Note: Descriptions are shown in the official language in which they were submitted.
CA 02342592 2001-04-03
U.S. PATENT
DOCKET NO. 45068.2
HEATED INSULATED CATALYTIC CONVERTER WITH AIR COOLING
to
FIELD OF THE INVENTION
The present invention relates to catalytic converters and in particular, to
insulated
catalytic converters having heating means, temperature control means and heat
storage means.
BACKGROUND TO THE INVENTION
When a cold internal combustion engine with a catalytic converter is started,
the emission
of pollutants is high. as the catalyst within the catalytic converter does not
function at low
2o temperatures. The e:chaust emitted at start up heats the e~chaust manifold
and the e~chaust pipe
before heating the catalytic converter. It takes several minutes for the cold
catalytic converter to
be heated to ''light off' temperature. The "light off' temperature is the
temperature at which the
catalytic converter oxidizes at least fifty percent of hydrocarbons in engine
e~chaust. It has been
reported that 60 to 80 percent of all hydrocarbon emissions occur during the
first few minutes
after engine startup. To reduce the emission of pollutants at startup efforts
have been dir~ctecl-at:--w°------
... - - Try ~ i:..(~~~ '.:Ill. P'=j(~'r:~HTY
1~a aiS ~ ., ,y.T OFt~~:"E
_ t' 1 tem erature u~ in fuel omb 4~ tio. ~~ t~
mamtaimng the catalytic converter at a func iona p 3 g
-preheating the catalytic converter,
_ ~ ~t~e,~a~'~. swe~
-ra idl heatin the catal is converter after startu usin ~ectric~~.~'~.~',,~-
~" x'-~~~u~i..~~
P Y g Yt P g __~_.~ ._':~P~t ,fir ~.~..~_._.._---.
increased fuel air ratio, and
-storing pollutants, in zeolites, until the catalytic converter has reached a
functional
temperature
Efforts have also been made to control catalytic converter temperature during
engine
operation. Aspects of the technology for controlling catalytic converter
temperature during
CA 02342592 2001-04-03
engine operation are related to aspects of maintaining the catalytic converter
at functional
temperatures between engine uses.
1. CATALYTIC CONVERTER INSULATION AND AIR FLOW CONTROL SYSTEMS
1o Benson et al. in U.S. patent number 5,477,676, dated December 26, 1995,
describes a
catalytic converter surrounded by a variable conductance insulation for
maintaining the operating
temperature of the catalytic converter at a optimal temperature. The
insulation "inhibits heat loss
when raising the catalytic converter temperature to light off temperature".
The variable
conductance insulation includes vacuum gas control and metal-to-metal thermal
shunt
mechanisms. This variable insulation is used to reduce the problem of
overheating the catalyst
which can lead to accelerated aging of the catalyst or even permanent damage
to the catalytic
converter. The variable conductance insulation system proposed is conceptually
and
mechanically complex, requiring numerous mechanical components and a complex
manufacturing, assembly and installation. .
Bainbridge in U.S. patent No. x,163,289, dated November 17, 1992, and in U.S.
patent
No. 5,092,122, dated March 3, 1992, discloses a "insulation jacket around the
exhaust pipe which
is composed of fibers that conduct heat better at higher temperatures than at
lower temperatures,
and "allowing the exhaust pipe to reach the light off temperature of the
catalytic converter in a
short time". The function of this refractory fiber insulation is based on
fiber density and on the
thickness of the blanket of fibers. The insulating refractory fibers are con -
in. a~_ double
~(~rJ~;; ~ ..
z _.
walled flexible tube that is slid over a existing exhaust pipe. The walls of
the fle°~~~~>~-~~-a~ '~'~~Y a
f
made of corrugated stainless steel tubes.
~ta~c~~~a~;~
_e_,
;o Ingermann et al. in U.S. patent No. 5,331,810, dated July 26,
~__ .,' ~ _~;,r_c_c~
pipe with a low thermal capacitance inner pipe and a outer heavy gauge pipe.
The thin pipe is ~-
supported in the center of the outer pipe such that an insulating air space
exists between the two
pipes. The outer pipe is not insulated. No effort is made to control air
movements within the
enclosed insulating air space. From this ''the thin walled pipe", "causes the
heat energy in the
2
CA 02342592 2001-04-03
combustion product's to reach the exhaust processor in a short period of time
during the start up
of a cold engine". The problem of overheating of the catalytic converter,
during extended engine
operation, caused by insulating the exhaust pipe is not dealt with.
Rohrbaugh in U.S. patent No. 5,904,042 dated May 18, 1999, discloses "a diesel
exhaust
to system that reduces harmful gases and particulate pollutants", the system
"includes at least one
combination catalytic converter and particulate filter". Rohrbaugh states "the
catalytic converter
is contained in a insulated canister which itself is contained in a shroud,
for containing the heat
generated by catalytic reactions. The insulation also serves to lower the
outside temperature of
the canister". An axial fan blows air between the canister and shroud to
reduce the exterior
temperature of the shroud to a acceptable level. However, air flow is directed
through the canister
and not the catalytic converter. The purpose of the air flow is to cool the
shroud while
maintaining the heat of the catalytic converter.
Kizer and Borroni-Bird in U.S. patent No. 5,987,885 dated Nov. 23, 1999, and
in U.S.
2o patent No. 5,983,628 dated Nov. 16, 1999, describes a fan blown cooling
system for blowing air
around tubes which are part of a combination catalytic converter and heat
exchanger unit. The
heat exchanger "unit includes a plurality of spaced apart tubes" the "tubes
include a substrate on
which is formed a catalyst that reduces or eliminates harmful by products".
The speed of the fan
is controlled variably to adjust the temperature of exhaust emissions in
response to various
output data", "two or more catalysts that have different operating ranges" can
be used. The tubes
may be electrically heated to extend the duration whereby the catalytic
converter is operating
within its efficient conversion window. ~~~ ir~TF:et~~cr~ial_-F~o-~~T
DIS~f wiC T U~FICE
er~~cw~-a~a
Yamada et al. in U.S. patent No. 3,947,44 dated Mar~h 30, 19~~e~c~in
pipe upstream of the catalyst provided with a double wall conduit.
Secondmn~~r~ise~~ntii
RUR~AU ~:'~- t':?STF'-.!CT
passed through the outer conduit and selectively directed into (rhP
~~.!~r~..~1_.~~
atmosphere depending upon temperature conditions in the catalyst bed. The
primary objective of
Yamada and Kitamura is "avoiding over heating and thermal destruction of the
catalyst bed"
while insulating the exhaust pipe upstream of the catalytic converter.
3
CA 02342592 2001-04-03
Yuge et al. in U.S. patent No. 3,910,042 dated Oct. 7, 1975, describe using a
"blower to
be driven so that air is forced into and flows through the second group of
passages", a heat
exchanger within a catalytic converter, to thereby prevent the catalyst from
being melted. Also
disclosed is a heat source such that the air supplied to the bed is heated to
heat the bed to a
l0 temperature at which the catalyst is appropriately activated. A forced air
circulation through a
combined catalytic converter heat exchanger is used to control catalytic
converter temperature.
However, heating of air electrically, then passing the air through the
catalytic converter is
inefficient and results in a loss of energy. More energy is required to heat
the increased mass of
a catalytic converter combined with a heat exchanger. This increased energy
requirement slows
the temperature increase of the catalytic converter at start up leading to
higher emissions. This
comment also applies to the exhaust pipe heat exchanger and the catalytic
converter heat
exchanger described by Kizer et al.
