JP4538429B2 - Diesel engine exhaust system - Google Patents

Description

  The present invention relates to an exhaust device for a diesel engine, and more particularly to an exhaust device for a diesel engine that can be made compact.

As an exhaust device of a conventional diesel engine, liquid fuel is supplied from a liquid fuel supply source to a gas generator as in the present invention, and the liquid fuel is made into a combustible gas by the gas generator, and the combustible gas is supplied from the gas generator. Deriving the supply path, connecting the flammable gas outlet of this flammable gas supply path to the exhaust path upstream of the diesel particulate filter, and burning the flammable gas flowing out from the flammable gas outlet in the exhaust There is one in which the exhaust particulate accumulated in the filter can be burned by the combustion heat (see, for example, Patent Document 1).
This type of exhaust device has an advantage that even during a light load operation where the exhaust temperature is low, the temperature of the exhaust gas flowing into the filter is increased by the combustion heat of the combustible gas, the exhaust particulates are combusted, and the filter can be regenerated.

  However, the conventional exhaust device has a problem because the gas generator is separated from the filter housing case.

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

The above prior art has the following problems.
<Problem> The exhaust system is getting larger.
Since the gas generator is separated from the filter housing case, the exhaust device is enlarged.

  An object of the present invention is to provide an exhaust device for a diesel engine that can solve the above problems, that is, an exhaust device for a diesel engine that can make the exhaust device compact.

Invention specific matters of the invention according to claim 1 are as follows.
As illustrated in FIG. 1 (A), liquid fuel (6) is supplied from a liquid fuel supply source (5) to a gas generator (3), and the liquid fuel (6) is combustible by this gas generator (3). A combustible gas (7), a combustible gas supply path (8) is led out from the gas generator (3), and the combustible gas outlet (9) of the combustible gas supply path (8) is connected to diesel particulates. -The exhaust (1) is communicated upstream of the filter (2), the combustible gas (7) flowing out from the combustible gas outlet (9) is combusted in the exhaust (10), and the filter ( In the exhaust system of a diesel engine, which can combust the exhaust particulate accumulated in 2),
An exhaust system for a diesel engine, wherein the gas generator (3) is housed in a filter housing case (11) for housing the filter (2).

(Invention according to Claim 1)
<Effect> The exhaust device can be made compact.

  As illustrated in FIG. 1A, since the gas generator (3) is accommodated in the filter accommodation case (11) for accommodating the filter (2), the gas generator (3) is connected to the filter accommodation case (11). The exhaust device can be made compact as compared with the case where it is separated from the exhaust system.

(Invention according to Claim 2)
In addition to the effect of the invention according to claim 1, the following effect is achieved.
<Effect> Even when the exhaust gas temperature is low, the combustible gas can be burned.
As illustrated in FIG. 1A, an oxidation catalyst (12) that promotes combustion of the combustible gas (7) is provided between the combustible gas outlet (9) and the inlet (2a) of the filter (2). Due to the arrangement, the combustible gas (7) can be combusted even when the temperature of the exhaust (10) is low.

<Effect> The exhaust device can be made compact.
As illustrated in FIG. 1A, since the oxidation catalyst (12) is accommodated in the filter accommodation case (11), compared with the case where the oxidation catalyst (12) is separated from the filter accommodation case (11). The exhaust device can be made compact.

(Invention according to claim 3)
In addition to the effect of the invention according to claim 2, the following effect is achieved.
<Effect> Even when the exhaust gas temperature is low, the activation temperature of the oxidation catalyst is secured.
As illustrated in FIG. 1A, the combustible gas (7) heated by the exothermic reaction in the gas generator (3) is sent from the combustible gas outlet (9) to the upstream of the oxidation catalyst (12). For the outflow, an upstream oxidation passage (14) is formed in the exhaust passage (13) upstream of the oxidation catalyst (12), the exhaust passage (13) has a double cylinder structure, and the inside of the upstream oxidation passage (14). The upstream oxidation catalyst (15) is accommodated in the gas generator and the combustible gas outlet (9) of the gas generator (3) is opened toward the upstream oxidation passage (14) upstream of the upstream oxidation catalyst (15). The high-temperature combustible gas (7) is a part of all exhaust (10), (10), (10) passing through the exhaust passage (13), and part of the exhaust (10) flowing into the upstream oxidation passage (14). And flows into the upstream oxidation catalyst (15). Therefore, even when the temperature of the exhaust (10) is low, the mixture of the combustible gas (7) and the exhaust (10) flows into the upstream oxidation catalyst (15) while maintaining a relatively high temperature, and the upstream oxidation catalyst ( The activation temperature of 15) is ensured, and a part of the combustible gas (7) burns in the upstream oxidation catalyst (15). This combustion heat raises the temperature of all exhausts (10), (10), (10) that have passed through the exhaust passage (13), and this exhaust gas (10), (10), (10) is downstream of the oxidation catalyst (12). The activation temperature of the oxidation catalyst (12) is ensured. As a result, the remaining combustible gas (7) is combusted by the oxidation catalyst (12), the temperature of all exhausts (10), (10) and (10) is further increased, and the exhaust (10) causes the filter (2) to Exhaust particulates can be burned.

