U.S. patent application number 14/404368 was filed with the patent office on 2015-04-30 for particulate matter processing apparatus.
This patent application is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. The applicant listed for this patent is Shinichi Mitani, Hiroshi Nomura. Invention is credited to Shinichi Mitani, Hiroshi Nomura.
Application Number | 20150113959 14/404368 |
Document ID | / |
Family ID | 49672635 |
Filed Date | 2015-04-30 |
United States Patent
Application |
20150113959 |
Kind Code |
A1 |
Mitani; Shinichi ; et
al. |
April 30, 2015 |
PARTICULATE MATTER PROCESSING APPARATUS
Abstract
Aggregation of the particulate matter is facilitated. A
particulate matter processing apparatus (1) comprises an electrode
(5) which is provided in an exhaust gas passage (3) of an internal
combustion engine, which extends from a wall surface of the exhaust
gas passage (3) toward an inner side of the exhaust gas passage
(3), which is bent at a bent portion (51) toward an upstream side
or a downstream side in a flow direction (B) of an exhaust gas, and
which extends toward the upstream side or the downstream side in
the flow direction (B) of the exhaust gas, wherein the electrode
(5) is formed so that a field intensity, which is provided between
the electrode (5) and the wall surface of the exhaust gas passage
(3) on the upstream side, is larger than that provided on the
downstream side.
Inventors: |
Mitani; Shinichi;
(Susono-shi, JP) ; Nomura; Hiroshi; (Gotenba-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mitani; Shinichi
Nomura; Hiroshi |
Susono-shi
Gotenba-shi |
|
JP
JP |
|
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
Toyota-shi, Aichi
JP
|
Family ID: |
49672635 |
Appl. No.: |
14/404368 |
Filed: |
May 29, 2012 |
PCT Filed: |
May 29, 2012 |
PCT NO: |
PCT/JP2012/063735 |
371 Date: |
November 26, 2014 |
Current U.S.
Class: |
60/275 ;
60/311 |
Current CPC
Class: |
B03C 3/38 20130101; B03C
2201/10 20130101; Y02T 10/40 20130101; B03C 2201/24 20130101; F01N
3/033 20130101; F01N 3/01 20130101; B03C 3/49 20130101; F01N 9/002
20130101; Y02T 10/47 20130101; Y02T 10/12 20130101; B03C 2201/30
20130101; F01N 3/021 20130101; Y02T 10/20 20130101; B03C 3/41
20130101; B03C 3/68 20130101; B03C 3/0175 20130101 |
Class at
Publication: |
60/275 ;
60/311 |
International
Class: |
F01N 3/033 20060101
F01N003/033; F01N 3/021 20060101 F01N003/021 |
Claims
1. A particulate matter processing apparatus comprising an
electrode which is provided in an exhaust gas passage of an
internal combustion engine, which extends from a wall surface of
the exhaust gas passage toward an inner side of the exhaust gas
passage, which is bent at a bent portion toward an upstream side or
a downstream side in a flow direction of an exhaust gas, and which
extends toward the upstream side or the downstream side in the flow
direction of the exhaust gas, wherein: the electrode is formed so
that a field intensity, which is provided between the electrode and
the wall surface of the exhaust gas passage on the upstream side,
is larger than that provided on the downstream side.
2. The particulate matter processing apparatus according to claim
1, further comprising: a power source which supplies an electric
power to the electrode, wherein: the power source supplies the
electric power to one portion of the electrode to apply an
identical voltage to the entire electrode.
3. The particulate matter processing apparatus according to claim
1, wherein: the electrode is provided with a plurality of
protruding portions which extend toward a wall surface side of the
exhaust gas passage in a direction perpendicular to the flow
direction of the exhaust gas at a part extending toward the
upstream side or the downstream side of the flow direction of the
exhaust gas; and the field intensity between the electrode and the
wall surface of the exhaust gas passage is changed by changing at
least one of a distance between the protruding portion and the wall
surface of the exhaust gas passage or an installation spacing in
the flow direction of the exhaust gas between the protruding
portions, between the upstream side and the downstream side of the
flow of the exhaust gas.
4. The particulate matter processing apparatus according to claim
3, wherein the exhaust gas passage, which is disposed around the
electrode, has an identical inner diameter, and the field intensity
between the electrode and the wall surface of the exhaust gas
passage is changed by changing at least one of a length of the
protruding portion and the installation spacing in the flow
direction of the exhaust gas between the protruding portions.
5. The particulate matter processing apparatus according to claim
4, wherein: the electrode extends from the bent portion toward the
downstream side in the flow direction of the exhaust gas; and a
length of the protruding portion is short and the installation
spacing in the flow direction of the exhaust gas between the
protruding portions is short at a portion which is disposed far
from the bent portion as compared with a portion which is disposed
near to the bent portion.
6. The particulate matter processing apparatus according to claim
4, wherein: the electrode extends from the bent portion toward the
upstream side in the flow direction of the exhaust gas; and a
length of the protruding portion is long and the installation
spacing in the flow direction of the exhaust gas between the
protruding portions is long at a portion which is disposed far from
the bent portion as compared with a portion which is disposed near
to the bent portion.
7. The particulate matter processing apparatus according to claim
3, wherein a thickness of the protruding portion is changed between
the upstream side and the downstream side of the flow of the
exhaust gas.
8. The particulate matter processing apparatus according to claim
1, further comprising: a detecting unit which detects a current
allowed to pass through the electrode; a judging unit which judges
whether or not a pulse current is generated in the current detected
by the detecting unit; and a control unit which reduces an
application voltage applied to the electrode as compared with that
provided at a present point in time if it is judged by the judging
unit that the pulse current is generated.
Description
TECHNICAL FIELD
[0001] The present invention relates to a particulate matter
processing apparatus.
BACKGROUND ART
[0002] A technique is known, wherein a discharge electrode, which
has a needle-like shape, is provided for an exhaust gas passage of
an internal combustion engine to electrify the particulate matter
(hereinafter referred to as "PM" as well), and the electrified PM
is allowed to stay on a dust collection electrode (see, for
example, Patent Document 1). Further, according to this technique,
the particulate diameter of PM is increased, and hence PM can be
easily collected by using a filter when the filter is provided on
the downstream side.
[0003] Another technique is known, wherein a discharge electrode,
which is provided with a protruding portion, is arranged in an
exhaust gas pipe to collect PM (see, for example, Patent Document
2).
[0004] Still another technique is known, wherein the insulation is
secured for a discharge electrode in a particulate matter
processing apparatus which utilizes the corona discharge (see, for
example, Patent Document 3).
[0005] Still another technique is known, wherein a forward end
portion of an insulating portion of a discharge electrode is
thin-walled to raise the temperature by means of the heat of the
exhaust gas, and PM, which adheres to the forward end portion, is
oxidized (see, for example, Patent Document 4).
[0006] Still another technique is known, wherein the condensation
(dew) of water is suppressed by heating a discharge unit (see, for
example, Patent Document 5).
[0007] Still another technique is known, wherein three to six
projecting portions having needle-like shapes are arranged in a
radial form at equal intervals (equal spacings) in the
circumferential direction of a discharge electrode. Further, it is
assumed that D0 represents the distance from the forward end of the
projecting portion to the inner surface of a duct, and P represents
the installation spacing in the length direction (lengthwise
direction) between the discharge electrodes of the projecting
portions. On this assumption, the relationship between the both is
set to be in a range of 0.6D0.ltoreq.P.ltoreq.2.4D0 (see, for
example, Patent Document 6).
[0008] Still another technique is known, wherein
D/5.ltoreq.P.ltoreq.D is given assuming that D represents the
spacing between counter electrodes arranged in parallel to one
another, and P represents the spacing between projections provided
for discharge electrodes arranged at intermediate positions of the
counter electrodes (see, for example, Patent Document 7).
[0009] Further, an electric dust collector is known, in which a
discharge electrode having a needle-like shape is provided in a
pipe (see, for example, Patent Documents 8 and 9).
[0010] Further, a technique is known, in which PM is collected
after electrifying PM by using an electrode unit provided for an
exhaust gas pipe (see, for example, Patent Document 10).
[0011] In this context, if the strong electric discharge, which is
exemplified, for example, by the corona discharge or the arc
discharge, is generated from the electrode, PM is pulverized and
made to be fine and minute by means of the high speed electrons
resulting from the strong electric discharge. As a result, the
effect to aggregate PM is lowered. In relation thereto, it is
conceived that the application voltage is controlled so that the
strong electric discharge is not generated. However, in the case of
the construction of the conventional technique, the field intensity
(electric field strength) is scarcely taken into consideration.
Even if PM is aggregated, the effect is small.