Kinnear et al. in U.S. patent No. 5,155,995 dated October 20, 1992, describes
an
2o electrically energized heater in association with a catalytic converter.
Kinnear et al. also
describes pre-heating which is triggered by a mobile transmitter and a
"functional verification
device". Also described is a catalytic converter which is a unit comprising a
outer casing which
surrounds, but is spaced from, an inner canister. The gap forms a thermal
barrier and can be
filled with a thermal resistant or insulating material such as asbestos or
glass fiber. No solution
is given for the problem of catalytic converter over heating and loss of '
that results when
wr~t_e~cr~a~- f=f,~»C~~r~r
a catalytic converter is insulated °~sT~;'~~r o~~v;
_ . ~~~~rv a~ae~
~~t~J"
Onoda et al. in U.S. patent No. 3,747,346 dated July 24, 1 73 describes a "e
ng
E D P4'l O ,~.' ~,"f:'o ?~
structure disposed about the exhaust pipe upstream of the catalytic co
vertae~?da~d fret~ye
.._ f_nv-;_;.; ~,;~-~~m~
exhaust pipe. This gap functions to prevent heat loss from the exhaust pipe
and which~periil"3'ts---
the air to pass there through to prevent an excessive high temperature of the
exhaust pipe".
Further "the walls of the encasing structure may be insulated with fibers or
foam insulation, if
desired". Also " the encasing structure has an air inlet passage found at its
upstream side and air
outlet passage found at its downstream side". The air inlet and outlet have
"mechanically
4
CA 02342592 2001-04-03
connected", "valves". These valves are controlled by a system receiving
information from a
temperature sensor that " detects the temperature of the catalyst". This air
flow control system
reduces heat losses from the exhaust pipe heating the catalytic converter more
rapidly to a
operating temperature at startup. By allowing increased air flow around the
exhaust pipe during
engine operation the risk of over heating the catalytic converter is reduced.
to
Yamashita et al. in U.S. patent No. 5,845,486 dated December 8, 1998,
discloses an
exhaust damper for opening and closing an exhaust pipe which is disposed
downstream of a
catalyst. The closed exhaust damper keeps the warmth of the catalyst. The
invention described
here has insulated flaps that open in the direction of the exhaust stream.
There are two flaps in
tandem in front of, and behind, the catalytic converter. The space between the
two flaps being a
air insulating space. The flaps are made of either a low thermal conductance
ceramic, or thin
vacuum panels. The flow of exhaust from the engine moves the flaps to a
horizontal position
opening the exhaust pipe. When the engine is turned off the flap mov~~~~a
~_e~rti~alt,~o,si~tipn___ ,
D!; icy UF. r-ICE
where they block air movement in the exhaust pipe. , E ~ ~ ,~ ~ ~ ~ ~ ,
'-° j ~ F? ~ -- ~~~f
2. HEATING OF THE CATALYTIC CONVERTER B~~~EA~ ~ ~,STF3,cr
~a~or~~-rc:at~
~':=i~PF?~ET~ ;ivTL:c.;.~i; T~Jiv1_! 'c
There are many prior art disclosures of electrically heated catalytic
converters. None,
however, adequately deal with the large amount of power needed to heat a
converter to its light
off temperature from ambient temperature and the problem of overheating if the
converter is
insulated. As well, electrical heating can heat catalytic converters too
rapidly which may damage
the catalyst. Rapid heating will cause natural deterioration of the catalyst
over time.
Tandem catalytic converter inventions are also known and usually have a small
catalytic
converter positioned near the engine so that they are heated more rapidly than
the main catalytic
converter, which is positioned well away from the engine to prevent
overheating, as is
conventional practice. Tandem catalytic converter systems protect the main
catalytic converter
from over heating. The small catalytic converter near the engine is subjected
to rapid heating and
temperatures which can result in damage and loss of catalytic converter
function. The strategy of
5
CA 02342592 2001-04-03
tandem catalytic converter proposals appears to~ be to sacrifice the small
catalytic converter at
regular invervals. The servicing costs, and time loss related to the vehicle
being in for service
likely exceed the cost to the consumer of replacing the main catalytic
converter. The degradation
of the small catalytic converter is the general problem associated with tandem
catalytic converter
proposals.
Inventions using side-by-side catalytic converters have a small catalytic
converter next to
a large main catalytic converter. The small catalytic converter receives the
exhaust at engine
start-up and is rapidly heated to a operational temperature. After a initial
period the exhaust is
diverted to the main catalytic converter. Side-by-side catalytic converters do
not reduce
emissions. The main catalytic converter still has to be heated to a operating
temperature by the
passage of exhaust through it. While the small and main catalytic converters
are being heated the
exhaust is not treated and pollution emissions are high. Proposals based on a
side by side
catalytic converter system may reduce the level of pollutants emitted during
the initial period, but
extend cold start emissions over a longer time period. Since two exhaust pipes
need to be heated
2o the emissions of side by side catalytic converter proposals may actually be
higher than if a a
small catalytic converter were not used.
3. FUEL COMBUSTION HEATNG
Mondt in U.S. patent No. 3,911,675 dated Oct. 14, 1975, describes "a converter
heating
system to maintain the catalytic converter at a predetermined temperature so
that it is effective
upon engine start-up to diminish products of combustion. The converter heating
system includes
in combination a small pump which draws a air fuel mixture from the fuel tank,
a igniter and a
pilot burner". Mondt states "the present invention provides continuous heating
means which
3o maintain the catalytic bed temperature" and "includes a pilot burner for
heating". The invention
of Mondt has a "housing formed preferably of a high chromium stainless steel",
no mention is
made of the use of insulation to reduce heating requirements. Fuel burning
systems require many
parts which can break down, and safety concerns exist regarding having a
c~t~~r6~ ~~ ,~ Y
~~~.~~~,s-r~~
~1~~ 3 ~- ~~~r~
~ r~ n,~ ~ r~ r;.~ r~a '
6 euR~,a~: ~,(- ~~;~;T~~cr
a--tilPa;fE7t~,i~'::.°' ~~.t.E-!.''':IF~L~ s
CA 02342592 2001-04-03
operating without supervision. A fuel burning system cannot operate when a
vehicle is parked
within an enclosed area, a problem not addressed by Mondt.
SUMMARY OF THE INVENTION
to This invention concerns heating a catalytic converter (CC) and,
alternatively, an exhaust
pipe (EP) of a internal combustion engine between uses using electricity, or
fuel combustion. To
reduce heating requirements the CC and the EP are enclosed in a insulated
vessel. To prevent the
CC from overheating during extended periods of engine use, the insulated
vessel has ports which
may be opened to allow air to enter the insulated vessel and circulate around
the CC and EP.
Electrical power for heating the CC and EP may be obtained from photovoltaic
cells
(PV), from the engine starter battery, from an additional battery, or from a
alternating current
(AC) source.
L11" t~-h: T p~~=~r~F
2o A phase change material (PCM) within the insulated vesse may be p~~~r~~tore
thermal energy thereby reducing heating requirements between engine uses. ~~t~
~ - ZQ~~
~on~ca~-rw~
~, ~us,E,~il nE_ ca~s;tncr
A catalytic converter thermal control system (CCTCS), and tie
eYh"~~~iusipi~!'e~~~il~'~..__.,a
control system (EPTCS), or a system which combines both control functions,
monitors the CC
and EP temperature and activates the electrical or combustion heating system,
opens and closes
the ports of the insulated vessel, and activates fans on the ports depending
on the temperature of
the CC or the EP. The control systems may have a timer function that can be
set by the driver to
heat the CC or EP prior to a expected use of the vehicle. The systems may also
have a recording
system that can be used to monitor the drivers use of the vehicle and its
emissions of pollutants.
