JPS6218725B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust gas purification device in which a catalytic converter is interposed in the exhaust gas passage of a multi-cylinder engine having a plurality of cylinders.

In order to prevent the exhaust gas pressure pulsation of each cylinder from interfering with the exhaust stroke of other cylinders, the exhaust gas passage of a multi-cylinder engine with multiple cylinders is designed to be as long as possible. It is preferable that the exhaust gas passage is formed independently of the exhaust gas passage of the cylinder.

The present invention relates to an exhaust gas purification device that allows an exhaust gas passage in which a catalytic converter is disposed to be independent for as long as possible. That is, the present invention is formed by supporting a catalyst material on a carrier having a large number of small passages that are continuous and independent in the gas flow direction without being blocked between an upstream end face and a downstream end face. We focused on the fact that the monolithic catalyst itself has a large number of small passages that do not communicate with each other, and grouped the large number of passages of the monolithic catalyst into groups, each of which is a part of an independent exhaust gas passage. This was achieved by forming an engine body with multiple cylinders, an exhaust gas passage that releases exhaust gas from the plurality of cylinders into the atmosphere, and an exhaust gas flow that is interposed in the exhaust gas passage. comprising a plurality of monolithic catalysts arranged in series in the direction,
At least the upstream side of the monolithic catalyst of the exhaust gas passage is divided into a plurality of passages, which are opened near the upstream side surface of the monolithic catalyst, and the gap between the downstream end face of the upstream monolithic catalyst and the upstream end face of the downstream monolithic catalyst is divided into the plurality of passages. The subject matter is an exhaust gas purification device characterized in that the exhaust gas purification device is divided into sections corresponding to the passages of the exhaust gas.

Therefore, according to the present invention, a large number of independent small passages formed in the monolithic catalyst cooperate with a plurality of divided exhaust gas passages on the upstream side of the catalyst, and act as an extension of each exhaust gas passage. Therefore, each exhaust gas passage is formed to be substantially long and interference due to pulsation of exhaust gas pressure is reduced, thereby providing an exhaust gas purification device that increases output and improves fuel efficiency.

A first embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

Reference numeral 2 indicates an engine body, and the exhaust gas discharged from each of the exhaust port 4 of the first cylinder, the exhaust port 6 of the second cylinder, the exhaust port 8 of the third cylinder, and the exhaust port 10 of the fourth cylinder is connected to the engine body. The exhaust gas is discharged into the atmosphere through an exhaust gas passage of an exhaust system 12 provided at 2. The exhaust system 12 includes a branch pipe 1 that communicates with each of the exhaust ports 4, 6, 8, and 10.
Exhaust manifold 2 with 4, 16, 18, 20
2 and a catalytic converter 28 having a flange 26 fixed to a flange 24 provided on the downstream end face of the exhaust manifold 22;
The exhaust pipe 34 has a flange 32 fixed to a flange 30 provided on the downstream end face of the exhaust pipe 32 and is connected to a muffler (not shown).

In the exhaust manifold 22, branch pipes 14 and 20 forming mutually independent exhaust gas passages merge to form a first composite passage 36, and branch pipes 16 and 18 forming mutually independent exhaust gas passages merge. A second composite passage 38 is formed.

In the catalytic converter 28, a case body 44 is formed by a first case 40 and a second case 42 having a dividing surface along the exhaust gas flow direction, and flanges 46, 48 of the first case 40 and the second case 42 form a case body 44.
flanges 50 and 52 are welded together, and an upstream opening 54 and a downstream opening 56 are formed in the flanges 26 and 30.
is fixed. Inside the case body 44, a first monolith catalyst 58 and a second monolith catalyst 60 are disposed in series in the exhaust gas flow direction, each of which is made of an elastic retaining catalyst made of corrugated compression-molded heat-resistant steel wire woven into a wire mesh shape. It is held via members 62 and 64. In addition, in the exhaust gas flow direction, the case body 4
a conical side wall 66 forming an upstream opening 54 of 4;
A concave molded portion 68 provided at the center of the case body 44 and a conical side wall 70 forming the downstream opening 56 of the case body 44 are connected to both monolithic catalysts 58 , respectively.
Since the cross section is smaller than that of 60, it is held so that it does not move excessively.

72 is fixed to the inner wall of the conical side wall 66, divides the upstream opening 54 into two, and connects the exhaust manifold 22.
The first auxiliary passage 7 communicates with the first composite passage 36 of
4 and a second auxiliary passage 76 that communicates with the second composite passage 38 of the exhaust manifold 22, and is integrally welded to both the first and second cases 40, 42, and the downstream The end 78 is provided adjacent to the upstream end surface 80 of the first monolithic catalyst 58 .

Reference numeral 82 denotes a partition wall member which is held by the flanges 46, 48 and 50, 52 of the first case 40 and the second case 42 at the center of the case main body 44 and is welded integrally with the case main body 44; The gap between the downstream end surface 84 of the monolith catalyst 58 and the upstream end surface 86 of the second monolith catalyst 60 is defined as a first divided passage 88 corresponding to the first auxiliary passage 74 and a second divided passage corresponding to the second auxiliary passage 76, respectively. It is divided into 90 parts.

Reference numeral 92 denotes a first secondary air supply device in which a reed valve 98 is provided between the air cleaner 94 and a supply passage 96 that communicates with the first divided passage 88. Next, supply air. 100 is a second secondary air supply device in which a reed valve 106 is provided between the air cleaner 102 and a supply passage 104 communicating with the second divided passage 90;
Secondary air is supplied by exhaust gas pulsation in the second divided passage 90.

