JP5167216B2 - Diesel engine exhaust treatment equipment - Google Patents

Description

The present invention relates to an exhaust treatment device for a diesel engine, and more particularly, to an exhaust treatment device for a diesel engine that can burn a combustible gas with oxygen in the exhaust gas even when the temperature of the exhaust gas is low.
In this specification and claims, DPF means diesel particulate filter and PM means particulate matter in exhaust gas.

Conventionally, a combustible gas is generated by a combustible gas generator, the combustible gas is discharged from the combustible gas discharge port to the exhaust passage upstream of the DPF, and the combustible gas is burned with oxygen in the exhaust. There is one in which the temperature of exhaust gas is raised by combustion heat so that PM accumulated in the DPF can be burned and removed by the heat of exhaust gas (see Patent Document 1).
According to this type of apparatus, even when the temperature of the exhaust gas is low, there is an advantage that the temperature of the exhaust gas can be raised by the combustible gas and the PM accumulated in the DPF can be burned and removed.
However, this conventional technique has a problem because there is no means for raising the temperature of the combustible gas.

Japanese Patent Laying-Open No. 2005-256769 (see FIG. 1)

<< Problem >> When the temperature of the exhaust gas is low, the combustible gas may not be burned with oxygen in the exhaust gas.
Since there is no means for raising the temperature of the combustible gas, when the temperature of the exhaust gas is low, the combustible gas may not be ignited and the combustible gas may not be combusted with oxygen in the exhaust gas.

  An object of the present invention is to provide an exhaust treatment device for a diesel engine capable of burning a combustible gas with oxygen in the exhaust gas even when the temperature of the exhaust gas is low.

(Invention-specific matters common to the inventions of claims 1 and 2)
As illustrated in FIG. 1, the combustible gas generator (1) generates a combustible gas (4) as illustrated in FIG. 1, and the combustible gas (4) is combusted upstream of the DPF (5). The combustible gas (4) is burned with oxygen in the exhaust (8), and the exhaust (8) is heated with the heat of combustion. In the exhaust treatment device for a diesel engine, the PM accumulated in the DPF (5) can be burned and removed by the heat of (8).
As illustrated in FIG. 2, the combustible gas generator (1) is provided with a combustible gas generating catalyst chamber (11), and the combustible gas generating catalyst chamber (11) accommodates the combustible gas generating catalyst (13). An annular wall (14) is disposed at the start end of the combustible gas generation catalyst chamber (11), and an air / fuel mixing chamber (12) is formed inside the annular wall (14). 12) By supplying air (3) and liquid fuel (2) to 12), an air-fuel mixed gas (23) is formed in the air-fuel mixing chamber (12), and this air-fuel mixed gas (23) is combustible. The gas generation catalyst (13) is supplied and the combustible gas generation catalyst (13) generates the combustible gas (4).
As illustrated in FIG. 2, the combustible gas generation catalyst chamber (11) is connected to the secondary air mixing chamber (44), the secondary air mixing chamber (44) is connected to the combustion catalyst chamber (45), and combustion is performed. A combustion catalyst (46) is accommodated in the catalyst chamber (45), and the combustible gas discharge port (6) is communicated with the combustion catalyst chamber (45).
By supplying the combustible gas (4) and the secondary air (48) from the combustible gas generating catalyst chamber (11) and the secondary air supply source (47) to the secondary air mixing chamber (44),
In the secondary air mixing chamber (44), the combustible gas (4) and the secondary air (48) are mixed to form a secondary air mixed gas (49), and this secondary air mixed gas (49) becomes a combustion catalyst ( 46), a part of the combustible gas (4) is catalytically combusted by the secondary air (48), and the remaining heat of the combustible gas (4) that has passed through the combustion catalyst (46) is generated by the combustion heat. The temperature of the combustible gas (4) is increased, and the heated combustible gas (4) is discharged from the combustible gas discharge port (6) to the exhaust passage (7) .
As illustrated in FIG. 9A, a partition plate placement surface (50) (51) is provided in the lower part of the combustible gas generation catalyst chamber (11), and the partition plate placement surface (50) (51) is provided on the partition plate placement surface (50) (51). The partition plate (52) is placed and fixed, and the partition plate (52) partitions the secondary air mixing chamber (44) below the combustible gas generating catalyst chamber (11),
(Invention specific matters specific to the invention of claim 1)
As illustrated in FIG. 9 (A), a plurality of combustible gas outlet holes (54) are formed in the peripheral portion (53) of the partition plate (52) at predetermined intervals in the circumferential direction, and a combustible gas generating catalyst is formed. Diesel engine exhaust characterized in that the combustible gas (4) generated in (13) is supplied to the secondary air mixing chamber (44) through the combustible gas outlet hole (54). Processing equipment.
(Invention-specific matters specific to the invention of claim 2)
In the exhaust treatment device of the diesel engine according to claim 1,
As illustrated in FIG. 9 (A), a plurality of combustible gas outlet holes (54) are formed in the peripheral portion (53) of the partition plate (52) at predetermined intervals in the circumferential direction, and a combustible gas generating catalyst is formed. Instead of supplying the combustible gas (4) generated in (13) to the secondary air mixing chamber (44) via the combustible gas outlet hole (54),
As illustrated in FIG. 9B, the peripheral portion of the partition plate (52) is disposed between the peripheral portion (53) of the partition plate (52) and the chamber wall (55) of the secondary air mixing chamber (44). A combustible gas outlet gap (56) is provided along (53), and the combustible gas (4) generated by the combustible gas generating catalyst (13) is mixed with the secondary air through the combustible gas outlet gap (56). An exhaust treatment device for a diesel engine, characterized by being supplied to a chamber (44).

(Invention of Claim 1)
The invention according to claim 1 has the following effects.
<Effect 1-1 > Even when the temperature of the exhaust gas is low, the combustible gas can be burned with oxygen in the exhaust gas.
As illustrated in FIG. 2, when the secondary air mixed gas (49) passes through the combustion catalyst (46), a part of the combustible gas (4) is catalytically combusted with the secondary air (48), and the combustion is performed. The remainder of the combustible gas (4) that has passed through the combustion catalyst (46) is heated by heat, and the heated combustible gas (4) is passed from the combustible gas discharge port (6) to the exhaust passage (7). Since it was made to discharge | release, even when the temperature of exhaust_gas | exhaustion (8) is low, combustible gas (4) can be ignited and combustible gas (4) can be burned with the oxygen in exhaust_gas | exhaustion (8).

<< Effect 1-2 >> A secondary air mixing chamber can be easily formed.
As illustrated in FIG. 9A, a partition plate placement surface (50) (51) is provided in the lower part of the combustible gas generation catalyst chamber (11), and the partition plate placement surface (50) (51) is provided on the partition plate placement surface (50) (51). Since the partition plate (52) is placed and fixed, and the secondary air mixing chamber (44) is formed below the combustible gas generation catalyst chamber (11) by the partition plate (52), the secondary air mixing chamber (44 ) Can be formed easily.

<< Effect 1-3 >> Combustible gas can be generated efficiently.
As illustrated in FIG. 9 (A), a plurality of combustible gas outlet holes (54) are formed in the peripheral portion (53) of the partition plate (52) at predetermined intervals in the circumferential direction, and a combustible gas generating catalyst is formed. Since the combustible gas (4) generated in (13) is supplied to the secondary air mixing chamber (44) through the combustible gas outlet hole (54), the air-fuel mixture gas supply gap (20 The air-fuel mixture gas (23) introduced into the central portion of the combustible gas generating catalyst (13) via the peripheral portion of the partition plate (52) at the lower portion of the combustible gas generating catalyst chamber (11) ( 53) can pass through the combustible gas generating catalyst (13) evenly toward the plurality of combustible gas outlet holes (54), and the combustible gas (4) can be efficiently generated.

(Invention of Claim 2 )
The invention according to claim 2 has the following effect in addition to effect 1-1 of the invention according to claim 1.
<Effect> The secondary air mixing chamber can be easily formed.
As illustrated in FIG. 9B, partition plate placement surfaces (50) and (51) are provided in the lower part of the combustible gas generation catalyst chamber (11), and the partition plate placement surfaces (50) and (51) are provided. Since the partition plate (52) is placed and fixed, and the secondary air mixing chamber (44) is formed below the combustible gas generation catalyst chamber (11) by the partition plate (52), the secondary air mixing chamber (44 ) Can be formed easily.

<Effect> A combustible gas can be efficiently generated.
As illustrated in FIG. 9B, the peripheral portion of the partition plate (52) is disposed between the peripheral portion (53) of the partition plate (52) and the chamber wall (55) of the secondary air mixing chamber (44). A combustible gas outlet gap (56) is provided along (53), and the combustible gas (4) generated by the combustible gas generating catalyst (13) is mixed with the secondary air through the combustible gas outlet gap (56). Since the air-fuel mixture gas (23) supplied to the combustible gas generating catalyst (13) is supplied to the chamber (44), a partition plate ( 52) can pass through the combustible gas generating catalyst (13) without a bias toward the combustible gas outlet gap (56) along the peripheral edge portion (53) of 52) and efficiently generate the combustible gas (4). it can.

