U.S. patent application number 10/558738 was filed with the patent office on 2006-11-16 for exhaust gas-purifying device.
This patent application is currently assigned to HINO MOTORS, LTD.. Invention is credited to Koichi Machida, Yoshihide Takenaka.
Application Number | 20060254264 10/558738 |
Document ID | / |
Family ID | 33508508 |
Filed Date | 2006-11-16 |
United States Patent
Application |
20060254264 |
Kind Code |
A1 |
Takenaka; Yoshihide ; et
al. |
November 16, 2006 |
Exhaust gas-purifying device
Abstract
An exhaust emission control device with less electricity
consumption comprises a cylindrical outer electrode 7 extending in
a direction of flow of exhaust G, a plurality of inner electrodes 5
and 6 constituted by electrically conductive filters capable of
capturing particulates and aligned in the direction of flow of the
exhaust G within an outer electrode 7, captured particulate amount
estimating means 2 for estimating captured particulate amounts of
the respective inner electrodes 5 and 6 and an electric discharge
controller 3 for supplying electric power for generation of
electric discharge to the outer electrode 7 and any of the inner
electrodes 5 and 6 on the basis of calculated values of the
estimating means 2.
Inventors: |
Takenaka; Yoshihide; (Tokyo,
JP) ; Machida; Koichi; (Tokyo, JP) |
Correspondence
Address: |
C. IRVIN MCCLELLAND;OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
HINO MOTORS, LTD.
Hino-shi, Tokyo
JP
191-8660
|
Family ID: |
33508508 |
Appl. No.: |
10/558738 |
Filed: |
June 2, 2004 |
PCT Filed: |
June 2, 2004 |
PCT NO: |
PCT/JP04/07612 |
371 Date: |
December 1, 2005 |
Current U.S.
Class: |
60/297 ; 60/275;
60/311 |
Current CPC
Class: |
F01N 3/0275 20130101;
Y02T 10/40 20130101; Y02T 10/47 20130101; B03C 3/08 20130101; F01N
2900/1606 20130101; B03C 3/41 20130101; F01N 9/002 20130101; B03C
2201/30 20130101; F01N 3/01 20130101 |
Class at
Publication: |
060/297 ;
060/275; 060/311 |
International
Class: |
F01N 3/00 20060101
F01N003/00; F01N 3/02 20060101 F01N003/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 4, 2003 |
JP |
2003-159333 |
Claims
1. An exhaust emission control device comprising an integral
electrode extending in a direction of flow of exhaust gas, a
plurality of divided electrodes constituted by electrically
conductive filters capable of capturing particulates and aligned in
the direction of flow of the exhaust and an electric discharge
controller for supplying electric power for generation of electric
discharge to the integral electrode and to any of the divided
electrodes.
2. The exhaust emission control device as claimed in claim 1
further comprising captured amount estimating means for estimating
particulate amounts captured by the respective divided electrodes,
the integral electrode and any of the divided electrodes being
supplied with electric power for generation of electric discharge
on the basis of calculated values of the estimating means.
3. An exhaust emission control device comprising an integral
electrode extending in a direction of flow of exhaust gas, a
plurality of divided electrodes aligned in the direction of flow of
the exhaust, a filter between both of the electrodes and capable of
capturing particulates and an electric discharge controller for
supplying electric power for generation of electric discharge to
the integral electrode and any of the divided electrodes.
4. The exhaust emission control device according to claim 3 further
comprising captured amount estimating means for estimating
distribution of a captured particulate amount on the filter, the
integral electrode and any of the divided electrodes being supplied
with electric power for generation of electric discharge on the
basis of calculated amounts of the estimating means.
Description
TECHNICAL FIELD
[0001] The present invention relates to an exhaust emission control
device.
BACKGROUND ART
[0002] Particulates or particulate matter in exhaust (burned gas of
diesel oil) from a diesel engine is mainly constituted by carbonic
soot and a soluble organic fraction of high-boiling hydrocarbon and
contains a trace of sulfate (misty sulfuric acid fraction).
[0003] In order to suppress the particulates from being diffused
into atmosphere, conventionally a particulate filter is
incorporated in an engine exhaust system to capture the
particulates.
[0004] An example of such particulate filter comprises a honeycomb
core made of ceramics such as cordierite and having a number of
passages compartmentalized by porous thin walls, exhaust gas from
an engine flowing through the passages.
[0005] In the particulate filter, alternate ones of the parallel
passages have plugged one ends so as to guide the exhaust gas to
unplugged one ends of the gas passages adjacent thereto; the
passages through which the exhaust gas flows have the plugged other
ends so as to connect unplugged other ends of the gas passages
adjacent thereto to a muffler.