PRECEDING TECHNICAL DOCUMENTS
Patent Documents
Patent Document 1: JP2006-136766A;
Patent Document 2: JP2009-114872A;
Patent Document 3: JP2006-342730A;
Patent Document 4: JP2006-291708A;
Patent Document 5: JP2006-122849A;
Patent Document 6: JP06-031199A;
Patent Document 7: JP11-216388A;
Patent Document 8: JP2009-208041A;
Patent Document 9: JP2009-082901A;
Patent Document 10: JP09-112246A.
SUMMARY OF THE INVENTION
Task to be Solved by the Invention
[0012] The present invention has been made taking the foregoing
problem into consideration, an object of which is to facilitate the
aggregation of the particulate matter.
Solution for the Task
[0013] In order to achieve the object as described above, according
to the present invention, there is provided a particulate matter
processing apparatus comprising an electrode which is provided in
an exhaust gas passage of an internal combustion engine, which
extends from a wall surface of the exhaust gas passage toward an
inner side of the exhaust gas passage, which is bent at a bent
portion toward an upstream side or a downstream side in a flow
direction of an exhaust gas, and which extends toward the upstream
side or the downstream side in the flow direction of the exhaust
gas, wherein:
[0014] the electrode is formed so that a field intensity, which is
provided between the electrode and the wall surface of the exhaust
gas passage on the upstream side, is larger than that provided on
the downstream side.
[0015] In this arrangement, when the voltage is applied to the
electrode, it is possible to electrify or electrically charge PM.
The electrified PM is moved toward the wall surface of the exhaust
gas passage in accordance with the Coulomb force and/or the flow of
the exhaust gas. PM, which arrives at the wall surface of the
exhaust gas passage, releases the electrons to the exhaust gas
passage. Therefore, the electricity flows to the ground side as
compared with the electrode. Further, PM, from which the electrons
are released, is aggregated with other PM existing in the
neighborhood. Therefore, it is possible to decrease the number of
particulates.
[0016] In this context, when the field intensity (electric field
strength), which is provided between the electrode and the wall
surface of the exhaust gas passage, is made large on the upstream
side of the flow of the exhaust gas, it is possible to electrify PM
more reliably on the upstream side on which the field intensity is
relatively large. Further, PM, which is electrified on the upstream
side, is allowed to flow to the downstream side on which the field
intensity is relatively small, and PM gently advances toward the
wall surface of the exhaust gas passage in accordance with the
influence of the electric field. That is, it is possible to
facilitate the electrification of PM by relatively increasing the
field intensity on the upstream side. On the other hand, it is
enough on the downstream side that PM, which has been already
electrified, is merely directed to the wall surface of the exhaust
gas passage. Therefore, it is enough that the field intensity is
relatively small. Therefore, it is possible to simplify the
apparatus or realize a light weight of the apparatus. Further, even
when the field intensity on the downstream side is made relatively
small, PM is electrified on the upstream side. Therefore, it is
possible to increase the opportunities of aggregation of PM.
Accordingly, it is possible to reduce the number of particulates of
PM.
[0017] It is also appropriate that the electrode is bent toward the
upstream side in the flow direction of the exhaust gas, or the
electrode is bent toward the downstream side. Further, it is also
appropriate that the direction, in which the electrode extends, is
not parallel to the flow direction of the exhaust gas. Further, it
is also appropriate that the field intensity is decreased in a
stepwise manner from the upstream side to the downstream side in
the flow direction of the exhaust gas, or the field intensity is
decreased continuously and gradually.
[0018] In the present invention, the particulate matter processing
apparatus may further comprise:
[0019] a power source which supplies an electric power to the
electrode, wherein:
[0020] the power source can supply the electric power to one
portion of the electrode to apply an identical voltage to the
entire electrode.
[0021] In this way, when the field intensity is changed between the
upstream side and the downstream side while supplying the power
source from one portion, it is thereby possible to simplify the
apparatus and the control. Further, it is necessary to provide a
hole through the exhaust gas passage in order to allow the
electrode to pass therethrough. However, it is enough to provide
one hole. Therefore, it is possible to lower the production
cost.
[0022] In the present invention, the electrode may be provided with
a plurality of protruding portions which extend toward a wall
surface side of the exhaust gas passage in a direction
perpendicular to the flow direction of the exhaust gas at a part
extending toward the upstream side or the downstream side of the
flow direction of the exhaust gas; and
[0023] the field intensity between the electrode and the wall
surface of the exhaust gas passage can be changed by changing at
least one of a distance between the protruding portion and the wall
surface of the exhaust gas passage or an installation spacing in
the flow direction of the exhaust gas between the protruding
portions, between the upstream side and the downstream side of the
flow of the exhaust gas.
[0024] It is also appropriate that the field intensity, which is
provided between the electrode and the wall surface of the exhaust
gas passage, is the field intensity which is provided around the
electrode. In this arrangement, the nearer the distance between the
protruding portion and the wall surface of the exhaust gas passage
is, the larger the field intensity is. This feature is also
referred to such that the longer the protruding portion is, the
larger the field intensity is. Further, the shorter the
installation spacing in the flow direction of the exhaust gas
between the protruding portions is, the larger the field intensity
is. This feature is also referred to such that the shorter the
distance between the protruding portions adjoining in the flow
direction of the exhaust gas is, the larger the field intensity is.
In this way, it is possible to adjust the field intensity by
changing the distance between the protruding portion and the wall
surface of the exhaust gas passage or the installation spacing in
the flow direction of the exhaust gas between the protruding
portions. Therefore, the field intensity, which is provided between
the electrode and the wall surface of the exhaust gas passage, can
be made large on the upstream side as compared with the downstream
side by changing at least one of the distance between the
protruding portion and the wall surface of the exhaust gas passage
or the installation spacing in the flow direction of the exhaust
gas between the protruding portions. It is also appropriate that
the length of the protruding portion or the installation spacing in
the flow direction of the exhaust gas between the protruding
portions is changed gradually, or changed for each of the plurality
of protruding portions installed in the flow direction of the
exhaust gas.
[0025] In the present invention, the exhaust gas passage, which is
disposed around the electrode, may have an identical inner
diameter, and the field intensity between the electrode and the
wall surface of the exhaust gas passage can be changed by changing
at least one of a length of the protruding portion and the
installation spacing in the flow direction of the exhaust gas
between the protruding portions.
[0026] It is possible to shorten the distance between the forward
end of the protruding portion and the wall surface of the exhaust
gas passage by lengthening the protruding portion. In this
arrangement, the longer the protruding portion is, the larger the
field intensity is. The shorter the protruding portion is, the
smaller the field intensity is. Further, it is possible to reduce
the mass by shortening the protruding portion. Further, even when
the protruding portion is shortened, it is possible to suppress the
decrease in the field intensity by shortening the installation
spacing in the flow direction of the exhaust gas between the
protruding portions. Therefore, it is possible to adjust the mass
of the protruding portion while securing the necessary field
intensity by adjusting the length of the protruding portion and the
installation spacing in the flow direction of the exhaust gas
between the protruding portions. Accordingly, it is possible to
suppress such a situation that the electrode is deformed and/or
broken due to the mass of the protruding portion.
[0027] In the present invention, the electrode may extend from the
bent portion toward the downstream side in the flow direction of
the exhaust gas; and;
[0028] a length of the protruding portion may be short and the
installation spacing in the flow direction of the exhaust gas
between the protruding portions may be short at a portion which is
disposed far from the bent portion as compared with a portion which
is disposed near to the bent portion.
[0029] That is, when the length of the protruding portion is
shortened on the downstream side of the flow of the exhaust gas, it
is possible to reduce the mass in the vicinity of the downstream
end of the electrode, i.e., in the vicinity of the forward end of
the electrode. Accordingly, it is possible to reduce the magnitude
of the force applied to the electrode and the attachment portion of
the electrode. Therefore, it is possible to suppress, for example,
the deformation of the electrode. On the other hand, when the
length of the protruding portion is shortened, it is feared that
the field intensity may be unnecessarily decreased. In relation
thereto, it is possible to suppress the decrease in the field
intensity by shortening the installation spacing in the flow
direction of the exhaust gas between the protruding portions.
Therefore, it is possible to facilitate the aggregation of PM,
while suppressing the malfunction or breakdown of the particulate
matter processing apparatus.
[0030] In the present invention, the electrode may extend from the
bent portion toward the upstream side in the flow direction of the
exhaust gas; and
[0031] a length of the protruding portion may be long and the
installation spacing in the flow direction of the exhaust gas
between the protruding portions may be long at a portion which is
disposed far from the bent portion as compared with a portion which
is disposed near to the bent portion.