(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 >> A secondary air merging chamber and a secondary air mixed gas expansion chamber can be easily formed.
9A and 9B, an annular partition wall (57) is provided at the center of the secondary air mixing chamber (44), and the annular partition wall (57) surrounds the annular partition wall (57). The secondary air merging chamber (58) and the secondary air mixed gas expansion chamber (59) (59) inside the annular partition wall (57) are partitioned, and the secondary air mixed gas expansion chamber (59) (59) ) Is closed with a partition plate (52), a throttle hole (60) is formed at the inlet of the secondary air mixed gas expansion chamber (59), and the secondary air is discharged at the outlet of the secondary air mixed gas expansion chamber (59). Since the mixed gas outlet (61) is opened, the secondary air merging chamber (58) and the secondary air mixed gas expansion chamber (59) can be easily formed.

<Effect> Catalytic combustion with a combustion catalyst can be performed efficiently.
As illustrated in FIGS. 9A and 9B, the combustible gas generation catalyst chamber (11) and the secondary air supply source (47) are connected to the secondary air merge chamber (58) with the combustible gas (4). By supplying the secondary air (48), a secondary air mixed gas (49) in which the combustible gas (4) and the secondary air (48) are merged is formed in the secondary air merge chamber (58). After the secondary air mixed gas (49) is throttled by the throttle hole (60), it is diffused while expanding in the secondary air mixed gas expansion chamber (59), and the secondary air mixed gas outlet (61) , The concentration distribution of the secondary air mixed gas (49) supplied to the combustion catalyst (46) is made uniform, and catalytic combustion in the combustion catalyst (46) is achieved. Can be performed efficiently.

(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 >> The combustible gas can be efficiently generated.
3 (A) (B), FIG. 4 (A) (B), and FIG. 7, the air / fuel mixture gas (23) in the air / fuel mixing chamber (12) is converted into the air / fuel mixing chamber (12). Since the end portion is supplied to the center portion of the combustible gas generating catalyst (13), the heat is difficult to escape, the high temperature state is maintained, and the high portion of the combustible gas generating catalyst (13) is obtained. Thus, the combustible gas (4) can be efficiently generated.

(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> Thermal damage to the combustible gas generating catalyst and the annular wall can be prevented.
As illustrated in FIGS. 3 (A), 3 (B), 4 (A), 4 (B) and FIG. 7, the air / fuel mixture gas (23) in the air / fuel mixing chamber (12) is moved to the air / fuel mixture introduction gap ( ) Is introduced into the combustible gas generating catalyst (13) through the flame extinguishing function of the air-fuel mixture gas introduction gap (28), so that the occurrence of flame combustion of the air-fuel mixture gas (23) is suppressed and combustible Thermal damage to the gas generating catalyst (13) and the annular wall (14) can be prevented.

<< Effect >> The combustible gas can be efficiently generated.
3 (A) (B), FIG. 4 (A) (B), and FIG. 7, the air / fuel mixture gas (23) in the air / fuel mixing chamber (12) is converted into the air / fuel mixing chamber (12). Since it is introduced into the air / fuel mixture gas inlet surface (27) near the center of the combustible gas generating catalyst (13) through the air / fuel mixture introduction gap (28) from the end portion, it is difficult for heat to escape and a high temperature state is The combustible gas (4) can be efficiently generated at the air-fuel mixture gas inlet surface (27) near the center of the combustible gas generating catalyst (13) that is maintained and has high catalytic activity.

(Invention of Claim 6 )
The invention according to claim 6 has the following effect in addition to the effect of the invention according to claim 4 .
<Effect> Thermal damage to the combustible gas generating catalyst and the annular wall can be prevented.
As shown in FIGS. 3 (A), (B), FIGS. 4 (A), (B), and FIG. 7, the air / fuel mixture gas supply throttle ( 17) and the air / fuel mixture gas supply throttle gap (20) is formed between the air / fuel mixture gas supply throttle portion (17) and the outer peripheral surface (18) of the core (15). The flame extinguishing function of the gas supply throttle gap (20) suppresses the occurrence of flame combustion of the air-fuel mixture gas (23) and can prevent thermal damage to the combustible gas generating catalyst (13) and the annular wall (14). .

<Effect> Assembly of the combustible gas generator can be facilitated.
As shown in FIGS. 3A, 3B, 4A, 4B and 7, the inner peripheral surface 16 of the annular wall 14 and the air / fuel mixture through the spacer projection 29 Since the gas supply throttle portion (17) and the outer peripheral surface (18) of the core member (15) are aligned with each other, the alignment can be accurately performed without using a jig or the like. The assembly of the combustible gas generator (1) can be facilitated.

(Invention of Claim 7 )
The invention according to claim 7 has the following effect in addition to the effect of the invention according to claim 5 .
<Effect> Thermal damage to the combustible gas generating catalyst and the annular wall can be prevented.
As shown in FIGS. 3 (A), (B), FIGS. 4 (A), (B), and FIG. 7, the air / fuel mixture gas supply throttle ( 17) and the air / fuel mixture gas supply throttle gap (20) is formed between the air / fuel mixture gas supply throttle portion (17) and the outer peripheral surface (18) of the core (15). The flame extinguishing function of the gas supply throttle gap (20) suppresses the occurrence of flame combustion of the air-fuel mixture gas (23) and can prevent thermal damage to the combustible gas generating catalyst (13) and the annular wall (14). .

<Effect> Assembly of the combustible gas generator can be facilitated.
As shown in FIGS. 3A, 3B, 4A, 4B and 7, the inner peripheral surface 16 of the annular wall 14 and the air / fuel mixture through the spacer projection 29 The gas supply throttle portion (17) and the outer peripheral surface (18) of the core member (15) are aligned with each other, and the peripheral wall (10) and the annular wall (10) of the combustible gas generation catalyst chamber (11) 14) and the spacer protrusion (29), the air-fuel mixture gas inlet surface (27) of the combustible gas generating catalyst (13) and the outer peripheral surface (18) of the core member (15) are aligned with each other. Therefore, these positions can be accurately aligned without using a jig or the like, and the combustible gas generator (1) can be easily assembled.

(Invention of Claim 8 )
The invention according to claim 8 has the following effects in addition to the effects of the invention according to any one of claims 4 to 7 .
<< Effect >> Gas leakage from between the mounting surface and the mounting surface of the annular wall can be suppressed.
As shown in FIGS. 3 (A), (B), 4 (A), (B), and FIG. 7, the spigot protrusion located on the inner end of the mounting surface (32) at the end of the annular wall (14). Since the spigot (30) is fitted into the start end of the peripheral wall (10) of the combustible gas generating catalyst chamber (11), the start end of the combustible gas generating catalyst chamber (11) is provided. Leakage of the air / fuel mixture gas (23) and the combustible gas (4) from the air is prevented by the fitting of the spigot projection (30), and the mounting surface of the mounting surface (31) and the annular wall (14) Gas leakage from between (32) can be suppressed.

(Invention according to claim 9 )
The invention according to claim 9 has the following effect in addition to the effect of the invention according to claim 8 .
<< Effect >> It is possible to suppress a reduction in the axial force of the mounting bolt.
As illustrated in FIGS. 4 (A) and 4 (B), a heat insulating space (34) is provided in the spigot projection (30) between the combustible gas generating catalyst (13) and the mounting bolt (33). The heat generated in the combustible gas generating catalyst (13) is prevented from being transferred in the heat insulating space (34), and the thermal expansion of the mounting bolt (33) is suppressed, resulting in a reduction in the axial force of the mounting bolt (33). Can be suppressed.

(Invention of Claim 10 )
The invention according to claim 10 has the following effect in addition to the effect of the invention according to claim 9 .
<< Effect >> It is possible to suppress a reduction in the axial force of the mounting bolt.
As illustrated in FIG. 4B, the heat insulating space (34) is recessed in the outer peripheral surface of the spigot projection (30), and the sealing material (35) is disposed in the heat insulating space (34). (35) sealing the space between the peripheral wall (10) of the combustible gas generating catalyst chamber (11) and the spigot projection (30), thereby placing the mounting surface (31) of the combustible gas generating catalyst chamber (11). Since the gasket between the ring wall 14 and the mounting surface 32 of the annular wall 14 is not required, it is possible to suppress a reduction in the axial force of the mounting bolt 33 due to a decrease in the elastic force of the gasket.

(Invention of Claim 11 )
The invention according to claim 11 has the following effects in addition to the effects of the invention according to any one of claims 1 to 10 .
<Effect> Processing of the annular wall can be facilitated.
As illustrated in FIGS. 5A and 5B, FIGS. 6A to 6C, and FIGS. 8A to 8D, a plurality of gaskets 40 are held at predetermined intervals in the circumferential direction. Liquid fuel inlets (42) and liquid fuel outlets (36) are provided, and the liquid fuel outlets (36) are led out from the respective liquid fuel inlets (42) toward the inside of the gasket (40), and the annular wall (14). A liquid fuel guide groove (41) along the circumferential direction is formed in any one of the lid placement surface (38) and the placement surface (39) of the lid (37), and the liquid fuel guide groove ( 41) is connected to each liquid fuel inlet (42), and the liquid fuel (2) supplied to the liquid fuel guide groove (41) passes through each liquid fuel inlet (42) from the liquid fuel outlet (36). Since it flows out to the air-fuel mixing chamber (12), the processing of the annular wall (14) can be facilitated as compared with the case where the liquid fuel guide passage and the liquid fuel outlet are formed in the annular wall (14). .