[0006] Thus, particulates entrained in the exhaust gas are captured
by the porous thin walls and only the exhaust gas passing through
the walls is discharged to the atmosphere.
[0007] The particulates attached to the thin walls will
spontaneously ignite to be oxidized when an engine operational
status is shifted to an area with exhaust gas temperature
increased.
[0008] However, for example, in a shuttle-bus running mainly on
city roads with generally lower running speeds, there is few chance
to continue an engine operational status capable of obtaining
exhaust temperature suited for oxidation treatment of the
particulates. As a result, a captured particulate amount will
exceed an oxidized amount, leading to clogging of the pore thin
walls.
[0009] Thus, recently, a plasma assisted exhaust emission control
device (gas treatment reactor vessel) has been proposed which can
oxidize particulates even if exhaust temperature is low (see, for
example, Reference 1).
[0010] In this exhaust emission control device, outer and inner
electrodes made of drilled stainless cylinders are arranged
coaxially in a chamber; a gap between the electrodes is charged
with electric conductor in the form of pellets so as to allow the
exhaust gas to pass. The exhaust gas from the engine is guided to a
gap between the chamber and the outer electrode.
[0011] Thus, the particulates in the exhaust supplied from between
the chamber and the outer electrode to the pellet charged layer are
attached to the pellets, only the exhaust passing through the
pellet charged layer being discharged to the atmosphere.
[0012] Moreover, higher voltage is applied to the inner and outer
electrodes to generate discharge plasma and excite the exhaust gas,
so that unburned hydrocarbon, oxygen and nitrogen monoxide are
activated into oxygen-containing hydrocarbon, ozone and nitrogen
dioxide, respectively.
[0013] Thus, even with lower exhaust gas temperature, the
particulates attached to the pellets will spontaneously ignite to
be oxidized.
[Reference 1] JP 2002-501813A
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0014] However, in the plasma assisted exhaust emission control
device as mentioned above, the discharge plasma is generated all
over the inner and outer electrodes although quantitative
distribution of the captured particulates is not always uniform in
a direction of flow of the exhaust, leading to too much electricity
consumption.
[0015] The invention was made in view of the above and has its
object to provide an exhaust emission control device with less
electricity consumption.
Means or Measure for Solving the Problems
[0016] In order to attain the above object, according to a first
aspect of the invention, provided are an integral electrode
extending in a direction of flow of exhaust, a plurality of divided
electrodes constituted by electrically conductive filters capable
of capturing particulates and aligned in the direction of flow of
the exhaust and an electric discharge controller for supplying
electric power for generating electric discharge to the integral
electrode and to any of the divided electrodes. Further provided is
captured amount estimating means to estimate particulate amounts
captured by the respective divided electrodes. On the basis of
calculated values of the estimating means, the integral electrode
and any of the divided electrodes may be supplied with electric
power for generation of electric discharge.
[0017] According to a second aspect of the invention, provided are
an integral electrode extending in a direction of flow of exhaust
gas, a plurality of divided electrodes aligned in the direction of
flow of exhaust gas, a filter between both of the electrodes and
capable of capturing particulates and an electric discharge
controller for supplying electric power for generation of electric
discharge to the integral electrode and to any of the divided
electrodes. Further provided is captured amount estimating means to
estimate distribution of captured particulate amount on the filter.
On the basis of calculated amounts of the estimating means, the
integral electrode and any of the divided electrodes may be
supplied with electric power for generation of electric
discharge.
[0018] In the first aspect of the invention, the discharge
controller supplies the electric power for generation of electric
discharge to the integral electrode and to the particular ones of
the divided electrodes with excessive captured particulate amounts
so as to oxidize the particulates. The captured particulate amounts
of the respective divided electrodes may be calculated by the
estimating means.
[0019] In the second aspect of the invention, the discharge
controller supplies the electric power for generation of electric
discharge to the integral electrode and to the particular ones of
the divided electrodes which correspond to filter portions each
with an excessive captured particulate amount so as to oxidize the
particulates. Distribution of the captured particulate amount on
the filter may be calculated by the estimating means.
Effects of the Invention
[0020] According to an exhaust emission control device of the
invention, the following various excellent meritorious effects are
obtained.
[0021] (1) In the first aspect of the invention, the discharge
controller supplies the electric power for generation of electric
discharge to the integral electrode and to the particular ones of
the divided electrodes each with excessively captured particulate
amount, so that power consumption may be decreased.