(Invention of Claim 4)
In addition to the effect of the invention according to claim 3, the following effect is achieved.
<< Effect >> The oxidation promotion function of the upstream oxidation catalyst can be reliably obtained.
As illustrated in FIG. 1B, the cross-sectional area of the upstream oxidation passage (14) in the exhaust passage (13) having a double cylinder structure is the entire exhaust passage (13) including the upstream oxidation passage (14). Is less than ¼ of the cross-sectional area of the upstream oxidation passage (14), the cross-sectional area of the upstream oxidation catalyst (15) is too small, and the oxidation promotion function of the upstream oxidation catalyst (15) is sufficient. If the ratio exceeds 1/2, the amount of exhaust (10) flowing into the upstream oxidation passage (14) becomes too large, and the exhaust (10) is at a low temperature. Has a problem that it becomes difficult to ensure the activation temperature of the upstream oxidation catalyst (15) by mixing the high temperature combustible gas (7) with a large amount of low temperature exhaust gas (10). On the other hand, in the double-cylinder exhaust passage (13), the cross-sectional area of the upstream oxidation passage (14) is 1 / of the overall cross-sectional area of the exhaust passage (13) including the upstream oxidation passage (14). When it is set within the range of 4 to 1/2, the above problem does not occur, and the oxidation promotion function of the upstream oxidation catalyst (15) can be reliably obtained.

(Invention according to claim 5)
In addition to the effect of the invention according to claim 3 or claim 4, the following effect is produced.
<Effect> Combustion of combustible gas in the upstream oxidation catalyst is promoted.
As illustrated in FIG. 1A, the end (8a) of the combustible gas outlet pipe (8) facing the passage formation direction of the upstream oxidation passage (14) is closed, and the combustible gas outlet pipe (8) A plurality of combustible gas outlets (9) oriented in the radial direction of the upstream oxidation passage (14) are opened in the peripheral wall near the terminal end (8a), so that the combustible gas (7) has a diameter of the upstream oxidation passage (14). Diffusing in the direction, the combustibility of the combustible gas (7) and the exhaust gas (10) passing through the upstream oxidation passage (14) is enhanced, and the combustion of the combustible gas (7) in the upstream oxidation catalyst (15) is promoted Is done.

(Invention of Claim 6)
In addition to the effects of the invention according to any one of claims 3 to 5, the following effects are provided.
<< Effect >> An oxidation catalyst can be used effectively.
As illustrated in FIG. 1A, an upstream oxidation passage (14) is formed in the oxidation catalyst inlet front passage (4), and the oxidation catalyst inlet front passage (4) has a double cylinder structure. 12) The end (14a) of the upstream oxidation passage (14) facing the inlet (33) is closed, and the diameter of the oxidation catalyst inlet front passage (4) is formed on the peripheral wall near the end (14a) of the upstream oxidation passage (14). Since the plurality of upstream oxidation passage outlets (16) oriented in the direction are opened, the mixture (35) of the combustible gas (7) and the exhaust (10) from the upstream oxidation passage outlet (14) is passed through the oxidation catalyst inlet passage. It diffuses in the radial direction of (4) and flows into the oxidation catalyst (12) from the entire inlet (33). For this reason, an oxidation catalyst (12) can be utilized effectively.

(Invention of Claim 7)
In addition to the effects of the invention according to any one of claims 3 to 6, the following effects are achieved.
<< Effect >> The dimension of the filter housing case in the front-rear direction can be shortened.
As illustrated in FIG. 2, the axial direction of the filter housing case (11) is the front-rear direction, and the exhaust inlet pipe (21) is placed in the exhaust inlet chamber (19) along the radial direction of the filter housing case (11). Since the oxidation catalyst (12) and the gas generator (3) are arranged in this order from the upstream side in the exhaust inlet pipe (21), it is necessary to provide a dedicated storage space in the filter storage case (11). Thus, the size of the filter housing case (11) in the front-rear direction can be shortened.