(Invention of Claim 12 )
The invention according to claim 12 has the following effects in addition to the effects of any one of claims 1 to 11 .
<Effect> Processing of the annular wall can be facilitated.
As illustrated in FIGS. 5A and 5B and FIGS. 6A to 6C, a plurality of air inlets (42b) and an air outlet ( 36b), and the air outlets (36b) are led out from the air inlets (42b) toward the inside of the gasket (40), and the lid mounting surface (38) of the annular wall (14) and the lid (37) An air guide groove (41b) along the circumferential direction is recessed in any surface of the mounting surface (39), and each air inlet (42b) communicates with the opening of the air guide groove (41b) to The air (3) supplied to the guide groove (41b) flows out from the air outlet (36b) to the air-fuel mixing chamber (12) through each air inlet (42b), so that the inside of the annular wall (14) The processing of the annular wall (14) can be facilitated as compared with the case where the air guide passage and the air outlet are formed.

(Invention of Claim 13 )
The invention according to claim 13 has the following effects in addition to the effects of the invention according to any one of claims 1 to 12 .
<Effect> Generation of combustible gas can be promoted.
As shown in FIGS. 3 (A), (B), FIGS. 4 (A), (B), and FIG. 7, predetermined in the circumferential direction along the upper edge of the inner peripheral surface (16) of the annular wall (14). A plurality of liquid fuel outlets (36) maintaining a gap are provided, and the liquid fuel (2) flowing out from each liquid fuel outlet (36) has its own weight along the inner peripheral surface (16) of the annular wall (14). Since it was made to flow down, a plurality of flows of the liquid fuel (2) flowing down along the inner peripheral surface (16) of the annular wall (14) contacted the air (3) to become an air-fuel mixture gas (23), The concentration distribution of the fuel mixed gas (23) is made uniform, and the generation of the combustible gas (4) can be promoted.

<< Effect >> Even if the combustible gas generator is tilted, the air-fuel mixture gas can be formed without hindrance.
As illustrated in FIGS. 3A, 3B, 4A, 4B, and 7, the inner peripheral surface 16 of the annular wall 14 is tapered toward the lower end portion. Even if the combustible gas generator (1) is inclined, the liquid fuel (2) flows down along the inner peripheral surface (16) of the annular wall (14) by its own weight, and the air-fuel mixture gas (23) Can be formed without hindrance.

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 longitudinal cross-sectional view of the exhaust pipe provided with the combustible gas generator of the apparatus shown in FIG. FIGS. 3A and 3B are diagrams illustrating the assembly structure of the combustible gas generator shown in FIG. 2, FIG. 3A is an enlarged view of a portion taken along the line IIIA in FIG. 2, and FIG. 3B is FIG. ) Equivalent figure. FIG. 4A is a diagram for explaining another modified example of the assembly structure of the combustible gas generator, FIG. 4A is a diagram corresponding to FIG. 3A of the second modified example, and FIG. 4B is a diagram of the third modified example. 3 is a diagram corresponding to (A). 5A and 5B are views for explaining a supply structure of liquid fuel or the like to the air-fuel mixing chamber of the combustible gas generator shown in FIG. 2, FIG. 5A is a sectional view taken along the line VA-VA in FIG. 2, and FIG. FIG. 6 is a sectional view taken along line BB in FIG. FIG. 6A is a plan view of an annular wall in which a core member is fitted, and FIG. 6B is a bottom view. FIG. 6C is a plan view of the upper gasket, and FIG. 6C is a plan view of the upper gasket. FIG. 6 is a view corresponding to FIG. 3A for explaining a first modification of the structure for supplying liquid fuel or the like to the air-fuel mixing chamber shown in FIG. 5. FIG. 8A is a diagram for explaining a modification of the structure for supplying liquid fuel or the like to the air-fuel mixing chamber shown in FIG. 5. FIG. 8A is a diagram corresponding to FIG. 5A of the first modification, and FIG. FIG. 8A is a cross-sectional view taken along line BB in FIG. 8A, FIG. 8C is a view corresponding to FIG. 8B of the second modification, and FIG. 8D is the second modification of FIG. It is the longitudinal cross-sectional view longitudinally cut in the part. 9A and 9B are diagrams for explaining a partition structure of a secondary air mixing chamber of the combustible gas generator shown in FIG. 2, FIG. 9A is a cross-sectional view taken along the line IXA-IXA in FIG. 2, and FIG. FIG. FIGS. 10A and 10B are diagrams for explaining a structure for fixing a combustion catalyst for an exhaust pipe shown in FIG. 2, FIG. 10A is an enlarged view of a main part of FIG. 2, and FIG. 10C is a diagram corresponding to FIG. 10A of the first modification, FIG. 10D is a diagram corresponding to FIG. 10A of the second modification, and FIG. 10E is a diagram of the third modification. FIG. 10A is a view corresponding to FIG. 10A, and FIG. 10F is a view corresponding to FIG. It is a principal part side view of the diesel engine provided with the exhaust processing apparatus shown in FIG. It is a principal part top view of the diesel engine provided with the exhaust-gas processing apparatus shown in FIG. It is a principal part front view of the diesel engine provided with the exhaust-gas processing apparatus shown in FIG.

  1 to 13 are diagrams for explaining an exhaust treatment device for a diesel engine according to an embodiment of the present invention. In this embodiment, an exhaust treatment device for a vertical multi-cylinder diesel engine will be explained.

The outline of the exhaust treatment device is as follows.
As shown in FIGS. 11 to 13, an exhaust manifold (113) is attached to the side of the cylinder head (112), and a supercharger (75) is attached to the upper portion of the exhaust manifold (113). A DPF case (67) is connected to an exhaust turbine (76) of 75) via an exhaust pipe (66). A combustible gas generator (1) is attached to the exhaust pipe (66).

  As shown in FIG. 1, the combustible gas generator (1) generates a combustible gas (4), and the combustible gas (4) is exhausted from the combustible gas discharge port (6) upstream of the DPF (5). The combustible gas (4) is discharged into the passage (7) and burned with oxygen in the exhaust (8). The temperature of the exhaust (8) is increased by the combustion heat, and the DPF (5) ) Can be removed by combustion.

As shown in FIG. 1, the DPF case (67) accommodates the DOC (100) on the upstream side and the DPF (5) on the downstream side. DOC is an abbreviation for diesel oxidation catalyst.
The DPF (5) is a wall flow monolith which is a ceramic honeycomb carrier and in which the ends of adjacent cells (5a) are alternately plugged. The exhaust gas passes through the inside of the cell (5a) and the wall (5b) of the cell (5a), and traps PM at the wall (5b) of the cell (5a).
The DOC (100) is a ceramic honeycomb carrier that supports an oxidation catalyst and has a flow-through structure in which both ends of the cell (100a) are opened. The exhaust (8) passes through the cell (100a). Yes. When the combustible gas (4) passes through the DOC (100) together with the exhaust (8), the combustible gas (4) is catalytically combusted by oxygen in the exhaust (8) by the DOC (100), and the exhaust (8) is The temperature is raised and PM accumulated in the DPF (5) is burned and removed by the heat of the exhaust (8).

The configuration of the combustible gas generator is as follows.
As shown in FIGS. 1 and 2, the combustible gas generator (1) is provided with a combustible gas generating catalyst chamber (11), and the combustible gas generating catalyst chamber (11) is provided with a combustible gas generating catalyst (13). An annular wall (14) is disposed at the start end (upper end) of the combustible gas generation catalyst chamber (11), and an air / fuel mixing chamber (12) is formed inside the annular wall (14), By supplying air (3) and liquid fuel (2) to the air-fuel mixing chamber (12), an air-fuel mixed gas (23) is formed in the air-fuel mixing chamber (12). (23) is supplied to the combustible gas generating catalyst (13), and the combustible gas generating catalyst (13) generates the combustible gas (4).

The liquid fuel (2) is light oil which is a diesel fuel, and is supplied from the liquid fuel supply source (22), and the air (3) is supplied from the air supply source (21). The liquid fuel supply source (22) is a fuel tank, and the air supply source (21) is an air cleaner.
The combustible gas generating catalyst (13) is a ceramic carrier on which a partial oxidation catalyst component is supported. By combusting the liquid fuel (2) partially, a combustible gas (4) containing hydrogen and carbon monoxide is obtained. Is generated.
The combustible gas generating catalyst (13) may be a metal wire carrier having a three-dimensional network structure, or may be one carrying an oxidation catalyst component. When the oxidation catalyst component is used, a part of the liquid fuel (2) is oxidized, and a combustible gas (4) is generated by vaporizing the liquid fuel (2) by the generated heat.

As shown in FIG. 2, a core member (15) is fitted into the center of the annular wall (14), and the inner peripheral surface (16) of the annular wall (14) and the outer peripheral surface (18) of the core member (15). The air-fuel mixing chamber (12) is formed between the air-fuel mixing chamber (12) and the air-fuel mixing gas (23) in the air-fuel mixing chamber (12) is generated from the end (lower end) of the air-fuel mixing chamber (12). The catalyst (13) is supplied to the central portion.
As a result, it is possible to efficiently generate the combustible gas (4) at a portion near the center of the combustible gas generating catalyst (13) in which heat is difficult to escape, a high temperature state is maintained, and high catalytic activity is obtained.

As shown in FIG. 2, a heater (25) is used as the core material (15), and the heat radiating outer peripheral surface (26) of the heater (25) is exposed to the air-fuel mixing chamber (12), so that the combustible gas (4) At the start of generation, heat is radiated directly from the heat radiating outer peripheral surface (26) of the heater (25) to the air / fuel mixing chamber (12).
Thereby, the heat of the heater (25) is quickly transmitted to the air / fuel mixing chamber (12), the air / fuel mixed gas (23) is rapidly formed, and the generation of the combustible gas (4) can be started smoothly. it can. In addition, there is no inclusion between the heater (25) and the air-fuel mixing chamber (12), and the combustible gas generator (1) can be downsized.
The heater (25) is an electric heater for heating at the start of generation of the combustible gas (4), and a sheathed heater containing a heating wire in a metal pipe is used.

