JP6209467B2 - Engine exhaust treatment equipment - Google Patents

Description

  The present invention relates to an engine exhaust treatment apparatus, and more particularly to an engine exhaust treatment apparatus capable of preventing thermal damage of a mating surface of a catalyst portion constituting a combustible gas catalyst.

  Conventionally, as an exhaust treatment device for an engine, a combustible gas generating catalyst and an exhaust treatment unit are provided, and a combustible gas is generated by a catalytic reaction accompanied by heat generation in the combustible gas generating catalyst, and the combustible gas passes through the engine exhaust path. There is a configuration in which exhaust gas mixed in passing exhaust gas and heated by combustion of a viscous gas is supplied to an exhaust processing unit (see, for example, Patent Document 1).

  According to this type of exhaust treatment apparatus, there is an advantage that the treatment in the exhaust treatment unit can be promoted by the heat of the exhaust gas whose temperature has been raised.

  In the thing of patent document 1, the combustible gas production | generation catalyst is comprised by the aggregate | assembly of several catalyst parts.

JP 2012-188971 A (see FIGS. 1 and 2)

<Problem> Thermal damage may occur on the mating surfaces of the catalyst parts.
In Patent Document 1, the combustible gas generating catalyst is constituted by an assembly of a plurality of catalyst parts, and the molding of the combustible gas generating catalyst is facilitated. Damage may occur.

  An object of the present invention is to provide an exhaust treatment apparatus for an engine that can prevent thermal damage of the mating surfaces of the catalyst portions constituting the combustible gas catalyst.

As a result of research, the inventors of the present invention have found that the gap along the inlet recess is a gap edge between the gaps between adjacent surfaces of the catalyst portions, and the combustible gas material flowing into the inlet recess is the gap edge. It has been found that by avoiding direct entry into the catalyst, thermal damage to the mating surfaces of the catalyst portions can be prevented, leading to the present invention.
The reason is estimated as follows.
That is, the combustible gas raw material flows in a concentrated manner in the gap between the mating surfaces with low resistance, and overheating due to the catalytic reaction causes thermal damage to the mating surfaces of the catalyst portions. For this reason, by avoiding that the combustible gas material that has flowed into the inlet recess directly enters the gap edge along the inlet recess, the combustible gas material does not flow in the gap and the catalytic reaction It was possible to prevent thermal damage of the mating surfaces caused by overheating.

Invention specific matters of the invention according to claim 1 are as follows.
As illustrated in FIG. 1, a combustible gas generating catalyst (2) and an exhaust treatment unit (10) are provided, and the combustible gas (8) is generated by a catalytic reaction accompanied by heat generation in the combustible gas generating catalyst (2). The generated exhaust gas (8) is mixed into the exhaust gas (9) passing through the engine exhaust path (4), and the exhaust gas (9) heated by the combustion of the combustible gas (8) is discharged into the exhaust gas processing unit (10 In the engine exhaust treatment device configured to be supplied to
As illustrated in FIGS. 3 (A) to 3 (C) and FIGS. 4 (A) to 4 (B), the combustible gas generating catalyst (2) is located on the central axis (2c) of the combustible gas generating catalyst (2). Composed of an assembly of a plurality of catalyst parts (2a) (2a) with vertical mating surfaces (2b) along;
As illustrated in FIG. 3 (A) and FIGS. 4 (A) to 4 (C), an inlet serving as an inlet for the raw material (7) of the combustible gas (8) at the upper central portion of the combustible gas generating catalyst (2). A recess (12) is provided, and the gap (2d) between the mating surfaces (2b) and (2b) of the adjacent catalyst portions (2a) and (2a) is laterally oriented along the inner bottom surface (12a) of the inlet recess (12). Let the part be the lateral gap edge (2e), and let the vertical part along the inner peripheral surface (12b) of the inlet recess (12) be the vertical gap edge (2f) (2f),
As illustrated in FIGS. 3 (A) and 4 (A) to 4 (C), a guide bottom plate (13) is disposed on the inner bottom surface (12a) of the inlet recess (12) so as to cover the lateral gap edge (2e). The standing walls (13a) and (13a) covering the standing gap edges (2f) and (2f) are erected on the peripheral edge of the guide bottom plate (13).
As illustrated in FIG. 3A, the raw material (7) of the combustible gas (8) flowing into the inlet recess (12) was covered with the guide bottom plate (13) and the standing walls (13a) (13a). An engine characterized by avoiding the lateral gap edge (2e) and the vertical gap edge (2f) (2f) and being diverted in the circumferential direction by the guide bottom plate (13). Exhaust treatment equipment.

