Saddle type vehicle.

First international publication Number 2004/113696

Below, embodiments of the present invention while referring to the drawings. Furthermore, the present invention is not limited to the following embodiment.

In fig. 1, in this embodiment, saddle-ride type vehicle is provided with a constitution of an exhaust gas purifying system shown schematically. In this embodiment, the saddle-ride type vehicle, as shown in fig. 1, and an internal combustion engine 1, and the first and second catalyst 2B 1 2 of catalyst 2A, and a secondary air introducing device 3 is provided.

An internal combustion engine (typically 4-stroke gasoline engine) 1 is, the theoretical air-fuel ratio is smaller than (of gasoline when 14.7) in combustion of the air-fuel ratio. The air-fuel ratio smaller than the stoichiometric air-fuel ratio, i.e., the fuel-rich side air-fuel ratio by performing combustion, combustion is performed at a theoretical air-fuel ratio higher than that when the output is obtained. Typically, more than 12.5 14.5 combustion is performed. The internal combustion engine 1, the air-fuel mixture supplied through the intake passage 5a from a carburetor (carburetor) 4. The suction passage 5a, and a space surrounded by the intake pipe 5 is connected to an intake port of the internal combustion engine 1, on the upstream side of the carburetor 4, is provided with an air cleaner 6.

1 of the first catalyst 2A, combustion gas is discharged from the internal combustion engine 1 is provided in the exhaust passage 7a, the first catalyst 2B 2, 1 within the first exhaust passage 7a formed on the downstream side of the catalyst 2A. The exhaust passage 7a, the exhaust port of the internal combustion engine 1 is connected to a space surrounded by an exhaust pipe 7.

The secondary air introducing device 3, an exhaust passage 7a, of the first and second catalyst 2B 1 2 between catalyst 2A part 7a ' of the secondary air is introduced. For example, a secondary air introducing device 3 is shown, and a secondary air introducing pipe 3a is connected to an exhaust pipe 7, includes a reed valve (lead valve) 3b and a secondary air introducing pipe   3a and between the air cleaner 6. The lead valve 3b, function as a check valve to prevent backflow of the secondary air supplied from the air cleaner 6 on the secondary air introducing pipe 3a. Furthermore, the secondary air introducing device 3, 2 and 1 of the first catalyst 2A between the first catalyst 2B by introducing the secondary air is enough, the configuration of the secondary air introducing device 3 illustrated herein is not limited to that. A downstream end of the exhaust pipe 7, in order to reduce the exhaust noise of the muffler (silencer) 8 is connected.

Each of the first and second catalyst 2B 2 1 of the catalyst 2A, comprises a precious metal component. The precious metal component, specifically, platinum (Pt), rhodium (Rh), palladium (Pd) and gold (Au), at least one of 1. 1 2 of the first and second catalyst 2A of the noble metal catalyst 2B, combustion gas discharged from the internal combustion engine 1 (exhaust gas) in the CO, HC, NOx purification by oxidation or reduction.

In this embodiment of an exhaust gas purification system of the second catalyst 2B 2, further, ammonia-containing constituents ammonia decomposition. The ammonia decomposition components, specifically, iridium (Ir) and barium (Ba). The iridium and barium, single or compound contained in a first catalyst 2B as 2. Furthermore, the first catalyst 2A 1, does not contain barium and iridium.

In this embodiment, the exhaust gas purification system, the above-mentioned configuration of the first and second catalyst 2A having catalyst 2B 1 2 includes, fuel rich-side air-fuel ratio in the exhaust gas from the internal combustion engine 1 can be cleaned with a high efficiency. Especially, NH₃ can be derived for preventing the formation of NOx, NOx purification rate final. Below, specifically explaining this reason.

First, as shown in fig. 15, in the conventional exhaust gas purifying system 200, a sufficiently high NOx purifying ratio of the reason is explained. Table 1 a, 1 a conventional exhaust gas purifying system 200 of the first and second catalyst 202A of reaction in the catalyst 202B 2.