The timer function can be used without a insulating vessel to heat the CC to a
functional
temperature just prior to a use of the vehicle. When the engine is started the
CCTCS quickly
heats the CC to optimal functional temperature.
7
CA 02342592 2001-04-03
g The CCTCS and the EPTCS may start the engine when the charge on the
batteries is low.
The insulated vessel described maintains the CC at a high temperature thus
increasing the
effectiveness of emission reduction systems that rapidly heat the catalytic
converter at start up.
The insulated vessel also increases the effectiveness of emission reduction
systems that store
1o pollutants until the CC reaches a functional temperature, such as zeolites.
The heating of the catalytic converter while it is within a insulated vessel
eliminates
catalytic converter overheating associated with rapid start up heating using
electricity or fuel.
The ability to open the insulated vessel and allow the free passage of air
over the catalytic
15 converter and exhaust pipe eliminates the problem of overheating of the
catalytic converter
during extended operation of the engine.
This invention maintains the catalytic converter at an elevated temperature
when the
engine is not operating. The insulated vessel may use vacuum insulation or
conventional
2o insulating materials such as glass wool, ceramics or aerogel. The
insulating vessel has ports that
are opened when the catalytic converter is at or above optimal operating
temperature. When the
ports are opened air can flow through the insulated vessel and around the
catalytic converter
preventing the catalytic converter from over heating during extended periods
of engine operation.
With the ports closed the catalytic converter's operating temperature is
maintained by electrical
25 heating or fuel combustion. Electrical power requirements for heating are
reduced by enclosing
the catalytic converter in an insulated vessel with controlled air flow. Phase
change materials
which store and release heat may also used to reduce electrical heatin
z~I~~.:v--------- ---.-.--.~
~t~~. i :.W - F~s?:; ::~;,:._f
a~S~:;~c; r r_~;-'=~:::;~
~~~~~r~°~ ~~t
BRIEF DESCRIPTION OF THE FIGURES
30 ~c~r~ac~ra~~::~e~
BaJRE;='.tJ j'rF_- i ~Tt-?';~T
Embodiments of the invention may be described with referen a tot~li~-
~g~;__'~~~
FIGURE 1 Horizontal cross section of the insulating vessel and catalytic
converter
FIGURE 2 Vertical cross section of the insulating vessel and catalytic
converter
8
CA 02342592 2001-04-03
FIGURE 3 Frontal view of the insulating vessel
FIGURE 4 Insulating material configurations
FIGURE 5 Cross section of insulating vessel and catalytic converter
FIGURE 6 Side view of the insulating vessel showing open port flaps
FIGURE 7 Side view of the insulating vessel showing closed port flaps
to FIGURE 8 Side view of insulating vessel showing fan and air scoop
FIGURE 9 Cross section of valves on the exhaust pipe showing open and closed
positions of
flaps
FIGURE 10 Diagram of temperature control of the CCTCS
FIGURE11 Cross sectional view of the insulating vessel showing various
locations of the
PCM containers
FIGURE 12 Schematic diagram of a fuel heating system that passes combustion
products into
the exhaust pipe.
FIGURE 13 Schematic diagram of a fuel heating system that passes combustion
products into
the insulated vessel, showing partially open port flaps.
2o FIGURE 14 Schematic cross sectional view of a exhaust pipe temperature
control system
FIGURE 15 Cross section of the insulating pipe and exhaust pipe.
DESCRIPTION OF THE INVENTION
The catalytic converter (2) may be of well known conventional construction
such as the
two-way converter (oxidization), or the three-way converter (oxidization and
reduction) type. A
three-way catalytic converter has air pumped into the catalytic converter.
This airflow into the
three-way catalytic converter reduces the emission of oxides of nitrogen
(NOX). The catalyst
(4), may be in pellet form, monolith form, or honey comb form..-_The...wall
.o~.tl~~...catalytic.=__
INTO L? l:-~, s~"-'Zi_ 'r ~ ~.:~'Y
.converter (6) directs the flow of exhaust through the catalyst. An xhaust p~
~~~~~-~if~ke~ts to
the front and rear of the catalytic converter.
APs~ ~ -~ ~5 ~~
~ ~ tar ~:= s.: _:~ ,:. ~,'
Surrounding the catalytic converter is a insulating vessel ( 0).
~,'.~~~Z~~~',;Y~'g;,~:~~~e~~_'y"~,
wall can be made several ways. The insulating vessel wall can be made using
two sheets of
9
CA 02342592 2001-04-03
metal (9) with insulating materials (12) sandwiched therebetween. Insulating
materials are well
known in the art and include refractory beads, refractory oxide fibers,
refractory ceramic blocks,
or refractory aerogel. Refractory fiber blankets can be used to insulate the
catalytic converter.
Refractory fiber blankets may be 40% silica, 40% to 60% alumina, with the
remainder being
other oxides. Cerawool Blanket provides service to temperatures of 750 C (1600
F), Cerablanket
to provides service to 1100 C (2400 F), and Cerachem and Cerachrome Blankets
provide service to
1200 C (2600 F). The insulating vessels wall can be made of vacuum panels
formed from two
sheets of metal (9), with a vacuum (11), between the two metal sheets. Vacuum
panels usually
have a powder, microspheres, or a internal supporting framework that prevents
atmospheric
pressure from collapsing the vacuum panel. Layers of reflective materials
reduce radiative heat
transfer through evacuated spaces. The insulating vessel wall can be a single
sheet of metal (9),
with insulating ceramic materials (15), fixed to the inside.
Vacuum insulating panels ( 11 ), may be thin while providing a high thermal
resistance
barner and are therefore preferred. In situations where there is limited
clearance between the
2o bottom of the vehicle and the ground, the thinnest insulating vessel
possible is desirable. A heat
shield (16) may be provided between the catalytic converter (2), and the auto
body (14).
Figure 2 shows an insulating vessel (10), using vacuum pan s-fl-'~~~ -
to.forxxi tie top and~"~
I~~~i ' ~.~. ~ .=,i i ; ii~rv
bottom of the insulating vessel, the sides of the insulating vessel a
insulat~~~~,~if~~t~tory
ceramic bricks or foamed aerogel ( 19).
n~~
~~~ 3 '
2~,~
~ ~ r~ L..~ ~.3 ~- ~ ~~
On the front and back of the insulated vessel ( 10), are air ow ~ ~
,',;~;~il,~i ~i6~t is
_.._.....r. _..._~....~._....__._,_~
blocked with a screen (7) that prevent particles from entering the insulated
vessel. These screens
do not unduly restrict airflow and are removable for cleaning the interior of
the insulating vessel.
3o Attached to the ports (18), are movable insulated flaps (21). When the
engine is not running the
flaps cover the ports (18), of the insulating vessel (10). With the insulated
flaps (21), covering
the ports (18), thermal energy is held within the insulating vessel,
minimizing heat loss. When
the catalytic converter is at optimal operating temperature and the engine is
running, the flaps
(21) move away from the insulating vessel (10), opening the ports (18). With
the ports open, air
CA 02342592 2001-04-03
can move through the insulated vessel (10), and around the catalytic converter
(2), cooling the
catalytic converter. When the vehicle is moving, air is rammed into the
forward facing ports
(20), increasing cooling of the catalytic converter. The flaps (21), may be
joined by a linkage
(23), so that all ports can all be opened and closed by one electric motor
(24). The electric motor
is controlled by the catalytic converter temperature control system (CCTCS).
