basket assembly 2, and the air
management mechanism 1. The article cleaning apparatus 1000 further
comprises a clean fluid device 8 that is coupled to the cleaning
basket assembly 2 and the fluid regeneration device 7. The article
cleaning apparatus 1000 further comprises a controller 5 which is
coupled to the air management mechanism 1, the cleaning basket
assembly 2, the working fluid device 6, the regeneration device 7,
and the clean fluid device 8. The controller 5 is configured to
perform the cleaning process 350.
[0037] The cleaning basket assembly 2 of FIG. 1 typically comprises
a rotating basket 14 coupled to a motor 3. The rotating basket 14
has a plurality of holes 17. The motor 3 rotates the rotating
basket 14. Suitable drive system alternatives, presented for
illustration and without limitation include, direct drive,
pulley-belt drive, transmissions, and any combination thereof. The
direct drive orientation of the rotating basket 14 and the motor 3
is provided for illustrative purposes and it is not intended to
imply a restriction to the present invention. In one embodiment of
the present invention (not shown in FIG. 1), the motor 3 has a
different major longitudinal axis than the longitudinal axis 220 of
the rotating basket 14, and the motor 3 is coupled to the rotating
basket 14 by a pulley and a belt.
[0038] As shown in FIG. 2, the working fluid device 6, the fluid
regeneration device 7, and the clean fluid device 8 comprise a
fluid processing mechanism 4.
[0039] In one embodiment of the present invention, the working
fluid device 6 comprises a check valve 40 in a drain conduit line
70 that couples the cleaning basket assembly 2 to a working tank
45. Fluid from the cleaning basket assembly 2 passes through the
check valve 40 and is collected in the working tank 45. The fluid
in the working tank 45 is defined as a working fluid 165. A drain
tray 73 is disposed in the air management mechanism 1 to collect
condensate. An additional drain conduit 71 couples the working tank
45 to the drain tray 73. Condensate in the drain tray 73 is
typically gravity drained to the working tank 45, where it is
collected as part of the working fluid 165. A regeneration pump 115
is coupled to the working tank 45 and to a conductivity sensor 151.
A waste water drain valve 155 is disposed between the conductivity
sensor 151 and the fluid regeneration device 7. The waste water
drain valve 155 is coupled to waste water discharge piping 154.
[0040] In one embodiment of the present invention, the controller 5
of FIG. 7 is configured to direct the working fluid 165 of FIG. 2
through to the fluid regeneration device 7 when the conductivity
sensor 151 indicates that the working fluid 165 comprises less than
about 10% water by weight. The controller 5 of FIG. 7 is further
configured to divert the working fluid 165 of FIG. 2 through the
waste water drain valve 155 and the waste water discharge piping
154 when the working fluid 165 flowing through the conductivity
sensor 151 comprises a minimum of at least about 10% by weight of
water to avoid overwhelming the water adsorption capability of the
fluid regeneration device 7.
[0041] In another embodiment of the present invention, a water
separator 152 is disposed in the working tank 45. In another
embodiment of the present invention, the water separator 152 is
disposed between the waste water drain valve 155 and the fluid
regeneration device 7. In another embodiment of the present
invention, a bypass line 145 of FIG. 2 is disposed between the
discharge of the water separator 152 and the inlet of the clean
fluid device 8 to reduce the possibility of overwhelming the water
removal capability in the fluid regeneration device 7. In another
embodiment of the present invention (not shown in FIG. 2), the
bypass line 145 is disposed between the waste water drain valve 155
and the clean fluid device 8. The bypass line 145 is typically
sized to bypass a range from about one-quarter to about
three-quarter of the total flow of the working fluid 165 around the
fluid regeneration device 7.
[0042] In one embodiment of the present invention, the water
separator 152 is fabricated from materials selected form the group
consisting of calcined clay, water adsorbing polymers, sodium
sulfate, paper, cotton fiber, lint, and any combination thereof. In
another embodiment of the present invention, the water separator
152 comprises a distillination device that utilizes heat to remove
water.
[0043] The fluid regeneration device 7 comprises a regeneration
cartridge 141. The inlet side of the regeneration cartridge 141 is
typically coupled to the working fluid device 6. The regeneration
cartridge 141 typically comprises at least a water absorption media
130 coupled to a cleaning fluid regeneration absorption media 135.
In one embodiment of the present invention, the regeneration
cartridge 141 further comprises a mechanical filter 120 and a
particulate filter 125. In one embodiment of the present invention,
the working fluid 165 passes sequentially through the mechanical
filter 120, particulate filter 125, water absorption media 130, and
cleaning fluid regeneration absorption media 135. The cleaning
fluid regeneration adsorption media 135 contains a portion of the
solvent based cleaning fluid 30 in order to replenish the solvent
based cleaning fluid 30 that is consumed during the solvent
wash/dry process 500 of FIG. 13. The cleaning fluid regeneration
adsorption media 135 also contains a replacement amount of solvent
based cleaning fluid 30 which is disposed of when changing out the
regeneration cartridge 141.
[0044] In one embodiment of the present invention, the cleaning
fluid regeneration adsorption media 135 is selected from a group
consisting of a packed bed column, a flat plate bed, a tortuous
path bed, a membrane separator, a column with packed trays, and
combinations thereof.
[0045] In one embodiment of the present invention, the materials to
fabricate the cleaning fluid regeneration adsorption media 135 are
selected from the group consisting of activated charcoal, carbon,
calcined clay, Kaolinite, adsorption resins, carbonaceous type
resins, silica gels, alumina in acid form, alumina in base form,
alumina in neutral form, zeolites, molecular sieves, and any
combination thereof. Both the amount of solvent based cleaning
fluid regeneration and the speed of solvent based cleaning fluid
regeneration depend on the volume of the cleaning fluid
regeneration adsorption media 135.
[0046] In one embodiment of the present invention, the regeneration
cartridge 141 containing the cleaning fluid regeneration adsorption
media 135 in the packed bed column form is disposed in a single
packed bed column cartridge form. In another embodiment of the
present invention, the regeneration cartridge 141 comprising the
cleaning fluid regeneration adsorption media 135 in the packed bed
column form is disposed in a plurality of packed bed column
cartridges. In an alternative embodiment of the present invention,
the regeneration cartridge 141 comprises the cleaning fluid
regeneration adsorption media 135 in a plurality of packed bed
column cartridges, which are disposed in series with respect to one
another. In yet another embodiment of the present invention, the
regeneration cartridge 141 further comprises the cleaning fluid
regeneration adsorption media 135 in the plurality of packed bed
column cartridges, which are disposed in parallel with respect to
one another.
[0047] In another embodiment of the present invention, the
mechanical filter 120 of FIG. 3 and the particulate filter 125 are
part of the working fluid device 6. The mechanical filter 120 and
the particulate filter 125 are disposed in the drain conduit line
70 that couples the cleaning basket assembly 2 to the working tank
45. The mechanical filter 120 and the particulate filter 125 are
disposed in the drain conduit 70 between the cleaning basket
assembly 2 and the check valve 40.
[0048] In another embodiment of the present invention, the
mechanical filter 120 of FIG. 4 and the particulate filter 125 are
disposed in the drain conduit 70 between the check valve 40 and the
working tank 45. In an alternative embodiment of the present
invention, the mechanical filter 120 is disposed in the drain
conduit 70, while the particulate filter 125 is disposed in the
regeneration cartridge 141. In another embodiment of the present
invention, the mechanical filter 120 is not present and the
particulate filter 125 is disposed in the regeneration cartridge
filter 141. In another embodiment of the present invention, the
mechanical filter 120 is not present and the particulate filter 125
is disposed in the drain conduit 141. Both the arrangement of the
internals of the regeneration cartridge 141 and the location and
application of the mechanical filter 120 and the particulate filter
125 are provided for illustrative purposes and are not intended to
imply a restriction on the present invention.
[0049] In one embodiment of the present invention, mechanical
filter 120 has a mesh size in a range from about 50 microns to
about 1000 microns. In one embodiment of the present invention, the
particulate filter 125 has a mesh size in a range from about 0.5
microns to about 50 microns.
[0050] In one embodiment of the present invention, the particulate
filter 125 is a cartridge filter fabricated from materials selected
from the group consisting of thermoplastics, polyethylene,
polypropylene, polyester, aluminum, stainless steel, metallic mesh,
sintered metal, ceramic, membrane diatomaceous earth, and any
combination thereof.