[0032] Also in such a situation, the field intensity is large on
the upstream side as compared with the downstream side. Therefore,
it is possible to more reliably electrify PM on the upstream side
on which the field intensity is relatively large. Therefore, it is
possible to facilitate the aggregation of PM.
[0033] In the present invention, a thickness of the protruding
portion can be changed between the upstream side and the downstream
side of the flow of the exhaust gas.
[0034] In this arrangement, the rigidity is raised by thickening
the protruding portion, but the field intensity is lowered. When
the protruding portion is thickened in order to raise the rigidity,
it is possible to suppress the decrease in the field intensity by
shortening the installation spacing in the flow direction of the
exhaust gas between the protruding portions or lengthening the
protruding portion. Therefore, it is possible to change the field
intensity around the electrode between the upstream side and the
downstream side while securing the rigidity by changing the
thickness of the protruding portion between the upstream side and
the downstream side of the flow of the exhaust gas. It is also
appropriate that the thickness of the protruding portion is a
diameter of the cross section of a root of the protruding portion.
Further, it is also appropriate that the field intensity is made
relatively large, for example, by relatively thickening the
protruding portion on the upstream side of the flow of the exhaust
gas and shortening the installation spacing in the flow direction
of the exhaust gas.
[0035] In the present invention, the particulate matter processing
apparatus may further comprise:
[0036] a detecting unit which detects a current allowed to pass
through the electrode;
[0037] a judging unit which judges whether or not a pulse current
is generated in the current detected by the detecting unit; and
[0038] a control unit which reduces an application voltage applied
to the electrode as compared with that provided at a present point
in time if it is judged by the judging unit that the pulse current
is generated.
[0039] Accordingly, it is possible to suppress the generation of
the pulse current allowed to pass through the electrode. In this
arrangement, if the strong electric discharge is generated in the
electrode, the pulse current is generated in the current allowed to
pass through the electrode. That is, it is considered that the
strong electric discharge is generated in the electrode when the
pulse current is detected by the detecting unit. It is feared that
PM may be pulverized by the strong electric discharge and PM may be
made fine and minute. In relation thereto, it is possible to
suppress the generation of the strong electric discharge by
reducing the application voltage when the pulse current is
generated. It is noted that PM can be aggregated even by using an
application voltage which does not generate the strong electric
discharge including, for example, the corona discharge and the arc
discharge. Therefore, if the generation of the pulse current is
suppressed by reducing the application voltage when the pulse
current is generated, then it is possible to aggregate PM while
suppressing PM from being made to be fine and minute.
[0040] In the present invention, it is also appropriate that the
control unit increases the application voltage as compared with
that provided at a present point in time if it is judged by the
judging unit that the pulse current is not generated. PM is
aggregated more easily by further increasing the application
voltage in a range in which the pulse current is not generated.
That is, it is possible to facilitate the aggregation of PM by
increasing the application voltage in the range in which the pulse
current is not generated. It is also appropriate that the feedback
control is performed so that the application voltage is maximized
in the range in which the pulse current is not generated.
Effect of the Invention
[0041] According to the present invention, it is possible to
facilitate the aggregation of the particulate matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] FIG. 1 shows an schematic arrangement of a particulate
matter processing apparatus according to a first embodiment.
[0043] FIG. 2 shows a field intensity distribution around an
electrode according to the first embodiment.
[0044] FIG. 3 shows a field intensity distribution provided when
protruding portions disposed on the forward end side of the
electrode are relatively shortened and protruding portions disposed
in a region ranging from a bent portion to the forward end of the
electrode are arranged at equal intervals (equal spacings).
[0045] FIG. 4 shows a schematic arrangement of a particulate matter
processing apparatus according to a second embodiment.
[0046] FIG. 5 shows a field intensity distribution according to the
second embodiment.
[0047] FIG. 6 shows a schematic arrangement of a particulate matter
processing apparatus according to a third embodiment.
[0048] FIG. 7 shows a schematic arrangement of a particulate matter
processing apparatus according to a fourth embodiment.
[0049] FIG. 8 shows a schematic arrangement of a particulate matter
processing apparatus according to a fifth embodiment.
[0050] FIG. 9 shows an electrode of a particulate matter processing
apparatus according to a sixth embodiment as viewed from the
downstream side of the flow of the exhaust gas.
[0051] FIG. 10 shows a schematic arrangement of a particulate
matter processing apparatus according to a seventh embodiment.
[0052] FIG. 11 shows a schematic arrangement of a particulate
matter processing apparatus according to an eighth embodiment.
[0053] FIG. 12 shows a schematic arrangement of a particulate
matter processing apparatus according to a ninth embodiment.
[0054] FIG. 13 shows a flow chart illustrating a control flow of an
air supply unit according to the ninth embodiment.
[0055] FIG. 14 shows a schematic arrangement of a particulate
matter processing apparatus according to a tenth embodiment.
[0056] FIG. 15 shows a schematic arrangement of a particulate
matter processing apparatus according to an eleventh
embodiment.
[0057] FIG. 16 shows the transition of the current detected by a
detecting unit in relation to each of application voltages.
[0058] FIG. 17 shows a schematic arrangement of a particulate
matter processing apparatus according to a twelfth embodiment.
[0059] FIG. 18 shows a schematic arrangement of a particulate
matter processing apparatus according to a thirteenth
embodiment.
[0060] FIG. 19 shows a schematic arrangement of a particulate
matter processing apparatus according to a fourteenth
embodiment.
MODE FOR CARRYING OUT THE INVENTION
[0061] An explanation will be made below on the basis of the
drawings about specified embodiments of the particulate matter
processing apparatus according to the present invention. It is
noted that the following embodiments can be appropriately combined
with each other.
First Embodiment
[0062] FIG. 1 shows a schematic arrangement of a particulate matter
processing apparatus 1 according to this embodiment. The
particulate matter processing apparatus 1 is provided, for example,
for an exhaust gas passage 2 of a gasoline engine. The particulate
matter processing apparatus 1 can be also provided for an exhaust
gas passage of a diesel engine.
[0063] The particulate matter processing apparatus 1 is constructed
to include a housing 3 which has both ends connected to the exhaust
gas passage 2. A stainless steel material is used for a material of
the housing 3. The housing 3 is formed to have a hollow columnar
shape. Both ends of the housing 3 are formed to have tapered shapes
such that the cross-sectional area of the flow passage for the
exhaust gas is decreased at positions disposed nearer to the end
portion. In FIG. 1, the exhaust gas flows in the direction of the
arrow B through the exhaust gas passage 2. Therefore, the housing 3
may be regarded as a part of the exhaust gas passage 2. That is,
the wall surface of the housing 3 can be regarded as the wall
surface of the exhaust gas passage 2.
[0064] A flange 21 is formed at an end portion of the exhaust gas
passage 2, and a flange 31 is formed at an end portion of the
housing 3. The exhaust gas passage 2 and the housing 3 are
fastened, for example, by bolts and nuts by the aid of the flange
21 disposed on the side of the exhaust gas passage and the flange
31 disposed on the side of the housing 3. An electric insulator may
be provided between the flange 21 disposed on the side of the
exhaust gas passage and the flange 31 disposed on the side of the
housing 3.
[0065] An electrode 5 having a circular cross section is attached
to the housing 3. It is also allowable that the cross-sectional
shape of the electrode 5 is any other shape including, for example,
a polygonal shape. The electrode 5 penetrates through the side
surface of the housing 3. The electrode 5 extends from the side
surface of the housing 3 in the direction of the central axis A of
the housing 3, and the electrode 5 is bent toward the downstream
side of the flow of the exhaust gas at a bent portion 51 in the
vicinity of the central axis A. The electrode 5 extends toward the
downstream side of the flow of the exhaust gas in parallel to the
central axis A. Therefore, in this embodiment, the central axis of
the electrode 5 disposed on the downstream side from the bent
portion 51 is the same as the central axis A of the housing 3.
[0066] Further, an insulator portion 52, which is composed of an
electric insulator, is provided for the electrode 5 so that the
electricity does not flow between the electrode 5 and the housing 3
at the portion at which the electrode 5 penetrates through the
housing 3. The insulator portion 52 is positioned between the
electrode 5 and the housing 3. The insulator portion 52 insulates
the electricity, and the insulator portion 52 fixes the electrode 5
to the housing 3.
[0067] A plurality of protruding portions 54, which extend toward
the side surface of the housing 3 perpendicularly to the central
axis A, are provided on the downstream side of the flow of the
exhaust gas from the bent portion 51. The protruding portion 54 is
formed to have a needle-like shape. The plurality of protruding
portions 54 are formed while providing spacings from the upstream
side to the downstream side of the flow of the exhaust gas.