Many other flap,
gate or door systems can be devised to open and close the ports on the
insulating vessel
providing control of air flow through the insulating vessel.
Fans (22), located on the insulating vessel may be provided and activated to
force air
through the insulating vessel (10), providing additional cooling of the
catalytic converter. This
forced air circulation generated by the fans is important when the engine is
running but the
vehicle is not moving, and the temperature of the catalytic converter
approaches a maximum
temperature. These fans may be a variable speed type that is controlled as a
function of
temperature. These variable speed fans allow greater control of catalytic
converter temperature
during various engine operating conditions. The fans are controlled by t
~C'TCS. .
iy~.Lt~ y-;' . _._ _
."\!_ ;,, : F. ~ ~ f
C)1L;-i;-,~~:T ~j~,~y~~';r
..
C~ ~~sw; rii ~ ~.'~ f~°_
The insulated flaps (24) are located over the insulting vessel pods (18); A~~
uct (20), can
..
be connected to the front of the insulating vessel ( 10). This duct c be
mdene~ fo ct~.'' a~ a ;
ra nn. : ~ ~,.; r ,,<s ~~a
scoop that rams air into the insulating vessel when the vehicle is movi
g.~~;"p~' t~ ~o~,',(~~~ j
4.;. ~ (''''l ~~t C '
dirt and debris into the insulated vessel the duct (?0), is elongated to move
the opening-of~'the ~ ~-
duct under the hood of the vehicle. The fans (22), are located in the opening
of the duct (20),
removable screens or filters (7), are located in front of the fans. The fans
are located outside the
insulated enclosure and away from other hot vehicle components that could
damage the fans.
The catalytic converter wall may be finned (26), externally and/or internally,
to increase
thermal energy transfer. The catalytic converter may be fabricated with air
channels, or heat
exchange tubes (29), passing through the catalytic converter wall and
contained catalyst. These
channels or tubes increase heat transfer from catalyst to air flowing through
the insulated vessel.
Catalyst can be applied directly to the exterior of the tubes (29). All air
entering the insulated
vessel can be passed through the tubes going through the catalytic converter.
The controlled
CA 02342592 2001-04-03
movement of air through the insulating vessel and the tubes going through the
catalytic converter
provides control of catalyst temperature under various engine operating
conditions. The CCTCS
monitors the catalytic converter temperature, and opens and closes the ports,
and operates the
fans, to (a) control catalytic converter temperature during operation, and (b)
maintain the
catalytic converter at a functional temperature between uses.
Valves (25) may be provided in the exhaust pipe in front of, and behind, the
catalytic
converter (2). These valves prevent connective heat flows within the exhaust
pipe when the
engine is not operating. The movement of air in the exhaust pipe can remove
thermal energy
from the catalytic converter and the insulating vessel. These valves are
weighted hinged flaps
that are pulled by gravity to a vertical position (27). In this vertical
position the flaps block air
movement through the exhaust pipe. When the engine is running the exhaust flow
moves the
flaps to a horizontal position (29). When the engine is turned off, the
exhaust flow stops, and the
flaps return to a vertical position. The return of the flaps to a vertical
position can be assisted by
springs, or by increasing the weight of the insulated flaps. To reduce thermal
energy transfer
2o through the valves (25), two valve flaps are placed on the exhaust pipe in
front of and behind,
the catalytic converter (2). The air space between the two flaps acts as a
insulating dead air
space. To reduce thermal energy transfer the flaps may be made of thin vacuum
panels or
ceramic plates.
~5 Within the insulated vessel (10), or catalytic converter (2), are
electrical heating elements
28 . The electrical heatin elements ma be owered b electric ~ from ~a f J' s
se'iv~_i~
( ) g Y P Y tY
__. s ,-,, ,,~ , .y ~;~.i
battery (30), electricity stored in a additional battery (32), electricity om
photovoltaic cells (34),
~v6~V'~ '~ Gi
or electricity from a AC electrical power source(36).
t~~a,c:::;a.r.,,,.~.r
BUREA;J ~;a L~i;;f-?ICT
r'. :'')Pr;[[Ty i~~-!~r;.' -'~;rJLL.!_.~t
3o Rapid electrical heating of the catalytic converter at engine start up h s
beee p p'~'ttr' "w~
other patents. The high energy output associated with rapid electrical heating
of the catalytic
converter can overheat and permanently damage the catalytic converter. These
rapid electrical
heating systems can be used to provide a continual heating of the catalytic
converter inside the
insulating vessel proposed here. The CCTCS maintains the catalytic converters
temperature
12
CA 02342592 2001-04-03
between uses by decreasing the power supplied to the heating elements of the
rapid electrical
heating system. At start up the CCTCS provides a higher power output to
rapidly heat the
catalytic converter to optimal operating temperature from a functional but
lower temperature.
The possibility of damaging the catalytic converter by rapid heating at start
up is reduced due to
the small amount of energy required to raise the catalytic converter from a
functional temperature
1o to optimal functioning temperature. Rapid electrical heating systems
proposed in other patents
combine the heating element and the catalyst into one element to heat the
catalyst by conduction.
Similar combined heating element and catalyst systems can be used to maintain
the temperature
of a catalytic converter in a insulating vessel, between vehicle uses.
Photovoltaic cells (34), on the vehicle provide electrical power to electrical
heating
elements that heat the catalytic converter. Photovoltaic cells convert light
to electricity.
Photovoltaic cells can provide electrical power to heat the catalytic
converter only during
daylight hours when they are e:cposed to sunlight. Power from the photovoltaic
cells can also be
used to charge the engines starter battery, or a additional battery carried by
the vehicle. The
power supplied by photovoltaic cells depends on the availability of sunlight.
A vehicles used'in
northern areas would have limited photovoltaic power produced during the
winter. Vehicles
parked inside would obtain limited heating of the catalytic converter from
photovoltaic cells.
The photovoltaic cells can be placed on multiple surfaces of the vehicle in
multiple orientations,
in this manner some photovoltaic cells will be exposed to direct sunlight when
the vehicle is
outside on a sunny day. If the driver knows the vehicle will be parked a
particular direction
during the day then PV cells are placed on the side of the vehicle exposed to
the sun. PV cells
placed horizontally on the roof of the car will produce the most power at
noon. PV cells placed
vertically, or standing up, on the roof of the car are placed in a front
to".back orientation to reduce
drag when the vehicle is in motion. Vertically placed PV cells wo 1d
prodE=~~',y'~er
r= r': aa~~ ~~. >~~ i >~ Pa
3o early and late in the day.
~:~'~ ;~ °- i,."'1~
~D~,::s_~~rv ;r.~~
PV cells can be used to effectively heat the catalytic convene if the
dated<<vessel;ltras a
~.~~r,p~:.,;E~-_ .. . ...,..~!~~:'.t.~
high thermal resistance, and therefore little heating or electrical power is
required to mainfain the ~~-~°~-~
catalytic converter at a functional temperature.