[0051] After the working fluid 165 passes through the regeneration
cartridge 141, it exits the regeneration cartridge 141 as the
solvent based cleaning fluid 30. An outlet side of the regeneration
cartridge 141 is typically coupled to an optical turbidity sensor
140. The optical turbidity sensor 140 is typically coupled to a
storage tank 35 in the clean fluid device 8. The optical turbidity
sensor 140 is tuned to a specific absorbance level that provides
information about the cleanliness of the solvent based cleaning
fluid 30. When the solvent based cleaning fluid 30 exiting the
optical turbidity sensor 140 reaches a preset specific absorbance
level, the controller 5 of FIG. 7 sends a "replace regeneration
cartridge" message to the operator on a display panel 200 (FIG.
9).
[0052] The storage tank 35 of FIG. 2 in the clean fluid device 8
stores the solvent based cleaning fluid 30 received from the fluid
regeneration device 7. The clean fluid device 8 further comprises a
pump 25 that is coupled to the storage tank 35. The pump 25 is
coupled to the cleaning basket assembly 2 via an inlet line 26. In
one embodiment of the present invention, the pump 25 is also
typically coupled to the air management mechanism 1 via cooling
coil wash down tubing 160. In another embodiment of the present
invention, the clean fluid device 8 further comprises a spray
nozzle 67 that is typically disposed in the cooling coil wash down
tubing 160 to control the flow of the solvent based cleaning fluid
30 to the air management mechanism 1. As used herein, the term,
"spray nozzle" is defined to be a nozzle, an orifice, a spray
valve, a pressure reducing tubing section, and any combination
thereof. In one embodiment of the present invention, the spray
nozzle 67 is coupled to the controller 5 as is shown in FIG. 7 when
the spray nozzle 67 is a spray valve.
[0053] The air management mechanism 1 of FIG. 5 comprises a cooling
coil 65, a heater 55, and a fan 50. The air management mechanism 1
is coupled to the cleaning basket assembly 2 by suction ventilation
ducting 51 and discharge ventilation ducting 52. The fan 50 is
disposed to provide airflow 53 through the cooling coil 65, the
heater 55, the discharge ventilation ducting 52, the cleaning
basket assembly 2, and the suction ventilation ducting 51. A
temperature sensor 57 is also typically disposed in the airflow 53.
The temperature sensor 57 is typically disposed in the suction
ventilation ducting 51, the discharge ventilation ducting 52, the
cleaning basket assembly 2, and any combination thereof.
[0054] The cooling coil 65 is configured to have a cooling medium
disposed to flow across one side of a heat transfer surface of the
cooling coil 65, while the airflow 53 passes across the opposite
side of the heat transfer surface of the cooling coil 65. The heat
transfer surface of the cooling coil 65 separates the cooling
medium and the airflow 53. The inlet temperature of the cooling
medium utilized is typically cooler that the temperature of the
airflow 53 in order to condense vapors in the airflow 53. As used
herein, the term, "cooling medium" is defined, for illustrative
purposes and without limitation, as being selected from water,
refrigerants, air, other gasses, ethylene glycol/water mixtures,
propylene glycol/water mixtures and any combination thereof. The
drain tray 73 is disposed under the cooling coil 65 and is coupled
to the working tank 45 as described above.
[0055] In one embodiment of the present invention, the air
management mechanism 1 typically further comprises an air intake
156 and an air exhaust 157. The air intake 156 and air exhaust 157
are disposed to provide air exchange between the airflow 53 and the
air that is outside of the air management mechanism 1 to promote
the drying of articles that have been subjected to the water
cleaning process 600 of FIG. 14. The air intake 156 and air exhaust
157 are disposed in a similar configuration to that of a
conventional dryer. In one embodiment of the present invention, the
air intake 156 of FIG. 5 is disposed in the ventilation path
between the heater 55 and the fan 50, while the air exhaust 157 is
disposed between the cooling coil 65 and the cleaning basket
assembly 2. The locations of the air intake 156 and air exhaust 157
are provided for illustration and in no way imply a restriction to
the present invention.
[0056] A solvent sensor 59 may quantifiably detect the presence of
the solvent based cleaning fluid 30 in the airflow 53 that
circulates between the cleaning basket assembly 2 and the air
management mechanism 1. For example, the solvent sensor 59 may be
used to determine whether a solvent vapor pressure level or a
solvent concentration reaches a predetermined level that indicates
that the airflow 53 is no longer entraining specified amounts of
the solvent based cleaning fluid 30 of FIG. 2. As will be
appreciated by those skilled in the art, solvent vapor pressure and
solvent vapor concentration are parameters that may be related to
one another through the molar mass of the solvent. That is, if one
measures one of these parameters, one may calculate the other from
the measurement. The solvent sensor 59 of FIG. 6 may be disposed in
the discharge ventilation ducting 52. In another embodiment of the
present invention, the solvent sensor 59 may be disposed in the
suction ventilation ducting 51, the discharge ventilation ducting
52, the cleaning basket assembly 2, and any combination thereof. As
set forth in greater detail below in the context of FIGS. 17
through 24, aspects of the present are specifically directed to
various practical exemplary embodiments for the solvent sensor 59.
That is, a chemical-specific sensor. Examples of sensor types that
may be used for solvent sensor 59 may include spectroscopic
sensors; piezo-based sensors with specific coatings; strain-gauge
based sensors including an appropriate coating; and capacitive
sensors.
[0057] The cooling coil 65 of FIG. 6 further comprises a cooling
coil air inlet 66. In one embodiment of the present invention, one
end of the cooling coil wash down tubing 160 is aimed at the
cooling coil air inlet 66 of FIG. 6. The spray nozzle 67 and the
pump 25 flushes away lint and debris that accumulates on the
surface of the cooling coil air inlet 66 of FIG. 6 to maintain
airflow 53 (i.e. decrease the pressure drop across the cooling coil
65) through the air management mechanism 1 and the cleaning basket
assembly 2. In one embodiment of the present invention, spraying
the solvent based cleaning fluid 30 of FIG. 2 at the cooling inlet
66 of FIG. 6 provides additional cooling and condensation of vapor
in the airflow 53.
[0058] As shown in FIG. 6, in another embodiment of the present
invention, the air management mechanism 1 further comprises a
compressor 75, high-pressure tubing 80, low-pressure tubing 85 and
pressure reducing tubing 90 are disposed in a vapor compression
cycle. As used herein, the term, "high-pressure tubing" is used to
indicate that the high-pressure tubing is designed to contain a
refrigerant 95 at a higher pressure than the "low-pressure tubing".
The use of the terms "high-pressure tubing" and "low-pressure
tubing" are used to express a relative pressure differential across
the compressor 75. As used herein, the term, "pressure reducing
tubing" is defined to indicate that the "pressure reducing tubing"
comprises a flow restriction that is sufficient to provide the
relative pressure differential at a junction between the
"high-pressure tubing" and the "low-pressure tubing". The
high-pressure tubing 80 of FIG. 6 is disposed from the compressor
75 to the heater 55. The pressure reducing tubing 90 is disposed
between the heater 55 and the cooling coil 65. The low-pressure
tubing 85 is disposed from the compressor 75 to the cooling coil
65. The refrigerant 95 is disposed to flow between the compressor
75, heater 55, and cooling coil 65.
[0059] The vapor compression cycle attains a higher coefficient of
performance (COP) for solvent wash/dry process 500 of FIG. 13. The
vapor compression cycle operating in a heat pump configuration
reduces energy requirements for the solvent cleaning process 375 of
FIG. 11. Energy is conserved as the refrigerant 95 of FIG. 6
passing through the cooling coil 65 absorbs heat from the airflow
53 and then the refrigerant 95 rejects the heat back into the
airflow 53 by passing through the heater 55. In one embodiment of
the present invention, the refrigerant 95 is fluorocarbon R-22;
however, other refrigerants known to one skilled in the refrigerant
art would be acceptable. The heater 55 functions as a condenser
(warming the air flow 53 through the heater 55), while the cooling
coil 65 functions as an evaporator (cooling the air flow 53 through
the cooling coil 65 and condensing any vapor).
[0060] In another embodiment of the present invention, the air
management mechanism 1 further comprises an auxiliary heater 158 of
FIG. 6. The fan 50 is further disposed to provide airflow 53
through the auxiliary heater 158. Typically, the auxiliary heater
158, used in conjunction with the heater 55, provides a higher
temperature in the airflow 53 that enters the cleaning basket
assembly 2. The auxiliary heater 158 is disposed in the discharge
ventilation ducting 52. In another embodiment of present invention,
the auxiliary heater 158 is disposed in the suction discharge
ventilation ducting 53. Raising the air temperature of the airflow
53 typically decreases the drying time for the articles in the
humidity sensing process 400 of FIG. 12 and the solvent wash/dry
process 500 of FIG. 13.