Further, the plurality of protruding portions 54 are provided, for
example, at equal angles around the central axis A about the center
of the central axis A. It is also allowable that the plurality of
protruding portions 54 are provided in a radial form about the
center of the central axis A. The housing 3, which is disposed
around the protruding portions 54, has the constant inner
diameter.
[0068] In this embodiment, the protruding portion 542, which is
provided on the relatively downstream side, has the length that is
shorter than the length of the protruding portion 541 which is
provided on the relatively upstream side. Further, in the case of
the protruding portions 541 which are provided on the upstream
side, the installation spacing in the flow direction of the exhaust
gas between the protruding portions 541 is relatively long. In the
case of the protruding portions 542 which are provided on the
downstream side, the installation spacing in the flow direction of
the exhaust gas between the protruding portions 542 is relatively
short.
[0069] As shown in FIG. 1, for example, the protruding portions 541
(hereinafter referred to as "upstream side protruding portions 541"
as well), which include the first to third protruding portions 541
as counted in the flow direction of the exhaust gas from the
protruding portion 541 disposed near to the bent portion 51, have
the length that is longer than the length of the protruding
portions 542 which are disposed on the downstream side therefrom
(hereinafter referred to as "downstream side protruding portion
542" as well). That is, the length L3 of the upstream side
protruding portion 541 is longer than the length L4 of the
downstream side protruding portion 542. Accordingly, the distance
L5, which ranges from the forward end of the upstream side
protruding portion 541 to the wall surface of the housing 3, is
shorter than the distance L6 which ranges from the forward end of
the downstream side protruding portion 542 to the wall surface of
the housing 3. It is also allowable that the length of the
protruding portion 54 is the distance from the central axis A to
the forward end of the protruding portion 54. Alternatively, it is
also allowable that the length of the protruding portion 54 is the
length from the root of the protruding portion 54 to the forward
end.
[0070] It is also allowable that the length of the protruding
portion 542 existing in a region of not less than a predetermined
distance from the bent portion 51 is shorter than the length of the
protruding portion 541 existing in a region of less than the
predetermined distance from the bent portion 51. All of the lengths
of the protruding portions 541 existing in the region of less than
the predetermined distance from the bent portion 51 may be
identical with each other. Alternatively, the lengths of the
protruding portions 541 existing in the region of less than the
predetermined distance from the bent portion 51 may be shortened at
positions disposed on the more downstream side of the flow of the
exhaust gas. Further, all of the lengths of the protruding portions
542 existing in the region of not less than the predetermined
distance from the bent portion 51 may be identical with each other.
Alternatively, the lengths of the protruding portions 542 existing
in the region of not less than the predetermined distance from the
bent portion 51 may be shortened at positioned disposed at the more
downstream side of the flow of the exhaust gas.
[0071] Further, as shown in FIG. 1, the installation spacing L1 in
the flow direction of the exhaust gas between the upstream side
protruding portions 541 is longer than the installation spacing L2
in the flow direction of the exhaust gas between the downstream
side protruding portions 542.
[0072] It is also allowable that the spacing in the flow direction
of the exhaust gas between the protruding portions 542 existing in
the region of not less than the predetermined distance from the
bent portion 51 is shorter than the spacing in the flow direction
of the exhaust gas between the protruding portions 541 existing in
the region of less than the predetermined distance from the bent
portion 51. Further, it is also allowable that the longer the
protruding portion 54 is, the longer the spacing in the flow
direction of the exhaust gas is.
[0073] The electrode 5 is connected to a power source via an
electric wire 53. That is, the electrode 5 is connected to the
power source via the electric wire 53 at one portion. The power
source can apply the electricity to the electrode 5, and the power
source can change the application voltage. Further, the housing 3
is electrically grounded.
[0074] In the particulate matter processing apparatus 1 constructed
as described above, the negative DC high voltage is applied from
the power source to the electrode 5, and thus the electrons are
released from the electrode 5. That is, the electrons are released
from the electrode 5 by lowering the electric potential of the
electrode 5 as compared with the housing 3. Thus, PM contained in
the exhaust gas can be negatively electrified by the electrons.
Negatively electrified PM is moved in accordance with the Coulomb
force and the gas flow. Then, when PM arrives at the housing 3, the
electrons, with which PM has been negatively electrified, are
released to the housing 3. PM, from which the electrons have been
released to the housing 3, are aggregated, and the particulate
diameter is increased. Further, the aggregation of PM reduces the
number of particulates of PM. That is, the particulate diameter of
PM can be increased and the number of particulates of PM can be
reduced by applying the voltage to the electrode 5.
[0075] Further, the length of the protruding portion 542 disposed
on the downstream side of the flow of the exhaust gas is shorter
than that of the protruding portion 541 disposed on the upstream
side of the flow of the exhaust gas. Therefore, it is possible to
reduce the mass on the forward end side of the electrode 5, i.e.,
on the downstream end side of the electrode 5. Accordingly, it is
possible to decrease the bending moment generated in the electrode
5, and hence it is possible to suppress the breakage and the
deformation of the electrode 5.
[0076] FIG. 2 shows a field intensity distribution around the
electrode 5 according to this embodiment. Broken lines shown in
FIG. 2 indicate the field intensity distribution. The field
intensity (electric field strength) is large in the vicinity of the
central axis A of the housing 3, and the field intensity is
decreased at positions separated farther from the central axis
A.
[0077] In the meantime, as the spacing between the protruding
portions 54 is more shortened, the range, in which the field
intensity is large, is more spread in the radial direction of the
housing 3. Further, as the length of the protruding portion 54 is
more lengthened, the range, in which the field intensity is large,
is more spread in the radial direction of the housing 3. Therefore,
when the protruding portion 542, which is disposed on the
downstream side of the flow of the exhaust gas, is relatively
shortened, the field intensity, which is provided on the forward
end side of the electrode 5, is relatively decreased thereby. In
relation thereto, it is possible to suppress the decrease in the
field intensity by shortening the spacing in the flow direction of
the exhaust gas between the protruding portions 542 disposed on the
forward end side of the electrode 5. That is, it is possible to
suppress a situation in which the field intensity is excessively
decreased on the forward end side of the electrode 5.
[0078] In this context, FIG. 3 shows the field intensity
distribution provided when the protruding portions 54 disposed on
the forward end side of the electrode 5 are relatively shortened,
and the protruding portions 54 are arranged at equal intervals
(equal spacings) in the region ranging from the bent portion 51 to
the forward end of the electrode 5. As shown in FIG. 3, when all of
the spacings between the protruding portions 54 are identical in
the region ranging from the bent portion 51 to the forward end of
the electrode 5, the field intensity is greatly lowered on the
forward end side of the electrode 5. Therefore, the force, which is
exerted to direct or move PM toward the wall surface of the housing
3, is excessively decreased, and it is difficult to aggregate
PM.
[0079] On the other hand, when the spacing between the protruding
portions 54 is shortened in conformity with the shortening of the
length of the protruding portion 54, it is possible to suppress the
excessive decrease in the field intensity. Therefore, it is
possible to facilitate the aggregate of PM. The length of the
upstream side protruding portion 541 and the installation spacing
in the flow direction of the exhaust gas between the upstream side
protruding portions 541 are set in such ranges that PM contained in
the exhaust gas can be electrified. The ranges can be determined,
for example, by an experiment. On the other hand, the length of the
downstream side protruding portion 542 and the installation spacing
in the flow direction of the exhaust gas between the downstream
side protruding portions 542 are set in such ranges that PM can be
directed toward the wall surface of the housing 3. The ranges can
be also determined, for example, by an experiment.
[0080] As explained above, according to this embodiment, the field
intensity around the upstream side protruding portion 541 can be
made larger than the field intensity around the downstream side
protruding portion 542. Accordingly, it is possible to electrify PM
more reliably around the upstream side protruding portion 541 for
which the field intensity is relatively large. Further, when PM,
which is electrified around the upstream side protruding portion
541, is allowed to flow to the downstream side on which the field
intensity is relatively small, PM is gently moved toward the wall
surface of the housing 3. That is, even when the field intensity is
decreased on the downstream side, the aggregation between PM is
facilitated. Therefore, it is possible to enhance the effect to
reduce the number of particulates of PM.
[0081] Further, when the downstream side protruding portion 542 is
made shorter than the upstream side protruding portion 541, and the
spacing in the flow direction of the exhaust gas between the
downstream side protruding portions 542 is made shorter than the
spacing in the flow direction of the exhaust gas between the
upstream side protruding portions 541, then it is thereby possible
to reduce the mass of the downstream side protruding portion 542.