<Effect> The oxidation catalyst and the gas generator are hardly damaged.
As illustrated in FIG. 1A, the exhaust inlet pipe (21) is inserted into the exhaust inlet chamber (19) along the radial direction of the filter housing case (11), and oxidized into the exhaust inlet pipe (21). Since the catalyst (12) and the gas generator (3) are arranged, the oxidation catalyst (12) and the gas generator (3) are doubled by the wall of the filter housing case (11) and the wall of the exhaust inlet pipe (21). The oxidation catalyst (12) and the gas generator (3) are not easily damaged.

<Effect> Even when the exhaust gas temperature is low, the activation temperature of the oxidation catalyst is secured.
As illustrated in FIG. 1A, the exhaust inlet pipe (21) is inserted into the exhaust inlet chamber (19) along the radial direction of the filter housing case (11), and oxidized into the exhaust inlet pipe (21). Since the catalyst (12) is arranged, the oxidation catalyst (12) is doubly wrapped by the wall of the filter housing case (11) and the wall of the exhaust inlet pipe (21), and the heat of the oxidation catalyst (12) is difficult to escape. For this reason, even when the temperature of the exhaust (10) is low, the activation temperature of the oxidation catalyst (12) is secured.

<Effect> Damage to the flammable gas outlet tube hardly occurs.
As illustrated in FIG. 1 (A), the exhaust inlet pipe (21) is inserted into the exhaust inlet chamber (19) along the radial direction of the filter housing case (11), and upstream into the exhaust inlet pipe (21). The oxidation catalyst (12) and the gas generator (3) are arranged in this order from the side, and the combustible gas supply path (8) derived from the gas generator (3) is connected to the oxidation catalyst (12) and the upstream oxidation catalyst (15). And the flammable gas outlet (9) is opened upstream of the upstream oxidation catalyst (15) into the upstream oxidation passage (14), so that the flammable gas supply passage (8) is connected to the filter housing case ( 11), the wall of the exhaust inlet pipe (21), the wall of the upstream oxidation passage (14), the oxidation catalyst (12) and the upstream oxidation catalyst (15), and damage to the combustible gas supply passage (8). Is unlikely to occur.

(Invention according to Claim 8 or Claim 9)
The invention according to claim 8 or claim 9 has the following effect in addition to the effect of the invention according to claim 7.
<Effect> The diameter of the exhaust inlet pipe can be reduced.
As illustrated in FIG. 3 (A), as an oxidation catalyst (12), a catalyst component is applied to a carrier (25) in which a corrugated metal sheet (23) and a flat metal sheet (24) are rolled up. Since the supported one is used, a relatively wide in-catalyst passage (34) is formed between the thin metal plates (23) and (24), and even if the exhaust inlet pipe (21) has a small diameter, the oxidation catalyst (12 ) Of the passage in the catalyst is sufficiently secured. For this reason, the exhaust inlet pipe (21) can be reduced in diameter. Further, since the corrugated metal thin plate (23) is used for the carrier (25), the carrier (25) itself has elasticity, and the carrier (25) is used without using a cushion material in the exhaust inlet pipe (21). Can be held. In this respect as well, the exhaust inlet pipe (21) can be reduced in diameter.
As illustrated in FIG. 3B, the same effect can be obtained even when an oxidation catalyst (12) having a catalyst component supported on a carrier (27) made of a metal mesh (26) is used.

(Invention of Claim 10 or Claim 11)
The invention according to claim 10 or claim 11 has the following effect in addition to the effect of the invention according to claim 8 or claim 9.
<Effect> The diameter of the upstream oxidation passage can be reduced.
As illustrated in FIG. 4A, as an upstream oxidation catalyst (15), a catalyst component is placed on a carrier (25) in which a corrugated thin metal plate (23) and a flat metallic thin plate (24) are wound. Therefore, even if the upstream oxidation passage (14) has a small diameter, the upstream oxidation catalyst (34) is formed between the metal thin plates (23) and (24). The cross-sectional area in the catalyst passage of (15) is sufficiently secured. For this reason, the diameter of the upstream oxidation passage (14) can be reduced. Further, since the corrugated metal thin plate (23) is used for the carrier (25), the carrier (25) itself is elastic, and the carrier (25) is used without using a cushion material in the upstream oxidation passage (14). Can be held. Also in this respect, the upstream oxidation passage (14) can be reduced in diameter.
As illustrated in FIG. 4B, the same effect can be obtained even when the upstream oxidation catalyst (15) is a catalyst (27) made of a metal mesh (26) and having a catalyst component supported thereon.