(Invention of Claim 1)
The invention according to claim 1 has the following effects.
<Effect> It is possible to prevent thermal damage of the mating surfaces of the catalyst portions.
As illustrated in FIG. 3A, the raw material (7) of the combustible gas (8) flowing into the inlet recess (12) is covered with the guide bottom plate (13) and the standing walls (13a) (13a). Since it is constructed so as to avoid the gap edge (2e) and the vertical gap edge (2f) (2f) and to be diverted in the circumferential direction by the guide bottom plate (13), the combustible gas (8) The raw material (7) of the catalyst parts (2a) (2a) becomes difficult to pass through the gap (2d) of the mating surfaces (2b) (2b) of the catalyst parts (2a) (2a). Thermal damage of the mating surfaces (2b) and (2b) can be prevented.

<Effect> The combustible gas generating catalyst can be easily molded.
As illustrated in FIGS. 4A to 4D, the combustible gas generating catalyst (2) is composed of an assembly of a plurality of catalyst portions (2a) and (2a). The molding of (2) becomes easy.

<Effect> The generation efficiency of combustible gas is increased.
As illustrated in FIG. 3A, the raw material (7) of the combustible gas (8) that has flowed into the inlet recess (12) is diverted in the peripheral direction by the guide bottom plate (13). Is dispersed throughout the combustible gas generating catalyst (2), and the generation efficiency of the combustible gas (8) is increased.

(Invention of Claim 2)
The invention according to claim 2 has the following effect in addition to the effect of the invention according to claim 1.
<Effect> It is possible to prevent thermal damage of the mating surfaces of the catalyst portions.
As illustrated in FIG. 4 (A), the standing walls (13a) and (13a) are prevented from rotating with respect to the circumferential direction of the inlet recess (12). Ingress of raw material (7) of combustible gas (8) from gap edge (2f) (2f) is prevented, and heat damage of mating surfaces (2b) (2b) of catalyst parts (2a) (2a) is prevented can do.

(Invention of Claim 3)
The invention according to claim 3 has the following effect in addition to the effect of the invention according to claim 1 or claim 2.
<Effect> Manufacture of a combustible gas generating catalyst is facilitated.
As illustrated in FIGS. 3 (A) to (C) and FIGS. 4 (A) to (C), the two catalyst portions (2a) and (2a) are configured so as to have the same shape. The combustible gas generating catalyst (2) can be constituted by using two parts formed by the mold, and the combustible gas generating catalyst (2) can be easily manufactured.

(Invention of Claim 4)
The invention according to claim 4 has the following effects in addition to the effects of the invention according to any one of claims 1 to 3.
<Effect> It is possible to prevent thermal damage of the exhaust treatment unit.
As shown in FIG. 1, the oxidation catalyst (3) is disposed in the exhaust path (4), and the combustible gas (8) is catalytically burned by the oxidation catalyst (3), and rises by catalytic combustion in the oxidation catalyst (3). Since the heated exhaust (9) is configured to be supplied to the exhaust treatment section (10) downstream of the oxidation catalyst (3), the temperature of the exhaust (9) is reduced by catalytic combustion of the oxidation catalyst (3). The temperature can be raised gradually, and thermal damage to the exhaust treatment section (10) can be prevented.

(Invention according to claim 5)
The invention according to claim 5 has the following effect in addition to the effect of the invention according to claim 4.
<Effect> The function of preventing thermal damage of the mating surfaces of the catalyst portions becomes obvious.
As illustrated in FIG. 1, when PM deposited on the oxidation catalyst (3) is removed by combustion, a highly ignitable combustible gas (8) is generated by the catalytic reaction of the combustible gas generating catalyst (2). Since the calorific value of the mating surfaces (2b) and (2b) of the portions (2a) and (2a) tends to increase, each catalyst portion (2a) (2a) is formed by the guide bottom plate (13) and the standing walls (13a) and (13a). The function of preventing the thermal damage of the mating surfaces (2b) and (2b) of the) becomes obvious.