[0022] (2) The captured particulate amounts by the respective
divided electrodes may be calculated by the estimating means.
[0023] (3) In the second aspect of the invention, the discharge
controller supplies the electric power for generation of electric
discharge to the integral electrode and particular ones of the
divided electrodes corresponding to filter portions each with
excessively captured particulate amount, so that power consumption
may be decreased.
[0024] (4) The distribution of the captured particulate amount of
the filter may be calculated by the estimating means.
Best Mode for Carrying Out the Invention
[0025] Embodiments of the invention will be described with
reference to the drawings.
[0026] FIG. 1 shows a first embodiment of an exhaust emission
control device according to the invention which comprises a
capturing cell 1, captured amount estimating means 2 and an
electric discharge controller 3.
[0027] The cell 1 comprises a housing 4 incorporated in a flow
passage of exhaust G to be purified, a plurality of hollow inner
electrodes 5 and 6 (divided electrodes) constituted by electrically
conductive filters capable of capturing particulates and aligned
coaxially in a direction of flow of the exhaust G within the
housing 4, a cylindrical outer electrode (integral electrode) 7
arranged within the housing 4 so as to peripherally surround the
inner electrodes 5 and 6 and an electric conductor 8 made of for
example ceramics to cover an inner surface of the outer electrode
7.
[0028] Moreover, a particulate filter, using for example
cordierite, is incorporated separately from the capturing cell 1 in
the flow passage of the exhaust G.
[0029] The electrically conductive filter may be fibrous metal
laminated and sintered into integrity, sintered body of metallic
powder, fine metallic mesh laminated and sintered into integrity or
metallic powder carried through sintering by fine metallic mesh;
any of them may capture the particulates while ensuring passing of
the gas.
[0030] The inner electrode 5 has closed and opened upstream and
downstream ends, respectively, in the direction of flow of the
exhaust G while the inner electrode 6 has opened opposite ends.
[0031] The inner electrodes 5 and 6 are connected together through
an annular insulant 9. To downstream ends of the inner and outer
electrodes 6 and 7 in the direction of flow of the exhaust G, an
annular insulant 10 contacts all over peripheries of the ends.
[0032] The insulant 9 not only retains electric insulation between
the inner electrodes 5 and 6, but also sufficiently separates the
electrodes 5 and 6 so as not to cause electric discharge between
the electrodes 5 and 6.
[0033] Thus, the exhaust G from the engine (not shown) flows into a
gap 11 between outer surfaces of the inner electrodes 5 and 6 and
an inner surface of the electric conductor 8 in the capturing cell
1, passes through the inner electrodes 5 and 6 from outward to
inward and flows out to a muffler (not shown) through inner spaces
of the inner electrodes 5 and 6; the particulates are captured by
the inner electrodes 5 and 6 which are the conductive filters.
[0034] The estimating means 2 is constructed such that electric
power for searching is applied to the inner electrodes 5 and 6 to
measure electric characteristics (resistance, current and voltage
values) of these bodies to be tested and that, on the basis of
correlation between parametric electric characteristics and
preliminarily obtained captured particulate amounts of the
respective electrodes 5 and 6 through actual measurement, captured
particulate amounts of the respective inner electrodes 5 and 6 at
that point of time are calculated so as to output a signal.
[0035] A main component of the particulates is carbon (electric
conductor). Thus, the more the captured particulate amount on the
inner electrode 5 is increased, the more the resistance value as
judgment factor for the captured amount is lowered, the more the
current value is increased and the more remarkably the voltage
value is lowered.
[0036] Thus, the captured particulate amounts of the respective
inner electrodes 5 and 6 may be estimated by measuring electric
characteristic values on the respective inner electrodes 5 and 6 at
appropriate intervals when no electric discharge occurs.
[0037] Connected to the electric discharge controller 3 are the
above-mentioned estimating means 2 as well as an in-vehicle power
supply 12 such as alternator.
[0038] The discharge controller 3 is constructed such that, when
captured particulate amount of the inner electrode 5 or 6 at that
point of time obtained by the estimating means 2 exceeds a
predetermined value, the electric power is applied to the outer
electrode 7 and the very one of the inner electrodes 5 and 6 with
excess captured particulate amount so as to generate discharge
plasma.
[0039] Thus, discharge plasma is generated only between the outer
electrode 7 and any of the inner electrodes 5 and 6 with captured
particulate amount. The particles may be oxidized through for
example ozone and oxygen radical.
[0040] FIG. 2 shows a second embodiment of an exhaust emission
control device according to the invention which comprises a
capturing cell 21, captured amount estimating means 22 and an
electric discharge controller 23.
