U.S. patent application number 13/808512 was filed with the patent office on 2013-07-25 for internal combustion engine.
This patent application is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. The applicant listed for this patent is Masahiro Fujiwara, Shunichi Hanada, Eiji Hashimoto, Chika Kanba, Taiichi Mori, Koki Uno. Invention is credited to Masahiro Fujiwara, Shunichi Hanada, Eiji Hashimoto, Chika Kanba, Taiichi Mori, Koki Uno.
Application Number | 20130186074 13/808512 |
Document ID | / |
Family ID | 45440834 |
Filed Date | 2013-07-25 |
United States Patent
Application |
20130186074 |
Kind Code |
A1 |
Kanba; Chika ; et
al. |
July 25, 2013 |
INTERNAL COMBUSTION ENGINE
Abstract
The present invention provides an internal combustion engine
includes: a turbocharger arranged in exhaust passage; EGR passage
branching off from the exhaust passage downstream of a turbine of
the turbocharger and connected to intake passage; a burner device
arranged in the exhaust passage between the turbine and the portion
where the EGR passage branches off to increase exhaust temperature;
a bypass passage branching off from the exhaust passage between the
turbine and the burner device and connected to the EGR passage; and
a bypass valve to adjust flow rate of exhaust gas passing through
bypass passage. When flow rate of the exhaust gas is increased, the
bypass valve is open, and part of the exhaust gas is guided to the
bypass passage. The flow rate of the exhaust gas to be supplied to
the burner device is reduced, and the ignition performance of the
burner device is ensured.
Inventors: |
Kanba; Chika; (Susono-shi,
JP) ; Hashimoto; Eiji; (Susono-shi, JP) ;
Mori; Taiichi; (Susono-shi, JP) ; Uno; Koki;
(Susono-shi, JP) ; Fujiwara; Masahiro;
(Mishima-shi, JP) ; Hanada; Shunichi;
(Mishima-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kanba; Chika
Hashimoto; Eiji
Mori; Taiichi
Uno; Koki
Fujiwara; Masahiro
Hanada; Shunichi |
Susono-shi
Susono-shi
Susono-shi
Susono-shi
Mishima-shi
Mishima-shi |
|
JP
JP
JP
JP
JP
JP |
|
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
Toyota-shi, Aichi
JP
|
Family ID: |
45440834 |
Appl. No.: |
13/808512 |
Filed: |
July 7, 2010 |
PCT Filed: |
July 7, 2010 |
PCT NO: |
PCT/JP2010/004436 |
371 Date: |
March 18, 2013 |
Current U.S.
Class: |
60/286 ;
60/303 |
Current CPC
Class: |
F02B 37/00 20130101;
Y02T 10/144 20130101; F02M 26/05 20160201; F01N 3/106 20130101;
F02M 26/15 20160201; F02M 26/71 20160201; F02M 26/24 20160201; F01N
2240/14 20130101; F02M 26/25 20160201; F01N 3/08 20130101; F01N
3/2033 20130101; F02M 26/35 20160201; F02M 26/44 20160201; F02M
26/06 20160201; Y02T 10/12 20130101; Y02T 10/26 20130101 |
Class at
Publication: |
60/286 ;
60/303 |
International
Class: |
F01N 3/08 20060101
F01N003/08 |
Claims
1. An internal combustion engine characterized by comprising: a
turbocharger, arranged in an exhaust passage; an EGR passage, which
branches off from the exhaust passage downstream of a turbine of
the turbocharger, and is connected to an intake passage; a burner
device, arranged in the exhaust passage between the turbine and the
portion where the EGR passage branches off, to increase exhaust
temperature; a bypass passage, which branches off from the exhaust
passage between the turbine and the burner device, and is connected
to the EGR passage; and a bypass valve, to adjust a flow rate of
exhaust gas passing through the bypass passage.
2. The internal combustion engine according to claim 1,
characterized by further comprising: acquisition means, for
obtaining the flow rate of exhaust gas discharged by the turbine;
and bypass valve control means, for controlling the bypass valve
based on the exhaust gas flow rate obtained by the acquisition
means.
3. The internal combustion engine according to claim 2,
characterized in that the bypass valve control means opens the
bypass valve when the exhaust gas flow rate, obtained by the
acquisition means, is greater than a predetermined value, and
closes the bypass valve when the exhaust gas flow rate, obtained by
the acquisition means, is equal to or smaller than the
predetermined value.
4. The internal combustion engine according to claim 1,
characterized by further comprising: a switching valve, for
switching a state of communication between the EGR passage and the
bypass passage, and a closed/open state of the EGR passage; and
switching valve control means, for controlling the switching valve,
wherein the switching valve control means controls the switching
valve in such a manner that when the bypass valve is closed,
communication between the EGR passage and the bypass passage is not
established and the EGR passage is open, and when the bypass valve
is open, communication between the EGR passage and the bypass
passage is established and the EGR passage is closed.
5. The internal combustion engine according to claim 1,
characterized by further comprising: an EGR valve provided in the
EGR passage between a portion where the bypass passage is connected
and the intake passage; a second EGR passage that branches off from
the exhaust passage upstream of the turbine of the turbocharger,
and is connected to the intake passage; a second EGR valve arranged
in the second EGR passage; and EGR control means for controlling
the EGR valve and the second EGR valve, wherein the EGR control
means closes the EGR valve and opens the second EGR valve when the
internal combustion engine is in a predetermined first operating
range in a low load side, and opens the EGR valve and closes the
second EGR valve when the internal combustion engine is in a
predetermined second operating range in a higher load side than the
first operating range, and opens the EGR valve when the bypass
valve is open, even when the internal combustion engine is in the
first operating range.
6. The internal combustion engine according to claim 1,
characterized by further comprising: an EGR cooler, arranged in the
EGR passage between the portion where the bypass passage is
connected and the intake passage; a cooler bypass passage, which
bypasses a cooling passage of the EGR cooler; a cooler switching
valve, for switching the passage between the cooling passage and
the cooler bypass passage; and cooler control means, for
controlling the cooler switching valve, wherein the cooler control
means controls the cooler switching valve in such a manner that
when the bypass valve is closed, the cooling passage is open and
the cooler bypass passage is closed, and when the bypass valve is
open, the cooling passage is closed and the cooler bypass passage
is open.
7. The internal combustion engine according to claim 1,
characterized in that the EGR pas sage is connected to the intake
passage upstream of a compressor of the turbocharger.