1 is a schematic diagram of an exhaust treatment device for a diesel engine according to an embodiment of the present invention. It is a vertical side view of the combustible gas production | generation mixer used with the apparatus of FIG. 3A is a sectional view taken along line IIIA-IIIA in FIG. 2, FIG. 3B is a sectional view taken along line IIIB-IIIB in FIG. 2, and FIG. 3C is a sectional view taken along line IIIC-IIIC in FIG. FIG. 4A is a plan view, FIG. 4B is a cross-sectional view taken along the line BB in FIG. 4A, and FIG. 4C is a diagram illustrating a combustible gas generating catalyst used in the apparatus of FIG. These are CC sectional view taken on the line of FIG. 4 (B). It is the perspective view which looked down at the combustible gas production | generation mixer of FIG. 2 diagonally downward from the side. 6 (A) is a plan view of the combustible gas generating mixer of FIG. 2, and FIG. 6 (B) is a sectional view taken along the line VIB-VIB of FIG. 7A is a view taken in the direction of the VIIA arrow in FIG. 2, and FIG. 7B is a cross-sectional view taken along the line BB in FIG. 7A. It is a VIII direction arrow directional view of Drawing 7 (A). It is a time chart of DPF regeneration and oxidation catalyst regeneration.

  FIG. 1 to FIG. 9 are diagrams for explaining an exhaust treatment device for an engine according to an embodiment of the present invention. In this embodiment, an exhaust treatment device for a diesel engine will be explained.

The main configuration of the exhaust treatment apparatus is as follows.
As shown in FIG. 1, a combustible gas generating catalyst (2) and an exhaust treatment section (10) are provided, and a combustible gas (8) is generated by a catalytic reaction accompanied by heat generation in the combustible gas generating catalyst (2). Then, the combustible gas (8) is mixed into the exhaust (9) passing through the engine exhaust path (4), and the exhaust (9) is heated by the combustion of the combustible gas (8). It is configured to be supplied.

The exhaust processing unit (10) is a DPF (19). DPF is an abbreviation for diesel particulate filter. In the DPF (19), PM contained in the exhaust (9) is trapped and accumulated, and when the estimated PM accumulation value of the DPF (19) reaches a predetermined regeneration start value, the temperature is raised by combustion of the gas (8). PM is incinerated and removed by the heat of the exhaust (9), and the DPF (19) is regenerated. The exhaust processor (10), other DPF (19), can be used an exhaust gas purification catalyst (SCR catalyst and _the NO _X storage catalyst, etc.). SCR catalyst is an abbreviation for selective reduction catalyst, and NO _X is an abbreviation for nitrogen oxides.

The configuration of the combustible gas generating catalyst is as follows.
As shown in FIGS. 3 (A) to (C) and FIGS. 4 (A) to (B), the combustible gas generating catalyst (2) is along the central axis (2c) of the combustible gas generating catalyst (2). It is composed of an assembly of a plurality of catalyst parts (2a) (2a) having a vertical mating surface (2b).
As shown in FIG. 3 (A) and FIGS. 4 (A) to (C), an inlet recess serving as an inlet for the raw material (7) of the combustible gas (8) at the upper center of the combustible gas generating catalyst (2). (12) provided in the gap (2d) between the mating surfaces (2b) and (2b) of the adjacent catalyst portions (2a) and (2a), the laterally facing portion along the inner bottom surface (12a) of the inlet recess (12) Is the lateral gap edge (2e), and the standing portion along the inner peripheral surface (12b) of the inlet recess (12) is the standing gap edge (2f) (2f).
As shown in FIG. 3 (A) and FIGS. 4 (A) to (C), a guide bottom plate (13) is disposed on the inner bottom surface (12a) of the inlet recess (12) so as to cover the lateral gap edge (2e). Further, standing walls (13a) and (13a) are provided on the peripheral edge of the guide bottom plate (13) so as to cover the clearance gap edges (2f) and (2f).
As a result, as shown in FIG. 3A, the raw material (7) of the combustible gas (8) flowing into the inlet recess (12) is covered with the guide bottom plate (13) and the standing walls (13a) (13a). The horizontal gap edge (2e) and the vertical gap edges (2f) and (2f) are avoided, and the guide bottom plate (13) is configured to divert in the peripheral direction.

Figure 4 (A), the vertical wall (13a) protruding outwardly projecting (13b) (13b) is provided in (13a), the projection (13b) (13b) is standing facing gap edges (2f) (2f) is entered, and the standing walls (13a) (13a) are prevented from rotating with respect to the circumferential direction of the inlet recess (12).