Further, it is possible to suppress the excessive decrease in the
field intensity on the downstream side. According to the features
as described above, it is possible to facilitate the aggregation of
PM, while suppressing the malfunction or breakdown of the
particulate matter processing apparatus 1. Further, it is possible
to decrease the number of particulates of PM. Further, when the
mass is reduced in the vicinity of the forward end portion of the
electrode 5, the breakage and the deformation are suppressed, even
when the electrode 5 is supported at one portion. Therefore, it is
enough that the insulator portion 52 is provided at one portion as
well. Therefore, it is possible to reduce the production cost as
compared with such a situation that the electrode 5 is supported at
two or more portions. Further, it is enough that the power source
supplies the electric power to one portion of the electrode 5, and
the identical voltage is applied to the entire electrode 5.
Therefore, it is also possible to reduce the production cost by
means of this feature.
Second Embodiment
[0082] FIG. 4 shows a schematic arrangement of a particulate matter
processing apparatus 1 according to this embodiment. Components or
parts, which are the same as those of the embodiment described
above, are designated by the same reference numerals, any
explanation of which will be omitted. As for protruding portions 54
according to this embodiment, the lengths are shorter at positions
disposed on the more downstream side of the flow of the exhaust
gas. Accordingly, it is possible to decrease the mass of the
protruding portion 54 at positions farther from the bent portion
51. Thus, it is possible to decrease the mass on the forward end
side of the electrode 5. Therefore, it is possible to decrease the
bending moment generated in the electrode 5. Therefore, it is
possible to improve the reliability.
[0083] Further, in this embodiment, the spacing in the flow
direction of the exhaust gas between the protruding portions 54 is
shorter on the more downstream side of the flow of the exhaust gas.
That is, the shorter the length of the protruding portion 54 is,
the shorter the spacing between the protruding portions 54 is. For
example, it is also appropriate that the lengths of the respective
protruding portions 54 are set so that the forward ends of the
other protruding portions 54 are positioned on a line to connect
the forward end of the most upstream protruding portion 54 and the
forward end of the most downstream protruding portion 54.
[0084] In this context, FIG. 5 shows a field intensity distribution
according to this embodiment. Broken lines shown in FIG. 5 indicate
the field intensity distribution. In this way, the field intensity
is more uniformized as compared with the case shown in FIG. 2 or
FIG. 3. Therefore, it is possible to facilitate the aggregation of
PM.
[0085] Further, in the particulate matter processing apparatus 1
according to this embodiment, it is possible to reduce the mass of
the protruding portion 54 disposed on the downstream side. Further,
it is possible to suppress such a situation that the field
intensity is excessively decreased on the downstream side.
According to the features as described above, it is possible to
facilitate the aggregation of PM, while suppressing the malfunction
or breakdown of the particulate matter processing apparatus 1.
Therefore, it is possible to decrease the number of particulates of
PM.
Third Embodiment
[0086] FIG. 6 shows a schematic arrangement of a particulate matter
processing apparatus 1 according to this embodiment. Components or
parts, which are the same as those of the embodiment described
above, are designated by the same reference numerals, any
explanation of which will be omitted. As for an insulator portion
52 according to this embodiment, the protruding amount protruding
into the exhaust gas is decreased as compared with the embodiment
described above. For example, it is also appropriate that the
protruding amount is necessary and minimum to secure the insulation
of the electricity. The protruding amount is the protruding amount
ranging from the wall surface of the housing 3. It is also
appropriate that the protruding amount resides in the distance
ranging from the wall surface of the housing 3 to the forward end
of the insulator portion 52.
[0087] In this way, when the protruding amount of the insulator
portion 52 protruding into the exhaust gas is decreased, it is
thereby possible to suppress the sudden change of the temperature
of the insulator portion 52. If the insulator portion 52 greatly
protrudes into the exhaust gas, the temperature of the insulator
portion 52 is suddenly changed, for example, when the fuel cut is
carried out after the internal combustion engine is operated at the
maximum output. Further, when the water contained in the exhaust
gas is condensed to form water droplets which are allowed to adhere
to the insulator portion 52, the temperature of the insulator
portion 52 is also suddenly changed. If the temperature of the
insulator portion 52 is suddenly changed as described above, it is
feared that the insulator portion 52 may be broken.
[0088] On the contrary, it is possible to suppress, for example,
the adhesion of water droplets by decreasing the protruding amount
of the insulator portion 52 protruding into the exhaust gas as far
as possible. Therefore, it is possible to suppress the sudden
change of the temperature of the insulator portion 52. Accordingly,
it is possible to suppress the breakage of the insulator portion
52.
Fourth Embodiment
[0089] FIG. 7 shows a schematic arrangement of a particulate matter
processing apparatus 1 according to this embodiment. Component or
parts, which are the same as those of the embodiment described
above, are designated by the same reference numerals, any
explanation of which will be omitted.
[0090] In the particulate matter processing apparatus 1 according
to this embodiment, the electrode 5, which is disposed on the side
of the insulator portion 52 as compared with the bent portion 51,
has the diameter of the cross section that is larger than the
diameter of the cross section of the electrode 5 which is disposed
on the side of the forward end as compared with the bent portion 51
(on the downstream side of the flow of the exhaust gas). Further,
the diameter of the cross section is more decreased at positions
nearer to the forward end side of the electrode 5 at the bent
portion 51. That is, the thickness of the electrode 5 is changed at
the bent portion 51.
[0091] In the particulate matter processing apparatus 1 constructed
as described above, it is possible to decrease the field intensity
at the bent portion 51. Accordingly, it is possible to improve the
insulation performance. That is, if the protruding amount of the
insulator portion 52 protruding into the exhaust gas is merely
decreased, it is feared that the insulation performance may be
deteriorated. However, it is possible to suppress the decrease in
the insulation performance by changing the thickness of the
electrode 5. Accordingly, it is possible to suppress the electric
discharge caused by any portion other than the protruding portion
54. Therefore, it is possible to improve the reliability, and it is
possible to facilitate the aggregation of PM.
Fifth Embodiment
[0092] FIG. 8 shows a schematic arrangement of a particulate matter
processing apparatus 1 according to this embodiment. Component or
parts, which are the same as those of the embodiment described
above, are designated by the same reference numerals, any
explanation of which will be omitted.
[0093] In the particulate matter processing apparatus 1 according
to this embodiment, the electrode 5, which is disposed on the side
of insulator portion 52 as compared with the bent portion 51, has
the diameter of the cross section that is larger than the diameter
of the cross section of the electrode 5 which is disposed on the
forward end side as compared with the bent portion 51 (on the
downstream side of the flow of the exhaust gas). Further, as for
the portion of the electrode 5 ranging from the insulator portion
52 to the bent portion 51, the diameter of the cross section is
more decreased at positions nearer to the bent portion 51. Further,
in relation to the bent portion 51, the diameter of the cross
section is more decreased at positions disposed nearer to the
forward end side of the electrode 5. That is, the thickness of the
electrode 5 is changed in the region ranging from the insulator
portion 52 to the bent portion 51.
[0094] In the particulate matter processing apparatus 1 constructed
as described above, it is possible to decrease the relative field
intensity at the bent portion 51. Accordingly, it is possible to
improve the insulation performance. Further, when the diameter of
the cross section of the electrode 5 is increased in the vicinity
of the insulator portion 52, it is thereby possible to especially
decrease the field intensity at this portion. That is, any short
circuit is easily formed in the vicinity of the insulator portion
52. However, it is possible to suppress the short circuit by
decreasing the field intensity. Accordingly, it is possible to
suppress the electric discharge caused by any portion other than
the protruding portion 54. Therefore, it is possible to improve the
reliability, and it is possible to facilitate the aggregation of
PM.
Sixth Embodiment
[0095] FIG. 9 shows an electrode 5 of a particulate matter
processing apparatus 1 according to this embodiment as viewed from
the downstream side of the flow of the exhaust gas. Component or
parts, which are the same as those of the embodiment described
above, are designated by the same reference numerals, any
explanation of which will be omitted.
[0096] The electrode 5 shown in FIG. 9 is constructed to include
protruding portions 541A (hereinafter referred to as "protruding
portions 541A of the first array") which are installed at positions
having the shortest distance from the bent portion 51, protruding
portions 541B (hereinafter referred to as "protruding portions 541B
of the second array") which are installed at positions of the
second shortest distance from the bent portion 51, and protruding
portions 541C (hereinafter referred to as "protruding portions 541C
of the third array) which are installed at positions of the third
shortest distance from the bent portion 51. That is, the protruding
portions 541A of the first array, the protruding portions 541B of
the second array, and the protruding portions 541C of the third
array are installed from the upstream side while providing the
spacings in the flow direction of the exhaust gas.