13
CA 02342592 2001-04-03
A additional battery carried by the vehicle can provide electricity to heat
the catalytic
converter. With a additional battery the engines starter battery is used to
heat the catalytic
converter when the additional battery has been substantially discharged. When
the engines starter
battery is used to heat the catalytic converter, the starter batteries charge
is monitored, to insure
the starter battery maintains sufficient charge to start the engine when
required. The charge of
the additional battery is monitored to reduce deep discharge events which may
reduce the life
span of the battery.
In one embodiment, the catalytic converter can be heated by plugging the
vehicle into a
alternating current (AC) power source. A AC heating element can be placed
within the insulated
vessel, or catalytic converter, or the AC power can be transformed to direct
current (DC), to
provide power to DC heating elements within the insulated vessel, or catalytic
converter. Using
AC heating elements would require that DC heating elements also be carried in
the insulated
vessel, or catalytic converter, for use when the no AC power source was
available. Transforming
the AC power to DC, and using DC heating elements to heat the insulated
vessel, or catalytic
converter, would eliminate the need for AC heating elements. The CCTCS
controls the power
supplied to the heating elements. The AC power supply can also be used to
maintain the
electrical charge of the vehicles starter battery, or a additional battery, or
to power a engine block
heater, or vehicle interior heater, or a battery heater.
In one embodiment, the insulating vessel ( 10), may be provided with
containers of a
phase change material (26). The phase change material (PCM) changes from a
solid to liquid at
a temperature below the optimal operating temperature of the catalytic
converter, but above the
minimum desired functional temperature of the catalytic converter. When a
phase change
material changes from a liquid to a solid thermal energy is released. This
thermal energy release
maintains the catalytic converter at a high temperature well after the engine
has been turned off.
The energy released by the phase change material reduces the energy required
to heat the
catalytic converter between engine uses. The phase change materi stor~e~r~anal
;~ne,~gy .,_~nw
Gt::v , , E
L~~ ~~
14 ~e~~r:c~~'Y:...,f9
E~Jf=tE.~,tt C~E: ,;~s,"FE~'~
~;''Ft!~T~ !~'~:'.: ~.~,=_r::.,'fj;~t-,1_E:.
CA 02342592 2001-04-03
the engine is running and releases the thermal energy when the engine is not
running. The PCM
should not be flammable, toxic or expensive, and should have a high latent
heat of fusion.
The phase change material (PCM) changes from a solid to a liquid phase at a
temperature
below the temperature at which the catalytic converter operates at optimal
efficiency. The
to temperature selected for the melting point of the phase change material is
a temperature at which
the catalytic converter has a high level of functional efficiency, but not
optimal efficiency. When
the temperature of the catalytic converter has dropped below the PCM melting
point electrical
heating is activated. Electrical heating maintains the catalytic converter at
a temperature at
which the catalytic converter has a high level of functional efficiency, but
not optimal efficiency.
The lower the temperature that the PCM melts at, and the lower the temperature
maintained by
electrical heating, the less energy is required to heat the catalytic
converter between engine uses.
With the catalytic converter at a high functional efficiency little pollutants
are produced before
the catalytic converter reaches optimal efficiency. This is due to the
catalytic converter being at
a functional temperature at start up. When the catalyst is at a functional
temperature, it breaks
2o down hydrocarbons, generating heat that increases the catalytic converters
temperature.
A.
Suitable phase change materials may include metals, metal alloys, etal
~X~rh~~i~.t~~,ar a
hydride of trimethylol ethane or other polyhydric alcohols. '~~"s ~-'4 ~~ ~ a
i
f
The phase change material (PCM) container (26), can be plac d wit
~~~~~n~u~~ted
~~!-'' ;t;'
,i
vessel (10), in several locations. The PCM container can be located on
t'h~"~cat~ie ~at~l~tm;.-_;_~_- V. I
converter (40), with a air space between the PCM container and the insulating
vessel (10). The
PCM container can be on the wall of the insulated vessel (42), with a air
space between the
catalytic converter (2), and the PCM container (42). The PCM container (44),
can be on the
3o exhaust pipe (8), behind the catalytic converter (2), in a elongated
insulating vessel (10). The
PCM container (46), can be in front of the catalytic converter (2), in a
elongated insulated vessel
(10). The phase change material containers (47), can be located within the
catalytic converter.
1~
CA 02342592 2001-04-03
PCM containers that are positioned away from the exhaust pipe, or the
catalytic
converter, and on the interior wall of the insulated vessel, are cooled by air
flowing through the
insulated vessel. The PCM containers positioned in this manner are not heated
to high
temperatures. When the PCM containers are positioned against the exhaust pipe,
or catalytic
converter they are heated to higher temperatures. The surfaces of PCM
containers that are
1o exposed to air flowing through the insulated vessel, may be insulated to
reduce heat loss and
increase their temperature.
In one embodiment, the electrical heating of the catalytic converter may be
controlled by
the catalytic converter temperature control system (CCTCS). The CCTCS monitors
the
temperature of temperature sensors (38), within the catalytic converter (2),
and/or insulating
vessel (10). If the temperature falls below a minimum temperature the heating
systems are
activated. The CCTCS opens the ports on the insulating vessel when the engine
is running and
the catalytic converter is at optimal operating temperature. The CCTCS closes
the ports on the
insulating vessel when the engine is turned off. The CCTCS closes the ports
when the engine is
2o running and the catalytic converters temperature is below a desired
temperature. When the
optimal operating temperature of the catalytic converter is exceeded, the
CCTCS turns on fans
(~''), to provide additional cooling of the catalytic converter. The CCTCS
informs the driver
when the catalytic converter is near a temperature that could damage the
catalytic converter. The
driver can then alter the use of the vehicle to reduce the temperature of the
catalytic converter.
?5 The CCTCS may maintain a record of any incident that could ha rest #~
d~rna~e- to. the ~.y
dr~-r7~'- t ~, r_i ~~-Y.__
catalytic converter. a ~° f~" 4r s'~f x~~; ;.,~
The CCTCS has a timer function that can be set by th driver t~ da~ the;
.catalytic
EiiF~~61!.l y. r:h/
converter to operating temperature just prior to a expected use ' ~~~'I~., t
T~~;'y~l,~t~d
3o vessel, or catalytic converter is not heated, until just prior to the
expected use of the vehicle. The
timer function may reduce the energy required to heat the catalytic converter
between engine
uses.
16
CA 02342592 2001-04-03
The CCTCS timer function can be used by catalytic converter electrical heating
systems
not having a insulated vessel. A catalytic converter electrical heating system
operated over a
several minute period at a low power level heats the catalytic converter to a
functional
temperature. This long low power heating phase allows conduction and
convection within the
catalytic converter, heating the catalyst evenly. The low power heating phase
is followed by a
1o high power heating phase after the engine is started. The high power phase
heats the catalytic
converter from a functional temperature to optimal temperature. With the
catalytic converter
heated to a functional temperature less energy and time is required to heat
the catalytic converter
to optimal functional temperature. The reduction in the high energy input to
the catalytic
converter at start up reduces the possibility of the damaging the catalytic
convener.
The driver can turn off the CCTCS if the vehicle will not be used for a
extended period.
When the driver wishes to use the vehicle the driver can activate the CCTCS to
heat the catalytic
converter to a functional or operation temperature over a short period of time
prior to the vehicle
being started. The driver can choose to wait before for the catalytic
converter to reach a
2o functional temperature before starting the engine. This allows the driver
to have control over
minimizing engine emissions.
The CCTCS may have a monitoring and recording function that informs the
driver,
mechanic, automobile manufacturer, or governmental body regarding how the
CCTCS system is
being used by the driver. If the driver is not using the CCTCS system to
reduce emissions of
pollutants at vehicle start up, the driver can alter their usage of the
vehicle.