As shown in FIG. 3, the catalyst temperature detection device (14) is provided, and the insertion hole (15) for inserting the temperature detection portion (14a) of the catalyst temperature detection device (14) into the combustible gas generation catalyst (2) is penetrated. It is provided in the shape.
As shown in FIGS. 4 (A) and 4 (B), the combustible gas generating catalyst (2) is composed of two catalyst portions (2a) and (2a).
As shown in FIG. 3 (C), the central axis (15a) of the insertion hole (15) is orthogonal to the central axis (2c) of the combustible gas generating catalyst (2), and the catalyst parts (2a) (2a) ) Is formed in a direction parallel to the mating surfaces (2b) and (2b), so that the two catalyst portions (2a) and (2a) have the same shape.

As shown in FIG. 4 (C), the combustible gas generating catalyst (2) has an inverted truncated cone shape, and the catalyst parts (2a) and (2a) have the combustible gas generating catalyst (2) as a central axis (2c). It is set as the split shape divided along.
Each catalyst part (2a) (2a) of the combustible gas generating catalyst (2) is made by weaving an iron chrome wire and press-molding it into a half-conical truncated cone shape. Is carried.

As shown in FIG. 1, the oxidation catalyst (3) is disposed in the exhaust path (4), and the combustible gas (8) is catalytically burned by the oxidation catalyst (3), and rises by catalytic combustion in the oxidation catalyst (3). The heated exhaust (9) is supplied to the exhaust treatment section (10) downstream of the oxidation catalyst (3).
The oxidation catalyst (3) is DOC (10). DOC is an abbreviation for diesel oxidation catalyst.

As shown in FIG. 1, an ignition device (16) and a control device (17) are provided, and the ignition device (16) is arranged upstream of the oxidation catalyst (3), and a predetermined amount is supplied to the oxidation catalyst (3). In the case where PM is deposited, highly flammable gas (8) is generated by the catalytic reaction of the flammable gas generating catalyst (2) , and the highly ignitable flammable gas ignited by the ignition device (16). The exhaust gas (8) is heated by the flame combustion heat of the natural gas (8), and the PM deposited on the oxidation catalyst (3) is combusted and removed by the heat of the exhaust gas (9).
When the fuel (8) raw material (7) is an air-fuel mixture that is a mixture of liquid fuel (5) and air (6), and a predetermined amount of PM is deposited on the oxidation catalyst (3) the, the control unit (17), combustible gas generator (1) air-fuel mixture of air (6) the mixing ratio is set high in the heating value of the combustible gas producing catalyst (2) is Due to the higher catalytic reaction, highly ignitable combustible gas (8) is produced.
The main configuration of the exhaust treatment apparatus is as described above.

Next, the overall configuration of the exhaust treatment device will be described.
As shown in FIG. 1, the exhaust treatment apparatus includes a combustible gas generation mixer (22), an exhaust treatment case (23), and a control device (17).
The combustible gas generation mixer (22). A combustible gas generator (1), a combustible gas supply passage (24), and a combustible gas mixing passage (25) are provided.
The exhaust treatment case (23) contains an oxidation catalyst (3) and a DPF (19).

As shown in FIG. 2, the combustible gas generation mixer (22) has a combustible gas generator (1), a combustible gas supply passage (24), and a combustible gas mixing passage (25) integrated. This is a cast block body.
The appearance of the combustible gas generation mixer (22) is as shown in FIG. 5, FIG. 6 (A), FIG. 7 (A), and FIG.
As shown in FIG. 2, the combustible gas generator (1) includes an upper mixer part (1a) and a lower catalyst housing part (1b), and a gasket (1c) is sandwiched between the mixer part (1a). The lid (1d) is attached from above, the heater (26) for warming up the catalyst is attached to the boss (1e) of the lid (1d), and the mixer chamber (1f) is formed around the boss (1e). Has been. An electrothermal glow plug is used for the catalyst warm-up heater (26).
As shown in FIG. 1 or FIG. 6 (B), the fuel supply groove (27) provided on the upper surface of the mixer section (1a) and the air supply groove (28) to the fuel supply port (27a) of the gasket (1c) Liquid fuel (5) and air (6) are supplied to the mixer chamber (1f) through the air supply port (28a), and these are mixed in the mixer chamber (1f) to become an air-fuel mixture, which is combustible. It becomes the raw material (7) of the gas (8).