[0097] Further, the two protruding portions 541A of the first array
are provided, and they are mutually directed in the opposite
directions while interposing the central axis A. That is, the two
protruding portions 541A of the first array are provided while
giving an angle of 180 degrees about the center of the central axis
A. The two protruding portions 541B of the second array are also
provided, and they are mutually directed in the opposite directions
while interposing the central axis A. Further, the protruding
portions 541A of the first array and the protruding portions 541B
of the second array are arranged while being deviated by 60 degrees
about the center of the central axis A. Further, the two protruding
portions 541C of the third array are also provided, and they are
mutually directed in the opposite directions while interposing the
central axis A. The protruding portions 541A of the first array and
the protruding portions 541C of the third array are arranged while
being deviated by 120 degrees about the center of the central axis
A. That is, the protruding portions 541B of the second array and
the protruding portions 541C of the third array are arranged while
being deviated by 60 degrees about the center of the central axis
A. Accordingly, the arrangement appears such that the protruding
portions 541A, 541B, 541C are provided at every 60 degrees about
the center of the central axis A as viewed from the downstream side
of the flow of the exhaust gas.
[0098] In this way, the arrangement is made while deviating the
angle about the central axis at the positions disposed on the more
downstream side as directed from the bent portion 51 to the
protruding portions 541A of the first array, the protruding
portions 541B of the second array, and the protruding portions 541C
of the third array. Accordingly, it is possible to uniformize the
spatial distribution of the electric field. Therefore, it is
possible to facilitate the aggregation of PM. When other protruding
portions are further provided on the downstream side, the
consideration may be made in the same manner as described above. It
is also allowable that the respective protruding portions are
arranged in a radial form as viewed from the downstream side of the
flow of the exhaust gas. Further, it is also allowable that the
protruding portion is more shortened and the spacing in the flow
direction of the exhaust gas between the protruding portions is
more shortened at positions disposed on the more downstream side of
the flow of the exhaust gas.
Seventh Embodiment
[0099] FIG. 10 shows a schematic arrangement of a particulate
matter processing apparatus 1 according to this embodiment.
Component or parts, which are the same as those of the embodiment
described above, are designated by the same reference numerals, any
explanation of which will be omitted.
[0100] In the particulate matter processing apparatus 1 according
to this embodiment, the diameter D1 of the housing 3 around the
protruding portion 54 is smaller than the diameter D2 of the
housing 3 at the portion at which the insulator portion 52 is
provided. Accordingly, the exhaust gas hardly flows around the
insulator portion 52. It is also allowable that the distance
between the central axis A and the housing 3 at the portion at
which the insulator portion 52 is provided is longer than the
distance between the central axis A and the housing 3 around the
protruding portion 54.
[0101] In the particulate matter processing apparatus 1 constructed
as described above, it is possible to suppress such a situation
that the water droplets and the substance discharged from the
internal combustion engine (for example, combustion product) pass
through the surroundings of the insulator portion 52. That is, it
is possible to suppress such a situation that the water droplets
and the combustion product adhere to the insulator portion 52 and
the insulation performance is deteriorated. Accordingly, it is
possible to suppress the electric discharge caused by any portion
other than the protruding portion 54. Therefore, it is possible to
improve the reliability, and it is possible to facilitate the
aggregation of PM.
Eighth Embodiment
[0102] FIG. 11 shows a schematic arrangement of a particulate
matter processing apparatus 1 according to this embodiment.
Component or parts, which are the same as those of the embodiment
described above, are designated by the same reference numerals, any
explanation of which will be omitted.
[0103] In the particulate matter processing apparatus 1 according
to this embodiment, the diameter D3 of the housing 3 around the
protruding portion 54 is small as compared with the arrangement of
the seventh embodiment. Therefore, the diameter D3 of the housing 3
around the protruding portion 54 is much smaller than the diameter
D4 of the housing 3 at the portion at which the insulator portion
52 is provided. Accordingly, the exhaust gas hardly flows around
the insulator portion 52, and the field intensity around the
protruding portion 54 becomes relatively large. Therefore, it is
possible to further suppress the decrease in the insulation
performance, and it is possible to further facilitate the
aggregation of PM. Accordingly, it is possible to suppress the
electric discharge caused by any portion other than the protruding
portion 54. Therefore, it is possible to improve the reliability,
and it is possible to facilitate the aggregation of PM.
Ninth Embodiment
[0104] FIG. 12 shows a schematic arrangement of a particulate
matter processing apparatus 1 according to this embodiment.
Component or parts, which are the same as those of the embodiment
described above, are designated by the same reference numerals, any
explanation of which will be omitted.
[0105] In the particulate matter processing apparatus 1 according
to this embodiment, an air supply unit 6 is provided, which
supplies the air to the surroundings of the insulator portion 52.
The air supply unit 6 is constructed to include an air supply tube
61 and a pump 62. The pump 62 is controlled by the control unit 7.
When the pump 62 is operated, the air is discharged from the pump
62. The air flows through the air supply tube 61, and the air is
supplied to the surroundings of the insulator portion 52. It is
also allowable that the air is supplied to the surroundings of any
other electric insulation member provided around the insulator
portion 52.
[0106] In this arrangement, when the air is supplied to the
surroundings of the insulator portion 52, it is possible to
suppress the adhesion of the water droplets and the combustion
product to the insulator portion 52. Therefore, it is possible to
suppress the decrease in the insulation performance. Accordingly,
it is possible to suppress the electric discharge caused by any
portion other than the protruding portion 54. Therefore, it is
possible to improve the reliability, and it is possible to
facilitate the aggregation of PM.
[0107] FIG. 13 shows a flow chart illustrating a control flow of
the air supply unit 6 according to this embodiment. This routine is
executed by the control unit 7 every time when a predetermined time
elapses.
[0108] In Step S101, it is judged whether or not an IG switch is
turned ON. The IG switch is the switch which is to be turned ON
when the driver starts the internal combustion engine. That is, in
this step, it is judged whether or not the request is given to
start the internal combustion engine. If the affirmative judgment
is made in Step S101, the routine proceeds to Step S102. On the
other hand, if the negative judgment is made, this routine is
completed.
[0109] In Step S102, the electric insulation resistance of the
electrode 5 is measured. In this procedure, if the water droplet or
the like adheres to the electrode 5, the electric insulation
resistance is lowered. Therefore, when the decrease in the electric
insulation resistance is measured, it is possible to judge whether
or not the water droplet or the like adheres to the electrode 5.
For example, when a predetermined voltage is applied to the
electrode 5, and the current provided in this situation is
measured, then it is possible to detect the electric insulation
resistance. After the completion of the process of Step S102, the
routine proceeds to Step S103.
[0110] In Step S103, it is judged whether or not the electric
insulation resistance of the electrode 5 is less than a
predetermined value. The predetermined value referred to herein is
the lower limit value of the electric insulation resistance to be
provided when the water droplet or the like does not adhere. It is
also allowable that the predetermined value is the value to be used
in order to judge the decrease in the electric insulation
resistance. The predetermined value is previously determined, for
example, by an experiment. If the affirmative judgment is made in
Step S103, it is considered that the water droplet or the like
adheres. Therefore, the routine proceeds to Step S104. On the other
hand, if the negative judgment is made in Step S103, it is
considered that the water droplet or the like does not adhere.
Therefore, the routine proceeds to Step S106.
[0111] In Step S104, the pump 62 is operated. That is, the air is
supplied to the surroundings of the insulator portion 52, and the
water droplet or the like is removed. After the completion of the
process of Step S104, the routine proceeds to Step S105.
[0112] In Step S105, it is judged whether or not the electric
insulation resistance is larger than a predetermined value. The
predetermined value referred to herein may be the same as the
predetermined value used in Step S103. It is also allowable that
the predetermined value is the value to judge whether or not the
electric insulation resistance is recovered. The predetermined
value is previously determined, for example, by an experiment. If
the affirmative judgment is made in Step S105, the water droplet or
the like is removed. Therefore, the routine proceeds to Step S106.
On the other hand, if the negative judgment is made in Step S105,
the water droplet or the like remains. Therefore, the routine
returns to Step S104, and the supply of the air is continued.
[0113] In Step S106, the internal combustion engine is started.
That is, the internal combustion engine is started in the state in
which the water droplet or the like does not adhere to the
electrode 5. After the completion of the process of Step S106, this
routine is completed.
[0114] In this embodiment, when the water droplet or the like does
not adhere to the electrode 5, the air may be supplied from the
pump 62 to the exhaust gas purification catalyst. Accordingly, it
is possible to facilitate the oxidation of HC and CO contained in
the exhaust gas.
Tenth Embodiment
[0115] FIG. 14 shows a schematic arrangement of a particulate
matter processing apparatus 1 according to this embodiment.