[0061] The inputs to the controller 5 of FIG. 7 are typically
selected from the group consisting of the door lock sensor 18, the
temperature sensor 57, the solvent sensor 59, the optical sensor
140, the conductivity sensor 151, the basket conductivity cell 170,
the basket level detector 172, the basket humidity sensor 173, the
operator interface 190, the access door lock sensor 248, and any
combination thereof. The outputs of the controller 5 are typically
selected from the group consisting of the motor 3, the door lock
19, the pump 25, the fluid heater 28, the check valve 40, the fan
50, the heater 55, the spray nozzle 67, the compressor 75, the
regeneration pump 115, the water separator 152, the waste water
drain valve 155, the auxiliary heater 158, the mixing valve 185,
the display panel 200, the access door lock 246, the water drain
valve 260, and any combination thereof.
[0062] The controller 5 is further configured to perform a solvent
based cleaning fluid recirculation process. In the solvent based
cleaning fluid recirculation process, the solvent based cleaning
fluid 30 passes through the fluid processing mechanism 4 and
cleaning basket assembly 2 as discussed above for a predetermined
amount of time. The solvent based cleaning fluid recirculation
process is performed when the article cleaning apparatus 1000 is
not engaged in either the cleaning process 350 of FIG. 11 or the
drying process 360. In the case where the operator selects either
the cleaning process 350 or the drying process 360 during the
solvent based cleaning fluid recirculation process, the controller
5 recovers the article cleaning apparatus 1000 using a cycle
interruption recovery process 800 of FIG. 16, which will be
subsequently described in detail. As used herein, the term,
"recovers the article cleaning apparatus," relates to placing the
article cleaning apparatus 1000 in a condition to perform either
the cleaning process 350 or the drying process 360.
[0063] The cleaning basket assembly 2 of FIG. 8 depicts one
embodiment of the present invention where a cleaning basket support
structure 12 supports the rotating basket 14 through a door end
bearing 22 and a motor end bearing 21. The motor 3 is disposed to
the rotating basket 14 at the opposite end of the rotating basket
where a basket door 15 is disposed. The cleaning basket assembly 2
further comprises a gasket 16, a door lock sensor 18, and a door
lock 19. The basket support structure 12 further comprises a liquid
drain connection to the drain conduit 70 and a solvent based
cleaning fluid supply connection to the inlet tubing 26. The basket
support structure 12 further comprises a connection to the
discharge ventilation ducting 52 and a connection to the suction
ventilation ducting 51. A lint filter 60 is typically situated in
the suction ventilation ducting 51. The cleaning basket assembly 2
of FIG. 8 further comprises a basket humidity sensor 173 that has
the capability to determine the humidity level in the rotating
basket 14. In one embodiment of the present invention, the basket
humidity sensor 173 is disposed inside the basket support structure
12 adjacent the rotating basket 14.
[0064] The air management mechanism 1 of FIG. 1, the cleaning
basket assembly 2, fluid processing mechanism 4, and the controller
5 are disposed inside an enclosure 230 of FIG. 9, where only the
cleaning basket assembly 2 is depicted in the cut away view of the
enclosure 230. Additionally, the controller 5 of FIG. 7 is
configured to receive input controls from the operator from an
operator interface 190 of FIG. 9 and configured to provide a
cleaning status at the display panel 200. The enclosure 230 further
comprises an enclosure floor 250 that is substantially
perpendicular to an enclosure rear wall 240. The rotating basket 14
has a longitudinal axis 220 that is about parallel to the enclosure
floor 250. As used herein, the term, "about parallel" is defined to
include a range from about -3 degrees to about +3 degrees from
parallel. The enclosure 230 further comprises an enclosure front
wall 242 that is on the side of the enclosure where the basket door
15 is disposed. In one embodiment of the present invention, the
operator interface 190 and the display panel 200 are disposed on
the enclosure front wall 242. The location of the operator
interface 190 and the display panel 200 is provided by way of
illustration and is not intended to imply a limitation to the
present invention. In one embodiment of the present invention, the
enclosure floor 250 is configured to act as a containment pan to
collect leakage of the solvent based cleaning fluid 30. In another
embodiment of the present invention, the enclosure 230 is
configured to act as the containment pan to collect leakage of the
solvent based cleaning fluid 30.
[0065] In one embodiment of the present invention, the enclosure
230 has an overall volumetric shape of about 0.7 meters in width,
by about 0.9 meters in depth, by about 1.4 meters in height. This
volumetric shape represents the typical space available in an
in-home laundry setting.
[0066] The regeneration cartridge 141 of FIG. 2 is typically the
one item in the fluid processing mechanism 4 requiring periodic
replacement. In one embodiment of the present invention, the
enclosure front wall 242 of FIG. 9 comprises an access door 244, an
access door lock 246, and an access door lock sensor 248. The
location of the access door 244, access door lock 246 and the
access door lock sensor 248 is provided by way of illustration and
is not intended to imply a limitation to the present invention. The
access door lock 246 and access door lock sensor 248 are coupled to
the controller 5 of FIG. 7. The controller logic in the controller
5 keeps the access door lock 246 locked during the cleaning process
350 of FIG. 11, the drying process 360, and the solvent based
cleaning fluid recirculation process. The controller logic only
permits replacing the regeneration cartridge 141 of FIG. 2 when the
article cleaning apparatus 1000 is not operating any of the
following: the cleaning process 350 of FIG. 11, the drying process
360 and the solvent based cleaning fluid recirculation process.
When the controller logic verifies that any of the following: the
cleaning process 350 of FIG. 11, the drying process 360, and the
solvent based cleaning fluid recirculation process are not in
progress, then the controller 5 of FIG. 7 unlocks the access door
lock 246 in response to an operator request via the operator
interface 190 to replace the regeneration cartridge 141. If an
operator requests to replace the regeneration cartridge 141 and the
article cleaning apparatus 1000 is operating any process, the
operator is notified that the replacement of the regeneration
cartridge 141 is not permitted via a notification message displayed
on the display panel 200. By not permitting the cleaning process
350 of FIG. 11, the drying process 360, and the solvent based
cleaning fluid recirculation process to be performed by the article
cleaning apparatus 1000 of FIG. 2 during the regeneration cartridge
141 replacement, the operator is afforded protection from an
inadvertent exposure to the solvent based cleaning fluid 30.
Additionally, the controller logic does not allow the article
cleaning apparatus 1000 to initiate any process until the access
door lock sensor 248 of FIG. 9 verifies that the access door 244 is
shut and the access door lock 246 is locked. The access door lock
sensor 248 is additionally configured to detect that the
regeneration cartridge 141 of FIG. 2 is properly installed before
indicating that the access door 244 of FIG. 9 is properly closed
and that the access door lock 246 is properly locked.
[0067] Additionally, in one embodiment of the present invention,
the regeneration cartridge 141 of FIG. 2 further comprises a leak
proof double inlet valves assembly 101 and a leak proof double
outlet valves assembly 106 to minimize the operator's contact with
the solvent based cleaning fluid 30. In another embodiment of the
present invention, the regeneration cartridge 141 (not shown in
FIG. 2) further comprises a leak proof single inlet valve assembly
100 and a leak proof single outlet valve assembly 105 to minimize
the operator's contact with the solvent based cleaning fluid 30. As
used herein, the term, "leak proof" is defined to mean that there
is no leakage of the solvent based cleaning fluid 30 beyond about 1
ml evident at 1) either end of the regeneration cartridge 141 after
removal and 2) the connection points where the regeneration
cartridge 141 installs into the fluid regeneration device 7.
[0068] The controller logic in the controller 5 of FIG. 7 is
designed to keep the basket door lock 19 locked shut while
performing any of the following: the cleaning process 350, the
drying process 360, and the solvent based cleaning fluid
recirculation process. This limits the operator's ability to expose
oneself to the solvent based cleaning fluid 30 during any of the
following: the cleaning process 350, the drying process 360, and
the solvent based cleaning fluid recirculation process thereby
reducing the number of opportunities that the operator is exposed
to the solvent based cleaning fluid 30.
[0069] In one embodiment of the present invention, the clean fluid
device 8 of FIG. 2 further comprises a fluid heater 27 disposed
between the pump 25 and the cleaning basket assembly 2 in the inlet
line 26. The fluid heater 27 is coupled to the controller 5 of FIG.
7. The fluid heater 27 has the ability to increase the temperature
of the solvent based cleaning fluid 30. The elevated temperature of
the solvent based cleaning fluid 30 has the effect of improving the
soil removal cleaning performance for some types of article and
soiling combinations.