As shown in FIG. 2, the combustible gas generating catalyst (2) is accommodated in the catalyst accommodating portion (1b).
As shown in FIG. 2, the combustible gas generating catalyst (2) has an upside-down inverted frustoconical shape, and as shown in FIG. 3 (A), the inlet recess (12) is recessed downward at the center upper part. A guide bottom plate (13) is provided on the inner bottom surface (12a), and a combustible gas generation start catalyst (29) is accommodated in the upper portion of the inner bottom surface (12a). A machine heater (26) is inserted. The combustible gas production start catalyst (29) is an alumina fiber mat on which a rhodium catalyst component is supported. The combustible gas production start catalyst (29) has a higher retention of the liquid fuel (5) than the combustible gas production catalyst (2). The guide bottom plate (13) and the standing walls (13a) (13a) are made of stainless steel flat plates.

As shown in FIG. 2, between the peripheral surface of the combustible gas generating catalyst (2) and the peripheral wall of the catalyst housing portion (1b), the upper surface of the combustible gas generating catalyst (2) and the bottom surface of the mixer portion (1a). Insulating cushion material (30) is interposed between each. The heat insulating cushion material (30) is made of an alumina fiber mat.
An insertion hole (15) for inserting the temperature detection part (14a) of the catalyst temperature detection device (14) is provided in a penetrating manner in the lower part of the combustible gas generating catalyst (2). The thermistor is used for the catalyst temperature detection device (14). The guide bottom plate (13) is disposed directly above the temperature detection unit (14a).

  As shown in FIG. 2, the combustible gas supply passage (24) is led out horizontally from directly below the catalyst housing portion (1b). A gas nozzle (31) is provided at the end of the combustible gas supply passage (24). The gas nozzle (31) protrudes into the secondary air mixing chamber (32). As shown in FIG. 7B, a secondary air supply passage (33) is provided in parallel with the combustible gas supply passage (24), and a gas nozzle (31) is provided in the secondary air mixing chamber (32). Combustible gas (8) and secondary air (34) are supplied from the secondary air supply passage (33) and mixed in the secondary air mixing chamber (32). The combustible gas (8) is ejected radially from the gas nozzle (31) in the radial direction of the secondary air mixing chamber (32), and the secondary air (34) swirls around the gas nozzle (31).

An ignition device housing chamber (35) is disposed downstream of the secondary air mixing chamber (32), and the ignition device (16) is disposed here. An electrothermal glow plug is used for the ignition device (16). The combustible gas (8) flowing into the ignition device accommodating chamber (35) is ignited by the ignition device (16) under a predetermined condition.
As shown in FIG. 6 (A) and FIG. 7 (A), heat is radiated to the outer projecting portion (16a) of the ignition device (16) projecting outside the wall (22a) of the combustible gas generating mixer (22). A plate (16b) is attached. Thereby, the combustion heat of the combustible gas (8) conducted to the ignition device (16) is radiated through the heat radiating plate (16b), and thermal damage of the ignition device (16) is suppressed.

As shown in FIG. 6A, the heat radiating plate 16b is disposed in the cooling air passage 50 of the engine cooling fan (not shown), and the cooling air 51 passing through the cooling air passage 50 is radiated. The heat radiating plate (16b), which is configured to blow against the plate (16b), is bent in a U-shape, and the outer protrusion (16a) of the ignition device (16) is surrounded by the heat radiating plate (16b). The ventilation inlet (16c) of the plate (16b) is provided on the upstream side of the cooling air passage (50), and the wind shielding wall (16d) of the heat radiating plate (16b) is provided on the downstream side of the cooling air passage (50). Yes.
Air exhaust ports (16f) and (16f) are provided on both side walls (16e) and (16e) of the heat radiating plate (16b) extending from the wind shielding wall (16d) to the upstream side of the cooling air passage (50).

  As shown in FIG. 6 (A) and FIG. 7 (A), a ventilation gap (22b) is formed in the wall (22a) of the combustible gas generation mixer (22) into which the ignition device (16) is inserted. A part of the insertion part (16g) of the ignition device (16) inserted into the wall (22a) of the gas generating mixer (22) is exposed in the ventilation gap (22b), and the ventilation gap (22b) is cooled by the cooling air. The cooling air (51) arranged in the passage (50) and passing through the cooling air passage (50) flows into the ventilation gap (22b) and blows to a part of the insertion portion (16g) of the ignition device (16). It is configured. Thereby, the combustion heat of the combustible gas (8) conducted to the ignition device (16) is dissipated to the cooling air (51) passing through the ventilation gap (22b), and thermal damage to the ignition device (16) is suppressed. Is done.