8. The internal combustion engine according to claim 2,
characterized in that the acquisition means includes an exhaust gas
flow sensor, arranged in the exhaust passage between the turbine
and the portion where the bypass passage branches off.
9. The internal combustion engine according to claim 1,
characterized in that the burner device includes a fuel addition
valve, employed to add fuel to the exhaust passage, and ignition
means, for igniting the fuel added through the fuel addition
valve.
10. The internal combustion engine according to claim 9,
characterized in that the burner device includes at least one of a
burner catalyst, for oxidizing the fuel that is added, and an
impingement plate, on which the added fuel impinges.
11. The internal combustion engine according to claim 1,
characterized by further comprising: an exhaust treatment device,
arranged in the exhaust passage downstream of the burner
device.
12. The internal combustion engine according to claim 11,
characterized in that the exhaust treatment device is located in
the exhaust passage between the burner device and the portion where
the EGR passage branches off.
Description
TECHNICAL FIELD
[0001] The present invention relates to an internal combustion
engine, and particularly relates to an internal combustion engine
in which a burner device is arranged in an exhaust passage to raise
exhaust temperature.
BACKGROUND ART
[0002] For internal combustion engines, there are cases wherein
burner devices are arranged in exhaust passages, upstream of
exhaust treatment devices (catalysts, etc.), and heated gases
generated by the burner devices are employed to increase the
exhaust temperatures, and to thereby supply heat to the exhaust
treatment devices and encourage the warm-up of those devices.
Typically, such burner devices are devices that employ appropriate
ignition means that ensures ignition and combustion of fuels that
are added in the exhaust passages.
[0003] In patent literature 1, a catalyst temperature raising
device is disclosed that includes: an addition valve, for injecting
a fuel; and ignition means having a heater element to ignite the
injected fuel. The addition valve and the ignition means are so
located that fuel injected via the addition valve directly contacts
the heater element.
[0004] The ignition performance of the burner device is degraded
when the flow rate of the exhaust gas supplied to the burner device
is increased. The reasons for this are that the atmospheric gas
temperature of the ignition means is reduced when the flow rate of
the exhaust gas is high, and that, due to the gas velocity that has
been increased, the ignition flame is extinguished after
ignition.
[0005] One objective of the present invention, therefore, is to
provide an internal combustion engine for which satisfactory burner
device ignition performance is ensured, even when the flow rate of
the exhaust gas supplied to the burner device is increased.
CITATION LIST
Patent Literature
[0006] PTL 1: Japanese Patent Laid-Open No. 2006-112401
SUMMARY OF INVENTION
[0007] One aspect of the present invention provides an internal
combustion engine that is characterized by comprising:
[0008] a turbocharger, arranged in an exhaust passage;
[0009] an EGR passage, which branches off from the exhaust passage
downstream of a turbine of the turbocharger, and is connected to an
intake passage;
[0010] a burner device, arranged in the exhaust passage between the
turbine and the portion where the EGR passage branches off, to
increase exhaust temperature;
[0011] a bypass passage, which branches off from the exhaust
passage between the turbine and the burner device, and is connected
to the EGR passage; and
[0012] a bypass valve, to adjust a flow rate of exhaust gas passing
through the bypass passage.
[0013] According to this arrangement, when the flow rate of the
exhaust gas that is discharged by the turbine and supplied to the
burner device is increased, the bypass valve is opened to introduce
part of the exhaust gas to the bypass passage, and to reduce the
flow rate of the exhaust gas to be supplied to the burner device.
Therefore, the appropriate ignition performance of the burner
device is ensured.
[0014] Preferably, the internal combustion engine further
comprises:
[0015] acquisition means, for obtaining the flow rate of exhaust
gas discharged by the turbine; and
[0016] bypass valve control means, for controlling the bypass valve
based on the exhaust gas flow rate obtained by the acquisition
means.
[0017] Preferably, the bypass valve control means opens the bypass
valve when the exhaust gas flow rate, obtained by the acquisition
means, is greater than a predetermined value, and closes the bypass
valve when the exhaust gas flow rate, obtained by the acquisition
means, is equal to or smaller than the predetermined value.
[0018] Preferably, the internal combustion engine further
comprises:
[0019] a switching valve, for switching a state of communication
between the EGR passage and the bypass passage, and a closed/open
state of the EGR passage; and
[0020] switching valve control means, for controlling the switching
valve,
[0021] wherein the switching valve control means controls the
switching valve in such a manner that when the bypass valve is
closed, communication between the EGR passage and the bypass
passage is not established and the EGR passage is open, and when
the bypass valve is open, communication between the EGR passage and
the bypass passage is established and the EGR passage is
closed.
[0022] Preferably, the internal combustion engine further
comprises:
[0023] an EGR valve located in the EGR passage between a portion
where the bypass passage is connected, and the intake passage;
[0024] a second EGR passage that branches off from the exhaust
passage upstream of the turbine of the turbocharger, and is
connected to the intake passage;
[0025] a second EGR valve arranged in the second EGR passage;
and
[0026] EGR control means for controlling the EGR valve and the
second EGR valve,
[0027] wherein the EGR control means closes the EGR valve and opens
the second EGR valve when the internal combustion engine is in a
predetermined first operating range, in a low load side, and opens
the EGR valve and closes the second EGR valve when the internal
combustion engine is in a predetermined second operating range in a
higher load side than the first operating range, and opens the EGR
valve when the bypass valve is open, even when the internal
combustion engine is in the first operating range.
[0028] Preferably, the internal combustion engine further
comprises:
[0029] an EGR cooler, arranged in the EGR passage between the
portion where the bypass passage is connected and the intake
passage;
[0030] a cooler bypass passage, which bypasses a cooling passage of
The EGR cooler;
[0031] a cooler switching valve, for switching the passage between
the cooling passage and the cooler bypass passage; and
[0032] cooler control means, for controlling the cooler switching
valve,
[0033] wherein the cooler control means controls the cooler
switching valve in such a manner that when the bypass valve is
closed, the cooling passage is open and the cooler bypass passage
is closed, and when the bypass valve is open, the cooling passage
is closed and the cooler bypass passage is open.
[0034] Preferably, the EGR passage is connected to the intake
passage upstream of a compressor of the turbocharger.
[0035] Preferably, the acquisition means includes an exhaust gas
flow sensor, arranged in the exhaust passage between the turbine
and the portion where the bypass passage branches off.