[0070] In another embodiment of the present invention the article
cleaning apparatus 1000 of FIG. 1 is further configured to add a
small quantity of water (in the range from about 1 percent to about
8 percent of the total weight of the solvent based cleaning fluid
30) and other cleaning agents to the rotating basket 14 to mix with
the solvent based cleaning fluid 30 entering the cleaning basket
assembly 2 through the inlet line 26. In one embodiment of the
present invention, the cleaning basket assembly 2 of FIG. 8 further
comprises a hot water inlet 175 and a cold-water inlet 180, both of
which are coupled to a mixing valve 185. A basket conductivity cell
170 and a basket level detector 172 are disposed in the cleaning
basket assembly 2, such that the basket conductivity cell 170
determines the conductivity of the fluid in the rotating basket 14
and the basket level detector 172 determines the level of the water
based cleaning fluid 31 or the solvent based cleaning fluid 30 in
the rotating basket 14. In one embodiment of the present invention,
a dispenser 300 is disposed off a line that couples the mixing
valve 185 to the basket support structure 12. Additionally, the
operator adds the cleaning agents to the dispenser 300 and the
subsequent action of the water running through the line coupling
the mixing valve 185 to the basket support structure 12 entrains
the cleaning agents that are disposed in the dispenser 300 into the
water entering the rotating basket 14.
[0071] In one embodiment of the present invention, the article
cleaning apparatus 1000 of FIG. 1 is further configured to perform
the water cleaning process 600 of FIG. 14 utilizing a water based
cleaning fluid 31. In addition to the above-discussed components
associated with monitoring and adding water to the rotating basket
14, a water drain line 270 connects to the drain conduit 70
upstream of the check valve 40. The water drain line 270 also
connects to the suction side of the regeneration pump 115. A water
drain valve 260 is disposed in the water drain line 270. The method
of adding cleaning agents to the water in the rotating basket 14 is
the same as discussed above.
[0072] A plot of retained moisture content as a percentage of an
article's weight versus the relative humidity is provided in FIG.
10 for a variety of materials that are commonly used to comprise
articles. As the fluid processing mechanism 4 of FIG. 2 contains a
finite quantity of water removal capability, the controller 5 of
FIG. 7 is configured to reduce the amount of water admitted to the
fluid processing mechanism 4 of FIG. 2. The reduction of the
retained moisture content is accomplished in a humidity sensing
process 400 of FIG. 11 that is part of the solvent cleaning process
375.
[0073] By way of example, a chemical-specific sensor, such as
solvent sensor 59, may be configured to monitor amounts of the
volatile solvent fluid, and may be coupled to the controller to
control a drying cycle for extracting a desired level of moisture
from the articles. A memory device or look-up table may comprise
means for relating a fixed or time dependent voltage level in the
output signal from the chemical specific sensor to moisture content
in the article being cleansed/dried. A comparator module may allow
for estimating additional time that may be needed to reach a
desired level of moisture based on a present reading from the
solvent sensor, or may allow for terminating the drying cycle, once
a desired level of dryness has been reached.
[0074] In one embodiment of the present invention, a process
selection 310 of FIG. 11 occurs at the operator interface 190 and
provides inputs to the controller 5 of FIG. 7. The operator selects
between the cleaning process 350 of FIG. 11 and a drying process
360. This drying process 360 refers to the drying of articles after
completing the water based cleaning 600 of FIG. 14. When the
operator selects the cleaning process 350 of FIG. 11, the operator
then further chooses between performing either the solvent cleaning
process 375 or the water cleaning process 600. In the present
invention, the solvent cleaning process 375 of FIG. 11 is defined
to include performing the humidity sensing process 400 and the
subsequent solvent wash/dry process 500. Conversely, when the
operator selects the drying process 360, a basket drying process
700 is performed. In one embodiment of the present invention, the
operator has the option to select an additional solvent wash
process as part of the solvent wash/dry process 500. The additional
solvent wash process is typically used in conjunction with
utilizing the solvent based cleaning fluid 30 that comprises
cleaning agents. The additional solvent wash process typically
improves the removal of the cleaning agents from the articles that
remain after initially completing step 540 as detailed below. In
another embodiment of the present invention, the operator has the
option to select an additional rinse process 675 as part of the
water cleaning process 600. In another embodiment of the present
invention, when the operator selects the drying process 360 the
operator is provided with a further option of selecting from either
the basket drying process 700 or a timed basket drying process
705.
[0075] The start of the solvent based cleaning cycle 375 of FIG. 11
starts with the controller 5 of FIG. 7 sensing the humidity in the
rotating basket 14 of FIG. 8 by initiating the humidity sensing
process 400 of FIG. 12. The start 410 of the humidity sensing
process 400 initially begins by verifying that the door lock 19 is
locked. A starting humidity in the rotating basket 14 of FIG. 8 is
determined in the sensing humidity step 410 of FIG. 12 by the
basket humidity sensor 173. The controller 5 of FIG. 7 then tumbles
the rotating basket 14 in step 430 of FIG. 12. The airflow 53 of
FIG. 5 is heated and passed through the air management mechanism 1
and the cleaning basket assembly 2 while tumbling the rotating
basket 14 for a predetermined pre-drying time in step 440 of FIG.
12. The moisture in the rotating basket 14 becomes vapor. The
airflow 53 containing the vapor comes out of the rotating basket 14
through the holes 17 of FIG. 8 and then passes through the lint
filter 60. The airflow 53 of FIG. 5 subsequently passes over the
cooling coil 65 where the vapor condenses to form condensate. The
rotating basket 14 is tumbled and the airflow 53 entering the
cleaning basket assembly 2 is heated for the predetermined amount
of time. The controller 5 of FIG. 7 then determines a finishing
humidity in the rotating basket 14 of FIG. 8. If the controller 5
of FIG. 7 determines that the finishing humidity is too high, then
the controller 5 of FIG. 7 sends a warning in step 470 of FIG. 12
to the operator at the display panel 200 indicating that it may
take longer to complete the solvent cleaning process 375 and a
longer humidity sensing process 400 is initiated.
[0076] After completing the humidity sensing process 400, the
solvent wash/dry process 500 of FIG. 13 is typically executed. The
following typical solvent wash/dry process 500 of FIG. 13 is
utilized in one embodiment of the present invention. The following
steps of the solvent wash/dry process 500 are provided for
illustration and in no way implies any restriction to the present
invention. The initial conditions at the start step 510 include
reverifying that the door lock 19 of FIG. 8 is locked. The solvent
based cleaning fluid 30 of FIG. 2 is added to the rotating basket
14 of FIG. 8 as depicted in step 520 of FIG. 13 and as described in
detail above. The rotating basket 14 of FIG. 8 is then tumbled as
shown in step 530 of FIG. 13. After tumbling for a predetermined
amount of time, the controller 5 of FIG. 7 opens the check valve
40, and the solvent based cleaning fluid 30 of FIG. 2 starts to
drain from the rotating basket 14 of FIG. 8. Substantially all of
the remaining portion of the solvent based cleaning fluid 30 of
FIG. 2 is spin extracted by spinning the rotating basket 14 in step
540 of FIG. 13. The solvent based cleaning fluid 30 is drained to
the working tank 45 and subsequently the controller 5 of FIG. 7
shuts the check valve 40 of FIG. 2.
[0077] Detection of solvent vapor in the rotating basket 14 of FIG.
8 is determined in step 560 of FIG. 13. The controller 5 of FIG. 7
then tumbles the rotating basket 14 and raises the temperature of
the airflow 53 of FIG. 5 in step 570 of FIG. 13. A substantial
amount of the remaining portion of the solvent based cleaning fluid
30 and any liquid becomes vapor. The vapor flows from the rotating
basket 14 through the lint filter 60 and passes over the cooling
coil 65. The vapor condenses on the cooling coil 65 to form a
condensate. The post-drying solvent vapor detection in the rotating
basket 14 of FIG. 8 is determined in step 580 of FIG. 13. The
process steps of 560 through 580 FIG. 13 as detailed above are
performed until the post-drying solvent vapor in the rotating
basket 14 of FIG. 8 reaches an acceptable level, at which point the
controller 5 of FIG. 7 unlocks the basket door 15 in step 590 of
FIG. 13. In another embodiment of the present invention, the
operator selects the additional solvent wash process. The
additional solvent wash process comprises completing step 520, step
530, and step 540 occurs after completing step 540 and before
performing step 560, where the individual steps are as described
above. In one embodiment of the present invention, the additional
solvent wash process enhances the cleaning performance of
especially soiled articles. In another embodiment of the present
invention, the additional solvent wash process enhances the removal
of cleaning agents. The operator selects the additional solvent
wash process at the operator interface 190.