1 in the first catalyst 202A, eq. (1), (2) and (3) as shown in, CO, HC and NOx purification is performed. Specifically, the CO and HC, as shown respectively at eq. (1) and (2), H₂ O reacts and CO₂ and H₂ and is generated. Furthermore, the NOx, H₂ reacts and NH₃ and H₂ O and is generated. A part of the NOx, which is generated by the reaction of eq. (3) NH₃ reacts and, as shown in eq. (4) N₂ and H₂ O and is disassembled, all NH₃ is not consumed by the reaction. Furthermore, as shown in the disassembled eq. (5) NH₃ is slight. In other words, in the conventional exhaust gas purifying system 200, in the upstream side of the NOx purification catalyst 202A and a second time of 1 NH₃ is generated, a part thereof is supplied to the second catalyst 202B 2.

2 in the second catalyst 202B, as shown at eq. (6) and (7), the remaining CO, HC purification is performed. Specifically, the CO and HC, as shown respectively at eq. (6) and (7), the oxide CO₂ or CO₂ and H₂ O and is generated. Furthermore, in the first catalyst 202B 2, as shown at eq. (8), NH₃ is oxidized to produce NOx.

In this way, in the conventional exhaust gas purifying system 200, in which the first NOx catalyst 202A 1 N₂ not only NH₃ since reduced even in, NH₃ 2 of which is oxidized by the first catalyst 202B that NOx is generated. Therefore, the purification rate of NOx cannot be sufficiently increased.

Subsequently, in the exhaust gas purification system in this embodiment, the explanation of the reason why the NOx purification rate can be improved. Table 2 is, in this embodiment of an exhaust gas purification system 1 of the first and second catalyst 2A showing the reaction in the catalyst 2B 2.

In the first catalyst 2A 1, in a conventional exhaust gas purifying system 1 of the first catalyst 202A and similarly, eq. (1), (2) and (3) occur as the main reaction represented by the reaction, the reaction is represented by reactions occur as eq. (4) and (5). That is, CO, HC and NOx purification is performed NH₃ is generated, a part thereof is supplied to the second catalyst 2B 2.

In the first catalyst 2B 2, as shown in the remaining CO eq. (6) and (7), the purification of HC is performed. Furthermore, since the first catalyst 2B 2 of this embodiment includes the components of an ammonia decomposition, NH₃ is generated by a decomposition reaction represented by eq. (9). In other words, in this embodiment the second catalyst 2B 2, ammonia decomposition reaction occurs as the main reaction eq. (9). Therefore, as shown in a eq. (8) NH₃ NOx generated by oxidation reaction is reduced. Therefore, generation of NOx is suppressed.

In this way, in this embodiment, the exhaust gas purifying system, which is included in the first component 2 by ammonia decomposition catalyst 2B NH₃ (NOx generated by reduction of NH₃) is being, in the first NOx catalyst 2B 2 is suppressed, and the NOx purification rate is improved.

Furthermore, in this embodiment, the first component 2 of ammonia decomposition catalyst 2B organoiridium. Ammonia is used as the metal element functions as the catalyst, vanadium (V), iron (Fe), copper (cu) or the like is well known, according to the inventor's study, even using an ammonia decomposition components as these, CO shown in eq. (6) and (7), while the purification of HC, eq. (9) shown in NH₃ decomposition reaction is difficult to proceed. 2 in the second catalyst 2B, under oxidizing atmosphere NH₃ and CO and HC oxidized since almost simultaneously, the vanadium, iron, and copper is used as the ammonia decomposition, NH₃ excessively oxidized NOx is produced, or, to suppress the generation of such NOx and a going and, a purification rate of CO or HC cannot be sufficiently increased. On the contrary, the component includes an ammonia decomposition by organoiridium, 2 in the second catalyst 2B, and the purification of CO and HC by the precious metal component, ammonia decomposition NH₃ cleaning and can be appropriately performed in parallel.

Furthermore, the organoiridium, also functions as an NOx purification catalyst capable of directly is, as shown in fig. 2, NOx purification rate than by organoiridium, NH₃ purification rate is much higher. Therefore, even when the NOx purifying catalyst to be used as organoiridium than, as in this embodiment, the first NOx catalyst 2A by the noble metal component 1 is first purified, its emission generated accompanying NH₃ ammonia decomposition catalyst 2B of the second component 2 (including organoiridium) by decomposing, NOx purification rate of the exhaust gas purification system as a whole can be enhanced.

Furthermore, in this embodiment, the component includes an ammonia decomposition by barium, pfc. NOx purification rate can be increased. This effect, so that the result is confirmed experimentally, and by reason of the obtd..