[0036] Preferably, the burner device includes a fuel addition
valve, employed to add fuel to the exhaust passage, and ignition
means, for igniting the fuel added through the fuel addition
valve.
[0037] Preferably, the burner device includes at least one of a
burner catalyst, for oxidizing the fuel that is added, and an
impingement plate, on which the added fuel impinges.
[0038] Preferably, the internal combustion engine further comprises
an exhaust treatment device, arranged in the exhaust passage
downstream of the burner device.
[0039] Preferably, the exhaust treatment device is located in the
exhaust passage between the burner device and the portion where the
EGR passage branches off.
[0040] According to the present invention, superior effects are
exhibited, such that even when the flow rate of exhaust gas
supplied to the burner device is increased, the satisfactory
ignition performance of the burner device is ensured.
BRIEF DESCRIPTION OF DRAWINGS
[0041] FIG. 1 is a schematic diagram for an internal combustion
engine according to one embodiment of the present invention;
[0042] FIG. 2 is a side view, in longitudinal section, of a burner
device;
[0043] FIG. 3 is a front view, in longitudinal section, of a burner
device, taken from the upstream side;
[0044] FIG. 4 is a schematic diagram for the internal combustion
engine when exhaust bypass is being performed;
[0045] FIG. 5 shows an EGR map;
[0046] FIG. 6 is a flowchart related to the EGR control; and
[0047] FIG. 7 is a flowchart related to the burner control.
DESCRIPTION OF EMBODIMENTS
[0048] A preferred embodiment of the present invention will now be
described in detail. However, it should be noted that the
embodiment of the present invention is not limited to that
described below, and that the present invention includes various
modifications and applications covered by the idea of this
invention as regulated by the appended claims. The sizes, the
materials and the shapes of components and the arrangement thereof
are not limited to those described in this embodiment to restrict
the technical scope of the present invention, unless they are
especially so designated.
[0049] In FIG. 1, an internal combustion engine (engine) according
to this embodiment is shown. The engine for this embodiment is a
vehicle-mounted inline four-cylinder four-stroke diesel engine.
In-cylinder fuel injection valves 9 are provided for the individual
cylinders of an engine body or block 1, and high-pressure fuel
retained in a common rail 9A is supplied to the individual
in-cylinder fuel injection valves 9. An intake pipe 2 and an intake
manifold 2A, which together form an intake passage, and an exhaust
manifold 3A and an exhaust pipe 3, which together form an exhaust
passage, are connected to the engine block 1. In the drawing, white
arrows indicate the air intake flow, and black arrows indicate the
exhaust gas flow. The upstream side is also called "the front", and
the downstream side is also called "the rear".
[0050] A turbocharger 5 is arranged downstream of the exhaust
manifold 3A. The turbocharger 5 includes a turbine 5T, arranged at
a location immediately following the exhaust manifold 3A, and a
compressor 5C, arranged in the middle of the intake pipe 2. It is
preferable that a variable capacity control mechanism, such as a
variable vane, be provided for the turbocharger 5.
[0051] An air flow meter 4 is provided in the intake pipe 2,
upstream of the compressor 5C, in order to output a signal in
accordance with the intake flow rate of air passing through the
intake pipe 2. The air flow meter 4 is employed to detect the air
intake volume (i.e., the intake flow rate) that enters the engine
block 1 per unit time. An air cleaner (not shown) is arranged
upstream of the air flow meter 4. An intercooler 25 and an
electronically controlled throttle valve 18 are provided in the
intake pipe 2 upstream of the compressor 5C.
[0052] The terminal end of the exhaust pipe 3 is connected to a
muffler (not shown), and is open to the atmosphere at the outlet of
the muffler. An oxidation catalyst 6 and an NOx catalyst (not
shown) are located in series, from upstream, in the named order, in
the exhaust pipe 3.
[0053] The oxidation catalyst 6 carries a reaction of unburned
elements, such as Hc or CO, to O.sub.2 to obtain Co, Co.sub.2,
H.sub.2O, etc. The catalyst material employed can be, for example,
Pt/CeO.sub.2, Mn/CeO.sub.2, Fe/CeO.sub.2, Ni/CeO.sub.2 or
Cu/CeO.sub.2.
[0054] The NOx catalyst is preferably formed of an NOx Storage
Reduction (NSR) catalyst. The NOx catalyst has as a function the
storage of NOx in exhaust gas, when the oxygen density of inflow
exhaust gas is high, or the reduction of NOx when the oxygen
density of inflow exhaust gas is low and a reduction element (e.g.,
fuel, etc.) is present. The NOx catalyst is provided by supporting,
on the surface of a base material consisting of an oxide, such as
alumina Al.sub.2O.sub.3, a catalyst element that is a precious
metal, such as platinum Pt, and an NOx absorbing element. The NOx
absorbing element is provided by selecting at least one, for
example, of the alkali metals such as potassium K, sodium Na,
lithium Li and cesium Cs, the alkaline earth elements such as
barium Ba and calcium Ca, and the rare earth elements such as
lanthanum Li and yttrium Y. It should be noted that the NOx
catalyst may be a Selective Catalytic Reduction (SCR) NOx
catalyst.
[0055] In addition to the oxidation catalyst 6 and the NOx
catalyst, a diesel particulate filter (DPF) may also be arranged to
collect particulate matter (PM), such as soot, in the exhaust gas.
Preferably, a DPF is a continuously regenerating trap type that
supports a catalyst made of precious metal, and continuously
performs the oxidizing and burning of trapped particulates. It is
preferable that the DPF be located at least downstream of the
oxidation catalyst 6, and either upstream or downstream of the NOx
catalyst. In the case of a spark ignition type internal combustion
engine (gasoline engine), it is preferable that a three-way
catalyst be provided in the exhaust passage. The oxidation catalyst
6, the NOx catalyst, the DPF and the three-way catalyst correspond
to the exhaust treatment equipment of this invention.
[0056] An air flow meter, i.e., an exhaust gas flow sensor 26, for
detecting the flow rate of exhaust gas discharged from the turbine
5T, and a burner device 30, for raising the temperature of the
exhaust gas, are arranged from upstream, in the named order, in the
exhaust pipe 3 between the turbine 5T and the oxidation catalyst 6.
Specifically, the exhaust gas flow sensor 26 is located near the
turbine 5T, and the burner device 30 is located near the oxidation
catalyst 6.
[0057] As illustrated in FIGS. 2 and 3 in detail, the burner device
30 includes a fuel addition valve 7 and a glow plug 21 that serves
as ignition means or as an ignition device. The burner device 30
also includes a burner catalyst 8 and an impingement plate 20.