As shown in FIG. 2, a communication port (36) is provided above the ignition device housing chamber (35), and the ignition device housing chamber (35) is connected to the combustible gas mixing passage (25) via the communication port (36). ). At the end of the ignition device housing chamber (35), a flame holding plate (37) is provided upright, and the upper end of the flame holding plate (37) extends from the communication port (36) to the combustible gas mixing passage (25). The flame generated by the ignition device (16) is prevented from being blown out by the exhaust gas (9) passing through the combustible gas mixing passage (25). An ignition detection device (38) is disposed in the combustible gas mixing passage (25). The thermistor is used for the ignition detection device (38).
As shown in FIG. 1, the combustible gas mixing passage (25) constitutes a part of the engine exhaust passage (4), and connects the compressor outlet (39a) of the supercharger (39) and the exhaust treatment case (23). It is arranged between the exhaust inlet (23a).

As shown in FIG. 1, the exhaust treatment case (23) constituting part of the engine exhaust path (4) contains an oxidation catalyst (3) on the upstream side and a DPF (19) on the downstream side. Yes. The oxidation catalyst (3) is a flow-through monolith in which an oxidation catalyst component is supported on a ceramic honeycomb carrier and both ends of the cell (3a) are opened. The exhaust (9) passes through the inside of the cell (3a). Is configured to do.
The DPF (19) is a wall flow monolith in which an oxidation catalyst component is supported on a ceramic honeycomb-shaped carrier and the ends of adjacent cells (19a) (19a) are alternately plugged, and adjacent cells (19a). The exhaust (9) passes through the wall (19b) between (19a), and the PM contained in the exhaust (9) is captured by the wall (19b). PM is an abbreviation for particulate matter.

As shown in FIG. 1, the exhaust treatment case (23) includes an exhaust temperature detecting device (40) at the oxidation catalyst inlet, an exhaust temperature detecting device (41) at the DPF inlet, and an exhaust temperature detecting device (42) at the DPF outlet. Is provided. An exhaust pressure detection device (43) upstream of the oxidation catalyst is provided in the combustible gas mixing passage (25) of the combustible gas generator (1). These detection devices (40) (41) (42) (43) are all connected to the control device (17). The control device (17) is an engine ECU. ECU is an abbreviation for electronic control unit.
The controller (17) includes a catalyst warm-up heater (26), a fuel pump (45) for supplying liquid fuel (5) from the fuel tank (44) to the mixer section (1a), a blower (46), a blower ( 46), an air adjustment solenoid valve (47) for adjusting the supply amount of air (6) from the blower (46) to the mixer section (1a), and secondary air (34) from the blower (46) to the secondary air mixing chamber (32). A secondary air adjusting solenoid valve (48) for adjusting the supply amount of gas, an ignition device (16), and an ignition detection device (38) are connected.

  As shown in FIG. 9, when the estimated value of the total amount of accumulated PM in the DPF (19) and the oxidation catalyst (3) reaches a predetermined regeneration required value, the regeneration process is permitted by the control device (17). The estimated PM deposition total amount is estimated by the control device (17) based on the exhaust pressure upstream of the oxidation catalyst by the exhaust pressure detection device (43) upstream of the oxidation catalyst. At the same time as the regeneration permission, the control device (17) determines whether the regeneration permission is for DPF regeneration or oxidation catalyst regeneration. As shown in FIG. 9, the control device (17) determines that DPF regeneration is permitted when the interval (49) from the end of the previous regeneration to the regeneration permission is equal to or longer than a predetermined time, and is less than the predetermined time. In this case, it is determined that the oxidation catalyst regeneration is permitted.

  The PM accumulated in the DPF (19) is almost entirely removed by one DPF regeneration process or one oxidation catalyst regeneration process, but the PM accumulated in the oxidation catalyst (3) Since it is not removed even in the DPF regeneration process and gradually accumulates, it is estimated that when the interval (49) is less than a predetermined time, a predetermined amount of PM is deposited on the oxidation catalyst (3) to be regenerated. can do. Therefore, the DPF regeneration and the necessity for regeneration of the oxidation catalyst are discriminated based on the length of the interval (49), and permission for DPF regeneration and permission for regeneration of the oxidation catalyst are determined.

As shown in FIG. 1, DPF regeneration, in either case of the oxidation catalyst regeneration also, the control unit (17), at the start of reproduction, the combustible gas generating catalyst in catalyst warm-up heater (26) (2) is warmed up Then, liquid fuel (5) and air (6) are supplied to the combustible gas generator (1), and an air-fuel mixture is formed in the mixer section (1a). The flammable gas (8) is generated by a catalytic reaction accompanied by heat generation in the flammable gas generating catalyst (2).