(Invention of Claim 12)
In addition to the effects of the invention according to any one of claims 7 to 11, the following effects can be obtained.
<Effect> The exhaust treatment device can be made compact.
As illustrated in FIG. 2, since the exhaust muffler (28) is used as the filter housing case (11), it is not necessary to prepare the filter housing case (11) and the exhaust muffler (28) individually, and the exhaust treatment device Can be made compact.
(Invention of Claim 13)
In addition to the effects of the invention according to any one of claims 1 to 12, the following effects are provided.
<Effect> Even when the exhaust gas temperature is low, the combustible gas can be burned.
As illustrated in FIG. 1A, the liquid fuel (6) is partially oxidized by the gas generator (3), so that the liquid fuel (6) is combustible gas (7) containing carbon monoxide and hydrogen. Therefore, even when the combustible gas (7) is ignited at a relatively low temperature, the combustible gas (7) can be combusted even when the temperature of the exhaust (10) is low.
(Invention of Claim 14)
In addition to the effects of the invention according to any one of claims 1 to 12, the following effects are provided.
<Effect> The combustion heat of the combustible gas can be stably obtained.
By vaporizing the liquid fuel (6) with the gas generator (3), this liquid fuel (6) is made into a combustible gas (7). Compared to reactions such as partial oxidation, combustible gas There is little fluctuation in the component ratio of (7), and the combustion heat of the combustible gas (7) can be obtained stably.

  Embodiments of the present invention will be described with reference to the drawings. 1 to 4 are diagrams illustrating an exhaust device for a diesel engine according to an embodiment of the present invention.

The outline of the embodiment of the present invention is as follows.
As shown in FIG. 1A, the liquid fuel (6) is supplied from the liquid fuel supply source (5) to the gas generator (3), and the liquid fuel (6) is combustible by the gas generator (3). A gas (7), a combustible gas supply path (8) is led out from the gas generator (3), and a combustible gas outlet (9) of the combustible gas supply path (8) is connected to a diesel particulate The combustible gas (7) flowing out from the combustible gas outlet (9) is combusted in the exhaust (10) by communicating with the exhaust passage (1) upstream of the filter (2), and the filter (2 ) Can be burned. This exhaust system is connected to the exhaust outlet (36) of the exhaust manifold of the diesel engine. The diesel particulate filter (2) is generally called a DPF and is a ceramic honeycomb structure. The diesel particulate filter (2) carries an oxidation catalyst. The filter (2) may be supported on the NO _X storing catalyst.

The configuration of the gas generator is as follows.
As shown in FIG. 1A, the gas generator (3) is housed in a filter housing case (11) that houses the filter (2). The gas generator (3) is filled with a partial oxidation catalyst (37). The partial oxidation catalyst (37) is obtained by supporting a catalyst component composed of palladium, rhodium, and ruthenium on an alumina pellet support. A liquid fuel supply source (5) is connected to the inlet side of the gas generator (3) via a liquid fuel supply path (46), and an air supply source (39) is connected via an air supply path (38). Communicate. The liquid fuel supply source (5) uses a liquid fuel tank of the engine, and the liquid fuel (6) uses light oil. A turbocharger for engine intake supercharging is used as the air supply source (5).

  A liquid fuel valve (40) is provided in the liquid fuel supply passage (46), an air valve (41) is provided in the air supply passage (38), and the back pressure is applied to each valve (40) (41) via the controller (42). The sensor (43) is linked. When exhaust particulates accumulate in the filter (2), the back pressure rises. Based on the detection by the back pressure sensor (43), the controller (42) connects the liquid fuel valve (40) and the air. By opening the valve (41), supplying liquid fuel (6) and air (44) to the gas generator (3), and partially oxidizing the liquid fuel (6) with the gas generator (3) The liquid fuel (6) is reformed into a combustible gas (7) containing carbon monoxide and hydrogen, and the combustible gas (7) is supplied into the exhaust gas. Reference numeral (45) in FIG. 1 (A) is a heater, and a mixture of liquid fuel (6) and air (44) is heated by the heater (45) to start partial oxidation (endothermic reaction at the start of the reaction). Facilitate. A heater (45) is also linked to the controller (42). The mixing ratio of the air (44) and the liquid fuel (6), that is, the air-fuel ratio A / F is set in the range of 0.8 to 1.8, which is around 1.3.