[0058] Referring to FIG. 1, the engine includes an electronic
control unit (hereinafter referred to as an ECU) 10 that controls
various devices in accordance with the operating state, or upon
receiving a request from an operator. The ECU 10 includes a CPU,
for performing various operations related to the control of the
engine, a ROM, used to store programs and data required for
control, a RAM, used to temporarily store operation results
obtained by the CPU, and an input/output port, for transmitting or
receiving signals with respect to the outside.
[0059] Various sensors, including not only the air flow meter 4 and
the exhaust gas flow sensor 26, but also a crank angle sensor 24,
which outputs an electric signal that corresponds to the crank
angle of the engine block 1, an accelerator position sensor 25,
which outputs an electric signal that corresponds to the
accelerator position, and a catalyst temperature sensor 27, which
outputs an electric signal that corresponds to the temperature of
the oxidation catalyst 6 (bed temperature), are connected to the
ECU 10 by electric wires, and these output signals are transmitted
to the ECU 10. Further, various devices, including the in-cylinder
fuel injection valve 9, the throttle valve 18, the fuel addition
valve 7 and the glow plug 21, are also connected to the ECU 10 by
electric wires, and these devices are controlled by the ECU 10. The
ECU 10 can detect the intake volume of air based on the output
value of the air flow meter 4, can detect the engine revolutions
based on the output value of the crank angle sensor 24, and can
detect the required load on the engine based on the output value of
the accelerator position sensor 25.
[0060] In this embodiment, when the burner device 30 is employed to
perform the temperature increase control for heating the exhaust
gas to increase the exhaust gas temperature, the ECU 10 operates
the fuel addition valve 7 and the glow plug 21 appropriately. That
is, the ECU 10 properly opens the fuel addition valve 7 (ON) to
inject the fuel from the fuel addition valve 7. Further, the ECU 10
renders the glow plug 21 active (ON) to obtain a satisfactorily
high temperature.
[0061] The burner device 30 will be described in detail, while
referring to FIGS. 2 and 3.
[0062] As illustrated, the fuel addition valve 7 is provided to add
or inject a liquid fuel (diesel fuel) F into the exhaust pipe 3,
and is connected to a fuel tank and a fuel pump (neither of them
shown) via a pipe. The fuel addition valve 7 has a single injection
hole 7a. A plurality of injection holes may also be provided.
[0063] The fuel addition valve 7 is inserted downward, in a
direction perpendicular to the axis of the exhaust pipe 3, and is
fixed to a valve mounting boss 11, which is attached to the
uppermost side of the outer face of the exhaust pipe. Inside the
valve mounting boss 11, a coolant passage 12 is defined, along
which a coolant passes in order to cool the fuel inside the fuel
addition valve 7. In the exhaust pipe 13, a valve hole 13 is formed
to pass the fuel F that is injected via the fuel addition valve
7.
[0064] The glow plug 21 is arranged so that a heater element 21a,
at the tip, is located slightly downstream of the fuel addition
valve 7. The glow plug 21 is connected to a vehicle-mounted DC
power supply via a boosting circuit (not shown), and when power is
supplied to the glow plug 21, the heater element 21a generates
heat. Through the heat generated by the heater element 21a, the
fuel F that is added through the fuel addition valve 7 is ignited,
forming a flame. Part of the added fuel F is ignited by directly
contacting the heater element 21a, while the remainder of the added
fuel F flows through the heater element 21a. Another type of
ignition device, such as a ceramic heater or a spark plug,
especially, a thermo-electric or a spark ignition type device, can
also be employed.
[0065] The glow plug 21 is inserted, laterally from the side of the
exhaust pipe 3, in a direction perpendicular to the axis of the
exhaust pipe 3 and the axis of the fuel addition valve 7, and is
fixed to a plug mounting boss 14 that is attached to the side
portion of the outer wall of the exhaust pipe 3, while the glow
plug 21 end is projected into the inside of the exhaust pipe 3
across the hole of the exhaust pipe 3.
[0066] The fuel addition valve 7 injects the fuel F to the heater
element 21a from above, obliquely downward so that the fuel goes
slightly downstream. The injected fuel F forms a fuel spraying
course having a predetermined angle of spray. The heater element 21
is located during the fuel spraying course.
[0067] When ignition of the added fuel F has occurred, heated gas
at a high temperature, including a flame, is generated. The heated
gas is mixed with the exhaust gas present to raise the temperature
of the exhaust gas. The exhaust gas, at the increased temperature,
is supplied to the oxidation catalyst 6 and the NOx catalyst to
encourage the warm-up and activation of these catalysts.
[0068] The burner catalyst 8 is employed to oxidize and reform the
fuel that has been added through the fuel addition valve 7, and is
located downstream of the fuel addition valve 7 and the glow plug
21. The burner catalyst 8 can be provided as an oxidization
catalyst obtained, for example, by supporting rhodium, etc., on a
zeolite carrier.
[0069] When the fuel F is supplied to the burner catalyst 8, which
is activated at this time, oxidizing of the fuel is performed in
the burner catalyst 8. Since heat is generated by an oxidation
reaction, the temperature of the burner catalyst 8 is raised.
Therefore, the temperature of the exhaust gas passing through the
burner catalyst 8 can be increased.
[0070] Further, when the temperature of the burner catalyst 8
becomes high, carbon hydrates in the fuel which have a large number
of carbons are broken down into carbon hydrates that have a smaller
number of carbons and are highly reactive, and therefore, the fuel
is reformed into a very reactive fuel.
[0071] In other words, the burner catalyst 8 serves in one way as a
quick heater element that quickly generates heat, and in the other
way as a reformed fuel discharging element that discharges reformed
fuel.
[0072] The impingement plate 20 is inserted into and fixed to the
plug mounting boss 14, and is projected to the inside of the
exhaust pipe 3 across the hole of the exhaust pipe 3. The
impingement plate 20 can be formed of a material, such as a SUS
material, having superior resistance and shock resistance. For this
embodiment, a rectangular shape is employed for the impingement
plate 20.
[0073] The burner catalyst 8 is provided to occupy a part of the
cross section of the exhaust passage. In this embodiment's case, as
shown in FIG. 3, the exhaust pipe 3 and the burner catalyst 8 are
circular in cross section, and are coaxially arranged with each
other. Further, the outer diameter of the burner catalyst 8 is
smaller than the inner diameter of the exhaust pipe 3. The burner
catalyst 8 is a so-called straight flow type that includes a
plurality of independent cells, extended linearly from the upstream
end to the downstream end.