As shown in FIG. 2, an air-fuel mixture gas inlet surface (27) is provided on the inner periphery of the annular combustible gas generating catalyst (13), and a core material (15) is provided at the center of the combustible gas generating catalyst (13). And an air-fuel mixture gas introduction gap (28) is formed between the air-fuel mixture gas inlet surface (27) and the outer peripheral surface (18) of the core member (15), and the air-fuel mixture chamber (12) The air / fuel mixture gas (23) from the end (lower end) of the air / fuel mixture chamber (12) through the air / fuel mixture introduction gap (28) is near the center of the combustible gas generating catalyst (13). The gas is introduced into the mixed gas inlet surface (27).
As a result, it is difficult for heat to escape, the high-temperature state is maintained, and high catalytic activity is obtained. The generation of the combustible gas (4) at the air / fuel mixture inlet surface (27) near the center of the combustible gas generating catalyst (13) Can be performed efficiently.
In addition, the flame extinguishing function of the air / fuel mixture introduction gap (28) suppresses the occurrence of flame combustion of the air / fuel mixture (23), thereby preventing thermal damage to the combustible gas generating catalyst (13) and the annular wall (14). Can be prevented.

As shown in FIG. 2, the heat radiation outer peripheral surface (26) of the heater (25) used for the core (15) is exposed to the air-fuel mixture gas introduction gap (28), and at the start of generation of the combustible gas (4). Further, heat is radiated directly from the heat radiation outer peripheral surface (26) of the heater (25) to the air-fuel mixture mixed gas introduction gap (28).
Thereby, the heat of the heater (25) is quickly transmitted to the air-fuel mixture gas introduction gap (28), the condensation of the air-fuel mixture gas (23) in the air-fuel mixture gas introduction gap (28) is suppressed, and combustibility is achieved. Generation of gas (4) can be started smoothly.
In addition, there is no inclusion between the heater (25) and the air / fuel mixture introduction gap (28), and the combustible gas generator (1) can be downsized.

As shown in FIG. 3 (A), an air-fuel mixture gas supply throttle portion (17) is provided at the end portion (lower end portion) of the inner peripheral surface (16) of the annular wall (14). An air / fuel mixed gas supply throttle gap (20) is formed between the portion (17) and the outer peripheral surface (18) of the core member (15).
As a result, the occurrence of flame combustion of the air-fuel mixture gas (23) is suppressed by the flame extinguishing function of the air-fuel mixture gas supply throttle gap (20), and thermal damage of the combustible gas generating catalyst (13) and the annular wall (14) is suppressed. Can be prevented.

As shown in FIG. 3A, spacer protrusions (29) are provided on the inner peripheral surface (16) of the annular wall (14), and the spacer protrusions (29) are applied to the outer peripheral surface (18) of the core member (15). By contacting, the inner peripheral surface (16) of the annular wall (14) and the air / fuel mixture gas supply throttle portion (17) and the outer peripheral surface (18) of the core member (15) through the spacer protrusion (29). They are aligned with each other.
Thereby, these alignment can be performed correctly, without using a jig | tool etc., and the assembly of a combustible gas generator (1) can be made easy.
The annular wall (14) and the spacer protrusion (29) are an integrally molded product of metal.
Spacer protrusions (29) may be provided on the outer peripheral surface (18) of the core member (15), and the spacer protrusions (29) may be brought into contact with the inner peripheral surface (16) of the annular wall (14).

As shown in FIG. 3 (A), an annular flammable gas generating catalyst (13) is fitted in the flammable gas generating catalyst chamber (11), and an inlay protrusion (30) is formed at the end of the annular wall (14). And the inlay projection (30) is fitted into the start end (upper end) of the peripheral wall (10) of the combustible gas generating catalyst chamber (11), thereby the peripheral wall of the combustible gas generating catalyst chamber (11). (10), the annular wall (14), and the spacer projection (29), the air-fuel mixture gas inlet surface (27) of the combustible gas generating catalyst (13) and the outer peripheral surface (18) of the core (15). Are aligned with each other.
Thereby, these alignment can be performed correctly, without using a jig | tool etc., and the assembly of a combustible gas generator (1) can be made easy.

As shown in FIG. 3 (A), an annular mounting surface (31) is provided at the start end (upper end) of the peripheral wall (10) of the combustible gas generation catalyst chamber (11), and the end of the annular wall (14) is provided. When the mounting surface (32) is provided on the mounting portion (lower end portion) and the mounting surface (32) of the annular wall (14) is mounted and fixed on the mounting surface (31), the end of the annular wall (14) An inlay protrusion (30) located on the inner side of the mounting surface (32) is provided at the portion (lower end), and is provided at the start end (upper end) of the peripheral wall (10) of the combustible gas generation catalyst chamber (11). An inlay projection (30) is fitted inside.
As a result, leakage of the air-fuel mixture gas (23) and the combustible gas (4) from the start end (upper end) of the combustible gas generation catalyst chamber (11) is prevented by the fitting of the spigot projection (30). Thus, gas leakage from between the placement surface (31) and the placement surface of the annular wall (14) can be suppressed.

  As shown in FIG. 3A, the mounting surface (32) of the annular wall (14) is mounted on the mounting surface (31) of the combustible gas generation catalyst chamber (11) via the gasket (19). Then, the lid (37) is placed on the placing surface (38) of the annular wall (14) via the gasket (40), and these are fastened together with the mounting bolt (33).

FIG. 3 (B) is a first modification of the assembly structure of the combustible gas generator. Between the peripheral surface of the combustible gas generating catalyst (13) and the peripheral wall (10) of the combustible gas generating catalyst chamber (11). The heat insulating cushioning material (9) is interposed between the starting end surface of the catalyst (13) and the spigot projection (30), and between the end surface of the catalyst (13) and a partition plate (52) described later, and is combustible. The combustible gas generating catalyst (13) is fixed and insulated in the combustible gas generating catalyst chamber (11).
A glass wool mat is used for the heat insulating cushion material (9).

FIG. 4 (A) shows a second modified example in which the mounting surface (31) of the annular wall (14) is placed on the mounting surface (31) of the combustible gas generating catalyst chamber (11) by the fastening force of the mounting bolt (33). 32) is placed and fixed, and when the combustible gas generating catalyst (13) is accommodated inside the inlay projection (30), the inlay is formed between the combustible gas generating catalyst (13) and the mounting bolt (33). The protrusion (30) is provided with a heat insulating space (34).
As a result, the transfer of heat generated in the combustible gas generating catalyst (13) is blocked by the heat insulating space (34), the thermal expansion of the mounting bolt (33) is suppressed, and the shaft of the mounting bolt (33) due to this is suppressed. The force drop can be suppressed.

FIG. 4 (B) is a third modified example, and in the second modified example of FIG. 4 (A), the heat insulating space (34) is recessed in the outer peripheral surface of the spigot projection (30), and the heat insulating space (34) A sealing material (35) is disposed on the inner wall, and the sealing material (35) is used to seal the space between the peripheral wall (10) of the combustible gas generation catalyst chamber (11) and the spigot projection (30). The gasket (19) between the mounting surface (31) of the production catalyst chamber (11) and the mounting surface (32) of the annular wall (14) is unnecessary.
Thereby, the axial-force fall of the attachment bolt (33) resulting from the elastic-force fall of a gasket (19) can be suppressed.
Other structures of the first to third modifications shown in FIGS. 3B and 4A and 4B are the same as those of the embodiment shown in FIG. Are given the same reference numerals.

The structure for supplying liquid fuel and air to the air-fuel mixing chamber is as follows.
As shown in FIGS. 5 (A) and 5 (B), a lid (37) is disposed at the starting end (upper end) of the annular wall (14), and the annular lid is disposed at the starting end (upper end) of the annular wall (14). A placement surface (38) is provided, a placement surface (39) is provided at the terminal end (lower end) of the lid (37), and an annular gasket (40) is provided on the lid placement surface (38) of the annular wall (14). The mounting surface (39) of the lid (37) is placed and fixed via
The gasket (40) is a two-piece set of a stacked lower gasket (40a) and upper gasket (40b).
The lower gasket (40a) is provided with a plurality of liquid fuel inlets (42) and liquid fuel outlets (36) while maintaining a predetermined interval in the circumferential direction, and the liquid fuel outlet (36) is provided for each liquid fuel inlet (42). The liquid fuel guide groove (41) is led out toward the inside of the gasket (40), and is provided in the lid mounting surface (38) of the annular wall (14) along the circumferential direction. Each liquid fuel inlet (42) communicates with the opening of (41), and the liquid fuel (2) supplied to the liquid fuel guide groove (41) passes through each liquid fuel inlet (42), and the liquid fuel outlet (36). To the air-fuel mixing chamber (12).
Thereby, the processing of the annular wall (14) can be facilitated as compared with the case where the liquid fuel guide passage and the liquid fuel outlet are formed in the annular wall (14).
As shown in FIG. 6 (B), the liquid fuel inlet (42), the liquid fuel outlet (36), and an air inlet (42a) described later are formed in a punched shape in a metal lower gasket (40a). ing.
The liquid fuel guide groove (41) may be provided on the placement surface (39) of the lid (37).