[0078] In one embodiment of the present invention the rotating
basket 14 of FIG. 8 has a typical load range between about 0.9 kg
and about 6.8 kg. The rotating basket 14 has a rotating basket
capacity with a typical range between about 17 liters and about 133
liters, which is generally useful for performing laundering
utilizing the solvent based cleaning fluid 30 of FIG. 2. The ratio
of liters of solvent based cleaning fluid 30 per kg of articles in
the laundry load is generally in a range from about 4.2 liters/kg
to about 12.5 liters/kg. The corresponding total capacity of the
solvent based cleaning fluid 30 per laundry load is generally in a
range from about 3.8 liters (4.2 liters/kg times 0.9 kg) to about
85 liters (12.5 liters/kg times 6.8 kg), respectively. The total
amount of solvent based cleaning fluid 30 in the article cleaning
apparatus 1000 of FIG. 1 is from about 1.05 to about 2.0 times the
amount of solvent based cleaning fluid 30 of FIG. 2 required per
load. The total amount of solvent based cleaning fluid 30 equates
to a range from about 4 liters (3.8 liters times 1.05) to about 170
liters (85 liters times 2), which corresponds to a typical ratio of
the capacity of the solvent based cleaning fluid 30 to laundry load
ranges from about 4.4 liters/kg (4 liters/0.9 kg) to about 25
liters/kg (170 liters/6.8 kg), respectively.
[0079] In another embodiment, the typical amount of articles in a
laundry load range from about 2.7 kg to about 5.4 kg. The
corresponding total capacity of the solvent based cleaning fluid 30
per laundry load is generally in a range from about 11.3 liters
(4.2 liters/kg times 2.7 kg) to about 67.5 liters (12.5 liters/kg
times 5.4 kg). The total amount of solvent based cleaning fluid 30
in the article cleaning apparatus 1000 of FIG. 1 is from about 1.05
to about 2.0 times the amount of solvent based cleaning fluid 30 of
FIG. 2 required per load. The total amount of solvent based
cleaning fluid 30 equates to a range from about 11.9 liters (11.3
liters times 1.05) to about 135 liters (67.5 liters times 2).
[0080] In another embodiment, the ratio of liters of solvent based
cleaning fluid 30 of FIG. 2 to kg of articles is from about 6.7
liters/kg to about 8.3 liters/kg. When the load capacity is in a
range from about 0.9 kg to about 6.8 kg, the corresponding total
capacity of the solvent based cleaning fluid 30 per laundry load is
generally in a range from about 6.0 liters (6.7 liters/kg times 0.9
kg) to about 56.4 liters (8.3 liters/kg times 6.8 kg),
respectively. When the load capacity is in a range from about 2.7
kg to about 5.4 kg, the corresponding total capacity of the solvent
based cleaning fluid 30 per laundry load is generally in a range
from about 18.1 liters (6.7 liters/kg times 2.7 kg) to about 44.8
liters (8.3 liters/kg times 5.4 kg), respectively. The total amount
of solvent based cleaning fluid 30 in the article cleaning
apparatus 1000 of FIG. 1 is from about 1.05 to about 2.0 times the
amount of solvent based cleaning fluid 30 of FIG. 2 required per
load. The total amount of solvent based cleaning fluid 30 equates
to a range from about 6.3 liters (6.0 liters times 1.05) to about
112.8 liters (56.4 liters times 2).
[0081] In order to reduce the total capacity of the solvent based
cleaning fluid 30 in the article cleaning apparatus 1000 of FIG. 1,
the cleaning fluid processing is performed on-line and the
processing is synchronized with the solvent wash/dry process 500 of
FIG. 13. Processing the solvent based cleaning fluid 30 of FIG. 2
on-line typically provides sufficient solvent based cleaning fluid
30 in the storage tank 35 to perform a subsequent solvent cleaning
process 350 of FIG. 11 after completing the previous solvent
cleaning process 350. The storage tank 35 of FIG. 2 typically has a
sufficient capacity of the solvent based cleaning fluid 30 to make
up for any solvent based cleaning fluid 30 that is held up in the
fluid regeneration device 7, in the working fluid device 6, and
retention in the "dried" articles. The regeneration cartridge 141
is capable of replenishing the amount of solvent based cleaning
fluid 30 that is retained in the "dried" articles. In one
embodiment of the present invention, the typical solvent capacity
of the storage tank 35 is from about 10.4 liters/kg to about 12.5
liters/kg when the load capacity ranges from about 2.7 kg to about
5.4 kg. The storage tank 35 has a corresponding typical range from
about 28.1 liters to about 67.5 liters. Therefore, the storage tank
35 of the present invention typically needs only about 36% (67.5
liter/190 liter) of the capacity of the about 190 liter storage
tank found in typical commercial chemical fluid dry cleaning
machines. In one embodiment of the present invention, the typical
solvent capacity of the storage tank 35 is from about 10.4
liters/kg to about 12.5 liters/kg when the load capacity ranges
from about 0.9 kg to about 6.8 kg. The storage tank 35 has a
corresponding typical range from about 9.4 liters to about 85
liters. Therefore, the storage tank 35 of the present invention
typically needs only about 45% (85 liter/190 liter) of the capacity
of the about 190 liter storage tank found in typical commercial
chemical fluid dry cleaning machines. The above comparison of
storage tank capacity typical range from about 9.4 liters to about
85 liters for the present invention compares favorably to the range
of the storage tank capacity of from about 190 liters to about 1325
liters for typical commercial chemical fluid dry cleaning
machines.
[0082] In another embodiment of the present invention, the solvent
wash/dry process 500 adds water to the solvent based cleaning fluid
30 of FIG. 2 in the rotating basket 14, where the maximum amount of
water added is in the range from about 1 percent to about 8 percent
of the total weight of the solvent based cleaning fluid 30 that is
in the rotating basket 14. Adding the water to the solvent based
cleaning fluid 30 that is in the rotating basket 14 is performed as
described above. In another embodiment of the present invention,
the solvent wash/dry process 500 adds water and cleaning agents to
the solvent based cleaning fluid 30 of FIG. 2 in the rotating
basket 14, where the maximum amount of water added does not exceed
a maximum of about 8 percent of the total weight of the solvent
based cleaning fluid 30 that is in the rotating basket 14. Adding
the water and the cleaning agents to the solvent based cleaning
fluid 30 that is in the rotating basket 14 is performed as
described above.
[0083] Steps 560 of FIGS. 13 through 580 in the solvent wash/dry
process 500 require a typical range from about 15 minutes to about
60 minutes for the typical laundry load, which ranges from about
0.9 kg of articles to about 6.8 kg of articles. The sensible heat
required to dry the clothes, which is the principle source of total
electrical power the machine requires, is in a range between about
430 watts to about 6300 watts. As used herein, the term, "sensible
heat" is defined to be the total amount of heat added by the
combination of the heater 55 and auxiliary heater 158 (if
installed). In another embodiment, the drying time is between about
20 and about 60 minutes with the typical laundry load range between
about 2.7 kg of articles and about 5.4 kg of articles. In this
case, the sensible heat required to dry the clothes is in a range
between about 1300 watts and about 5200 watts. In each of these
cases, the power is easily handled on a household circuit with a
maximum voltage of about 240V and a maximum amp rating of about 30
amps. In some embodiments, the article cleaning apparatus 1000 of
FIG. 1 is configured to run on about 220V service in an about
20-amp circuit, about 220V service in an about 30-amp circuit, and
about 110V service and in a circuit having a amperage range from
about 15 amps to about 20 amps. All of these circuit types are
typically available in homes for currently available cooking and
drying appliances; therefore, presenting no additional installation
difficulties.
[0084] The controller 5 of FIG. 7 controls the water cleaning
process 600 of FIG. 14. The controller 5 of FIG. 7 is configured to
reduce the opportunity for introducing large amounts of water into
the working tank 45 of FIG. 2 as discussed herein. In the present
invention, a fluid in the rotating basket 14 is defined to contain
a "large amount of water" when the fluid comprises greater than
about 10% water by weight. The water cleaning process 600 of FIG.
14 is provided to illustrate a series of steps used in one
embodiment of the present invention and in no way implies any
limitation to the water cleaning process 600 utilized in the
present invention.
[0085] The water cleaning process 600 begins with the initial
conditions of the cleaning agents loaded into the dispenser 300,
and the door lock 19 engaged and the door lock sensor 18 verifying
that the basket door 15 in the locked position at the start step
610 of FIG. 14. Water and cleaning agents are added to the rotating
basket 14 to produce the water based cleaning fluid 31 of FIG. 9 in
step 620. The water may be hot, cold or a mixture as detailed
above. The rotating basket 14 is tumbled in step 630 of FIG. 14.