Component or parts, which are the same as those of the embodiment
described above, are designated by the same reference numerals, any
explanation of which will be omitted.
[0116] In the particulate matter processing apparatus 1 according
to this embodiment, a throttle portion 4, at which the
cross-sectional area of the passage for the exhaust gas is
decreased, is formed for the housing 3 on the upstream side from
the insulator portion 52. Further, a check valve 41 is provided for
the throttle portion 4. The gas, which intends to flow from the
outside into the inside of the housing 3, is allowed to pass
through the check valve 41, while the gas, which intends to flow
from the inside to the outside of the housing 3, is shut off by the
check valve 41.
[0117] In the particulate matter processing apparatus 1 constructed
as described above, the flow rate of the gas is increased when the
gas, which is discharged from the internal combustion engine,
passes through the throttle portion 4. Accordingly, the check valve
41 is opened, and the air is introduced into the housing 3. The
position, at which the check valve 41 is provided, is determined so
that the air arrives at the insulator portion 52. In this way, even
when any pump is not provided, it is possible to supply the air to
the surroundings of the insulator portion 52. Therefore, it is
possible to suppress the decrease in the insulation performance.
Accordingly, it is possible to suppress the electric discharge
caused by any portion other than the protruding portion 54.
Therefore, it is possible to improve the reliability, and it is
possible to facilitate the aggregation of PM.
Eleventh Embodiment
[0118] FIG. 15 shows a schematic arrangement of a particulate
matter processing apparatus 1 according to this embodiment.
Component or parts, which are the same as those of the embodiment
described above, are designated by the same reference numerals, any
explanation of which will be omitted.
[0119] In this embodiment, the electrode 5 is connected to a power
source 8 via an electric wire 53. The power source 8 applies the
electricity to the electrode 5, and the power source 8 can change
the application voltage. The power source 8 is connected to a
control unit 7 and a battery 9 via the electric wire. The control
unit 7 controls the voltage which is applied to the electrode 5 by
the power source 8.
[0120] Further, a ground side electric wire 55 is connected to the
housing 3. The housing 3 is grounded via the ground side electric
wire 55. A detecting unit 10, which detects the current allowed to
pass through the ground side electric wire 55, is provided for the
ground side electric wire 55. The detecting unit 10 may be an
ammeter. For example, the detecting unit 10 detects the current by
measuring the electric potential difference between the both ends
of a resistor provided at an intermediate portion of the ground
side electric wire 55. The detecting unit 10 is connected to the
control unit 7 via an electric wire. Thus, the current, which is
detected by the detecting unit 10, is inputted into the control
unit 7.
[0121] An accelerator opening degree sensor 71, a crank position
sensor 72, a temperature sensor 73, and an air flow meter 74 are
connected to the control unit 7. The electric signal, which
corresponds to the amount obtained by pedaling an accelerator pedal
by a driver of a vehicle carried with the internal combustion
engine, is outputted by the accelerator opening degree sensor 71 to
detect the engine load. The crank position sensor 72 detects the
number of revolutions of the engine. The temperature sensor 73
detects the temperature of the internal combustion engine by
detecting the temperature of the cooling water of the internal
combustion engine or the temperature of the lubricating oil. The
air flow meter 74 detects the intake air amount of the internal
combustion engine.
[0122] In the particulate matter processing apparatus 1 constructed
as described above, the electrons are released from the electrode 5
by applying the negative DC high voltage from the power source 8 to
the electrode 5. That is, the electrons are released from the
electrode 5 by lowering the electric potential of the electrode 5
as compared with the housing 3. Thus, PM contained in the exhaust
gas can be negatively electrified with the electrons. The
negatively electrified PM is moved in accordance with the Coulomb
force and the gas flow. Further, when PM arrives at the housing 3,
the electrons, with which PM is negatively electrified, are
released to the housing 3. PM, from which the electrons have been
released to the housing 3, are aggregated, and the particulate
diameter is increased. Further, when PM is aggregated, the number
of particulates of PM is decreased. That is, when the voltage is
applied to the electrode 5, then it is possible to increase the
particulate diameter of PM, and it is possible to decrease the
number of particulates of PM.
[0123] In the meantime, when the negative voltage, which is applied
to the electrode 5, is increased, a larger amount of electrons are
released from the electrode 5. Therefore, it is possible to further
decrease the number of particulates of PM. However, if the
application voltage to the electrode 5 is excessively increased,
the strong electric discharge such as the corona discharge and the
arc discharge may be caused. If the strong electric discharge is
caused as described above, PM is made fine and minute by the high
speed electrons. Therefore, in order to decrease the number of
particulates of PM, it is appropriate that the voltage is regulated
to a voltage which is lower than the voltage at which the strong
electric discharge such as the corona discharge or the like is
caused.
[0124] In this procedure, if the strong electric discharge is
caused by the electrode 5, the current, which passes through the
electrode 5, is suddenly raised and then immediately lowered. FIG.
16 shows the transition of the current detected by the detecting
unit 10 in relation to each of the application voltages. The larger
the application voltage is, the larger the current detected by the
detecting unit 10 is. Further, the current, which is detected when
the application voltage is relatively small, is substantially
constant. When the current is substantially constant, any strong
electric discharge is not generated. However, PM is negatively
electrified by the electrons released from the electrode 5, and PM
releases the electrons to the housing 3. Therefore, the current is
detected. That is, even when any strong electric discharge such as
the corona discharge or the like is not generated, it is possible
to aggregate PM.
[0125] On the other hand, when the application voltage becomes
relatively large, then the current detected by the detecting unit
10 is increased, and the pulse current is generated. Further, the
larger the application voltage is, the higher the frequency of
generation of the pulse current is. The pulse current is generated
by the strong electric discharge such as the corona discharge or
the like. Whether or not the pulse current is generated is judged
by the control unit 7. That is, in this embodiment, the control
unit 7 corresponds to the judging unit of the present
invention.
[0126] In view of the above, in this embodiment, when the pulse
current is generated, the control unit 7 operates the power source
8 so that the application voltage is made smaller than that
provided at the present point in time. Accordingly, the generation
of the pulse current is suppressed, and the increase in the number
of particulates of PM is suppressed. On the other hand, the
application voltage is increased until the pulse current is
generated. Accordingly, it is possible to raise the application
voltage as high as possible. Therefore, it is possible to further
decrease the number of particulates of PM. It is also appropriate
that the sign of the generation of the pulse current is read from
the current before the pulse current is generated, and the
application voltage is decreased before the pulse current is
generated.
[0127] For example, when the application voltage is subjected to
the feedback control, it is thereby possible to raise the
application voltage as high as possible within a range in which the
pulse current is not generated. Accordingly, it is possible to
further facilitate the aggregation of PM. Therefore, it is possible
to further decrease the number of particulates of PM.
Twelfth Embodiment
[0128] FIG. 17 shows a schematic arrangement of a particulate
matter processing apparatus 1 according to this embodiment.
Component or parts, which are the same as those of the embodiment
described above, are designated by the same reference numerals, any
explanation of which will be omitted.
[0129] In the particulate matter processing apparatus 1 according
to this embodiment, the field intensity is changed by changing the
thickness of the protruding portion 54.
[0130] Further, in this embodiment, the diameter of the cross
section of the root of the protruding portion 541 disposed on the
upstream side is made larger than the diameter of the cross section
of the root of the protruding portion 542 disposed on the
downstream side. That is, the protruding portion 541 disposed on
the upstream side is thicker than the protruding portion 542
disposed on the downstream side. Further, the installation spacing
L7 in the flow direction of the exhaust gas between the protruding
portions 541 is made relatively short in relation to the protruding
portions 541 disposed on the upstream side. The installation
spacing L8 in the flow direction of the exhaust gas between the
protruding portions 542 is made relatively long in relation to the
protruding portions 542 disposed on the downstream side. All of the
protruding portions 54 have the same length. Therefore, the
distance from the protruding portion 54 to the wall surface of the
housing 3 is also the same in relation to all of the protruding
portions 54.
[0131] As shown in FIG. 17, for example, the first to fourth
nearest protruding portions 541, which are referred to in the flow
direction of the exhaust gas from the side near to the bent portion
51, have the diameters of the roots that are larger than the
diameters of the roots of the protruding portions 542 which are
disposed on the more downstream side. The diameter of the root is
the diameter provided at the portion at which the diameter is
maximized in relation to each of the protruding portions 54.