The arrangement of the oxidation catalyst and the upstream oxidation catalyst is as follows.
As shown in FIG. 1 (A), an oxidation catalyst (12) that promotes combustion of the combustible gas (7) is disposed between the combustible gas outlet (9) and the inlet (2a) of the filter (2). The oxidation catalyst (12) is housed in the filter housing case (11). When the combustible gas (7) heated by the exothermic reaction in the gas generator (3) flows out from the combustible gas outlet (9) to the upstream of the oxidation catalyst (12), the upstream of the oxidation catalyst (12). Thus, an upstream oxidation passage (14) is formed in the exhaust passage (13), the exhaust passage (13) has a double cylinder structure, and the upstream oxidation catalyst (15) is accommodated in the upstream oxidation passage (14). A combustible gas outlet (9) is opened upstream of the upstream oxidation catalyst (15) toward the upstream oxidation passage (14).

The setting of the passage cross-sectional area of the upstream oxidation passage is as follows.
As shown in FIG. 1 (B), the cross-sectional area of the upstream oxidation passage (14) in the exhaust passage (13) having a double cylinder structure is the same as the entire exhaust passage (13) including the upstream oxidation passage (14). It is set to 1/4 of the passage cross-sectional area. In order to reliably obtain the oxidation promotion function of the upstream oxidation catalyst (15), the cross-sectional area of the upstream oxidation passage (14) in the exhaust passage (13) of this double cylinder structure is changed to the upstream oxidation passage (14). It is desirable to set within a range of 1/4 to 1/2 of the total passage cross-sectional area of the exhaust passage (13) including.

The opening directions of the combustible gas outlet and the upstream oxidation passage outlet are as follows.
As shown in FIG. 1 (A), the end (8a) of the combustible gas outlet pipe (8) facing the passage formation direction of the upstream oxidation passage (14) is closed, and the end of the combustible gas outlet pipe (8) is closed. (8a) A plurality of combustible gas outlets (9) facing the radial direction of the upstream oxidation passage (14) are opened in the peripheral wall close to the surface. Further, an upstream oxidation passage (14) is formed in the oxidation catalyst inlet front passage (4), the oxidation catalyst inlet front passage (4) and the upstream oxidation passage (14) have a double cylinder structure, and the oxidation catalyst (12 The end (14a) of the upstream oxidation passage (14) facing the inlet (33) of the oxidation catalyst is closed, and the radial direction of the oxidation catalyst inlet front passage (4) is formed on the peripheral wall near the end (14a) of the upstream oxidation passage (14). A plurality of upstream oxidation passage outlets (16) facing to the side are opened.

The specific structure of the filter housing case is as follows.
As shown in FIG. 2, a cylindrical filter storage case (11) provided with end walls (17) and (18) at both ends is used, the axial length direction of the filter storage case (11) is the front-rear direction, and the filter ( 2) the front side of the inlet (2a) and the rear side of the outlet (2b), and the rear of the filter (2) in the filter housing case (11), the exhaust inlet chamber (19) is placed in front of the filter (2). An exhaust outlet chamber (20) is provided at the rear, and an exhaust inlet pipe (21) is connected to the exhaust inlet chamber (19), and an exhaust outlet pipe (22) is connected to the exhaust outlet chamber (20).
An exhaust muffler (28) is used as the filter housing case (11), the exhaust inlet chamber (19) is constituted by the first expansion chamber (29), and the exhaust outlet chamber (20) is constituted by the final expansion chamber (30). The exhaust inlet pipe (21) is constituted by the exhaust introduction pipe (31) of the first expansion chamber (29), and the exhaust outlet pipe (22) is constituted by the exhaust outlet pipe (32) of the final expansion chamber (30). .