If the photovoltaic cells are providing power and the batteries are fully
charged, the
catalytic converter is heated, even if the timer, as set by the driver,
indicates that the vehicle is
3o not going to be used. If the driver decides to use the vehicle earlier than
initially thought, the
catalytic converter is at operating temperature.
~..re : I r
~: ~-,",~ ;. ~_y .4 i~ 1,,~
~,~ r _ x~3$
~~~ 'a 1 SN
E i~ ~vs r ' .'~'. ~ ;~~!
amen,t.~ ;~$.: :;:;:~;~=::Yr
F; "~~~ftlET~- ~~dT'~'~ t r.~ ~fl,k~:.~.a-:
A.a..~,.~.~._.......W..._.~.."".
17
CA 02342592 2001-04-03
If photovoltaic cells are producing power and the vehicle batteries are fully
charged, the
power from the photovoltaic cells is used to heat the catalytic converter to a
maximum
temperature.
Power from photovoltaic cells can be used to heat the catalytic converter to
temperatures
1 o above optimal operating temperature. The thermal energy stored by slightly
overheating the
catalytic converter, is used to maintain the catalytic converter at a
functional operating
temperature when the photovoltaic cells are not producing power. The melting
of the phase
change material serves to store energy from the photovoltaic cells.
Some of the catalysts used to break down nitrogen oxides function at high
temperatures
and only in a narrow temperature range. In these cases the temperature that
the insulated vessel
is maintained at may be below the functional temperature of the catalyst. The
higher temperature
of the catalyst at start up still reduces the time required for the catalyst
to reach functional and
optimal performance temperatures. Maintaining the catalytic converter at a
lower temperature
than the catalyst functions at reduces the amount of energy required to
maintain the catalytic
converter's temperature.
If the CCTCS is plugged into a alternating current (AC) power supply the
engines
catalytic converter can be maintained at a optimal temperature for start up.
With the CCTCS
timer function the catalytic converter can be allowed to cool
between~us~~~~~r~~l~ the catalytic .._~._
t f ~ r~-~=,~
converter heated to a optimal functional temperature just prior to the dri rs
use otr'~f~~,~~=t~
'i cJ
With the CCTCS timer function the catalytic converter can a maint~i~ec~~..at,
a;,Flow
temperature during one time interval, when vehicle use is very unlikel
er~y'ti~i~GOt~v'ert~ , _
_._
_ ..._ . ... . ~~_.__....~
3o is then heated to the optimal functional temperature just prior to a
expected vehicle use. The
ability to maintain varied temperatures during time intervals before a
expected vehicle use
reduces the energy required to maintain the catalytic converters temperature,
while providing a
catalytic converter at functional temperature if the driver decided to use the
vehicle earlier than
expected.
18
CA 02342592 2001-04-03
The catalytic converter can be heated according to a recorded vehicle use
pattern by a
recording and memory system. For example, if the driver goes to work at 8 am
from Monday to
Friday the recording system could note this pattern, and heat the catalytic
converter for a vehicle
use at 8 am from Monday to Friday. If the vehicle is never used between 11:30
pm and 7:00 am
1o the catalytic converter is allowed to cool during this time period to
reduce energy use.
Alternatively, the driver can program a pattern of vehicle use into the CCTCS,
in a manner
similar to the timer function of a video cassette recording system.
The CCTCS can electrically heat the catalytic converter when the engine is
operating
should the temperature of the catalytic converter fall below optimal
functioning temperatures.
The CCTCS can move the insulating flaps to close the ports on the insulating
vessel and increase
the catalytic converters temperature during engine operation. Maintaining the
catalytic converter
temperature during engine operation is important when engines have a mode of
operation which
does not use all engine cylinders. However, in most cases the exhaust s am
~i~i.~t;e~~'me ~s . . .~
a. r ~;-,.r,,,"~_,;-:rw _
2o hot enough to maintain the catalytic converter at optimal operating tempe
ature. ~ ~' ~r~' ~' ~ r-r~~,
,~~n ..
<8%U
Enclosing the catalytic converter in a insulating vessel and mai
tainin~,Ji~,l1'~al
r.,,:.~ Ff'~1~T.-~ ~ .:;c;5,~, I
temperature enhances the performance of systems that rapidly heat the
cataTy~~c-ce~uei~~f:!at_, , i
up. Systems that increase the fuel air ratio during start up provide enhanced
performance when ..
the catalytic converter is maintained at a functional temperature. Less fuel
is required to heat the
catalytic converter to optimal operating temperature from a functional
temperature, and the
possibility of over heating the catalytic converter is reduced. Systems that
use electrical heating
elements to rapidly heat the catalytic converter at start up provide enhanced
performance when
the catalytic converter is maintained at a functional temperature. Systems
that store pollutants,
3o such as a zeolite system, have to store less pollutant after start up,
before a catalytic converter
maintained at a functional temperature reaches optimal functional temperature.
The present invention may be adapted to existing vehicles with little
modification to the
existing exhaust system. The vehicles catalytic converter can be removed from
the exhaust pipe
19
CA 02342592 2001-04-03
and temperature sensors, PCM containers, and electrical heating elements
attached to the
catalytic converter. The assembly is placed into a insulated vessel. The
exhaust pipe is
connected to the front and back of the insulated vessel and the insulated
vessel is attached to the
automobile.
1 o As an alternative to electrical heating elements, a fuel burner can be
used to put hot
combustion gases directly into the exhaust pipe, catalytic converter, or
insulated vessel. If the
catalytic converter is in a insulated vessel the amount of fuel required to
maintain the catalytic
converter at a functional temperature is reduced.
Fuel burning systems have a pump (50), that pumps air into a burner (52). The
burner
has a ignition plug (54), that ignites the fuel (56), that is pumped (58),
into the burner (52). A
catalyst may be located within the burner to assist combustion. The burner can
be outside or
inside the insulated vessel. The combustion products can enter the insulating
vessel, catalytic
converter, or exhaust pipe. If the burner is located inside the insulated
vessel, or the combustion
2o products from a burner outside the insulated vessel enter the insulated
vessel, the ports on the
insulating vessel are partially opened to allow the combustion products from
the burner to enter
and leave the insulating vessel. If the hot combustion products (60), enter
the exhaust pipe (8),
they pass through the catalytic converter (2), before leaving the exha ~st
pi~~'~n~'t~h,~~.(i,'rr,~-~----w
': E
vessel (10), surrounding the catalytic converter less fuel is burned to eep
the ::a~~ty~i"c ~~~rter
at a functional temperature.
ni)f~i~~"5 t r,'
P' 7f' t(~l . ~ r ~;F;(CT c
Fuel combustion is used to heat the catalytic converter when e'Iectfrcal_
'p~~~x. ~-t~bt_ _~, i
available. The CCTCS operates the fuel burning and electrical heating systems.
The fuel
burning system is a option for drivers that can not plug their vehicle into a
power outlet. A fuel
3o burning system would have to be deactivated when the vehicle was parked in
a enclosed area.
Automatic detection systems on the vehicle could detect the ceiling when a
vehicle is parked
inside. These detection systems could use ultrasound, radar or laser beams to
detect the ceiling
directly above the vehicle. The CCTCS would inform the driver the fuel heating
system would
be deactivated, the driver can over ride the deactivation system if the
vehicle is parked in a
CA 02342592 2001-04-03
covered but not enclosed area. The driver can manually switch off the fuel
burning system when
the vehicle is parked inside.