[0074] The burner catalyst 8 is located inside a cylindrical casing
8a that is supported in the exhaust pipe 3 by a plurality of stays
8b that are radially provided. An inside catalyst passage 8c is
formed inside the burner catalyst 8, while a ring-shaped catalyst
bypass 3a is formed in the circumference of the casing 8a.
[0075] Further, the burner catalyst 8 also includes a guide plate
15 that is projected to the upstream side. The guide plate 15 is
attached to the front end, in the lower half portion of the casing
8a, and is formed like a gutter, having a semi-circular shape, in
cross section, to be projected from the casing 8a to the upstream
side. Similarly to the casing 8a, the guide plate 15 is supported
in the exhaust pipe 3 by using a plurality of stays 8b that are
radially provided. The guide plate 15 accepts the added fuel F, and
guides and introduces the added fuel F to the burner catalyst 8 by
also employing the flow of the exhaust gas.
[0076] As shown in FIGS. 2 and 3, the fuel addition valve 7 and the
burner catalyst 8 are so arranged that the added fuel F goes from
the fuel addition valve 7 to the burner catalyst 8. Specifically,
the fuel addition valve 7 injects the fuel F from above to the
bottom face of the guide plate 15 of the burner catalyst 8,
obliquely downward so as to inject the fuel slightly downstream.
The thus injected fuel F forms a fuel injection course having a
predetermined angle of spray.
[0077] During the fuel injection course, the heater element 21a of
the glow plug 21 and the impingement plate 20 are located. The
impingement plate 20 is arranged close to and slightly below the
heater element 21a. Further, the glow plug 21 and the impingement
plate 20 are inserted into the exhaust pipe 3 from the upper side
portion of the exhaust pipe 3, and are extended parallel to each
other and linearly in the horizontal direction.
[0078] The added fuel F directly impinges on the heater element
21a. Furthermore, as shown in FIG. 2, the added fuel F impinges on
the entire impingement plate 20 in the directions to the front and
to the rear, but as shown in FIG. 3, the added fuel impinges on
only one part of the impingement plate 20 in the directions to the
right and to the left (especially, to the right).
[0079] Therefore, the impingement plate 20 blocks part of the
injection of the added fuel F, and returns the added fuel F to the
heater element 21a of the glow plug 21 at a predetermined ratio.
Further, the impingement plate 20 allows the remaining part of the
added fuel F to flow through, and supplies the fuel F to the burner
catalyst 8.
[0080] When the fuel F has impinged on the impingement plate 20,
droplet breakup and atomization of the fuel F is encouraged, and
dispersion and diffusion of the fuel is improved. Thus, ignition by
the glow plug 21 is encouraged. The glow plug 21 is positioned
substantially at the same height as the catalyst bypass 3a,
arranged above the burner catalyst 8. Therefore, a flame generated
by ignition is stretched mainly toward the catalyst bypass 3a,
located above.
[0081] On the other hand, when the fuel has passed through the
impingement plate 20 and is supplied to the burner catalyst 8, the
fuel is oxidized and reformed inside the burner catalyst 8, as
described above, and is discharged from the burner catalyst 8.
Thereafter, the reformed fuel is properly oxidized and burnt in the
oxidation catalyst 6 located below, and is then employed to further
increase the temperature of the exhaust gas.
[0082] A flame and heated gas, thus generated through ignition by
the glow plug 21, may also be employed to burn the reformed fuel
that is discharged from the outlet of the burner catalyst 8.
[0083] Since the burner catalyst 8 and the impingement plate 20 are
arranged in the burner device 30 in this manner, the performance of
the burner device 30 can be further improved.
[0084] Referring again to FIG. 1, two EGR (Exhaust Gas
Recirculation) devices, i.e., a high-pressure EGR device 40 and a
low-pressure EGR device 60, are provided in the engine. The
high-pressure EGR device 40 is a device that performs high-pressure
EGR during which comparatively high-pressure exhaust gas is
extracted from the upstream side of the turbine 5T, and is returned
to the intake side. The low-pressure EGR device 60 is a device that
performs low-pressure EGR during which comparatively low-pressure
exhaust gas is extracted from downstream of the turbine 5T, and is
returned to the intake side.
[0085] The high-pressure EGR device 40 includes a high-pressure EGR
passage 41 (corresponding to a second EGR passage for this
invention), which branches off from the exhaust passage upstream of
the turbine 5T and is connected to the intake passage, and a
high-pressure EGR valve 42 (corresponding to a second EGR valve for
this invention), which is provided in the high-pressure EGR passage
41. The high-pressure EGR passage 41 branches off from the exhaust
manifold 3A, and is connected to the intake manifold 2A. The
opening of the high-pressure EGR valve 42 can be continuously
changed, from the fully-closed position to the fully-open position,
in order to adjust the flow rate of the exhaust gas, i.e., the
high-pressure EGR gas, that flows in the high-pressure EGR passage
41. A high-pressure EGR cooler for cooling the high-pressure EGR
gas may be provided for the high-pressure EGR device 40.
[0086] Furthermore, the low-pressure EGR device 60 includes a
low-pressure EGR passage 61 (corresponding to an EGR passage for
this invention), which branches off from the exhaust passage
downstream of the turbine 5T and is connected to the intake
passage, and a low-pressure EGR valve 62 (corresponding to an EGR
valve for this invention), which is provided in the low-pressure
EGR passage 61. The low-pressure EGR passage 61 branches off from
the exhaust pipe 3 downstream of the oxidation catalyst 6, and is
connected to the intake pipe 2 between the air flow meter 4 and the
compressor 5C (i.e., the intake pipe 2 upstream of the compressor
5C). The opening of the low-pressure EGR valve 62 can be
continuously changed, from the fully-closed position to the
fully-open position, to adjust the flow rate of the exhaust gas,
i.e., the low-pressure EGR gas, that flows in the low-pressure EGR
passage 61.
[0087] The low-pressure EGR device 60 also includes a foreign
object trapper 63, an EGR filter 64 and an EGR cooler 65
(corresponding to an EGR cooler for this invention). From upstream,
these components are arranged, in the named order, in the
low-pressure EGR passage 61. Also, these components are located in
a portion extending from the portion where the low-pressure EGR
passage 61 branches off, or from the upstream end of the
low-pressure EGR passage 61, to the portion where the low-pressure
EGR valve 62 is located.