The barium contained in the ammonia decomposition components, NOx (first 1 catalyst 2A in purification cannot NOx or NH₃ NOx generated by oxidation of) acts to trap. For example, nitrogen monoxide (NO) present as barium oxide and barium are trapped by the reaction, is expressed by the following eq. (10). 2BaO+4NO+3O₂ → 2Ba (NO₃)₂ ··· (10)

In this way, by utilizing a NOx trap, NH₃ decomposition reaction. For example, by the reaction of NO eq. (10) by utilizing a trap, following eq. (11) by the decomposition reaction NH₃ is purified. 3Ba (NO₃)₂ +10NH₃ → 3BaO+8N₂ +15H₂ O··· (11)

As mentioned above, the ammonia decomposition contains barium component, i.e., ammonia decomposition by adding barium component, the remaining NOx (or NH₃ produced from) a NH₃ since it is possible to decompose, NOx purification rate can be increased further.

As already described, the NOx purification catalyst organoiridium can also function as directly. The inventor was confirmed, the effect of improving the purification rate by adding barium, even when using a NOx purifying catalyst as obtd. organoiridium. However, the effect of improving the purification rate, as in this embodiment NH₃ purifying catalyst (ammonia decomposition component) is used as the case of iridium.

In fig. 3 (a), as the NOx purification catalyst and barium additive organoiridium by adding a NOx purification rate and in the case of the example shown. Furthermore, the example shown NH₃ when and as the purification rate is not added when added to the barium and organoiridium, NH₃ purifying catalyst as in fig. 3 (b).

As shown in fig. 3 (a), as the NOx purification catalyst and barium organoiridium in addition, improving the purification rate of about 40%. In contrast to this, NH₃ purifying catalyst and barium as adding organoiridium, improving the purification rate of about 60%. In this way, NH₃ purifying catalyst (ammonia decomposition component) by adding barium organoiridium as, a remarkable effect is obtained. Incidentally, numeral (about 40%, about 60% that the effect of improving the purification rate) is shown in figs. 3 (a) and (b), as for example in the specification of the trial, if the absolute value of the different specifications of these scarce.

In the presence of ammonia decomposition components and in particular the ratio organoiridium barium is not limited, in a molar ratio of 5:1-1:20. In the case of a barium additive amount is less than a molar ratio of 5:1 and, sufficient purification efficiency improving effect can not be obtained. Furthermore, when the addition amount of barium is more than a molar ratio of 1:20 and, corresponding to the amount of additive effect cannot be obtained.

Furthermore, the first component 2 of the ammonia decomposition catalyst 2B, barium and not only organoiridium, ammonia and other functions as the catalyst may contain a metal element. However, from the viewpoint of suitably of ammonia decomposition, already described, vanadium, iron, preferably does not include copper.

Next, with reference to figs. 4 and 5, the first and second catalyst 2A 2 1 of a more concrete structure of catalyst 2B of the example explained. The figs. 4 and 5, the first and second catalyst 2A 1 2 near the surface of the catalyst 2B schematically showing a cross sectional structure of Fig.

1 of the first catalyst 2A, as shown in fig. 4, and the carrier base material 11, provided on the carrier base material 11 and a catalyst layer 12. The carrier base material 11, for example, is formed of a metal of a honeycomb structure ("metal carrier" and is called. ). The catalyst layer 12, the precious metal component. The catalyst layer 12, more preferably at least 1 including two alumina, ceria and zirconia. Alumina, ceria and zirconia is, function as a catalyst carrier and a precious metal component suitable for combustion.

The first catalyst 2B 2, as shown in fig. 5 (a), and a carrier base material 21, which is provided on a carrier base material 21 and the catalyst layer 22. The carrier base material 21, such as a metal carrier. The catalyst layer 22, and a noble metal component includes both of the ammonia decomposition. In other words, the noble metal component and ammonia decomposition components are mixed in the catalyst layer 22. The catalyst layer 22, preferably at least two further 1 including alumina, ceria and zirconia. Alumina, ceria and zirconia is, barium and precious metal component and a carrier component including an ammonia decomposition organoiridium and suitably function as a co-catalyst.