Substantially all of the water based cleaning fluid 31 of FIG. 9 is
spin extracted by rotating from the rotating basket 14 of FIG. 2 in
step 640 of FIG. 14. The controller 5 of FIG. 7 opens the water
drain valve 260 of FIG. 2 and operates the regeneration pump 115 as
necessary to drain the rotating basket 14 during the spin step 640,
when the basket conductivity cell 170 of FIG. 8 detects that the
water based cleaning fluid 31 of FIG. 9 in the rotating basket 14
comprises greater than about 10% water by weight. The controller 5
of FIG. 7 closes the water drain valve 260 of FIG. 2 after removing
the water based cleaning fluid 31 of FIG. 9 from the rotating
basket 14 of FIG. 2 after completing the spin basket step 640.
[0086] Rinse water is then added to the rotating basket 14 of FIG.
8 and the rotating basket 14 is tumbled in step 670 of FIG. 14. The
temperature of the rinse water is determined by the controller 5 of
FIG. 7 in conjunction with the mixing valve 185 of FIG. 8.
Substantially all of the remaining amount of rinse water is spin
extracted by spinning the rotating basket 14 in step 680 of FIG.
14. The rinse water is removed as described above. The rotating
basket 14 is tumbled in step 690 of FIG. 14. The basket door 15 of
FIG. 8 is then unlocked in step 695 of FIG. 14.
[0087] In another embodiment of the present invention, the operator
selects an additional rinse process. The additional rinse process
reperforms step 670, step 680, and step 690. The additional rinse
process occurs after step 690 and before the basket door 15 is
unlocked in step 695. The additional rinse process assists in
removing the entrained cleaning agents that are not removed during
steps 670, 680, and 690. The additional rinse process is especially
useful when using soft water. As used herein, the term "soft water"
is defined as comprising less than about 10 grains of hardness per
about 3.8 liters of water.
[0088] In another embodiment of the present invention, the article
cleaning apparatus 1000 of FIG. 1 is configured to perform the
basket drying process 700 of FIG. 15. The basket drying process 700
of FIG. 15 is provided to illustrate the basket drying process 700
used in one embodiment of the present invention and in no way
implies any limitation to the basket drying process 700 of the
present invention. The basket drying process 700 begins with the
initial conditions of the basket door 15 locked, and the door lock
sensor 18 verifying the basket door 15 locked at the start step 710
of FIG. 15. The basket drying process 700 initially begins by
performing a sensing humidity step 720 to determine a start
humidity, a tumble basket step 730 and heat airflow step 740
similar to that described above in steps 420, 430, and 440,
respectively. After tumbling and heating the airflow 53 for a
predetermined post-water wash drying time, the controller 5 of FIG.
7 determines a final humidity in the rotating basket 14 of FIG. 8
in step 760. When the controller 5 of FIG. 7 determines that the
final humidity is too high, then the controller 5 initiates a
longer drying sequence in step 760 by re-performing steps 730
through 760. When the final humidity is acceptable, the controller
5 of FIG. 7 stops the basket drying process 700 of FIG. 15 in step
770, and unlocks the basket door 15 of FIG. 8 in step 780 of FIG.
15.
[0089] In another embodiment of the present invention, a timed
basket drying process 705 of FIG. 11 is available to the operator
at the operator interface 190. The timed basket drying process 705
comprises the steps of starting the drying cycle 710 of FIG. 15 by
setting the predetermined amount of drying time, tumbling the
rotating basket 14 in step 730, heating the airflow 53 in step 740,
and stopping the timed basket drying process in step 770 when
predetermined amount of drying time is accomplished. The controller
5 of FIG. 7 unlocks the basket door 15 of FIG. 8 in step 780 of
FIG. 15.
[0090] It is important that a large amount of the water is not
inadvertently directed to the working tank 45 of FIG. 2 during the
solvent wash/dry process 500 of FIG. 13 that adds water, in the
range from about 1 percent to about 8 percent, to the solvent based
cleaning fluid 30 of FIG. 2 in the rotating basket 14 as discussed
above. It is also important to reduce the possibility that the
solvent based cleaning fluid 30 is not accidentally pumped out of
the article cleaning apparatus 1000 of FIG. 1. If the solvent
cleaning process 375 of FIG. 11 or the water cleaning process 600
is interrupted by either the operator or a loss of electrical
power, the controller 5 of FIG. 7 utilizes a cycle interruption
recovery process 800 of FIG. 16. The cycle interruption recovery
process 800 operates a series of logical sequence options to
control the subsequent operation of the article cleaning apparatus
1000 of FIG. 1. The logical sequence options include completing the
appropriate cleaning cycle, completing a fail-safe process, or
informing the operator to call service.
[0091] In one embodiment of the present invention, the cycle
interruption recovery process 800 starts by verifying the locked
status of door lock 19 of FIG. 8 via the door lock sensor 18 in
step 810 of FIG. 16. If the door lock sensor 18 of FIG. 8 is
determined to be non-operational in the component failure detected
step 892 of FIG. 16, then a call service message is generated in
step 894, which is then sent to the display 200. Conversely, if the
controller 5 of FIG. 7 does verify that the door lock 19 of FIG. 8
is locked in step 810 of FIG. 16, then the basket level detector
172 of FIG. 8 determines if there is liquid in the rotating basket
14 in step 820 of FIG. 16. If the controller 5 cannot tell if the
basket level detector 172 is operational, then the component
failure detected step 892 of FIG. 16 generates the call service
message in step 894. If liquid is detected in step 820 of FIG. 16
then the basket conductivity cell 170 of FIG. 8 determines whether
the liquid is the solvent based cleaning fluid 30 or the water
based cleaning fluid 31 in step 830 of FIG. 16. Siloxane is
non-conductive; therefore, the basket conductivity cell 170 of FIG.
8 typically provides a conductivity measurement of the liquid in
the article cleaning apparatus 1000. If the controller 5 cannot
tell if the basket conductivity cell 170 of FIG. 8 is operational,
then the component failure detected step 892 of FIG. 16 generates a
call service message in step 894.
[0092] If the basket conductivity cell 170 of FIG. 8 detects that
the fluid in the rotating basket 14 comprises greater than about
10% water, then the fluid is defined to be the water based cleaning
fluid 31. If the fluid in the rotating basket 14 is defined to be
the water based cleaning fluid 31, then a determination of where
the interruption occurred in the water cleaning process 600 is
performed in step 840. In step 840, if the controller 5 of FIG. 7
has a memory of where the water cleaning process interruption
occurred, then the water cleaning process 600 resumes as depicted
in step 860. If the controller 5 in step 840 of FIG. 16 cannot
remember where the water cleaning process interruption occurred,
then the water based cleaning fluid 31 is pumped out and the
cleaning process 350 of FIG. 11 is reset in step 850 of FIG. 16. If
the controller 5 in step 850 of FIG. 16 cannot tell if the
components required to perform step 850 are available, then the
component failure detected step 892 generates the call service
message in step 894.
[0093] If the basket conductivity cell 170 of FIG. 8 detects less
than about 10% water in the liquid in the rotating basket 14, then
the liquid is defined to be the solvent based cleaning fluid 30. If
the liquid is defined to be the solvent based cleaning fluid 30,
then a determination of where the interruption occurred in the
solvent cleaning process 375 is performed in step 845. In step 845,
if the controller 5 of FIG. 7 has a memory of where the solvent
cleaning process interruption occurred, then the solvent cleaning
process 375 resumes as depicted in step 870. If the controller 5 of
FIG. 7 in step 845 of FIG. 16 cannot determine where the
interruption occurred in the solvent cleaning process 375 of FIG.
11, then a warn operator fail-safe message is generated in step
880, which is then set to the display 200 of FIG. 9.
[0094] After generating the warn operator fail-safe message in step
880 of FIG. 16, the solvent based cleaning fluid 30 of FIG. 2 is
pumped out in step 882 of FIG. 16. Subsequently the rotating basket
14 of FIG. 8 is tumbled and rotated to spin extract substantially
all of the remaining portion of the solvent based cleaning fluid 30
of FIG. 2 from the rotating basket 14 in step 884 of FIG. 16. The
airflow 53 is then heated while tumbling the rotating basket 14 of
FIG. 8 in step 886 of FIG. 16. The operator is informed that the
fail-safe is completed in step 888, and the fail-safe completed
message is sent to the display 200 of FIG. 9, and the basket door
15 of FIG. 8 is unlocked in step 890 of FIG. 16. If it is
determined that the components required to operate each of the
steps 882, 884, 886, and 888 are non-operational, then the
component failure detected step 892 of FIG. 16 generates the call
service message in step 894.