[0088] When the exhaust gas is extracted from the downstream side
of the oxidation catalyst 6 and is returned to the intake system,
foreign objects (including weld splatters and residues of a
catalyst support) may damage the individual members, especially the
compressor 5C. Therefore, the foreign object trapper 63 is arranged
in the furthest upstream portion in order to collect and remove
such foreign objects. The foreign object trapper 63 includes a
filter (e.g., a net) for collecting foreign objects.
[0089] The EGR filter 64 is a filter, as is the DPF filter, that is
employed to collect particles, such as soot, in the low-pressure
EGR gas, and is formed of finer meshes than the foreign object
trapper 63. It is preferable that the EGR filter 64 also be a
continuously regenerating trap type, wherein a catalyst made of a
precious metal is supported. In this embodiment's case, the EGR
filter 64 and the EGR cooler 65 are integrally provided, and the
EGR filter is located immediately before the EGR cooler 65.
[0090] The EGR cooler 65 is employed to cool the low-pressure EGR
gas, and includes a main passage 66, which serves as a cooling
passage, through which the low-pressure EGR gas flows. It should be
noted that for this embodiment a cooler bypass passage 67, which is
an alternate passage for the main passage 66, and a cooler
switching valve 68, which switches between the main passage 66 and
the cooler bypass passage 67, are integrally formed for the EGR
cooler 65. As shown in FIG. 1, the cooler switching valve 68 can be
changed to either a cooler position, whereat the main passage 66 is
open and the cooler bypass passage 67 is closed, or to the cooler
bypass position whereat the main passage 66 is closed and the
cooler bypass passage 67 is open.
[0091] The high-pressure EGR device 40 is the same type as a
conventional, generally employed EGR device. One of the reasons
that the low-pressure EGR device 60 is additionally provided is
that the EGR control is to be appropriately performed even in the
engine-operating range wherein the EGR process can not be properly
performed by the high-pressure EGR device 40, and the
engine-operating range where the EGR is enabled is to be expanded.
For example, the temperature of low-pressure EGR gas is lower than
the temperature of high-pressure EGR gas, and has a higher density.
Therefore, in a case wherein the same volume or the same flow rate
is employed for comparison, the EGR quantity can be increased.
Another reason is that since the high-pressure EGR device 40
extracts exhaust gas at a position preceding the turbine 5T, there
is a possibility that the amount of work performed by the
turbocharger 5 will be lowered, or the engine output will be
reduced. However, such a situation does not occur with the
low-pressure EGR device 60. Therefore, the low-pressure EGR device
60 is appropriate for use in the high-load operating range.
[0092] Moreover, in this embodiment, a bypass passage 70
(corresponding to a bypass passage for this invention), which
branches off from the exhaust pipe 3 between the turbine 5T and the
burner device 30 and is connected to the low-pressure EGR passage
61, and a bypass valve 71 (corresponding to a bypass valve for this
invention), which is employed to adjust the flow rate of exhaust
gas, i.e., bypass gas, that flows through the bypass passage 70,
are also provided.
[0093] The bypass passage 70 branches off from the exhaust pipe 3
at the position between the exhaust gas flow sensor 26 and the
burner device 30, and is connected to the low-pressure EGR passage
61 at the position between the foreign object trapper 63 and the
EGR filter 64. The opening of the bypass valve 71 can be
continuously changed from the fully-closed position to the fully
open position to adjust the flow rate of the bypass gas that flows
through the bypass passage 70.
[0094] Moreover, a switching valve 72 (corresponding to a switching
valve for this invention), which changes the state of communication
between the low-pressure EGR passage 61 and the bypass passage 70,
and switches between the open/closed state of the low-pressure EGR
passage 61, is also provided. The switching valve 72 is located at
the portion where the low-pressure EGR passage 61 and the bypass
passage 70 join together, and a butterfly valve, for example, is
employed; however, another type of valve, such as a shutter valve
or a spool valve, may be employed. The switching valve 72 can be
changed either to a bypass close position, shown in FIG. 1, at
which communication between the low-pressure EGR passage 61 and the
bypass passage 70 is inhibited and the low-pressure EGR passage 61
is open, or to a bypass open position, shown in FIG. 4, at which
communication between the low-pressure EGR passage 61 and the
bypass passage 70 is permitted and the low-pressure EGR passage 61
is closed.
[0095] The high-pressure EGR valve 42, the low-pressure EGR valve
62, the cooler switching valve 68, the bypass valve 71 and the
switching valve 72 are all connected to the ECU 10, and are
controlled by the ECU 10.
[0096] As described above, the ignition performance of the burner
device 30 tends to be degraded when the flow rate of the supplied
exhaust gas is increased. The reasons for this are that the
temperature of the atmospheric gas of the ignition means is reduced
when the flow rate of the exhaust gas is high, and that due to the
gas velocity that has been increased, the flame is extinguished
after ignition.
[0097] For example, when the flow rate of exhaust gas is increased
more than 14 g/s, the ignition performance of the burner device 30
tends to be deteriorated. In order to obtain satisfactory ignition
combustion at such a high flow rate, 150.degree. C. or higher is
required as the temperature of the atmospheric exhaust gas for the
glow plug 21. However, it is actually difficult for this exhaust
gas temperature to be acquired under such a condition with a high
exhaust gas flow rate.
[0098] Further, the burner device 30 is activated to encourage the
warning-up of the oxidation catalyst 6 when the temperature of the
oxidation catalyst 6 is equal to or smaller than a predetermined
value, or typically, when warming-up for the oxidation catalyst 6
is in progress. Furthermore, it is preferable that when the
temperature of the oxidation catalyst 6 is reduced, the burner
device 30 be activated, in order to prevent a reduction in the
temperature. Temperature reduction of the oxidation catalyst 6
occurs mainly during the deceleration of the engine. This is
because the exhaust gas at a comparatively low temperature, or
fresh air (in a case where a fuel cut is being performed), is
supplied to the oxidation catalyst 6 at a comparatively high flow
rate.
[0099] However, as described above, when the conditions are such
that there is a low exhaust temperature and a high exhaust flow
rate, there is a case wherein the ignition performance of the
burner device 30 is not appropriately exhibited, and the burner
device 30 can not be activated. Therefore, a problem exists in that
the range for the use of the burner device 30 is limited, and the
burner device 30 can not be effectively utilized.