The use of a fuel burning systems to heat the catalytic converter would be
limited to
situations where sufficient electrical power could not be stored by vehicle
batteries, and the
to vehicle could not be plugged into a AC power source. The fuel burning
system would be
considered rarely due to the emission of combustion products, and the
additional mechanical
components required to accomplish heating of the catalytic converter by
burning fuel rather than
using electricity.
The engine itself can be used as a fuel burning system. In this concept the
CCTCS
detects that the catalytic converter is at the minimum temperature desired,
that the PCM has
solidified, and that the batteries charge is low. The CCTCS then starts the
engine to reheat the
catalytic converter, melt the PCM and charge the batteries. The engine
starting system is
switched off by manual, or automatic, systems when the vehicle is parked
inside. When the
2o engine is started by the CCTCS the engine emits little pollutant as the
catalytic converter is at'a
functional temperature. Cold engine starting systems, that start the engine
when the engine, or
engine coolant, drops below a certain temperature are common in cold climate
areas. In this
concept, the CCTCS starts the engine to maintain the catalytic converter at or
close to a
functional temperature. The insulated vessel surrounding the catalytic
converter reduces heat
losses from the catalytic converter, reducing the frequency that the CCTCS
starts the engine.
This cold catalytic converter starting system, operated by the CCTCS when the
vehicle is parked
outside, combined with plugging the CCTCS into a AC power outlet when
the,vehicle, is parked
ln~J.:~J_' ; , -,'r . . Y '.--
inside would reduce engine emissions considerably. The CCTCS syst m can
y,~der:,~ 't'
c:~ ~a <.v :~ v w;: ~~c
radio transmission system. The driver activates a radio transmission th t
starts the vehicle engine
~~.~ s
to warm the engine for a expected vehicle use.
in
~: ~ r -: . .y r
~~iFSJr.r~s t ~'
g t .. ~~ r
The principles described above for controlling the temperatureY of the
catalytic conv~'t~r-s=~°--w--i
can be applied to the exhaust pipe (80), between the engines exhaust manifold
(82), and the
catalytic converter (2). These principles for controlling the temperature of
the catalytic converter
21
CA 02342592 2001-04-03
being a insulated vessel, with air flow ports that can be opened and closed,
fans to move air
through the insulated vessel, phase change materials to store energy,
electrical heating elements,
or fuel heating systems, to heat the catalytic converter, and a temperature
control system.
Maintaining the exhaust pipe at a high temperature means that exhaust gases
leaving the engine
(82) at start up, do not heat the exhaust pipe, and that hot exhaust gases
arrive at the catalytic
1o converter.
When the engine is started the exhaust gases leaving the engine are at a low
temperature,
and the exhaust pipe is at ambient temperature. The low temperature exhaust
gases leaving the
engine are further cooled as they heat the exhaust pipe. If the exhaust pipe
is hot when the
engine is started the exhaust gases reach the catalytic converter at a much
higher temperature. It
is possible for a catalytic converter maintained at a functional temperature
within a insulated
vessel, to be cooled below a functional temperature, at start up, by cold
exhaust. The cooling of
the catalytic converter to a temperature lower than that at which the catalyst
functions leads to
the emission of higher levels of pollutants.
2o
Therefore, in an alternative embodiment, a double walled insulated pipe (84)
surrounds
the exhaust pipe (80). The wall of the insulating pipe (84) can be made using
refractory ceramic
blocks, refractory ceramic beads, refractory insulating fiber blankets, vacuum
insulating panels,
or a combination of these insulating materials. To create a flexible
insulating pipe (84), the walls
of the insulated pipe are formed from corrugated stainless steel tubes and
refractory insulating
fiber blankets, or refractory ceramic beads are used for insulation. Sections
of the insulating pipe
canlbe rigid while other sections are flexible. A flexible insulated pipe can
_be slid over a existing . _ _-_
11V1~,'-
exhaust pipe. Between the exhaust pipe (80), and the insulating pip ~ (84), is
~..mr~space (-$~~.
c ~.: .. :. . , ,~
The insulating pipe is held in position around the exhaust pipe by supp rts.
r .: ~~~;
A°tr a ° c:~:J9
F_- L3 N "" ' ( ~
At the top and bottom of the insulated pipe (84), are insul ted
~s~~T~,4''J_'tl~ y~'~ ,'i
....r._.......T__...~_.__..._..__ _...w__._.w.__.__._~
clamped onto the exhaust pipe (80), so that a air tight seal is formed. These
collars (90), have a
air channel (91), within them that is continuous with the air space (88),
around the exhaust pipe.
On the collars (90), are ports (94), that can be covered or uncovered by
movable insulating flaps
22
CA 02342592 2001-04-03
(96). These insulating flaps are opened and closed by electrical motors (98),
and associated
mechanical linkages (100). The insulating flaps are closed when the engine is
not running
containing thermal energy within the insulated pipe (84). The insulating flaps
open when the
exhaust pipe is at a desired temperature and the engine is running. The
insulated flaps on the
collars open forward so that they functions as air scoops ( 1 O 1 ). This air
scoop effect rams air
to into the insulating pipe (84), when the vehicle is moving. Removable
screens or filters (99),
prevent dirt and debris from entering the insulating pipe (84). A fan (102),
located in the port
(94), or duct leading to the port, increases air flow through the insulating
pipe when the exhaust
pipe exceeds a desired temperature. The ability to cool the exhaust pipe
prevents very hot
exhaust gases from overheating the catalytic converter. The fans are located
outside the insulated
pipe, where they are protected from high temperatures.
Valves (103), in the exhaust pipe, similar to those used by the catalytic
converter heating
system, are located in the collars (90). These valves prevent air movements in
the exhaust pipe,
reducing convective heat transfer, and heat losses through the exhaust pipe
(80).
The exhaust pipe is heated by electrical heating elements ( 104), that are
powered using
electrical power from PV cells, the engine starter battery, a additional
battery, or a alternating
current power source. The electrical heating elements ( 104), are located in
the lower part of the
exhaust system near the catalytic converter. The electrical heating elements
can be located within
the exhaust pipe, or within the insulating pipe. The temperature in the
exhaust pipe is detected
by temperature sensors (106), within the insulated pipe, or exhaust pi e. ~
'~i~~ ~tempa~~~tux~e ~_f~-~~~~"-
~ ~r c:>; ~ E
sensors provide information to the exhaust pipe temperature control s stem
(EI~C~S~~TI~
EPTCS controls the heating systems. ~.~ i~ ~ °° G'~a
c~ ry ~~°: r~ 1~~ ~~ F, ~ a
~~e~;v;,~ o::c:: a.:L w:~~T
~~ . .~,~l~c.xcx '~ ~ ~'~ ~: ~~_ ~:
;p The exhaust pipe may also be heated by fuel combustion. A burn v0~ ','~~ ~
''
described for the catalytic converter has air and fuel pumped into it and the
hot combustion
products leaves the burner (108) and enter the exhaust pipe or insulating
pipe. The insulated flap
(96), on the lower collar (90), opens when combustion products from the burner
enter the
insulating pipe (84). If burner combustion products enter the exhaust pipe
they pass through the
23
CA 02342592 2001-04-03
catalytic converter before leaving the exhaust pipe. The EPTCS can also start
the engine when
the exhaust pipe is at minimum temperature, the PCM has solidified and the
charge on batteries
is low. This cold exhaust pipe engine starting system would be similar to the
cold catalytic
converter engine starting system.