In the DPF regeneration, when the exhaust temperature at the oxidation catalyst inlet is equal to or higher than the activation temperature of the oxidation catalyst (3), the combustible gas is not ignited by the ignition device (16) based on the control of the control device (17). (8) is mixed with the secondary air (34) in the exhaust (9) passing through the combustible gas mixing passage (25), and the combustible gas (8) is contained in the secondary air (34) and the exhaust (9). Exhaust gas (9), which is catalytically combusted by the oxidation catalyst (3) with air and heated by catalytic combustion in the oxidation catalyst (3), is supplied to the DPF (10) downstream of the oxidation catalyst (3).

In the DPF regeneration, when the exhaust gas temperature at the oxidation catalyst inlet is lower than the activation temperature of the oxidation catalyst (3), based on the control of the control device (17), the ignition device (16) ignites the combustible gas ( 8) is flame-combusted by the secondary air (34), the exhaust gas (9) passing through the combustible gas mixing passage (25) is heated by the heat of the flame combustion, and the exhaust temperature at the oxidation catalyst inlet becomes the oxidation catalyst (3 ) Reaches the activation temperature and the oxidation catalyst (3) is warmed up, the flame combustion is terminated, and the flammable gas (8) is combined with the secondary air (34) without ignition by the ignition device (16). It is mixed in the exhaust gas (9) passing through the combustible gas mixing passage (25), and the combustible gas (8) is catalytically combusted by the oxidation catalyst (3) by the air in the secondary air (34) and the exhaust gas (9). The exhaust gas (9) heated by catalytic combustion in the oxidation catalyst (3) is supplied to the DPF (10) downstream of the oxidation catalyst (3).
When the accumulated time when the exhaust temperature at the DPF inlet exceeds the predetermined temperature reaches a predetermined value, the DPF regeneration is finished.

Termination of ignition and flame combustion by the ignition device (16) is performed as follows.
The ignition device (16) is ignited based on the control of the control device (17). The ignition device (16) generates heat when energized, and the combustible gas generating catalyst (2) generates a highly ignitable combustible gas ( This is done by generating 8). Highly ignitable combustible gas (8) is a mixture of air and fuel that is supplied to the combustible gas generating catalyst (2) compared to the case of low ignitable combustible gas (8) that is catalytically combusted with the oxidation catalyst (3). It is generated by a catalytic reaction in which the mixing ratio of the atmospheric air (6) is set high and the calorific value becomes high. The end of the flame combustion is performed by generating a low ignitable combustible gas (8) with the combustible gas generating catalyst (2) and blowing off the flame combustion with the low ignitable combustible gas (8). Is called.
The generation of the combustible gas (8) is based on the control of the control device (17), and the deviation between the target temperature of the combustible gas generating catalyst (2) and the detected temperature detected by the catalyst temperature detection device (14) is reduced. By performing feedback control, the supply amount and the mixing ratio of the liquid fuel (5) and air (6) are adjusted. When generating highly ignitable combustible gas (8), the target temperature of combustible gas generating catalyst (2) is set high, the mixture ratio of air (6) in the air-fuel mixture increases, and low ignitability When the combustible gas (8) is produced, the catalyst temperature is set to a low target value, and the mixture ratio of the air (6) of the air-fuel mixture becomes low.

  Oxidation catalyst regeneration is based on the control of the control device (17), and the combustible gas (8) is flame-combusted by the secondary air (34) when ignited by the ignition device (16). This is done by raising the temperature of the exhaust gas (9) passing through the mixing passage (25). The ignition device (16) is ignited by the ignition device (16) generating heat when energized and the combustible gas generation catalyst (2) generating highly ignitable combustible gas (8). . Highly ignitable combustible gas (8) is a mixture of air and fuel that is supplied to the combustible gas generating catalyst (2) compared to the case of low ignitable combustible gas (8) that is catalytically combusted with the oxidation catalyst (3). It is generated by a catalytic reaction in which the mixing ratio of the atmospheric air (6) is set high and the calorific value becomes high. When a predetermined time elapses with the exhaust gas temperature at the oxidation catalyst inlet reaching the target temperature, the oxidation catalyst regeneration ends. The target temperature at the inlet of the exhaust catalyst for regeneration of the oxidation catalyst is higher than the activation temperature of the oxidation catalyst (3).