[0095] The cycle interruption recovery process 800 of FIG. 16 is
provided to illustrate the cycle interruption recovery process 800
used in one embodiment of the present invention and in no way
implies that any limitation to the cycle interruption recovery
process 800 employed in controlling operation of article cleaning
apparatus 1000 of FIG. 1 of the present invention.
[0096] The efficiency of operation of an appliance, as described
above, for cleansing clothes or any other articles washed with
water/detergent, and/or a volatile solvent, such as D5, or mixtures
of silicone-based fluids and water/detergent can be improved by
utilizing a chemical-specific sensor or sensors, e.g., solvent
sensor 59, configured to, for example, determine the vapor
concentration or vapor pressure of solvent in the appliance gas
exit stream. Controller 5 may process an output signal from such a
sensor indicative of the vapor concentration or vapor pressure of
the solvent to control inlet gas temperature and/or gas velocity to
maximize vapor removal from the clothes load with minimal waste of
energy. Such a sensor can also be used to detect leaks that may
develop in the appliance or to detect vapor leaks into the
surrounding living space.
[0097] There may be several desirable sensor capabilities for a
so-called In-Home dry cleaning appliance (HDC). Some of these
capabilities may be as follows:
[0098] 1) Determination of the state of dryness of a load
undergoing a drying cycle, such as may be performed by monitoring
an indication of siloxane solvent vapor in the drum exit gas
stream.
[0099] 2) Monitor siloxane solvent vapor concentration for leak
detection and fire safety; and
[0100] 3) Potential use as a separate environmental monitor of
siloxane solvent for use in the room housing the appliance. An
additional use could be as a point source detector of siloxane
solvent to be used by service personnel as a trouble-shooting
tool.
[0101] In all of these applications, the sensor technology used
should be selective for siloxane solvent, especially in the
presence of water vapor, sufficiently sensitive to detect low
levels of siloxane solvent vapor and have a range capable of
measuring saturation levels of siloxane solvent in air at
temperatures from about 0.degree. F. to about 200.degree. F. or any
sub-range therein.
[0102] As a result, several types of chemical-specific sensors were
evaluated for their potential utility for detection of siloxane
solvent. Exemplary sensor types evaluated for specific detection of
siloxane solvent include the following:
[0103] 1. Spectroscopic sensors. This group includes sensors that
utilize unique electro-optical absorbance bands of siloxane to
determine concentration in a gas stream.
[0104] 2. Piezo-based sensors with specific coatings: This group
includes surface acoustic wave sensors, quartz crystal
microbalances and arrays of piezo sensors that may viewed as an
"electronic sniffing" device.
[0105] 3. Strain-gauge based sensors. This group includes
micro-machined sensors and strain-gauge bridges with siloxane
solvent specific coatings.
[0106] 4. Capacitive Sensors. This group includes sensors where
changes in a dielectric layer in the sensor affects capacitance
properties, such as dielectric strength or a dimension,
proportional to the siloxane solvent concentration in the
surrounding atmosphere.
[0107] Spectroscopic Sensors:
[0108] Siloxane in the vapor state exhibits absorption at a
relatively short UV wavelength (for example <220 nm) and is then
transparent through the visible spectrum out to the near infrared
region. There are useful bands in the near- and mid-infrared
regions that could be utilized to detect siloxane and discriminate
against water vapor. Exemplary spectra of siloxane and water vapor
for the near infrared are shown in FIG. 17 and for the mid-infrared
in FIG. 18. Note that in the near-IR there are unique spectral
bands useful for siloxane detection between approximately 2300 nm
and approximately 2500 nm (4347 to 4000 cm-1), which show no
interference from the water vapor bands centered around 1900 nm and
1400 nm. In the mid-IR, the most prominent band comprises the
so-called Si--O stretch, which is centered at approximately 9216
nm, (1085 cm-1) and which is close to but distinguishable from the
nearby water vapor bands. The near IR region may be a more
accessible region of the spectrum since, presently, the choices of
commercially available detectors, optical filters and window
materials may be relatively broader than for the more demanding
mid-IR region. Also, the band separation width is presently
relatively larger in commercially available near IR bandpass
filters.
[0109] A respective block diagram of two exemplary near-IR siloxane
vapor sensors 601 and 650 is shown in FIGS. 19 and 20. Sensor 601
comprises an infrared source 602, a bandpass filter 604 centered at
a band of interest, a flow-through cell 606 for passing samples of
the fluid undergoing monitoring. Cell 606 may include windows, such
as may be made up of quartz, silicon or sapphire cell, for allowing
a beam of infrared radiation from source 602 to pass therethrough.
A detector 608, e.g., a photocell, thermopile or pyrometer IR
radiation detector, measures the amount of absorbance experienced
by the beam that passes through cell 606. Optionally, a piezo-based
chopper 609 may be used for allowing intermittent passage to the
beam from source 602. The use of a pulsed radiation source (e.g.,
comprising thin film resistive elements) can eliminate the need for
the piezo-based chopper. Sensor 601 could also be constructed with
commercially available duplex pyrometers and appropriately centered
filters to provide both water and siloxane detection.
[0110] Sensor 650 is similar in operation to sensor 601 and
functionally equivalent components are identified in FIG. 20 with
the same reference numerals used in FIG. 19. In sensor 650, in lieu
of a bandpass filter, a dispersive spectrograph 652 with slits 654,
a mirror 656 and a grating 658 is used to separate at least two
wavelengths of interest. Dispersive spectrograph 652 together with
two detector channels 660 and 662 may be configured to provide both
siloxane and water vapor detection.
[0111] A mid-IR prototype sensor was built using
commercially-available lab instrumentation along with a
controllably heated transfer line and gas cell. This prototype was
based on a Foxboro Miran 1B analyzer coupled to a Miran detector.
The analog output level from this prototype was in a range from
about 0 to 1 volt and was directly compatible with an exemplary
data acquisition and control electronics for the HDC appliance. The
prototype was installed to sample the drum exit stream with either
a pump or the pressure differential that developed across the heat
exchanger providing flow through the cell. It has been shown that
this type of sensor will permit monitoring the siloxane
concentration in the exit stream as a function of dry time and
under variable operating conditions. The radiation source
wavelength was set at approximately 9.2 microns, which
substantially corresponds with the Si--O stretch band in the
mid-IR. This band has no interference from water vapor and the
heated cell enclosure and teflon transfer lines were all heated to
temperatures above 150.degree. F. to prevent condensation.
[0112] A sequential vaporizer was constructed to provide
selectively switchable streams of dry air or air saturated with
water or siloxane vapor at a desired temperature. The sequential
saturator consisted of a series of gas washing bottles or impingers
that contained siloxane and, separately, water with control of the
gas flow rates from a common source. This saturator was used to
test each of the solvent sensor prototypes developed for this
invention.
[0113] Testing of the mid-IR sensor was carried out with a heated
cell and a transfer line temperature at approximately 150.degree.
F. (65.degree. C.). The slit width was approximately 1 mm and the
full-scale absorbance of 1 AU would be equal to 4 volts. A low-pass
filter was used to provide some noise reduction with a 1 second
time constant. The typical test procedure was to pass dry air
through the sensor followed by saturated siloxane vapor, then back
to dry air and then to water vapor and then again to dry air. In
the plot of FIG. 21 shows an exemplary response of the mid-IR
sensor in the presence of saturated siloxane vapor versus the
presence of dry air. For example, after 300 seconds with just dry
air passing through the cell, the gas source was switched to
provide saturated siloxane vapor at approximately 22.degree. C.
(72.degree. F). At 550 seconds the gas stream was switched back to
dry air and then again at 1060 seconds to saturated D5.
[0114] A useful figure of merit for a selective sensor is the
response ratio of the detected species to common interference or
background materials. In the case of the HDC appliance the most
common background is believed to be water vapor, either from the
clothes load, from mixed fluid cleaning or from ambient background.
The plot of FIG. 22 shows an exemplary response of the mid-IR
detector to both D5 and water vapor under the same conditions.
[0115] The saturation vapor pressure of water vapor at 21.degree.
C. is approximately 18.65 mm and the saturation vapor pressure of
siloxane under the same conditions is approximately 0.097 mm.
Accordingly, for a concentration ratio of approximately
5.2.times.10E-3 the measured signal ratio was approximately 17.
Thus, the siloxane/water selectivity value for this example was
approximately 3269. Given that the detector response to gas
concentrations is substantially linear at least up to 1 absorbance
unit, the maximum concentration capability for siloxane under these
experimental conditions is 50% saturation at a drum exit
temperature of 150.degree. F. If the siloxane saturation level in
the drum exit is higher than that, one can easily shorten a path
length from approximately 1.8" to approximately 0.75" and still
retain low concentration level capability.