to Phase change material containers (110), are placed within the exhaust pipe
(80), or the
insulating pipe (84). The phase change material (PCM) releases thermal energy
as the PCM
solidifies. This thermal energy release reduces the amount of electrical
energy or fuel, required
to heat the exhaust pipe between engine uses. Placing the phase change
material containers in
the exhaust pipe requires that the diameter of the exhaust pipe be increased,
to prevent the flow
of exhaust through the exhaust pipe from being restricted. If the PCM
containers ( 110), are
located within the insulating pipe (84), modification of the exhaust pipe is
not required. The
PCM containers (110), can be located on the wall of the exhaust pipe, with an
air gap between
the PCM container and the insulating vessel. The PCM container can be located
on wall of the
insulating pipe, with a air gap between the PCM container and the exhaust
pipe. When the PCM
2o containers are against the exhaust pipe, or within the exhaust pipe, they
are heated to higher
temperatures than if they are on the wall of the insulated pipe. Air flowing
through the insulated
pipe cools the PCM containers within the insulated pipe. The surface of the
PCM container
exposed to air flowing through the insulated pipe can be insulated to reduce
heat losses.
Placing electrical or fuel heating systems, phase change.. material containers
and __
temperature sensors in the exhaust pipe may require holes to be ma in the l of
tl~ ex~~l~~
_ ~ ~ tis. _. : ,i ~ ;.Y ~,r
pipe. These holes must be sealed to prevent engine exhaust fro leaving they
exhaust~pipe.
These holes represent areas where breakdown of the exhaust pipe c begin. or
these re-signs it
FYJi i.,..4 , ,' j' ~1
is preferred to locate components for maintaining the temperature o
thex~~~y~'wI'thm;-l~e
".,._..~_._ _ l~ ':-~;_~
3o insulating pipe and outside the exhaust pipe. If components are located in
the insulating pipe°fTie ~~w'w'
assembly can be slid over a existing exhaust pipe. PCM containers, electrical
heating elements,
and temperature sensors can be attached to the exhaust pipe and a flexible
insulated pipe slid
over the components and exhaust pipe.
24
CA 02342592 2001-04-03
The opening and closing of the flaps, operation of fans, electrical heating
system, or fuel
combustion heating systems are controlled by the exhaust pipe temperature
control system
(EPTCS). The EPTCS receives information from temperature sensors within the
exhaust pipe, or
insulating pipe. When the engine is not running the EPTCS closes the flaps
(96), to prevent air
flows from removing thermal energy from the insulating pipe. When the
temperature of the
1o exhaust pipe falls below a desired temperature the electrical heating or
fuel combustion heating
systems are activated. When the engine is running and the temperature of the
exhaust pipe, or
interior of the insulating pipe is above a desired temperature the insulating
flaps (96) on the
collars (90), open to allow air flow around the exhaust pipe (80), within the
insulating pipe (84).
If the temperature of the exhaust pipe, or interior of the insulating pipe
rises above a desired
temperature, fans ( 102) are activated to increase the air flow through the
insulating pipe to cool
the exhaust pipe, and thereby cool exhaust flowing through the exhaust pipe.
The fans may have
a variable speed that increases in relation to a increased temperature of the
exhaust pipe. These
variable speed fans provide control of the temperature of the exhaust pipe,
and thereby provide
control of the temperature of exhaust entering the catalytic converter,
providing further control of
2o the temperature of the catalytic converter.
In one embodiment, the exhaust pipe may be finned ( 112) internally and/or
externally to
increase the heat exchange between engine exhaust within the exhaust pipe, and
air within the
insulating pipe. Tubing's can be put through the exhaust pipe so that-
a..,.h~at, exchanger is
~~°vr ~ , . _
developed between the exhaust pipe and air flowing through the insul ting
pipes . ~.'h,t~=r~Y'~' ~ ~
r:: ~ ~.3~vv;,,~
exchanger systems increase control of the temperature of exhaust enterin the
catalytic converter,
~'r) r~,
and,thereby provides control of the temperature of the catalyst within the
atalytic onve~ter.''-~ b~
e~~- ' r.:
.._. _ . -;r ..;
Photovoltaic cell power, and AC power, can be used to heat the exhaust pipfe
and PCM ~ _ ..'
containers contained within the insulating pipe to a high temperature prior to
vehicle use. The
exhaust pipe cannot be damaged by high temperatures as the catalytic converter
may be. At start
up the cool exhaust leaving the engine is heated as it passes through the
exhaust pipe. The hot
exhaust leaving the exhaust pipe and entering the catalytic converter rapidly
heats the catalytic
converter to a functional and optimal operating temperature. Such a high
temperature exhaust
CA 02342592 2001-04-03
pipe heating systems could be used without having a insulated vessel
surrounding a catalytic
converter.
The EPTCS can be place on existing vehicles without modifying the existing
exhaust
system. Components such as PCM containers, electrical heating elements and
temperature
to sensors can be attached to a exhaust pipe and a flexible insulating pipe
slid over the components.
CCTCS AND EPTCS COMBINED SYSTEMS
Both the exhaust pipe temperature control system (EPTCS) and the catalytic
converter
t5 temperature control system (CCTCS) need not be used on a engine. For a
specific engine, or
vehicle design one system may be preferred. For optimal catalytic converter
temperature control
both a EPTCS and CCTCS may be used. Optimal catalytic converter temperature
control
reduces the emissions of pollutants to a minimum.
2o The EPTCS and the CCTCS function together to
- maintain the catalytic converter at a functional temperature between engine
uses
prevent over heating of the catalytic converter during extended engine
operation
- prevent exhaust from cooling the catalytic converter below a functional
temperature at start up
25 - provide a catalytic converter at functional temperature at start up, and
- regulate the temperature of the catalytic converter during engine operatio '
to i~~t~~ a ~,, _
_ -EY~~Y
~. , r~~-;
j optimum temperature for the breakdown of engine pollutant emissions ~ ~ r-'
~:r r~ ~~ 3
- keep the catalytic converter above a minimum temperature during engine
operation A; a~~ ~ .. ~~~~
kee the catal is converter below a maximum temperature during engine ope tion
~ ~ ~~ r, ,., .;.._.
Yt ei.~~w ~, . ~~.,,. ~ ,a
P ;a,, ::r
..._._. ',.~v 1F r-- , '
30 _ :. i. ~.
With both a CCTCS and a EPTCS on a engine the air space within the insulating
vessel
and the insulating pipe can be continuous. The number of flaps and the
associated mechanical
components, heating elements, phase change material containers, temperature
sensors, and other
components that are similar in the two systems may be reduced.
26
CA 02342592 2001-04-03
A timer function can be set by the driver to activate the CCTCS the EPTCS to
heat the
catalytic converter and exhaust pipe prior to a expected use of the vehicle.
When the vehicle is parked outside the CCTCS and the EPTCS use electrical
heating
to systems to heat the catalytic converter until the charge on batteries is
low. The CCTCS and the
EPTCS then use the cold catalytic converter engine starting system to start
the engine. When the
engine is running" fuel combustion heats the catalytic converter, melts the
PCM and recharges
the batteries. When the vehicle is parked inside, it is plugged into an AC
power source and the
CCTCS and EPTCS use electrical heating systems to heat the catalytic
converter. The use of a
CCTCS and EPTCS may reduce engine emissions by over 60 percent.