Alternatively, the second catalyst 2B 2, as shown in fig. 5 (b), and a carrier base material 21, provided on the carrier base material 21 and a second catalytic layer 1 23, provided on the first and the second catalytic layer 1 23 and 2 catalyst layer 24. The second catalyst layer 1 23, contains a precious metal component, the first catalyst layer 2 24, ammonia decomposition component. That is to say, on a carrier base material 21 containing a precious metal component and a second (however does not contain barium and iridium) and ammonia decomposition catalyst layer 1 23 including a first component 2 catalyst layer 24 are laminated in this order. Furthermore, and in other words, the first catalyst layer 2 24, 1 of the first catalyst layer 23 is arranged. The second catalyst layer 1 23, alumina, ceria and zirconia is preferably at least 1 further comprises two. Alumina, ceria and zirconia is, function as a catalyst carrier and a precious metal component suitable for combustion. Furthermore, the first catalyst layer 2 24, it is preferable to further include alumina. The alumina, barium and a carrier component including an ammonia decomposition organoiridium and suitably function as a co-catalyst.

To further improve the purification rate of NOx from the viewpoint, the first catalyst 2B 2, rather than a structure shown in fig. 5 (a), it is desirable to have the structure shown in fig. 5 (b). First, as shown in fig. 5 (b) is a catalyst 2B 2 2 by having a layered structure, the exhaust gas, a catalyst layer 1 23 containing a precious metal component before reaching the first ammonia decomposition catalyst layer 2 24 including a first component. Therefore, in the second catalyst layer 1 23 NH₃ due to oxidation can effectively suppress the generation of NOx, therefore, a purification rate of NOx can be further improved. Furthermore, the first catalyst 2B 2 has a structure which is shown in fig. 5 (a) and, second catalyst 2B 2 of advantage that the manufacturing process can be simplified.

Furthermore, the first catalyst 2B 2, having a structure as shown in fig. 6. In the structure shown in fig. 6, the first catalyst 2B 2, ammonia decomposition and including a first component 1 region R1, the first 1 region R1 is positioned on the downstream side, and including a first precious metal component 2 region R2. In other words, the first and second regions 1 R1 2 region R2 are arranged in sequence from the upstream side in the exhaust gas passage 7a. In the first region 1 R1, as shown in fig. 7 (a), on a carrier base material 21 containing ammonia decomposition catalyst layer 25 is provided. 2 region R2 in the second, as shown in fig. 7 (b), containing a precious metal component on a carrier base material 21 (but not including barium and iridium) catalyst layer 26 is provided. By the arrangement shown in fig. 6, the exhaust gas, containing a precious metal component 2 region R2 before reaching the first ammonia decomposition component including a first pass 1 region R1. Therefore, in the second region 2 R2 NH₃ due to oxidation can effectively suppress the generation of NOx, therefore, can improve the purification rate of NOx pfc..

The structure and fig. 6 fig. 5 (b) shows the structure shown, both of the high NOx purification ratio is preferable. The structure shown in fig. 5 (b) and, further, in the second catalyst layer 1 23 of CO, HC and the heat generated by the oxidation reaction of the catalytic layer 2 24 of first NH₃ decomposition reaction can be used, the effect of reducing the NOx is high even at a low temperature, the advantage is obtained. In contrast to this, and a structure is adopted as shown in fig. 6, to form a catalyst layer after the baking or drying of a slurry coated for workhours is 1 (two-layer structure as in the case of turning and 2), which gives the advantage that the manufacturing cost can be reduced.

In fig. 5 (b) shows a structure in which the average thickness of the first catalyst layer 2 24, NH₃ disassembled from the viewpoint of surely, it is preferred to be more than 10 µm 100 µm. Furthermore, in the structure shown in fig. 6 the length of the first region R1 1 (exhaust passage 7a in length along the direction of gas flow) the, NH₃ disassembled from the viewpoint of surely, 20 mm or more.

Next, while referring to fig. 8, further explaining the preferred configuration can improve the NOx purification rate of the exhaust gas purification system as a whole.

In the configuration shown in fig. 8, the blow-by gas leaking from a combustion chamber of the internal combustion engine 1 (blow-by   gas; BG and are shown in the drawing) is, on the upstream side of the lead valve 3b and the secondary air (SA and are shown in the drawing) and mixed. Therefore, the secondary air introducing device 3, and the blow-by gas to the first catalyst 2B 2 1 of the first catalyst 2A between parts 7a ' and the introduced secondary air. According to the inventor's study, secondary air is supplied in addition to the blowby gas, NOx purification rate in the entire system is further improved.