  As shown in FIG. 1 (A), the exhaust inlet pipe (21) is inserted into the exhaust inlet chamber (19) along the radial direction of the filter housing case (11), and the upstream side into the exhaust inlet pipe (21). The oxidation catalyst (12) and the gas generator (3) are arranged in order, and the combustible gas supply path (8) led out from the gas generator (3) is connected to the oxidation catalyst (12) and the upstream oxidation catalyst (15). The combustible gas outlet (9) is opened upstream of the upstream oxidation catalyst (15) and into the upstream oxidation passage (14). A plurality of outlet holes (47) of the exhaust introduction pipe (31) are provided in a portion of the peripheral wall of the exhaust introduction pipe (31) downstream of the oxidation catalyst (12) and opposite to the inlet (2a) of the filter (2). Individually formed. As shown in FIG. 2, a plurality of inlet holes (48) of the exhaust outlet pipe (32) are formed on the entire circumference of the peripheral wall of the exhaust outlet pipe (32).

The generation and function of the combustible gas is as follows.
As shown in FIG. 1 (A), when liquid fuel (6) and air (44) are supplied to the gas generator (3), the liquid fuel (6) mixes with air (44), and the liquid fuel (6) is atomized and flows into the gas generator (3). A part of the liquid fuel (6) is partially oxidized in the gas generator (3), reformed into a combustible gas (7) containing carbon monoxide and hydrogen, and a high temperature combustible gas (7). Become. As shown in FIG. 1A, the high-temperature combustible gas (7) is supplied from the combustible gas supply passage (8) to the upstream oxidation passage (14) in the exhaust passage (13). On the other hand, a part of the exhaust gas (10), (10), (10) passing through the exhaust passage (13) flows into the upstream oxidation passage (14), and the hot combustible gas (7). And pass through the upstream oxidation catalyst (15). The combustible gas (7) is oxidized (catalytic combustion or flame combustion) by oxygen in the mixed exhaust (10), and the mixed exhaust (10) is heated by the oxidation heat (combustion heat). The heated exhaust gas (10) flows out from the upstream oxidation passage outlet (16) as indicated by an arrow (35) and is mixed with the remaining exhaust gases (10) and (10) that have not flowed into the upstream oxidation passage (14). And passes through the oxidation catalyst (12). The remaining combustible gas (7) oxidized (catalytic combustion or flame combustion) by the upstream oxidation catalyst (15) is oxidized (catalytic combustion or flame combustion) by the oxygen in the mixed exhaust (10), and the oxidation heat (combustion). Heat the exhaust (10) mixed by heat).

  As shown in FIG. 1 (A), the exhaust gas (10) flows out of the oxidation catalyst (15) as indicated by an arrow (60), and further passes through the outlet hole (47) of the exhaust gas introduction pipe (31). After flowing out into the first expansion chamber (29), it passes through both sides of the exhaust introduction pipe (31) as shown by the arrow (62) and flows into the filter (2) from its inlet (2a). Pass through the filter (2). As shown in FIG. 3, the exhaust gas that has passed through the filter (2) flows into the final expansion chamber (30) from the outlet (2b) of the filter (2) as indicated by an arrow (63), and then the exhaust introduction pipe. It flows into the exhaust introduction pipe (32) from the inlet (48) of (32) and flows out from the exhaust outlet pipe (32) as shown by an arrow (64).

The configuration of the oxidation catalyst is as follows.
As shown in FIG. 3 (A), as an oxidation catalyst (12), a catalyst component is supported on a carrier (25) in which a corrugated metal sheet (23) and a flat metal sheet (24) are rolled up. We use what we let. Each metal thin film (23) (24) is a stainless steel thin plate having a thickness of 0.5 mm. Platinum is used as the catalyst component.
As shown in FIG. 3B, as the oxidation catalyst (12), a catalyst component supported on a carrier (27) made of a metal mesh (26) may be used. This metal mesh (26) is made of stainless steel and is generally called a wire mesh. Platinum is used as the catalyst component.

The structure of the upstream oxidation catalyst is as follows.
As shown in FIG. 4 (A), as an upstream oxidation catalyst (15), a catalyst component is applied to a carrier (25) in which a corrugated metal sheet (23) and a flat metal sheet (24) are rolled up. A supported one is used. Each metal thin film (23) (24) is a stainless steel thin plate having a thickness of 0.5 mm. Platinum is used as the catalyst component.
As shown in FIG. 4 (B), the upstream oxidation catalyst (15) may be a catalyst in which a catalyst component is supported on a carrier (27) made of a metal mesh (26). This metal mesh (26) is made of stainless steel and is generally called a wire mesh. Platinum is used as the catalyst component.