As shown in FIGS. 5A and 5B, the upper gasket (40b) is provided with a plurality of air inlets (42b) and air outlets (36b) at predetermined intervals in the circumferential direction thereof. 36b) are led out from the respective air inlets (42b) toward the inside of the gasket (40), and are provided with an air guide groove (41b) along the circumferential direction of the lid mounting surface (38) of the annular wall (14). The air inlets (42b) communicate with the openings of the air guide grooves (41b), and the air (3) supplied to the air guide grooves (41b) passes through the air inlets (42b). To the air-fuel mixing chamber (12).
Each air inlet (42b) communicates with the opening of the air guide groove (41b) via the air inlet (42a) of the lower gasket (40a).
Thereby, the processing of the annular wall (14) can be facilitated as compared with the case where the air guide passage and the air outlet are formed in the annular wall (14).
As shown in FIG. 6C, the air inlets (42b) and the air outlets (36b) are formed in a punched shape on the metal upper gasket (40b).
The air guide groove (41b) may be provided on the placement surface (39) of the lid (37).
6A to 6C are plan views of the annular wall 14, the lower gasket 40 a, and the upper gasket 40 b.

7 and 8 are diagrams for explaining a modification of the structure for supplying liquid fuel or the like to the air-fuel mixing chamber.
7 and 8 (A) and (B) show a first modified example in which only one gasket (40) is provided, and a plurality of liquid fuel inlets (with a predetermined interval in the circumferential direction) are held in the gasket (40). 42) and a liquid fuel outlet (36), and the liquid fuel outlet (36) is led out from each liquid fuel inlet (42) toward the inside of the gasket (40), and the lid mounting surface of the annular wall (14) The liquid fuel guide groove (41) along the circumferential direction is recessed in (38), and each liquid fuel inlet (42) is communicated with the opening of the liquid fuel guide groove (41), thereby the liquid fuel guide groove (41). The liquid fuel (2) supplied to the gas flows out from the liquid fuel outlet (36) to the air-fuel mixing chamber (12) through each liquid fuel inlet (42).
As shown in FIG. 8A, the liquid fuel inlet (42) and the liquid fuel outlet (36) are formed in a punched shape in the gasket (40).
An air outlet (24) is provided in the annular wall (14), and the air (3) is ejected tangentially from the air outlet (24) to the air-fuel mixing chamber (12), and the inner peripheral surface of the annular wall (14). It turns in the air-fuel mixing chamber (12) along (16).

FIGS. 8C and 8D show a second modification, in which a liquid fuel guide groove (41) is provided on the mounting surface (39) of the lid (37).
As shown in FIG. 8C, the liquid fuel (2) flows from the liquid fuel supply port (64) into a predetermined liquid fuel inlet (42) communicating therewith, and this predetermined liquid fuel inlet (42). 8 flows out from the liquid fuel outlet (36) led out to the air-fuel mixing chamber (12), and flows into the liquid fuel guide groove (41) through the predetermined liquid fuel inlet (42), and FIG. ), The liquid fuel is distributed from the liquid fuel guide groove (41) to the other liquid fuel inlets (42), and flows out from the liquid fuel outlets (36) derived therefrom to the air-fuel mixing chamber (12). .
In the second modified example, when the regeneration of the DPF (5) is completed and the supply of the liquid fuel (2) to the liquid fuel guide groove (41) is stopped, the liquid fuel (2) is supplied from the liquid fuel guide groove (41). Flows out into the air-fuel mixing chamber (12) through the liquid fuel inlet (42) and the liquid fuel outlet (36) under its own weight, so that the liquid fuel (2) does not remain in the liquid fuel guide groove (41), Clogging of the liquid fuel guide groove (41) and the like due to carbonization of the liquid fuel (2) can be suppressed.

The first and second modifications relating to the supply of the liquid fuel (2) are applied to the supply of air (3), and only one gasket (40b) shown in FIG. ) May be allowed to flow out from the gasket (40b) to the air / fuel mixing chamber (12), and the liquid fuel (2) may be allowed to flow out from locations other than the gasket to the air / fuel mixing chamber (12).
The other structures of the first and second modified examples shown in FIGS. 7 and 8A to 8D are the same as those of the embodiment shown in FIGS. The same reference numerals are given.

As shown in FIGS. 3A, 3B, 4A, 4B, and 7, the inner peripheral surface 16 of the annular wall 14 is tapered toward the lower end portion. A plurality of liquid fuel outlets (36) are provided along the upper edge of the inner peripheral surface (16) of the annular wall (14) in the circumferential direction so as to maintain a predetermined interval, and each liquid fuel outlet (36) The liquid fuel (2) that has flowed out flows down by its own weight along the inner peripheral surface (16) of the annular wall (14).
As a result, the plurality of flows of the liquid fuel (2) flowing down along the inner peripheral surface (16) of the annular wall (14) come into contact with the air (3) to become the air-fuel mixture gas (23), and the air-fuel mixture gas The concentration distribution of (23) is made uniform, and the generation of the combustible gas (4) can be promoted.
Further, even if the combustible gas generator (1) is inclined, the liquid fuel (2) flows down along the inner peripheral surface (16) of the annular wall (14) by its own weight, and the air-fuel mixture gas (23) can be prevented without any problem. Can be formed.

The structure for supplying the combustible gas to the exhaust is as follows.
As shown in FIG. 2, the secondary air mixing chamber (44) is connected to the combustible gas generating catalyst chamber (11), and the secondary air mixing chamber (44) is connected to the secondary air mixing gas outlet (61). The combustion catalyst chamber (45) is communicated, the combustion catalyst chamber (45) is accommodated with the combustion catalyst (46), and the combustion catalyst chamber (45) is communicated with the combustible gas discharge port (6) to combustible gas. By supplying the combustible gas (4) and the secondary air (48) from the production catalyst chamber (11) and the secondary air supply source (47) to the secondary air mixing chamber (44), the secondary air mixing chamber In (44), the combustible gas (4) and the secondary air (48) are mixed to form a secondary air mixed gas (49), and this secondary air mixed gas (49) passes through the combustion catalyst (46). At this time, a part of the combustible gas (4) is catalytically combusted by the secondary air (48), and the combustion heat causes the remainder of the combustible gas (4) passing through the combustion catalyst (46) to rise in temperature and rise. Warm combustible gas ( 4) is discharged from the combustible gas discharge port (6) to the exhaust passage (7).
Thereby, even when the temperature of the exhaust (8) is low, the combustible gas (4) is ignited, and the combustible gas (4) can be burned with oxygen in the exhaust (8).
The combustion catalyst (46) is an oxidation catalyst. Similar to the air supply source (47), the secondary air supply source (47) is an air cleaner.

The partition structure of the secondary air mixing chamber of the combustible gas generator is as follows.
As shown in FIG. 9A, a partition plate placement surface (50) (51) is provided at the terminal end (lower end) of the combustible gas generation catalyst chamber (11), and this partition plate placement surface (50). A partition plate (52) is placed and fixed on (51), and a secondary air mixing chamber (44) is partitioned and formed on the end side (lower end) of the combustible gas generation catalyst chamber (11) with the partition plate (52). A plurality of combustible gas outlet holes (54) are formed in the peripheral portion (53) of the partition plate (52) at predetermined intervals in the circumferential direction, and the combustible gas generated by the combustible gas generating catalyst (13) is formed. (4) is supplied to the secondary air mixing chamber (44) through the combustible gas outlet hole (54).
Thereby, a secondary air mixing chamber (44) can be formed easily.
The air-fuel mixture gas (23) introduced into the center of the combustible gas generation catalyst (13) through the air-fuel mixture gas supply throttle gap (20) is the end of the combustible gas generation catalyst chamber (11). Passing evenly through the combustible gas generating catalyst (13) toward the plurality of combustible gas outlet holes (54) in the peripheral portion (53) of the partition plate (52) in the portion, the combustible gas (4) Can be generated efficiently.
Of the two partition plate placement surfaces (50) and (51), one partition plate placement surface (50) is an upper end surface of an annular partition wall (57) described later, and the other partition plate placement surface ( 51) is formed along the inner periphery of the chamber wall (55) of the secondary air mixing chamber (44).

FIG. 9B is a modification of the partition structure of the secondary air mixing chamber, between the peripheral edge portion (53) of the partition plate (52) and the chamber wall (55) of the secondary air mixing chamber (44). A flammable gas outlet gap (56) is provided along the peripheral edge (53) of the partition plate (52), and the flammable gas (4) generated by the flammable gas generating catalyst (13) is transferred to the flammable gas outlet gap ( 56) to the secondary air mixing chamber (44).
The partition plate (52) is provided with three projections (73) projecting in the radial direction, the tips of which are in contact with the chamber wall (55) of the secondary air mixing chamber (44), and the partition plate (52) Radial movement is prevented.