Furthermore, the secondary air introducing device 3, a cold start of the internal combustion engine 1 from a predetermined period (cold start), the blowby gas is not introduced into the exhaust gas passage 7a is further preferable. And the cold start, the temperature of the internal combustion engine 1 is equal to or smaller than the outside air temperature at starting (cold state). Immediately after the cold start, i.e., activation of the first catalyst 2B 2 sufficiently before the introduction of the blow-by gas is not performed, after the lapse of a predetermined period from a cold start, i.e., a first catalyst 2B 2 sufficiently after activation by the introduction of the blow-by gas, the blow-by gas in the first combustion of the catalyst 2B 2 can be sufficiently performed. The introduction of the blow-by gas can be selectively configured as shown in the example of fig. 9.

In the configuration shown in fig. 9, the secondary air introducing device 3, the introduction of the blow-by gas to the blow-by gas switching valve 3c for switching the destination. By the blowby gas switching valve 3c, the prescribed period from a cold start, the blowby gas introduced into the suction passage 5a, after the lapse of a predetermined period of time, and a blow-by gas is mixed with the secondary air.

Furthermore, the blowby gas is not introduced into the exhaust path 7a of the "predetermined period" and, from cold start temperature of the first catalyst 2B 2 of an activation temperature or higher (typically 300 °C or higher) in a period, for example 20 seconds to 200 seconds.

Next, the exhaust gas purification system in this embodiment by actual trial, its effect is verified result is explained.

By the following method, an exhaust gas purification system in this embodiment (embodiment 1-4) 4 and kind, for a comparison of the exhaust gas purifying system (comparative example 1, 2) and is manufactured. The first catalyst 2B 2, in the embodiment 1, 4 a structure shown in fig. 5 (b), a structure in the embodiment 2 shown in fig. 6, in the embodiment 3 shown in fig. 5 (a). Furthermore, in the comparison example 1, 2, a catalyst provided on the upstream side of the exhaust passage (second catalyst 2A 1 equivalent) and provided in the downstream side catalyst (second catalyst 2B 2 equivalent) including the noble metal component. However, in the comparative example 1 and on the downstream side of the catalyst on the upstream side of the ammonia decomposition catalyst (iridium, barium) does not include a component. Furthermore, in the comparison example 2, downstream of the catalyst including organoiridium, does not contain barium.

(Embodiment 1) [Of first catalyst 1] A diameter of 45 mm and length of 60 mm, a cell number 100cpsi (=15.5 pieces/cm²) metal carrier 11 is prepared, and this metal carrier 11 on the market for reducing catalyst material (Pt=1.0 wt %, Rh=0.2 wt %, CeO₂-ZrO₂ =30 wt %, balance Al₂ O₃) to 100 g/l by coating a catalyst layer 12 is formed, a first catalyst 2A 1 is fabricated. 1 of the platinum catalyst 2A first, the concentration of rhodium, Pt=1.0 g/l, Rh=0.2 g/l.

[Second catalyst 2] First, a slurry is prepared for 1 catalyst layer 23. Specifically, first, the ion exchange water 70g 200g γ alumina, ceria-zirconia (Ce:Zr= 1:1) a 30g, platinum Pt in an amount of 0.5g dinitroglycerin Dimamine, in addition to palladium nitrate 1.5g, expressed in terms of Pd, 40 °C 2 (the pH changes from 2.0 to 2.5) at a time. Next, the mixture is dried at 120 °C after 12 hours, 1 hour at 600 °C. Furthermore, the fired material and, a slurry (pH 4.5 the), for the first time, the catalyst layer 1 23 1 100g of ion-exchanged water, and aluminum nitrate hexahydrate sol. 20g 5g and in a ball mill.

Next, the slurry is prepared for the second catalyst layer 2 24. Specifically, first, the ion exchange water 95g 200g γ alumina, barium acetate mixed 9.3g, is evaporated to dryness, 5% Ba-γ alumina is prepared. This 5% Ba-γ alumina 98g organoiridium nitrate ion exchanged water to 2.0g addition amount 200g and Ir, 2 hours with stirring to 40 °C, to adsorb the organoiridium 5% Ba-γ alumina. Next, the mixture is dried at 120 °C after 12 hours, 1 hour at 600 °C. Furthermore, the fired material and, a slurry (pH 4.5 the), for the first time, the catalyst layer 2 24 1 100g of ion-exchanged water, and aluminum nitrate hexahydrate sol. 20g 5g and in a ball mill.