  In the above embodiment, the liquid fuel (6) is reformed into a combustible gas (7) containing carbon monoxide and hydrogen by partially oxidizing the liquid fuel (6) with the gas generator (3). The liquid fuel (6) may be converted into a combustible gas (7) by vaporizing the liquid fuel (6) with the gas generator (3). In this case, an oxidation catalyst is used instead of the partial oxidation catalyst (37) in the gas generator (3), and a part of the liquid fuel (6) is oxidized (catalytic combustion), and its oxidation heat (combustion heat). Then, the remaining liquid fuel (6) is vaporized. As the oxidation catalyst, an alumina pellet carrier on which a platinum catalyst component is supported is used. The mixing ratio of the air (44) and the liquid fuel (6), that is, the air-fuel ratio A / F is set in the range of 0.05 to 0.2, around 0.1.

1A and 1B are diagrams illustrating an exhaust treatment apparatus according to an embodiment of the present invention, in which FIG. 1A is a cross-sectional view of a main part, and FIG. 1B is an end view of a cross section taken along line BB in FIG. FIG. 2 is a full sectional view of the exhaust treatment device of FIG. 1. FIGS. 3A and 3B are diagrams for explaining an oxidation catalyst of the exhaust treatment apparatus of FIG. 1, FIG. 3A is a sectional view taken along line III-III of FIG. 1A, and FIG. 3B is a diagram corresponding to FIG. It is. 4A and 4B are diagrams for explaining an upstream oxidation catalyst of the exhaust treatment apparatus of FIG. 1. FIG. 4A is a cross-sectional view taken along line IV-IV in FIG. 1A, and FIG. 4B is equivalent to FIG. FIG.

Explanation of symbols

(1) Exhaust route
(2) Diesel particulate filter
(2a) Entrance
(2b) Exit
(3) Gas generator
(4) Oxidation catalyst entrance passage
(5) Liquid fuel supply source
(6) Liquid fuel
(7) Combustible gas
(8) Combustible gas supply path
(8a) Termination
(9) Combustible gas outlet
(10) Exhaust
(11) Filter housing case
(12) Oxidation catalyst
(13) Exhaust passage
(14) Upstream oxidation passage
(14a) Termination
(15) Upstream oxidation catalyst
(16) Upstream oxidation passage outlet
(17) Front end wall
(18) Rear end wall
(19) Exhaust inlet chamber
(20) Exhaust outlet chamber
(21) Exhaust inlet pipe
(22) Exhaust outlet pipe
(23) Corrugated sheet metal
(24) Flat metal sheet
(25) Carrier
(26) Metal mesh
(27) Carrier
(28) Exhaust muffler
(29) First expansion chamber
(30) Final expansion chamber
(31) Exhaust pipe
(32) Exhaust outlet pipe
(33) Entrance

Claims (14)