[0041] The cell 21 comprises a housing 24 incorporated in a flow
passage of an exhaust G to be purified, a plurality of hollow inner
electrodes (divided electrode) 25-27 aligned coaxially in the
direction of flow of the exhaust G within the housing 24, a
cylindrical outer electrode (integral electrode) 28 arranged in the
housing 24 so as to circumferentially surround the inner electrodes
25-27, an electric conductor 29 made of for example ceramics to
cover an inner surface of the outer electrode 28 and a
particulate-capturing filter 30 between outer surfaces of the inner
electrodes 25-27 and the electric conductor 29.
[0042] The inner electrodes 25-27 are made of rigid and porous
material such that they allow the exhaust G to pass therethrough
form outward to inward and they can retain the filter 30.
[0043] The filter 30 may be made of, for example, ceramics pellet
or cordierite honeycomb.
[0044] The inner electrode 25 is closed and opened upstream and
downstream ends, respectively, in the direction of flow of the
exhaust G while each of the inner electrodes 26 and 27 has opened
opposite ends.
[0045] The inner electrodes 25 and 26 are connected together
through an annular insulant 31. The inner electrodes 26 and 27 are
connected together through an annular insulant 32.
[0046] To downstream ends of the inner and outer electrodes 27 and
28 in the direction of flow of the exhaust G, an annular insulant
33 contacts all over peripheries of the ends of the electrodes 27
and 28.
[0047] The respective insulants 31 and 32 not only retain electric
insulation between the inner electrodes 25-27 to each other, but
also sufficiently separate the electrodes 25-27 so as not to cause
electric discharge between the electrodes 25 and 26 and between the
electrodes 26 and 27, respectively.
[0048] Thus, the exhaust G from the engine flows through the filter
30 between the outer surfaces of the inner electrodes 25-27 in the
capturing cell 21 and the inner surface of the electric conductor
29, passes through the inner electrodes 25-27 from outward to
inward and flows out through these inner spaces of the inner
electrodes 25-27 into a muffler (not shown) downstream of the
capturing cell 21, the particulates being captured by the filter
30.
[0049] The estimating means 22 is constructed such that it detects
load information such as engine revolution speed or inner pressure
in the exhaust passage and, on the basis of a correlation between
the captured particulate amount of the filter 30 obtained by actual
measurement and the load information as parameter, distribution of
captured particulate amount on the filter 30 is calculated to
output a signal.
[0050] Connected to the discharge controller 23 are the
above-mentioned estimating means 22 as well as an in-vehicle power
supply 34 such as alternator.
[0051] This discharge controller 23 is constructed such that, on
the basis of the above-mentioned data on distribution of the
captured particulate amount, electric force is supplied to the
outer electrode 28 and to any of the inner electrodes 25-27
corresponding to the portions of the filter 30 with excessive
captured particulate amounts to generate discharge plasma.
[0052] Thus, discharge plasma is generated only between the
particular ones of the inner electrodes 25-27 and the outer
electrode 28. The particulates can be oxidized by ozone, oxygen
radical or the like.
[0053] It is to be understood that an exhaust emission control
device of the present invention is not limited to the
above-mentioned embodiments and that various changes and
modifications may be made without diverting the gist of the
invention. For example, though the electrodes for generation of
electric discharge plasma have been disclosed and illustrated in
the embodiments as cylinders, other shapes such as opposed flat
plates or lattices may be also employed. Proportions in length of
the divided electrodes may be suitably changed.
INDUSTRIAL APPLICABILITY
[0054] An exhaust emission control device according to the
invention may be applicable to various types of vehicles.
BRIEF DESCRIPTION OF THE DRAWINGS
[0055] FIG. 1 Conceptual diagram showing a first embodiment of an
exhaust emission control device according to the invention.
[0056] FIG. 2 Conceptual diagram showing a second embodiment of an
exhaust emission control device according to the invention.
EXPLANATION OF THE REFERENCE NUMERALS
[0057] 2 captured amount estimating means [0058] 3 discharge
controller [0059] 5 inner electrode (divided electrode) [0060] 6
inner electrode (divided electrode) [0061] 7 outer electrode
(integral electrode) [0062] 22 captured amount estimating means
[0063] 23 electric discharge controller [0064] 25 inner electrode
(divided electrode) [0065] 26 inner electrode (divided electrode)
[0066] 27 inner electrode (divided electrode) [0067] 28 outer
electrode (integral electrode) [0068] 30 filter [0069] G exhaust
gas
* * * * *