Subsequently, at a diameter of 54 mm length of 80 mm, a cell number 100cpsi (=15.5 pieces/cm²) on the surface of a metal carrier 21, the first catalyst layer 1 23 by applying a slurry, dried at 120 °C, fired at 600 °C. The amount of coating after firing, 100 g/l. Therefore, 0.5 g/l platinum, palladium containing 1.5 g/l, having an average thickness of the 55 µm 1 catalyst layer 23 is formed.

Next, on the first catalyst layer 1 23, for the first catalyst layer 2 24 is coated with the slurry, and dried at 120 °C, fired at 600 °C. The amount of coating after firing, 100 g/l. Therefore, to 2.0 g/l organoiridium, 5.0 g/l contains barium, having a mean thickness of the 55 µm 2 catalyst layer 24 is formed. In this way, the first catalyst 2B 2. In the first catalyst 2B 2 of platinum, palladium, iridium, concn. of barium, Pt=0.5 g/l, Pd=1.5 g/l, Ir=2.0 g/l, Ba=5.0 g/l.

As mentioned above the first and second catalyst 2A 2 1 of each exhaust passage 7a of the upstream side catalyst 2B and attached to the downstream side, the exhaust gas purifying system shown in fig. 1.

(Embodiment 2) [Of first catalyst 1] Embodiment 1 1 of the first catalyst 2A and similarly is fabricated.

[Second catalyst 2] Length 160 mm in diameter of 54 mm, a cell number 100cpsi (=15.5 pieces/cm²) prepared metal carrier 21. As the slurry 1 region R1 of the first catalyst layer 25, and by adjusting the slurry, a slurry of the same composition as that of the first embodiment 1 of 2 catalyst layer 24. Furthermore, for the second region 2 R2 as the slurry of catalyst layer 26, of the first embodiment 1 1 catalyst layer 23 of the same composition and slurry. Metal carrier 21 in the front half of the first (i.e., from the inlet to the point of 80 mm) for an 1 region R1 is coated with a slurry of catalytic layer 25, in the rear half of the metal carrier 21 (i.e., from the outlet to the point of 80 mm) 2 region R2 for the second catalyst layer 26 is coated with the slurry, drying, baking is performed by forming a catalyst layer 25, 26, of the first catalyst 2B 2. A second catalyst 2B 2 1 region R1 in the first (front half) organoiridium, concn. of barium, Ir=2.0 g/l, and Ba=5.0 g/l, 2 region R2 in the second (rear half) platinum, palladium concentration, Pt=0.5 g/l, Pd=1.5 g/l.

As mentioned above the first and second catalyst 2A 2 1 of each exhaust passage 7a of the upstream side catalyst 2B and attached to the downstream side, the exhaust gas purifying system shown in fig. 1.

(Embodiment 3) [Of first catalyst 1] Embodiment 1 1 of the first catalyst 2A and similarly is fabricated.

[Second catalyst 2] 2 of the first embodiment 1 for catalyst 2B and a metal carrier 21 of the metal carrier 21 is prepared having the same specification. The prepared slurry as follows for the catalyst bed 22. Specifically, first, the ion exchange water 95g 200g γ alumina, barium acetate mixed 9.3g, is evaporated to dryness, 5% Ba-γ alumina is prepared. This 5% Ba-γ alumina 98g organoiridium nitrate ion exchanged water added to 2.0g 200g and Ir in terms of amount, in terms of platinum Pt dinitroglycerin Dimamine 0.5g further, in terms of Pd Pd nitrate 1.5g applied to, 2 hours with stirring to 40 °C, etc., the adsorption organoiridium 5% Ba-γ alumina. Next, the mixture is dried at 120 °C after 12 hours, 1 hour at 600 °C. Furthermore, the fired material and, ion exchange water 100g, and aluminum nitrate hexahydrate sol. 20g in a ball mill for pulverizing the 5g and (the pH 4.5) 1 time, the slurry is obtained for the catalyst layer 22. A catalyst layer 22 is coated with a slurry, dried at 120 °C, fired at 600 °C. In this way, the first catalyst 2B 2. In the first catalyst 2B 2 of platinum, palladium, iridium, concn. of barium, Pt=0.5 g/l, Pd=1.5 g/l, Ir=2.0 g/l, Ba=5.0 g/l.

As mentioned above the first and second catalyst 2A 2 1 of each exhaust passage 7a of the upstream side catalyst 2B and attached to the downstream side, the exhaust gas purifying system shown in fig. 1.