As shown in FIGS. 9A and 9B, an annular partition wall (57) is provided in the center of the secondary air mixing chamber (44), and the annular partition wall (57) surrounds the annular partition wall (57). The secondary air merging chamber (58) and the secondary air mixed gas expansion chamber (59) (59) inside the annular partition wall (57) are partitioned, and the secondary air mixed gas expansion chamber (59) (59) ) Is closed with a partition plate (52), a throttle hole (60) is formed at the inlet of the secondary air mixed gas expansion chamber (59), and a secondary is formed at the outlet of the secondary air mixed gas expansion chamber (59). The air mixed gas outlet (61) is opened, and the combustible gas (4) and secondary air (from the combustible gas generation catalyst chamber (11) and the secondary air supply source (47) to the secondary air merge chamber (58) are provided. 48) to form a secondary air mixed gas (49) in which the combustible gas (4) and the secondary air (48) are merged in the secondary air merge chamber (58). The secondary air mixed gas (49) is connected to the throttle hole (60 ), The gas is diffused while expanding in the secondary air mixed gas expansion chamber (59), and is supplied to the combustion catalyst (46) through the secondary air mixed gas outlet (61).
Thereby, a secondary air merging chamber (58) and a secondary air mixed gas expansion chamber (59) can be easily formed.
Further, the concentration distribution of the secondary air mixed gas (49) supplied to the combustion catalyst (46) is made uniform, and the catalytic combustion in the combustion catalyst (46) can be performed efficiently.

The structure of the exhaust pipe is as follows.
As shown in FIG. 1, an exhaust pipe (66) is attached to an exhaust pipe mounting seat (65) in the exhaust path, and a DPF case (67) containing a DPF (5) is placed downstream of the exhaust pipe (66). As shown in FIG. 2, the exhaust pipe mounting seat (65) is provided with an exhaust outlet passage (68) and a projecting portion (69) projecting radially outward from the exhaust outlet passage (68). A passage start end portion (71) of the exhaust passage (7) and a passage end portion (74) of the combustible gas guide passage (70) are arranged in parallel in the pipe (66), and the passage start end portion of the exhaust passage (7) is provided. The central axis (71a) of (71) runs along the central axis (68a) of the exhaust outlet passage (68), and the passage central axis (74a) of the passage end portion (74) of the combustible gas guide passage (70) overhangs. Toward the portion (69), at the boundary between the passage end portion (74) of the combustible gas guide passage (70) and the passage start end portion (71) of the exhaust passage (7). Has opened gas outlet (6).

Thereby, the combustible gas (4) flowing along the passage axis (74a) of the passage end portion (74) of the combustible gas guide passage (70) is directed to the overhanging portion (69) and passes through the exhaust passage (7). The exhaust (8) is not directly hit, but is gradually released from the combustible gas discharge port (6) to the passage start end (71) of the exhaust passage (7). For this reason, the deflection | deviation of the flow of exhaust_gas | exhaustion (8) by combustible gas (4) is suppressed, and back pressure can be made small.
In addition, as shown in FIG. 12, the arrangement of the DPF case (67) is changed by properly using the exhaust pipe (66) or the straight exhaust pipe (66) where the exhaust passage end (63) side of the exhaust passage (7) is bent. Even in this case, since the deflection of the exhaust (8) is suppressed, the difference in the back pressure due to the difference in the shape of the exhaust pipe (66) is small, and a constant exhaust performance can be guaranteed. For this reason, it is possible to change the shape of the exhaust pipe (66) on the side of the passage end (63) and to increase the degree of freedom in arranging the DPF case (67).

As shown in FIG. 2, an exhaust turbine (76) exhaust pipe mounting seat of a supercharger (75) is used as an exhaust pipe mounting seat (65), and an exhaust outlet passage of the exhaust turbine (76) is used as an exhaust outlet passage (68). The waste gate valve (77) of the exhaust turbine (76) and its valve mounting part (78) are used as the overhanging part (69).
Thereby, an exhaust pipe (66) can be attached using a supercharger (77).

As shown in FIG. 2, the outlet side end face (79) of the combustion catalyst (46) is separated from the combustible gas discharge port (6) toward the start end side of the combustible gas guide passage (70).
As a result, even if the exhaust (8) enters the combustible gas guide passage (70) from the combustible gas discharge port (6) due to the pulsation of the exhaust (8), the exhaust (8) enters the combustion catalyst (46). To prevent the combustion catalyst (46) from being unnecessarily combusted by the oxygen in the exhaust gas (8) and preventing the combustion catalyst (46) from burning the combustible gas (4) unnecessarily, thereby preventing thermal damage to the combustion catalyst (46). Can do.

The fixed structure of the combustion catalyst is as follows.
As shown in FIG. 10A, a secondary air mixed gas inlet chamber (81) is provided between the secondary air mixed gas outlet (61) and the combustion catalyst chamber (45) of the secondary air mixing chamber (44). And a combustion catalyst receiving means (82) and a combustion catalyst retaining means (83) are provided in the secondary air mixed gas inlet chamber (81) and the combustion catalyst chamber (45), and the combustible gas guide passage (70) is provided. The combustion catalyst (46) is inserted into the combustion catalyst chamber (45) from the passage end portion (74) toward the secondary air mixed gas inlet chamber (81), and the secondary air mixed gas inlet is inserted by the combustion catalyst receiving means (82). The movement of the combustion catalyst (46) toward the chamber (81) is received, and the combustion catalyst removal prevention means (83) moves the combustion catalyst (46) toward the passage end portion (74) of the combustible gas guide passage (70). By stopping the removal, the combustion catalyst (46) is fixed to the catalytic combustion chamber (45).
Thereby, the combustion catalyst (46) can be easily fixed in the catalyst combustion chamber (45).

As shown in FIG. 10A, the inner peripheral surface (88) of the secondary air mixed gas inlet chamber (81) is expanded from the secondary air mixed gas outlet (61) toward the combustion catalyst chamber (45). The inner peripheral surface (88) of the secondary air mixed gas inlet chamber (81) is formed as a combustion catalyst receiving means (82).
Thus, the secondary air mixed gas (49) flowing out from the secondary air mixed gas outlet (61) is directed toward the inlet side end face (80) of the combustion catalyst (46) in the secondary air mixed gas inlet chamber (81). It diffuses widely, flows into the combustion catalyst (46) from the entire inlet side end face (80) of the combustion catalyst (46), and flows into the combustion catalyst (46) over the entire area of the combustion catalyst (46). 4) can be burned efficiently. Further, it is not necessary to provide the combustion catalyst receiving means (82) specially.

  As shown in FIGS. 10A and 10B, a sensor insertion hole (86) is formed in the passage wall (85) of the combustible gas guide passage (70), and the combustible gas guide passage is formed from the sensor insertion hole (86). The combustion catalyst outlet side temperature sensor (87) is inserted into (70), and the sensor temperature sensing part (89) of the combustion catalyst outlet side temperature sensor (87) is exposed to the outlet side end face (79) of the combustion catalyst (46). At first, the pipe (90) is inserted into the sensor insertion hole (86), the combustion catalyst outlet side temperature sensor (87) is inserted into the pipe (90), and the sensor is inserted from the insertion side end (91) of the pipe (90). By projecting the temperature sensing part (89) and receiving the outlet side end face (79) of the combustion catalyst (46) at the outer peripheral face (92) of the insertion side end part (91) of the pipe (90), the pipe (90) The insertion side end (91) of the combustion catalyst serves as a combustion catalyst retaining means (83), and the outlet side end surface (79) of the combustion catalyst (46) at the insertion side end (91) of the pipe (90). Sensor temperature sensing portion of al combustion catalyst outlet temperature sensor (87) which is separated (89).

  Thereby, it is not necessary to provide a new insertion hole for attaching the retaining means (83) to the passage wall (85) of the combustible gas guide passage (70). In addition, the outlet side end face (79) of the combustion catalyst (46) is caused by a problem that heat is directly input to the sensor temperature sensing part (89) from the outlet side end face (79) of the combustion catalyst (46) or vibration of the engine. The trouble of contacting the sensor temperature sensing part (89) is prevented, and damage to the sensor temperature sensing part (89) of the combustion catalyst outlet side temperature sensor (87) can be prevented.

As shown in FIG. 10 (B), the passage wall (85) of the flammable gas guide passage (70) is formed at a part of the back end of the sensor insertion hole (86) at the time of drilling the sensor insertion hole (86). The pipe receiving portion (93) is left and a part of the insertion side end surface (94) of the pipe (90) is received by the pipe receiving portion (93).
As a result, the pipe (90) does not enter the combustible gas guide passage (70) more than necessary, and the sensor temperature of the combustion catalyst outlet side temperature sensor (87) is detected at the insertion side end (91) of the pipe (90). A problem that the portion (89) is covered can be prevented.

10 (C) to 10 (F) show modifications of the combustion catalyst fixing structure.
The first modification shown in FIG. 10 (C) is a heat insulation between the chamber wall (62) of the combustion catalyst chamber (45) and the combustion catalyst (46) in the embodiment shown in FIGS. 10 (A) and (B). A cushioning material (96) is interposed. The heat insulating cushion material (96) is a glass wool sheet.

In the second modified example shown in FIG. 10D, a heat insulating cushion material (96) is interposed between the combustion catalyst chamber (45) and the combustion catalyst (46), and the chamber wall of the combustion catalyst chamber (45) ( 62) is thermally fixed to the heat insulating cushion material (96), and the combustion catalyst (46) is friction fixed to the heat insulating cushion material (96) to thereby prevent the heat insulating cushion material (96) from coming off the combustion catalyst. Means (83).
In the first and second modifications shown in FIGS. 10 (C) and 10 (D), the heat-insulating cushion material (96) can avoid the temperature drop and impact of the combustion catalyst (46), and the combustion catalyst (46). The catalytic activity and durability can be improved.