[0100] The burner device 30 also may not be operated in a case
wherein, after the temperature of the oxidation catalyst 6 has been
raised by activating the burner device 30, the conditions for a low
exhaust temperature and a high exhaust flow rate are established
by, for example, decelerating the engine, and thereby reducing the
temperature of the oxidation catalyst 6. When for this reason the
burner device 30 can not be activated, an increase in the
temperature and the encouraging of the warming-up of the oxidation
catalyst 6 can not be performed, and another problem, an increase
in carbon monoxide emissions, would also occur.
[0101] Therefore, to resolve these problems, the above described
arrangement is employed for this embodiment. That is, the bypass
passage 70 is provided, which branches off from the exhaust pipe 3,
before the burner device 30, and is connected to the low-pressure
EGR passage 61, and the bypass valve 71 is provided for the bypass
passage 70 to adjust the bypass gas flow rate.
[0102] With this structure, when the flow rate of the exhaust gas
that is discharged from the turbine 5T and is to be supplied to the
burner device 30 is increased, the bypass valve 71 can be opened to
guide part of the exhaust gas to the bypass passage 70, and the
flow rate of the exhaust gas to be supplied to the burner device 30
can be reduced. As a result, an appropriate burner device 30
ignition performance can be obtained.
[0103] Especially for this embodiment, the ECU 10 controls the
bypass valve 71 based on the flow rate of the exhaust gas that is
detected by the exhaust gas flow sensor 26. The ECU 10 opens the
bypass valve 71 when the detected exhaust gas flow rate is greater
than a predetermined value (e.g., 14 g/s), and closes the bypass
valve 71 when the detected exhaust gas flow rate is equal to, or
smaller than the predetermined value. As a result, when the exhaust
flow rate is increased, the exhaust bypass can be performed
properly, and a satisfactory ignition performance of the burner
device 30 can be obtained. At a time other than when the exhaust
flow rate has been increased, however, the exhaust bypass operation
will not be performed, and the normal state can be maintained.
[0104] Further, when the bypass valve 71 is closed, the ECU 10 sets
the switching valve 72 to the bypass closed position, and when the
bypass valve 71 is open, sets the switching valve 72 to the bypass
open position. Therefore, at a time other than when an exhaust
bypass is performed, the normal state can be maintained by closing
the bypass passage 70 and opening the low-pressure EGR passage 61,
and at a time when the exhaust bypass is performed, bypass gas can
be introduced into the low-pressure EGR passage 61.
[0105] Next, the EGR control and the control of the burner device
(burner control), performed in this embodiment, will be
described.
[0106] An EGR map employed for the EGR control is shown in FIG. 5.
In this EGR map, the entire operating range of the engine is
defined, and based on the number of revolutions and a torque (an
engine output torque or a target torque) is divided into a first
range I, a second range II and a third range III, in that order,
beginning from the low load side. The first range I, on the lowest
load side, is a range for performing only the high-pressure ERG
(corresponding to a first operating range for this invention). The
third range III, on the highest load side, is a range for
performing only the low-pressure EGR (corresponding to a second
operating range for this invention). The second range II for the
intermediate load, located between the first range I and the third
range III, is a range for performing both the high-pressure EGR and
the low-pressure EGR.
[0107] In the first range I, only the high-pressure EGR valve 42
can be open, and the low-pressure EGR valve 62 is not open. In the
third range III, only the low-pressure EGR valve 62 can be open,
and the high-pressure EGR valve 42 is not open. In the second range
II, both the low-pressure EGR valve 62 and the high-pressure EGR
valve 42 can be open.
[0108] For the individual ranges, the target openings of the EGR
valves 42 are 62 are determined in consonance with the number of
revolutions and the torque, and the EGR valves 42 and 62 are
controlled to match the target opening and the actual opening. That
is, based on the engine revolutions, obtained from the detection
output of the crank angle sensor 24, and the target torque, which
corresponds to the requested torque, obtained from the detection
output of the accelerator position sensor 25, the ECU 10 examines
the EGR map stored in advance to determine the target openings of
the EGR valves 42 and 62, and also controls the EGR valves 42 and
62 to match the actual openings with the target openings. The
target openings are set so as to obtain a target EGR ratio.
[0109] A flowchart for the routine related to the EGR control is
shown in FIG. 6. This routine is repetitively performed by the ECU
10 for each predetermined operation period (e.g., 16 msec).
[0110] At step S101, a check is performed to determine whether the
operating state of the engine is in the first range I. In a case
wherein it is determined that the operating state is in the first
range I, program control advances to step S102, whereat only the
high-pressure EGR valve 42 is properly opened, and the low-pressure
valve 62 is closed. Therefore, only the high-pressure EGR is
performed.
[0111] However, in a case wherein it is determined that the
operating state is not in the first range I, program control moves
to step S103, whereat a check is performed to determine whether the
engine operating state is in the second range II. In a case wherein
the operating state is in the second range II, program control
advances to step S104, whereat the high-pressure EGR valve 42 and
the low-pressure EGR valve 62 are appropriately opened. As a
result, both the high-pressure EGR and the low-pressure EGR are
performed.
[0112] Further, in a case wherein it is determined that the engine
operating state is not in the second range II, program control
moves to step S105, whereat only the low-pressure EGR valve 62 is
open, and the high-pressure EGR valve 42 is closed. Thus, only the
low-pressure EGR is performed.
[0113] A flowchart for the routine related to the burner control is
shown in FIG. 7. This routine is also repetitively performed by the
ECU 10 for each predetermined operation period (e.g., 16 msec).
[0114] First, at step S201, a check is performed to determine
whether a temperature Tc of the oxidation catalyst 6, detected by
the catalyst temperature sensor 27, has been falling. When the
falling of the temperature has not occurred, program control moves
to step S212, whereat the burner device 30 is set to the inactive
state, i.e., the fuel addition valve 7 is turned off, so as not to
provide additional fuel, and the glow plug 21 is also turned off.
This is done because, when the falling of the catalyst temperature
due to deceleration, etc., has not occurred, i.e., when the
catalyst temperature has been maintained, or has been rising, the
burner device 30, especially, need not be activated, and it is also
better for fuel efficiency not to activate the burner device
30.
[0115] Furthermore, in a case wherein it is determined that the
catalyst temperature Tc has been falling, program control advances
to step S202, whereat a check is performed to determine whether the
catalyst temperature Tc is a predetermined value Tc1 (e.g.,
200.degree. C.) or lower.