(Embodiment 4) Embodiment 1 1 and similarly prepd. by a first and a second catalyst 2A 2 of each exhaust passage 7a on the upstream side of the catalyst 2B and attached to the downstream side, the blowby gas is further introduced into the exhaust path 7a in fig. 8 shows the configuration of an exhaust gas purification system.

(Comparative example 1) [Of the upstream side catalyst] Embodiment 1 1 of the first catalyst 2A and by a similar method, a catalyst provided on the upstream side of the exhaust passage.

[Of the downstream side catalyst] The second catalyst layer 2 24 does not form a point 2 of the first embodiment 1 except a catalyst 2B and similarly, barium organoiridium and does not include a catalyst. The platinum in the catalyst, the concentration of the palladium, Pt=0.5 g/l, Pd=1.5 g/l.

As mentioned above, two catalyst 2 is fabricated by using the exhaust gas purifying system.

(Comparative example 2) [Of the upstream side catalyst] Embodiment 1 1 of the first catalyst 2A and by a similar method, a catalyst provided on the upstream side of the exhaust passage.

[Of the downstream side catalyst] Without the addition of barium acetate, γ-alumina is used as it is point 2 of the first embodiment 1 except the catalyst 2B and similarly, which does not contain a catalyst containing barium organoiridium is fabricated. In the catalyst and the concentration of platinum, palladium, iridium, Pt=0.5 g/l, Pd=1.5 g/l, Ir=2.0 g/l.

As mentioned above, two catalyst 2 is fabricated by using the exhaust gas purifying system.

(Verification result) Comparative example 1, 2 of the embodiment 1-4 and exhaust gas purification system mounted on the motorcycle exhaust amt. 125cc, CO (carbon monoxide) EU3 mode, THC (total hydrocarbon) and NOx (nitrogen oxide) emission amount is measured. EU3 mode, as shown in fig. 10, with the lapse of time while the vehicle speed is measured. Furthermore, in measurement, 850 °C exhaust temperature set in advance, the catalyst 6 time operation is performed by forcedly deterioration.

Embodiment 1, the result of the measurement of the comparative example 1 and 2 in figs. 11 (a)-(c) shows, as a comparative example 1 and example 1-4 fig. 12 shows the measurement results. Figs. 11 (a)-(c) are, respectively, CO discharge amount (g/km), THC emission quantity (g/km), NOx discharge quantity (g/km) being a graph showing. The fig. 12, the ratio of CO discharge amount relative to a transverse axis (comparative example 1 to 1 and a) is taken, the relative ratio of the NOx emission amount in a vertical axis (comparative example 1 to 1 and a) of the graph.

As shown in figs. 11 (a) and (b), CO or THC emission quantity for a quantity of discharge, and an example 1, comparative example 1 and 2 and at almost the same. In contrast to this, as shown in fig. 11 (c), the NOx emission amount, comparative example 1 is less than that of the comparative example 2, embodiment 1 is further reduced. Therefore, the downstream-side catalyst (second catalyst 2B 2) including a discharge amount of NOx by organoiridium is reduced, further containing a barium NOx discharge quantity by reducing pfc. is known.

Furthermore, as shown in fig. 12, all in the embodiment 1-4, NOx discharge amount is less than that of the comparative example 1. Furthermore, in the embodiments 1, 2 and 4, the NOx discharge amount is less than that of embodiment 3. In this way, the NOx purification ratio from a high point, fig. 5 (b) or fig. 6 fig. 5 (a) shows a structure in which it is known that the structure is preferable. Furthermore, a CO discharge amount and considering such, embodiments 1 and 4 is further preferably embodiment 2, fig. 5 (b) shows a structure at a point most known environmental performance is excellent. The structure shown in fig. 6 fig. 5 (b) is more excellent than the structure shown is the reason, in the structure shown in fig. 5 (b) in the first catalytic layer 1 23 of CO, HC and the heat generated by the oxidation reaction of the catalytic layer 2 24 of first NH₃ and can be used for the decomposition reaction, CO, HC and oxidation of the structure shown in fig. 6 than in the vicinity of the internal combustion engine 1 can be performed (i.e., temperature). Furthermore, in the embodiment 4 NOx discharge amount than that of the embodiment 1 is reduced, by the introduction of the blow-by gas into the exhaust path 7a, NOx purification rate is improved by pfc. is known.