In the third modification shown in FIG. 10 (E), a retaining ring (98) is fitted and fixed to the outlet of the combustion catalyst chamber (45), and this retaining ring (98) is used as the combustion catalyst retaining means (83). Yes.
In the fourth modification shown in FIG. 10 (F), a sleeve (99) is press-fitted from the passage end portion (74) of the combustible gas guide passage (70) toward the combustion catalyst chamber (45), and this sleeve (99 ) Is frictionally fixed to the passage wall (85) of the combustible gas guide passage (70), and the sleeve (99) serves as the combustion catalyst retaining means (83). The sleeve (99) is provided with a sensor insertion hole (99a), and the sensor temperature sensing part (89) of the combustion catalyst outlet side temperature sensor (87) protrudes into the sleeve (99) from the sensor insertion hole (99a). ing.
In the third and fourth modifications shown in FIGS. 10E and 10F, the combustion catalyst (46) can be firmly fixed in the catalyst combustion chamber (45).

As shown in FIG. 2, the chamber wall (95) of the secondary air mixed gas inlet chamber (81), the chamber wall (55) of the secondary air mixing chamber (44), and the annular partition wall (57) are continuously connected to each other. Secondary air through the secondary air mixed gas inlet chamber (81) and the secondary air mixed gas expansion chamber (59) from the passage end portion (74) of the combustible gas guide passage (70). Through a series of drilling of the drill that goes straight toward the merge chamber (58), the second through the boundary wall (97) between the secondary air mixed gas inlet chamber (81) and the secondary air mixed gas expansion chamber (59). A secondary air mixed gas outlet (61) and throttle holes (60) (60) penetrating the annular partition wall (57) are formed.
Thereby, formation of the secondary air mixed gas outlet (61) and the throttle holes (60), (60) can be easily performed.

The configuration of the exhaust path and the control of combustible gas generation are as follows.
The engine ECU (102) shown in FIG. 1 includes PM accumulation amount estimation means (101) and PM regeneration control means (111). Engine ECU is an abbreviation for engine electronic control unit.
The PM accumulation amount estimation means (101) is a predetermined calculation unit of the engine ECU (1), and is engine load, engine speed, detected exhaust temperature by the DPF upstream exhaust temperature sensor (103), DPF upstream exhaust pressure sensor. Based on the exhaust pressure upstream of the DPF (5) by (104), the differential pressure upstream and downstream of the DPF (5) by the differential pressure sensor (105), etc. presume.

  When the PM accumulation amount estimated value reaches a predetermined regeneration required value by the PM accumulation amount estimating means (101), the PM regeneration control means (111) generates heat in the heater (25), and supplies the liquid fuel pump (107) and air. The pump (108) and the secondary air supply pump (109) are driven. As a result, liquid fuel (2) and air (3) are supplied to the air-fuel mixing chamber (12), and combustible gas (4) is generated by the combustible gas generating catalyst (13). 44), a secondary air mixed gas (49) is formed, the combustible gas (4) is heated by the combustion catalyst (46), and the heated combustible gas (4) is upstream of the DPF (5). It is discharged from the combustible gas discharge port (6) into the exhaust passage (7).

Based on the temperature detected by the combustible gas generation catalyst (13) by the combustible gas generation catalyst temperature sensor (106), the PM regeneration control means (111) determines the liquid fuel supply amount of the liquid fuel pump (107) and the air pump ( 108) and the secondary air pump (109) based on the detected temperature of the combustible gas (4) on the outlet side of the combustion catalyst (46) by the combustion catalyst outlet side temperature sensor (87). ) Secondary air supply amount.
When the detected temperature of the exhaust (8) upstream of the DOC (100) by the DOC upstream exhaust temperature sensor (110) is lower than the activation temperature of the DOC (100), the PM regeneration control means (111) The secondary air supply amount of the secondary air pump (109) is adjusted, the temperature of the combustible gas (4) is increased, the temperature of the exhaust (12) is increased, and the DOC (10) is activated.
The PM regeneration control means (111) stops supplying the combustible gas (4) to the exhaust (8) when the exhaust temperature detected by the DPF downstream exhaust temperature sensor (112) reaches a predetermined abnormal temperature. To do.
At the beginning of the start of flammable (4) generation, the heater (25) is heated for a predetermined time. When generation of the flammable gas (4) is started, the flammable gas generating catalyst (13) generates an exothermic reaction. Therefore, when a predetermined time has elapsed after the generation of the combustible gas (4) is started, heat generation of the heater (25) is stopped by the timer.

(1) Combustible gas generator
(2) Liquid fuel
(3) Air
(4) Combustible gas
(5) DPF
(6) Combustible gas outlet
(7) Exhaust passage
(8) Exhaust
(10) Perimeter wall of combustible gas generation catalyst chamber
(11) Combustible gas generation catalyst chamber
(12) Air-fuel mixing chamber
(13) Combustible gas generation catalyst
(14) Annular wall
(15) Core material
(16) Inner circumferential surface of annular wall
(17) Air-fuel mixture gas supply throttle
(18) Outer surface of core material
(20) Air-fuel mixture gas supply gap
(21) Air supply source
(22) Liquid fuel supply source
(23) Air-fuel mixture gas
(24) Air outlet
(27) Air-fuel mixture gas inlet surface
(28) Air-fuel mixture gas introduction gap
(29) Spacer protrusion
(30) Inlay protrusion
(31) Block placement surface
(32) Placement surface
(33) Mounting bolt
(34) Thermal insulation space
(35) Seal material
(36) Liquid fuel outlet
(36b) Air outlet
(37) Lid
(38) Cover placement surface
(39) Placement surface
(40) Gasket
(41) Liquid fuel guide groove
(41b) Air guide groove
(42) Liquid fuel inlet
(42a) Air inlet
(42b) Air inlet
(44) Secondary air mixing chamber
(45) Combustion catalyst chamber
(46) Combustion catalyst
(47) Secondary air supply source
(48) Secondary air
(49) Secondary air mixed gas
(50) Partition plate mounting surface
(51) Partition plate mounting surface
(52) Partition plate
(53) Perimeter
(54) Combustible gas outlet hole
(55) Secondary air mixing chamber wall
(56) Flammable gas outlet clearance
(57) Annular partition wall
(58) Secondary air merge room
(59) Secondary air mixed gas expansion chamber
(60) Aperture hole

Claims (13)