The liquid fuel (6) is supplied from the liquid fuel supply source (5) to the gas generator (3). The gas generator (3) converts the liquid fuel (6) into a combustible gas (7). The flammable gas supply path (8) is derived from (3), and the flammable gas outlet (9) of the flammable gas supply path (8) is connected to the exhaust path upstream of the diesel particulate filter (2) ( 1) The combustible gas (7) flowing out from the combustible gas outlet (9) is combusted in the exhaust (10), and the exhaust particulate accumulated in the filter (2) is combusted by the combustion heat. In the exhaust system for diesel engines,
An exhaust system for a diesel engine, wherein the gas generator (3) is housed in a filter housing case (11) for housing the filter (2). The exhaust system for a diesel engine according to claim 1,
An oxidation catalyst (12) for promoting combustion of the combustible gas (7) is disposed between the combustible gas outlet (9) and the inlet (2a) of the filter (2),
An exhaust system for a diesel engine, characterized in that the oxidation catalyst (12) is housed in the filter housing case (11). The exhaust system for a diesel engine according to claim 2,
In flowing the combustible gas (7) heated by the exothermic reaction in the gas generator (3) from the combustible gas outlet (9) to the upstream of the oxidation catalyst (12),
Upstream of the oxidation catalyst (12), an upstream oxidation passage (14) is formed in the exhaust passage (13), the exhaust passage (13) has a double cylinder structure, and the upstream oxidation passage (14) The upstream oxidation catalyst (15) is accommodated in the upstream oxidation catalyst (15), and the combustible gas outlet (9) is opened toward the upstream oxidation passage (14) upstream of the upstream oxidation catalyst (15). Diesel engine exhaust system. The exhaust system for a diesel engine according to claim 3,
Of the double-cylinder exhaust passage (13), the cross-sectional area of the upstream oxidation passage (14) is ¼ of the overall cross-sectional area of the exhaust passage (13) including the upstream oxidation passage (14). An exhaust system for a diesel engine, characterized in that it is set within a range of ~ 1/2. The exhaust system for a diesel engine according to claim 3 or 4,
The end (8a) of the combustible gas outlet pipe (8) facing the passage forming direction of the upstream oxidation passage (14) is closed, and the peripheral wall near the end (8a) of the combustible gas outlet pipe (8) is closed. An exhaust system for a diesel engine, wherein a plurality of combustible gas outlets (9) facing the radial direction of the upstream oxidation passage (14) are opened. The exhaust system for a diesel engine according to any one of claims 3 to 5,
The upstream oxidation passage (14) is formed in the oxidation catalyst inlet passage (4), the oxidation catalyst inlet passage (4) has a double cylinder structure, and the inlet (33) of the oxidation catalyst (12). The end (14a) of the upstream oxidation passage (14) facing toward is closed, and the peripheral wall near the end (14a) of the upstream oxidation passage (14) faces in the radial direction of the oxidation catalyst inlet front passage (4). An exhaust system for a diesel engine, wherein a plurality of upstream oxidation passage outlets (16) are opened. The exhaust system for a diesel engine according to any one of claims 3 to 6,
A cylindrical filter housing case (11) having end walls (17) and (18) at both ends is used. The axial length direction of the filter housing case (11) is the front-rear direction, and the inlet (2a of the filter (2)) ) Side on the front and outlet (2b) side on the back, the exhaust inlet chamber (19) in front of the filter (2) in the filter housing case (11), and the exhaust outlet chamber in the rear of the filter (2). (20) is provided, the exhaust inlet pipe (21) is communicated with the exhaust inlet chamber (19), and the exhaust outlet pipe (22) is communicated with the exhaust outlet chamber (20).
The exhaust inlet pipe (21) is inserted into the exhaust inlet chamber (19) along the radial direction of the filter housing case (11), and the oxidation catalyst (12) is inserted into the exhaust inlet pipe (21) from the upstream side. ) And the gas generator (3) in this order,
The combustible gas supply path (8) derived from the gas generator (3) is passed through the oxidation catalyst (12) and the upstream oxidation catalyst (15), and combustible in the combustible gas supply path (8). An exhaust system for a diesel engine, characterized in that a gas outlet (9) is opened in the upstream oxidation passage (14) upstream of the upstream oxidation catalyst (15). The exhaust system for a diesel engine according to claim 7,
As the oxidation catalyst (12), a catalyst component supported on a carrier (25) in which a corrugated metal thin plate (23) and a flat metal thin plate (24) are wound together is used. Diesel engine exhaust system characterized. The exhaust system for a diesel engine according to claim 7,
An exhaust system for a diesel engine, characterized in that a catalyst component supported on a carrier (27) made of a metal mesh (26) is used as the oxidation catalyst (12). The exhaust system for a diesel engine according to claim 8 or 9,
As the upstream oxidation catalyst (15), a catalyst component supported on a carrier (25) in which a corrugated metal thin plate (23) and a flat metal thin plate (24) are rolled up is used. Diesel engine exhaust system. The exhaust system for a diesel engine according to claim 8 or 9,
An exhaust system for a diesel engine, characterized in that a catalyst component is supported on a carrier (27) made of a metal mesh (26) as the upstream oxidation catalyst (15). The exhaust system for a diesel engine according to any one of claims 7 to 11,
An exhaust muffler (28) is used as the filter housing case (11), the exhaust inlet chamber (19) is constituted by a first expansion chamber (29), and the exhaust outlet chamber (20) is constituted by a final expansion chamber (30). The exhaust inlet pipe (21) is constituted by the exhaust introduction pipe (31) of the first expansion chamber (29), and the exhaust outlet pipe (22) is constituted by the exhaust outlet pipe (32) of the final expansion chamber (30). An exhaust system for a diesel engine characterized by comprising: The exhaust system for a diesel engine according to any one of claims 1 to 12,
The liquid fuel (6) is reformed into a combustible gas (7) containing carbon monoxide and hydrogen by partially oxidizing the liquid fuel (6) with the gas generator (3). An exhaust system for a diesel engine. The exhaust system for a diesel engine according to any one of claims 1 to 12,
An exhaust system for a diesel engine, characterized in that the liquid fuel (6) is made into a combustible gas (7) by vaporizing the liquid fuel (6) with the gas generator (3).

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