INDUSTRIAL UTILITY
[0116] It is felt that the spectroscopic sensing solutions to
siloxane sensing in the HDC appliance are sufficiently selective
and offer a relatively low risk of interferences (water vapor)
being seen as siloxane. Sensor designs that integrate the filters
in the detector covers, pulsed IR sources and integral sample cells
are contemplated to provide further opportunities for a
siloxane-specific spectroscopic sensor, especially in the near-IR
range, that may be sufficiently cost effective to be viable for a
home appliance.
[0117] Piezo-Based Sensors:
[0118] Quartz crystal microbalances (QCM) comprised the exemplary
sensor elements evaluated in this class of sensors. These are
typically AT cut quartz crystals with electrodes applied to the
opposite surfaces. When driven with an oscillating electric field,
the crystal oscillates at the design resonant frequency. In the
case of exemplary crystals tested for verifying aspects of the
present invention, this frequency was approximately 10 MHz.
[0119] As will be appreciated by those skilled in the art, an
uncoated QCM is highly sensitive to changes in material weight on
the surface of the sensor. The response of a resonating crystal
comprises a decrease in resonant frequency proportional to the
increase of the mass on the active surface of the crystal. The
active resonant surface of the QCM is largely confined to the
electrode region of the crystal. Small increases in surface
adsorption can lead to rather large changes in frequency of the QCM
and this characteristic is innovatively used to detect siloxane in
a dry cleaning appliance.
[0120] The inventors of the present invention noted that an
uncoated QCM when exposed to siloxane or water vapor near
saturation accumulated a thin film, possibly a complete monolayer,
of the gas molecules on the resonant surface of the crystal and
this increased the weight of the crystal and thus decreased the
resonant frequency of the sensor. However, in the uncoated devices,
which typically have aluminum, gold or nickel electrodes on the
quartz crystal, are relatively unselective regarding condensable
vapors.
[0121] To increase the selectivity of the sensors, as conceptually
shown in FIG. 23, one should coat the active resonant surface of a
crystal 701 with a transducer film 702 of material that selectively
absorbs the analyte of interest and thus increases the film weight
and/or modulus of the crystal. This would affect the resonant
frequency of the QCM. Since, in aspects of the present invention,
one is primarily concerned with selecting siloxane vapor over water
vapor, in one exemplary embodiment, one may choose the transducer
film 702 to comprise a non-polar organic reagent or polymer. For
applications where water detection is of interest, polar polymers
including some ionic materials might be used as the coating
material. As used herein, the phrase "transducer film" refers to
any substance disposed on a resonator to render that resonator
responsive to the presence of a volatile dry cleaning solvent, such
as siloxane.
[0122] Initial experiments involved the use of 10 MHz QCM devices
available from International Crystal Manufacturing in Oklahoma
City. These devices are provided with removable contacts and
include gold electrodes that were found to provide an excellent
substrate for attaching monolayers of thio-organics or overcoating
with polymeric films. The --SH group is very effective at binding
to a gold surface and when a long hydrocarbon chain thiol is used,
the result is an organized film of hydrocarbon chains extending
from the surface of the gold electrode. Application as a
Langmuir-Blodgett film tends to create dense organized monolayers
of hydrocarbons. An exemplary thiol used was octadecylthiol, which
has a long hydrocarbon chain attached to the thiol and thus the
gold surface.
[0123] Experimental results obtained when binding or otherwise
disposing a monolayer of octadecylthiol on a gold electrode QCM
showed a shift of about 125 Hz indicating siloxane saturation at a
temperature of approximately 21.degree. C. The signal response was
relatively fast but the absolute change was somewhat low,
reflecting the relatively low capacity of a monolayer of
hydrocarbon chains to accommodate adsorbed siloxane. The
selectivity ratio was quite high with a siloxane/water selectivity
value of approximately 2115. Addition of a thin coating of RTV-615
(a platinum cured polysiloxane rubber) followed by a thermal cure
achieved a selectivity ratio of 3686.
[0124] Exemplary commercially available non-polar polymers that may
be useful for detecting volatile siloxane are listed below.
[0125] GE RTV-615 2-component unfilled silicone RTV
[0126] Polystyrene-polyisoprene-polystyrene block copolymer
[0127] Polybutadiene (5K MW)
[0128] GE SE-33 silicone gum
[0129] Ilfineum Polyisoprene C9925 2.5K MW
[0130] Hycar CS8596 reactive liquid rubber
[0131] Polypropylene co-ethylene
[0132] Trilene 65 (Uniroyal)
[0133] Hycar X-162 BF Goodrich (5.2K MW)
[0134] Hydrogenated polyisoprene (Aldrich)
[0135] Durasyn 180 Amoco Poly-.alpha.-olefin
[0136] Trilene 77 Ethylene/propylene/ethylene norbornene polymer
(Uniroyal)
[0137] Poly (propylene-alt-ethylene) multi-arm star polymer
(Aldrich)
[0138] The RTV-615 polymer was preferred and easiest to use to
prepare a robust cured film. It is recommendable to conduct further
experiments to evaluate possible structural variations on the
silicones, such as the effects of vinyl, phenyl, trifluoropropyl
groups or the effects of molecular weight (viscosity), cross-link
density and film thickness on the selectivity ratio and sensor
response times.
[0139] In additional experiments, another sensor device available
from Allied Electronics was evaluated. This other device exhibited
a generally rougher surface texture on the electrodes. This texture
led to thicker coatings and improved the magnitude of the response
of the device. These devices were cleaned with an appropriate
cleanser, e.g., chloroform, and dried before coatings were applied.
A plot of an exemplary response for the Allied device coated with
RTV-615 polymer is shown in FIG. 24.
[0140] The selectivity ratio for the Allied crystal coated with
RTV-615 was approximately 3750. This value is comparable to the
upper limit achieved with the gold electrode QCM and is also in the
same range as the value obtained with the spectroscopic mid-IR
device which showed a selectivity ratio of 3269. The change in
frequency for the Allied crystal with RTV-615 was about 1100 Hz,
which compares favorably with the response of 125 Hz for the gold
QCM devices.
[0141] The Allied Electronics QCM was mounted in a customized gas
cell comprising a 1/2" Swagelock "T" fitting. An RTV-61 coated
Allied QCM (active QCM) was placed cross-wise relative to the gas
flow and a hermetically sealed package of the same QCM type
(reference QCM) was attached to the exterior of the Swagelock
fitting. Signals from the two crystals were coupled to an HP53131A
frequency counter and the ratio of the two signals was used to
generate a ratiometric signal proportional to siloxane
concentration. This arrangement permits correction for temperature
drift. It will be appreciated, however, that some temperature drift
may go uncorrected if, for example, sample stream flow rates are
sufficiently high that the gas stream is not at thermal equilibrium
within the cell and thus the active QCM would be at a different
temperature relative to the reference crystal.
[0142] The QCM outputs may be processed with a relatively
inexpensive counter/timer or FN converter to provide a signal
(e.g., a DC signal) proportional to the siloxane concentration. In
further experiments, the temperature controlled gas flow cell will
be arranged to hold both a hermetically sealed QCM and an open
package with polymer coating as a sensor/reference pair.
[0143] Strain Gauge Based Devices:
[0144] An exemplary device tested was commercially available from
Hygrometrix Inc. and consisted of a micro-machined silicon chip
including four strain gauges, a thermistor temperature sensor and
signal processing circuitry in a TO-5 package. This sensor used
comprised approximately a 2 mm.times.2 mm sensor chip that combines
a sensing element and Wheatstone Bridge piezoresistor circuit to
deliver a DC output voltage that is linearly proportional to RH
from 0% to 100% FS. The vapor-sensing element may be constructed
from a thin polymer film deposited and bonded to the top surface of
four cantilever beams that are bulk-micromachined from the
surrounding silicon substrate. More specifically, it is
contemplated to coat the resonator beams with a non-polar polymer
film, such as those listed in the context of the discussion of
piezo-based sensors. This should provide a selective siloxane
sensor. This type of sensor has the potential to be a relatively
low-cost sensor due to the self-compensating structure and the
straightforward DC output indicative of vapor concentration.
[0145] While the preferred embodiments of the present invention
have been shown and described herein, it will be obvious that such
embodiments are provided by way of example only. Numerous
variations, changes and substitutions will occur to those of skill
in the art without departing from the invention herein.
Accordingly, it is intended that the invention be limited only by
the spirit and scope of the appended claims.
* * * * *