The combustible gas generator (1) generates the combustible gas (4), and the combustible gas (4) is discharged from the combustible gas discharge port (6) to the exhaust passage (7) upstream of the DPF (5). The combustible gas (4) is burned with oxygen in the exhaust (8), the temperature of the exhaust (8) is increased by the combustion heat, and the PM accumulated in the DPF (5) is heated by the heat of the exhaust (8). In an exhaust treatment device for a diesel engine that can be burned and removed,
A combustible gas generation catalyst chamber (11) is provided in the combustible gas generator (1), and the combustible gas generation catalyst (13) is accommodated in the combustible gas generation catalyst chamber (11). An annular wall (14) is disposed at the starting end of (11), an air / fuel mixing chamber (12) is formed inside the annular wall (14), and air (3) and By supplying liquid fuel (2), an air-fuel mixture gas (23) is formed in the air-fuel mixture chamber (12), and this air-fuel mixture gas (23) is supplied to the combustible gas generating catalyst (13). The combustible gas generation catalyst (13) generates the combustible gas (4),
The combustible gas generating catalyst chamber (11) is connected to the secondary air mixing chamber (44), the secondary air mixing chamber (44) is connected to the combustion catalyst chamber (45), and the combustion catalyst chamber (45) is connected to the combustion catalyst. (46) is accommodated, and the combustible gas discharge port (6) is communicated with the combustion catalyst chamber (45).
By supplying the combustible gas (4) and the secondary air (48) from the combustible gas generating catalyst chamber (11) and the secondary air supply source (47) to the secondary air mixing chamber (44),
In the secondary air mixing chamber (44), the combustible gas (4) and the secondary air (48) are mixed to form a secondary air mixed gas (49), and this secondary air mixed gas (49) becomes a combustion catalyst ( 46), a part of the combustible gas (4) is catalytically combusted by the secondary air (48), and the remaining heat of the combustible gas (4) that has passed through the combustion catalyst (46) is generated by the combustion heat. The temperature of the combustible gas (4) is increased, and the heated combustible gas (4) is discharged from the combustible gas discharge port (6) to the exhaust passage (7) .
A partition plate placement surface (50) (51) is provided at the lower part of the combustible gas generation catalyst chamber (11), and the partition plate (52) is placed and fixed on the partition plate placement surface (50) (51). A partition plate (52) forms a secondary air mixing chamber (44) below the combustible gas generating catalyst chamber (11),
A plurality of combustible gas outlet holes (54) are formed in the peripheral portion (53) of the partition plate (52) at predetermined intervals in the circumferential direction, and combustible gas generated by the combustible gas generating catalyst (13) ( 4) An exhaust treatment apparatus for a diesel engine, characterized in that 4) is supplied to the secondary air mixing chamber (44) through the combustible gas outlet hole (54). In the exhaust treatment device of the diesel engine according to claim 1 ,
A plurality of combustible gas outlet holes (54) are formed in the peripheral portion (53) of the partition plate (52) at predetermined intervals in the circumferential direction, and combustible gas generated by the combustible gas generating catalyst (13) ( 4) instead of being supplied to the secondary air mixing chamber (44) through the combustible gas outlet hole (54),
A flammable gas outlet gap along the peripheral edge (53) of the partition plate (52) between the peripheral edge (53) of the partition plate (52) and the chamber wall (55) of the secondary air mixing chamber (44). 56), and the combustible gas (4) generated by the combustible gas generating catalyst (13) is supplied to the secondary air mixing chamber (44) through the combustible gas outlet gap (56). An exhaust treatment device for a diesel engine, characterized by that. In the exhaust treatment device for a diesel engine according to claim 1 or 2 ,
An annular partition wall (57) is provided at the center of the secondary air mixing chamber (44), and the annular partition wall (57) and the secondary air merge chamber (58) around the annular partition wall (57) The secondary air mixed gas expansion chamber (59) (59) inside the wall (57) is partitioned, and the opening of the secondary air mixed gas expansion chamber (59) (59) is closed with a partition plate (52), A throttle hole (60) is opened at the inlet of the secondary air mixed gas expansion chamber (59), and a secondary air mixed gas outlet (61) is opened at the outlet of the secondary air mixed gas expansion chamber (59).
By supplying the combustible gas (4) and the secondary air (48) from the combustible gas generating catalyst chamber (11) and the secondary air supply source (47) to the secondary air merge chamber (58),
A secondary air mixed gas (49) in which the combustible gas (4) and the secondary air (48) are merged is formed in the secondary air merging chamber (58), and this secondary air mixed gas (49) After being throttled by the throttle hole (60), it diffuses while expanding in the secondary air mixed gas expansion chamber (59), and is supplied to the combustion catalyst (46) through the secondary air mixed gas outlet (61). An exhaust treatment device for a diesel engine, characterized by that. In the exhaust treatment device of the diesel engine according to any one of claims 1 to 3 ,
The core material (15) is fitted in the center of the annular wall (14), and air-fuel mixing is performed between the inner peripheral surface (16) of the annular wall (14) and the outer peripheral surface (18) of the core material (15). The air / fuel mixture gas (23) in the air / fuel mixing chamber (12) is supplied from the terminal end of the air / fuel mixing chamber (12) to the center of the combustible gas generating catalyst (13). An exhaust treatment device for a diesel engine, characterized by comprising: The exhaust gas treatment apparatus for a diesel engine according to claim 4 ,
An air-fuel mixture gas inlet face (27) is provided on the inner periphery of the ring-shaped combustible gas generating catalyst (13), and a core material (15) is fitted in the center of the combustible gas generating catalyst (13) to An air-fuel mixed gas introduction gap (28) is formed between the mixed gas inlet surface (27) and the outer peripheral surface (18) of the core member (15), and the air-fuel mixed gas (23 ) is introduced into the air-fuel mixture gas introduced through the gap (28) near the center air-fuel mixture gas inlet face of the combustible gas producing catalyst (13) (27) from the terminal end of the air-fuel mixing chamber (12) as to the exhaust processing device for a diesel engine, characterized in that. The exhaust gas treatment apparatus for a diesel engine according to claim 4 ,
An air-fuel mixture gas supply throttle portion (17) is provided at the end of the inner peripheral surface (16) of the annular wall (14), and the outer peripheral surface of the air-fuel mixture gas supply throttle portion (17) and the core (15) ( 18) to form an air / fuel mixed gas supply throttle gap (20),
Of the inner peripheral surface (16) of the annular wall (14) and the outer peripheral surface (18) of the core member (15), a spacer protrusion (29) is provided on one surface (16), and a spacer is provided on the other surface (18). By bringing the protrusion (29) into contact,
The inner peripheral surface (16) of the annular wall (14) and the air / fuel mixed gas supply throttle portion (17) and the outer peripheral surface (18) of the core member (15) are aligned with each other via the spacer projection (29). An exhaust treatment device for a diesel engine, characterized by comprising: In the exhaust treatment device for a diesel engine according to claim 5 ,
An air-fuel mixture gas supply throttle portion (17) is provided at the end of the inner peripheral surface (16) of the annular wall (14), and the outer peripheral surface of the air-fuel mixture gas supply throttle portion (17) and the core (15) ( 18) to form an air / fuel mixed gas supply throttle gap (20),
Of the inner peripheral surface (16) of the annular wall (14) and the outer peripheral surface (18) of the core member (15), a spacer protrusion (29) is provided on one surface (16), and a spacer is provided on the other surface (18). By bringing the protrusion (29) into contact,
The inner peripheral surface (16) of the annular wall (14) and the air / fuel mixed gas supply throttle portion (17) and the outer peripheral surface (18) of the core member (15) are aligned with each other via the spacer projection (29). As well as
An annular combustible gas generating catalyst (13) is fitted in the combustible gas generating catalyst chamber (11), and an inlay protrusion (30) is provided at the end of the annular wall (14). The inlay protrusion (30) Is fitted into the start end of the peripheral wall (10) of the combustible gas generating catalyst chamber (11), so that the peripheral wall (10), the annular wall (14), and the spacer protrusion (29) of the combustible gas generating catalyst chamber (11). The air-fuel mixture gas inlet surface (27) of the combustible gas generating catalyst (13) and the outer peripheral surface (18) of the core member (15) are aligned with each other. Diesel engine exhaust treatment equipment. In the exhaust treatment device for a diesel engine according to any one of claims 4 to 7 ,
An annular placement surface (31) is provided at the start end of the peripheral wall (10) of the combustible gas generation catalyst chamber (11), and a placement surface (32) is provided at the end of the annular wall (14). In placing and fixing the mounting surface (32) of the annular wall (14) on the surface (31),
An inlay protrusion (30) located inside the mounting surface (32) is provided at the end portion of the annular wall (14), and the inlay protrusion is formed at the start end of the peripheral wall (10) of the combustible gas generation catalyst chamber (11). An exhaust treatment apparatus for a diesel engine, characterized in that a part (30) is fitted therein. The exhaust gas treatment apparatus for a diesel engine according to claim 8 ,
The mounting surface (32) of the annular wall (14) is mounted and fixed on the mounting surface (31) of the combustible gas generation catalyst chamber (11) by the fastening force of the mounting bolt (33), and the spigot projection ( 30) In housing the combustible gas generating catalyst (13) inside,
An exhaust treatment apparatus for a diesel engine, characterized in that a heat insulating space (34) is provided in the spigot projection (30) between the combustible gas generating catalyst (13) and the mounting bolt (33). In the exhaust treatment device of the diesel engine according to claim 9 ,
A heat insulating space (34) is recessed in the outer peripheral surface of the spigot projection (30), a sealing material (35) is disposed in the heat insulating space (34), and the combustible gas generating catalyst chamber ( 11) by sealing between the peripheral wall (10) and the spigot projection (30),
Exhaust treatment of a diesel engine characterized by eliminating the need for a gasket between the mounting surface (31) of the combustible gas generation catalyst chamber (11) and the mounting surface (32) of the annular wall (14). apparatus. In the exhaust treatment device for a diesel engine according to any one of claims 1 to 10 ,
A lid (37) is disposed at the start end of the annular wall (14), an annular lid placement surface (38) is provided at the start end of the annular wall (14), and a placement surface is provided at the end of the lid (37). (39), and the placement surface (39) of the lid (37) is placed and fixed to the lid placement surface (38) of the annular wall (14) via the annular gasket (40),
The gasket (40) is provided with a plurality of liquid fuel inlets (42) and liquid fuel outlets (36) while maintaining a predetermined interval in the circumferential direction thereof, and the liquid fuel outlets (36) are connected to the gaskets from the liquid fuel inlets (42). Derived toward the inside of (40),
A liquid fuel guide groove (41) along the circumferential direction is recessed in any one of the lid mounting surface (38) of the annular wall (14) and the mounting surface (39) of the lid (37). Each liquid fuel inlet (42) communicates with the opening of the liquid fuel guide groove (41), and the liquid fuel (2) supplied to the liquid fuel guide groove (41) passes through each liquid fuel inlet (42). An exhaust treatment apparatus for a diesel engine, characterized in that it flows out from the outlet (36) to the air-fuel mixing chamber (12). The exhaust gas treatment apparatus for a diesel engine according to any one of claims 1 to 11 ,
A lid (37) is disposed at the start end of the annular wall (14), an annular lid placement surface (38) is provided at the start end of the annular wall (14), and a placement surface is provided at the end of the lid (37). (39), and the placement surface (39) of the lid (37) is placed and fixed to the lid placement surface (38) of the annular wall (14) via the annular gasket (40),
The gasket (40) is provided with a plurality of air inlets (42b) and air outlets (36b) at predetermined intervals in the circumferential direction, and the air outlets (36b) are connected to the gaskets (40) from the air inlets (42b). Derived inward,
An air guide groove (41b) extending along the circumferential direction is formed in any one of the lid mounting surface (38) of the annular wall (14) and the mounting surface (39) of the lid (37). Each air inlet (42b) communicates with the opening of the guide groove (41b), and the air (3) supplied to the air guide groove (41b) is burned from the air outlet (36b) through each air inlet (42b). An exhaust treatment apparatus for a diesel engine, characterized in that it flows out into the mixing chamber (12). The exhaust treatment apparatus for a diesel engine according to any one of claims 1 to 12 ,
The inner peripheral surface (16) of the annular wall (14) has a tapered shape that decreases in diameter toward the lower end portion,
A plurality of liquid fuel outlets (36) are provided in the circumferential direction along the upper edge of the inner peripheral surface (16) of the annular wall (14), and are allowed to flow out from each liquid fuel outlet (36). An exhaust treatment apparatus for a diesel engine, characterized in that the liquid fuel (2) flows down by its own weight along the inner peripheral surface (16) of the annular wall (14).

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