(2) Combustible gas generation catalyst
(2a) Catalyst part
(2b) Mating surface
(2c) Center axis
(2d) Clearance
(2e) Horizontal gap edge
(2f) Vertical gap edge
(3) Oxidation catalyst
(4) Engine exhaust path
(7) Raw material
(8) Combustible gas
(9) Exhaust
(10) Exhaust treatment part
(12) Entrance recess
(12a) Inner bottom
(12b) Inner peripheral surface
(13) Guide bottom plate
(13a) Standing wall
(13b) Projection
(14) Catalyst temperature detector
(14a) Temperature detector
(15) Insertion hole
(15a) Center axis
(16) Ignition device
(17) Control device

Claims (5)

A combustible gas generating catalyst (2) and an exhaust treatment section (10) are provided, and a combustible gas (8) is generated by a catalytic reaction accompanied by heat generation in the combustible gas generating catalyst (2). ) Is mixed with the exhaust (9) passing through the engine exhaust path (4), and the exhaust (9) heated by the combustion of the combustible gas (8) is supplied to the exhaust processing unit (10). In the engine exhaust treatment system,
The combustible gas generating catalyst (2) is an aggregate of a plurality of catalyst parts (2a) (2a) having a vertical mating surface (2b) along the central axis (2c) of the combustible gas generating catalyst (2). Configured,
An inlet recess (12) serving as an inlet for the raw material (7) of the combustible gas (8) is provided in the upper central part of the combustible gas generating catalyst (2), and the mating surfaces of the adjacent catalyst parts (2a) (2a) (2b) Of the gap (2d) between the two (2b), the laterally facing portion along the inner bottom surface (12a) of the inlet recess (12) is defined as the lateral gap edge (2e), and the inner peripheral surface of the inlet recess (12) ( 12b) as the standing gap edge (2f) (2f)
A guide bottom plate (13) covering the lateral gap edge (2e) is disposed on the inner bottom surface (12a) of the inlet recess (12), and the vertical gap edge (2f) (2f) is disposed on the peripheral edge of the guide bottom plate (13). ) Standing walls (13a) (13a) covering
The lateral gap edge (2e) and the vertical gap in which the raw material (7) of the combustible gas (8) flowing into the inlet recess (12) is covered with the guide bottom plate (13) and the standing walls (13a) (13a) An engine exhaust treatment apparatus characterized in that it is configured so as to be diverted in the circumferential direction by a guide bottom plate (13) while avoiding the edges (2f) (2f). The engine exhaust treatment apparatus according to claim 1,
Vertical wall (13a) (13a) protruding outwardly projecting (13b) (13b) is provided, to enter this protrusion (13b) (13b) is standing facing the gap edge (2f) (2f) An exhaust processing apparatus for an engine, characterized in that the standing walls (13a) (13a) are prevented from rotating with respect to the circumferential direction of the inlet recess (12). The engine exhaust treatment apparatus according to claim 1 or 2,
The catalyst temperature detection device (14) is provided, and an insertion hole (15) for inserting the temperature detection portion (14a) of the catalyst temperature detection device (14) into the combustible gas generation catalyst (2) is provided in a penetrating manner.
The combustible gas generating catalyst (2) is composed of two catalyst parts (2a) (2a),
The center axis (15a) of the insertion hole (15) is orthogonal to the center axis (2c) of the combustible gas generating catalyst (2), and the mating surfaces (2b) (2b) of the catalyst parts (2a) (2a) An exhaust treatment apparatus for an engine, characterized in that the two catalyst portions (2a) and (2a) have the same shape by being formed in a direction along a direction parallel to the engine. The engine exhaust treatment apparatus according to any one of claims 1 to 3,
The exhaust catalyst (3) is disposed in the exhaust passage (4), the combustible gas (8) is catalytically combusted by the oxidation catalyst (3), and the exhaust gas (9) is heated by the catalytic combustion in the oxidation catalyst (3). Is supplied to the exhaust treatment section (10) downstream of the oxidation catalyst (3). The engine exhaust treatment apparatus according to claim 4,
When an ignition device (16) and a control device (17) are provided, the ignition device (16) is disposed upstream of the oxidation catalyst (3), and a predetermined amount of PM is deposited on the oxidation catalyst (3). Is a flame of a highly ignitable combustible gas (8) which is generated by the catalytic reaction of the combustible gas generating catalyst (2) and is ignited by the ignition device (16). Exhaust treatment of an engine, characterized in that the exhaust (9) is heated by the combustion heat and the PM deposited on the oxidation catalyst (3) is burned and removed by the heat of the exhaust (9). apparatus.

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