In this way, in this embodiment, the exhaust gas purification system, NOx emission amount can be reduced more.

Furthermore, in fig. 1, 2 of the first and second catalyst 2A 1 catalyst 2B is a muffler 8 is disposed on the upstream side which shows a configuration, as shown in fig. 13, of the first and second catalyst 2B 1 2 catalyst 2A can be disposed on the inside of a muffler 8. In the exhaust gas purifying system of this embodiment, the first component 2 of ammonia decomposition catalyst 2B by which includes, at a lower temperature than before NOx purification rate sufficiently high can be realized. In other words, the exhaust gas purifying system of this embodiment, even in a low temperature can be suitably used. For example, a conventional exhaust gas purifying system shown in fig. 15 which can be used in respect of 650 °C -900 °C, the exhaust gas purifying system of this embodiment, and can be used in 550 °C -900 °C.

Therefore, the first and second catalyst 2B 1 2 of a catalyst 2A, compared to a conventional internal combustion engine 1 arranged at a position away. For example, in the conventional exhaust gas purifying system shown in fig. 15, in a position for a 150 mm -400 mm of the first catalyst 202A 1 away from the engine 201. In contrast to this, in the exhaust gas purifying system of this embodiment, the internal combustion engine 1 1 of the first catalyst 2A is arranged at a position apart from 150 mm -600 mm. Therefore, in the exhaust gas purifying system of this embodiment, the first and second catalyst 2A 2 1 of both catalyst 2B can be disposed in the muffler 8.

The first and second catalyst 2A 2 1 around the catalyst 2B, purification reaction and by reaction heat generated in accordance with temperature. As shown in fig. 13, of the first and second catalyst 2B 1 2 catalyst 2A arranged within a muffler 8, softening of the peripheral components (thermal damage) or deterioration can be prevented. Furthermore, the advantages of the external surface (such as improving the design) is also obtained.

As mentioned above, the exhaust gas purifying system of this embodiment, therefore, the air-fuel ratio smaller than the stoichiometric air-fuel ratio in a combustion gas discharged from the internal combustion engine, combustion is performed in the NOx can be purified at a high efficiency.

In this embodiment, the exhaust gas purifying system, since the NOx purifying performance, suitable for use in a motorcycle. In fig. 14, in this embodiment, the exhaust gas purifying system showing the motorcycle 100 is provided. The motorcycle 100, and the engine 1, the engine 1 is connected to the exhaust port of the exhaust pipe 7 and, connected to the exhaust pipe 7 and a muffler 8. In the exhaust pipe 7, which is not shown in the figure, the first catalyst 2A 1, 2 is provided with a first catalyst 2B, the motorcycle 100, furthermore, the exhaust pipe 7 for introducing secondary air into a secondary air introducing device 3 is also provided.

In the motorcycle 100, since the engine 1 is operating in a fuel rich side air-fuel ratio, the engine output is high, high drivability is obtained. Furthermore, the motorcycle 100, described above since it is provided with an exhaust gas purification system, the fuel-rich side of the engine 1 is operated at an air-fuel ratio from the NOx contained in the exhaust gas can be purified with high efficiency. Therefore, the motorcycle 100, both excellent running performance and environmental performance.

Furthermore, figs. 1, 8, 9 and 13 the, carburetor 4 is provided to be illustrative (carburetor system), the motorcycle 100, may have a constitution in which an injector is provided (that is, the air-fuel mixture in the injection system can be created. ).

Furthermore, in this embodiment, the exhaust gas purifying system, is not limited to the motorcycle, the rider rides over the saddle ride type vehicle suitable for use in general. For example, such as a buggy is also used on the ATV. In general, since the exhaust amount of the saddle-ride type vehicle, preferably an internal combustion engine operated with fuel rich side of the air-fuel ratio, the exhaust gas purifying system for mounting the significance of this embodiment.

1 internal combustion engine 2A of the first catalyst 1 2B of the second catalyst 2 3, a secondary air introducing device A secondary air introducing pipe 3a The reed valve 3b The blow-by gas switching valve 3c 4 carburetor 5 intake pipe The suction passage 5a 6 air cleaner 7 exhaust pipe The exhaust path 7a 8 silencer 11, 21 of a carrier base material 12, 22, 25, 26 catalyst layer 23 first catalytic layer 1 24 first catalyst layer 2 R1 of first catalyst 1 area 2 R2 2 2 area of the first catalyst 100 motorcycle