[0132] It is also appropriate that the diameters of the protruding
portions 541 existing in a region of less than a predetermined
distance from the bent portion 51 are larger than the diameters of
the protruding portions 542 existing in a region of not less than
the predetermined distance from the bent portion 51. Further, it is
also appropriate that all of the lengths of the protruding portions
541 existing in a region of less than a predetermined distance from
the bent portion 51 are identical, or the lengths are shorter at
positions on the more downstream side. Further, it is also
appropriate that all of the lengths of the protruding portions 542
existing in a region of not less than the predetermined distance
from the bent portion 51 are identical, or the lengths are shorter
at positions on the more downstream side.
[0133] It is also appropriate that the spacing in the flow
direction of the exhaust gas between the protruding portions 542
existing in a region of not less than a predetermined distance from
the bent portion 51 is shorter than the spacing in the flow
direction of the exhaust gas between the protruding portions 541
existing in a region of less than the predetermined distance from
the bent portion 51. Further, it is also appropriate that the
larger the diameter of the root of the protruding portion 54 is,
the shorter the spacing in the flow direction of the exhaust gas
is.
[0134] In this arrangement, the larger the diameter of the cross
section of the root of the protruding portion 54 is, i.e., the
thicker the protruding portion 54 is, the more increased the
rigidity of the protruding portion 54 is. The relatively high
rigidity is required for the protruding portion 541 provided on the
relatively upstream side of the flow of the exhaust gas. Therefore,
it is conceived that the protruding portion 541 disposed on the
upstream side is thickened. On the other hand, when the protruding
portion 54 is thickened, the field intensity is lowered. Therefore,
if the protruding portion 541 disposed on the upstream side is
merely thickened, it is feared that the field intensity on the
upstream side may be lowered. In relation thereto, when the
installation spacing in the flow direction of the exhaust gas
between the protruding portions 541 disposed on the upstream side
is shortened, it is thereby possible to suppress the decrease in
the field intensity. That is, it is possible to more reliably
electrify PM by means of the protruding portions 541 disposed on
the upstream side.
[0135] Further, it is also allowable that the protruding portion
542 disposed on the downstream side in the flow of the exhaust gas
has the low rigidity as compared with the protruding portion 541
disposed on the upstream side. Therefore, it is possible to
relatively thin the protruding portion 542 disposed on the
downstream side. Further, when the protruding portion 542 disposed
on the downstream side is relatively thinned, the field intensity
is thereby raised. Therefore, it is possible to lengthen the
installation spacing in the flow direction of the exhaust gas
between the protruding portions 542 disposed on the downstream
side. In this way, it is possible to relatively thin the protruding
portion 542 disposed on the downstream side, and it is possible to
lengthen the setting spacing in the flow direction of the exhaust
gas between the protruding portions 542 disposed on the downstream
side. Therefore, it is possible to reduce the mass in the vicinity
of the forward end of the electrode 5. Accordingly, it is possible
to suppress the deformation and the breakage of the electrode while
facilitating the aggregation of PM.
Thirteenth Embodiment
[0136] FIG. 18 shows a schematic arrangement of a particulate
matter processing apparatus 1 according to this embodiment.
Component or parts, which are the same as those of the embodiment
described above, are designated by the same reference numerals, any
explanation of which will be omitted.
[0137] In the particulate matter processing apparatus 1 according
to this embodiment, the field intensity is changed by changing the
thickness of the protruding portion 54 and the length of the
protruding portion 54.
[0138] Further, in this embodiment, the diameter of the cross
section of the root of the protruding portion 541 disposed on the
upstream side is larger than the diameter of the cross section of
the root of the protruding portion 542 disposed on the downstream
side. That is, the protruding portion 541 disposed on the upstream
side is thicker than the protruding portion 542 disposed on the
downstream side. Further, the length of the protruding portion 542
disposed on the downstream side is shorter than the length of the
protruding portion 541 disposed on the upstream side. The
installation spacing L9 in the flow direction of the exhaust gas
between the protruding portions 541 disposed on the upstream side
is the same as the installation spacing L10 in the flow direction
of the exhaust gas between the protruding portions 542 disposed on
the downstream side.
[0139] As shown in FIG. 18, for example, the first to fourth
nearest protruding portions 541, which are disposed in the flow
direction of the exhaust gas from the side near to the bent portion
51, have the diameters of the roots that are larger than the
diameters of the roots of the protruding portions 542 which are
disposed on the more downstream side therefrom.
[0140] It is also appropriate that the diameters of the protruding
portions 541 existing in a region of less than a predetermined
distance from the bent portion 51 are larger than the diameters of
the protruding portions 542 existing in a region of not less than
the predetermined distance from the bent portion 51. Further, it is
also appropriate that all of the lengths of the protruding portions
541 existing in a region of less than a predetermined distance from
the bent portion 51 are identical, or the lengths are shorter at
positions on the more downstream side. Further, it is also
appropriate that all of the lengths of the protruding portions 542
existing in a region of not less than the predetermined distance
from the bent portion 51 are identical, or the lengths are more
shortened at positions on the more downstream side.
[0141] It is also appropriate that the lengths of the protruding
portions 542 existing in a region of not less than a predetermined
distance from the bent portion 51 are shorter than the lengths of
the protruding portions 541 existing in a region of less than the
predetermined distance from the bent portion 51.
[0142] In this arrangement, it is also appropriate that the
protruding portion 542 disposed on the downstream side of the flow
of the exhaust gas has the low rigidity as compared with the
protruding portion 541 disposed on the upstream side. Therefore, it
is possible to relatively thin the protruding portion 542 disposed
on the downstream side. Further, the length of the protruding
portion 542 disposed on the downstream side is shortened as
compared with the protruding portion 541 disposed on the upstream
side. Therefore, it is possible to reduce the mass on the forward
end side of the electrode 5, i.e., on the downstream end side of
the electrode 5. Further, it is possible to suppress the decrease
in the field intensity by relatively shortening the spacing in the
flow direction of the exhaust gas between the protruding portions
542 disposed on the downstream side.
[0143] In this way, it is possible to reduce the mass in the
vicinity of the forward end of the electrode 5 by relatively
thinning and shortening the protruding portion 542 disposed on the
downstream side and shortening the spacing in the flow direction of
the exhaust gas between the protruding portions 542 disposed on the
downstream side. Accordingly, it is possible to suppress the
deformation and the breakage of the electrode while uniformizing
the field intensity.
Fourteenth Embodiment
[0144] FIG. 19 shows a schematic arrangement of a particulate
matter processing apparatus 1 according to this embodiment. In the
embodiment described above, the electrode 5 is bent toward the
downstream side of the flow of the exhaust gas. However, in this
embodiment, the electrode 5 is bent toward the upstream side.
[0145] Further, the length of the protruding portion 541 disposed
on the upstream side is made longer than the length of the
protruding portion 542 disposed on the downstream side. Further,
the installation spacing in the flow direction of the exhaust gas
between the protruding portions 541 disposed on the upstream side
is made longer than the installation spacing in the flow direction
of the exhaust gas between the protruding portions 542 disposed on
the downstream side. Even in the case of the arrangement as
described above, the field intensity on the upstream side can be
made larger than the field intensity on the downstream side.
Therefore, it is possible to more reliably electrify PM on the
upstream side on which the field intensity is relatively large.
Further, when PM, which is electrified on the upstream side, is
allowed to flow to the downstream side on which the field intensity
is relatively small, PM is gently moved to the wall surface of the
housing 3. Accordingly, the mutual aggregation of PM is
facilitated. Therefore, it is possible to enhance the effect to
reduce the number of particulates of PM.
[0146] Further, when the electrode 5 is bent toward the upstream
side of the flow of the exhaust gas, PM hardly adheres to the
insulator portion 52. That is, PM can be electrified on the
upstream side from the insulator portion 52. Therefore, PM is
directed or moved toward the inner circumferential surface of the
housing 3. Therefore, the amount of PM colliding with the insulator
portion 52 is decreased. Therefore, PM hardly adheres to the
insulator portion 52. However, when the electrode 5 is bent toward
the upstream side of the flow of the exhaust gas, the electrode 5
tends to be deformed on account of the force received from the flow
of the exhaust gas. Further, the influence is easily exerted by the
mass of the protruding portion 54. Therefore, this arrangement is
suitable for such a case that the electrode 5 is short. On the
other hand, when the electrode 5 is bent toward the downstream side
of the flow of the exhaust gas, then PM tends to adhere to the
insulator portion 52, but the electrode 5 is hardly deformed even
when the electrode 5 receives the force from the flow of the
exhaust gas. Therefore, the durability and the reliability are
high, and it is possible to lengthen the electrode 5.
PARTS LIST
[0147] 1: particulate matter processing apparatus, 2: exhaust gas
passage, 3: housing, 5: electrode, 6: air supply unit, 21: flange,
31: flange, 51: bent portion, 52: insulator portion, 53: electric
wire, 54: protruding portion.
* * * * *