[0116] In a case wherein the catalyst temperature Tc is the
predetermined value Tc1 or lower, it is assumed that the warming-up
of the oxidation catalyst 6 is being performed, and at step S203, a
check is performed to determine whether an exhaust flow rate Ge,
detected by the exhaust gas flow sensor 26, is a predetermined
value Gel (e.g., 14 g/s) or smaller.
[0117] In a case wherein it is determined that the exhaust flow
rate Ge is the predetermined value Gel or smaller, program control
advances to step S204, whereat the bypass valve 71 is either closed
or is fully closed, and thereafter, at step S205, the switching
valve 72 is held in the bypass closed position (see FIG. 1), and at
step S206, the cooler switching valve 68 is held in the cooler
position. That is, when the exhaust flow rate is low, as in this
case, the exhaust bypass is not performed upstream of the burner
device 30, and the normal state is selected, during which the
low-pressure EGR can be performed based on the engine operating
state.
[0118] Following this, at step S207, the burner device 30 is set to
the active state, i.e., the fuel addition valve 7 is turned on to
perform the addition of fuel, and the glow plug 21 is also turned
on.
[0119] However, in a case wherein it is determined at step S203
that the exhaust flow rate Ge is greater than the predetermined
value Gel, program control moves to step S208, whereat the bypass
valve 71 is open, and at step S209, the switching valve 72 is held
in the bypass open position (see FIG. 4), and at step S210 the
cooler switching valve 68 is held in the cooler bypass position,
and at step S211 the low-pressure EGR valve 62 is open. Then, at
step S207 the burner device 30 is set to the active state.
[0120] In other words, when the exhaust flow rate is high, as in
this case, an exhaust bypass is performed upstream of the burner
device 30, so as to reduce the flow rate of the exhaust gas to be
supplied to the burner device 30. Furthermore, since the
low-pressure EGR passage 61 is closed en route by closing the
switching valve 72, the low-pressure EGR is not performed by using
the exhaust gas extracted downstream of the oxidation catalyst
6.
[0121] It should be noted, however, that bypass gas is passed
through the bypass passage 70 and the low-pressure EGR passage 61,
and is returned to the intake passage. This is also one type of
low-pressure EGR. At this time, the bypass gas does not pass the
main passage 66 of the EGR cooler 65, but passes the cooler bypass
passage 67. Therefore, the cooling of the bypass gas by the EGR
cooler 65 does not occur, and the bypass gas, maintained at a
comparatively high temperature, is returned to the intake
passage.
[0122] As a result, compared with a case wherein the bypass gas is
cooled by the EGR cooler 65, the intake air temperature is
increased, and the temperature of the exhaust gas, especially the
exhaust gas that is to be supplied to the burner device 30, is
increased. This is very effective improvement for the ignition
performance of the burner device 30.
[0123] Preferably, at step S208, the opening of the bypass valve 71
is changed in accordance with the detected exhaust flow rate Ge.
That is, the opening of the bypass vale 71 is increased when the
detected exhaust flow rate is high. With this arrangement, when the
exhaust flow rate is high, the exhaust bypass flow rate can be
increased, and the supply of the exhaust gas to the burner device
30 can be continued at a flow rate equal to or smaller than the
predetermined value Gel.
[0124] With regard to step S211, if it is assumed that the EGR
control described above is performed, the low-pressure EGR valve 62
is not open when the engine operating state is in the first range
I. However, the process in this case is not performed based on the
EGR control, and even when the engine operating state is in the
first range I, the low-pressure EGR valve 62 is open. The burner
control takes precedence over the EGR control. Therefore, in a
situation during which the engine operating state is in the first
range I and deceleration is being performed, i.e., in a situation
where a condition for a low exhaust temperature and a high exhaust
flow rate is easily established, the low-pressure EGR can be
performed using the bypass gas to increase the temperature of the
exhaust gas to be supplied to the burner device 30. This is also a
very effective for the improvement of the ignition performance of
the burner device 30.
[0125] When the low-pressure EGR using the bypass gas is performed
while the engine operating state is in the first range I, the total
amount of EGR gas might become excessive, because the low-pressure
EGR that originally was not to be performed is actually performed,
in addition to the high-pressure EGR. As a countermeasure, it is
preferable that the opening of the high-pressure EGR valve 42 be
reduced to cancel out the surplus in the amount of the EGR gas.
Further, in a case, including the above case, wherein the
low-pressure EGR is to be performed using the bypass gas, it is
preferable that a map, for example, be additionally prepared, so
that the openings of the high-pressure EGR valve 42, the
low-pressure EGR valve 62 and the bypass valve 71 can be controlled
to obtain the desired amount of EGR gas.
[0126] The embodiment of the present invention has been described
in detail; however, various other embodiments are available for the
present invention. For example, at least one of the burner catalyst
8 and the impingement plate 20 may be eliminated from the burner
device 30. In this embodiment, the exhaust gas flow sensor 26 has
been employed to directly detect the flow rate of the exhaust gas
that is discharged from the turbine 5T; however, the exhaust flow
rate may be estimated. An estimation method employed can be an
estimation based on an intake air volume detected by the air flow
meter 4 and the openings of the EGR valves 42 and 62 and the bypass
valve 71. These detections and estimations are collectively called
acquisition.
[0127] It is preferable that the temperature of the exhaust
treatment device employed for controlling the burner device be the
temperature of the exhaust treatment device located at the furthest
upstream position (the oxidation catalyst 6), as in this
embodiment. However, the temperature of the exhaust treatment
device arranged at the second or third furthest upstream position
may be employed.
[0128] At least one of the burner catalyst and the exhaust pipe may
have a non-circular shape, such as an oval or elliptic shape, in
cross section. An arbitrary type and an arbitrary arrangement order
are employed for the exhaust treatment equipment located downstream
of the burner catalyst. The application and form of the internal
combustion engine are also arbitrarily employed, and are not
limited to the vehicle mount type, etc.
[0129] The present invention has been described with concreteness
to a degree, but it should be understood that various modifications
and alterations can be provided, without departing from the spirit
and scope of the present invention in the appended claims. The
embodiment of the present invention is not limited to the above
described one, and the present invention covers various
modifications and applications that are included in the idea of the
invention as regulated by the claims. Therefore, the present
invention should not be restrictively interpreted, and can also be
applied for another arbitrary technology that is within the range
of the idea of the present invention. Means of this invention for
the solution of problems can be employed in combinations in as many
ways as possible.
* * * * *