The operation of the first embodiment with the above configuration will be explained below. The firing order is 1st cylinder, 3rd cylinder, 4th cylinder,
Assuming that the order of the second cylinder is followed, the exhaust gas will flow to each exhaust port 4, 8, 10, 6 according to the above ignition order.
and is exhausted via the exhaust manifold 22. In the exhaust manifold 22, a branch pipe 14 communicating with the exhaust port 4 of the first cylinder and a branch pipe 20 communicating with the exhaust port 10 of the fourth cylinder merge to form a first composite passage 36, and The branch pipe 16 communicating with the exhaust port 6 of the third cylinder and the branch pipe 18 communicating with the exhaust port 8 of the third cylinder merge to form a second composite passage 38.
In addition, since the first composite passage 36 and the second composite passage 38 are formed so that the exhaust gas pulsation does not interfere with each other, the exhaust gas of the first and fourth cylinders and the second cylinder, The exhaust gas of the third cylinder is transferred to the upstream opening 5 of the catalytic converter 28 without interfering with each other.
4.

The catalytic converter 28 includes a monolithic catalyst in which a catalytic material is supported on a carrier having a large number of small passages that are continuous and independent in the gas flow direction without being blocked between an upstream end face and a downstream end face. but,
Two of them are arranged along the exhaust gas flow, and the upstream opening 54 located upstream of the first monolithic catalyst 58 arranged on the upstream side is connected to the first monolithic catalyst 58.
A partition member 72 is provided adjacent to the upstream end surface 80 of the passageway 72 to divide the passage into a first auxiliary passage 74 and a second auxiliary passage 76 . Therefore, the exhaust gas transmitted through the first complementary passage 36 and the second composite passage 38 of the exhaust manifold 22 without interfering with each other is transferred to the first auxiliary passage 74 and the second auxiliary passage 76, respectively. The small passages of the first monolithic catalyst 58 are connected to the first small passage group A.
and the second small passage group B, respectively, and the downstream end face 8 of the first monolithic catalyst 58.
Exhaust gas discharged from 4 is transmitted to the second monolithic catalyst 60 while being divided by the partition member 82, and the small passages of the second monolithic catalyst 60 are passed through the third small passage group A' and the second small passage group B. ' and is transmitted from the downstream opening 56 to the exhaust pipe 3.
4.

In other words, the exhaust gas discharged from the first and fourth cylinders passes through the exhaust pipe independently without substantially interfering with or mixing with the exhaust gas discharged from the second and third cylinders. transmitted to 34,
Released into the atmosphere.

In the catalytic converter 28, the case body 4
4, a first secondary air supply device 92 and a second secondary air supply device 100 are provided, and the exhaust gas flowing through the respective passages is provided to the first auxiliary passage 88 and the second auxiliary passage 90, respectively. Secondary air is supplied by exhaust pulsation.

Therefore, according to the above embodiment, the first cylinder and the fourth cylinder
Exhaust gas from the cylinder is routed from the branch passages 14 and 20 to the first
It merges into the composite passage 36 and passes through the first auxiliary passage 74, the first small passage group A in the first monolith catalyst 58, the first divided passage 88, and the third small passage group A' in the second monolith catalyst 60. , are discharged to the exhaust pipe 34 independently and without interference. Furthermore, the exhaust gases from the second and third cylinders are merged from the branch passages 16 and 18 into the second composite passage 38, and are then passed through the second auxiliary passage 76 and the first
The gas is discharged to the exhaust pipe independently and without interference via the second small passage group B in the monolith catalyst 58, the second divided passage 90, and the fourth small passage group B' in the second monolith catalyst 60. Therefore, interference due to exhaust pulsation in each cylinder is reduced, and effects such as improved exhaust efficiency, increased engine output, and improved fuel efficiency are achieved.

Furthermore, according to this embodiment, the exhaust gases from the first and fourth cylinders and the exhaust gases from the second and third cylinders are transmitted to the vicinity of the downstream opening 56 of the catalytic converter 28 without interfering with each other. , a first divided passage 8 provided in the case body of the catalytic converter 28
The exhaust gas pulsations transmitted through the reed valves 98 and 1 and the second divided passage 90 do not interfere with each other and are reduced, but reach a large value.
The amount of secondary air sucked through the monolithic catalyst 60 increases, and the oxidation reaction at the second monolithic catalyst 60 is promoted.

Next, a second embodiment of the present invention will be described with reference to FIGS. 5 to 7, in which the same or substantially the same members as those explained in the first embodiment are designated by the same reference numerals. The explanation will be omitted.

Reference numeral 112 indicates an exhaust system provided in the engine 2, in which an exhaust manifold 114, a case body 116, and an exhaust pipe 118 are connected to bolts 120 and 122, respectively.
are fixed together to form the case of the catalytic converter.

The exhaust manifold 114 has branch pipes 124, 1 communicating with exhaust ports 4, 6, 8, 10 of the engine 2.
26, 128, and 130, branch pipes 124 and 130 join together to form a first composite passage 134, and branch pipes 126 and 128 join together to form a second composite passage 136, Both composite passages 134 and 136 are substantially independently divided by a partition member 138.

The case body 116 has a catalyst holding portion 140 that protrudes inward in an annular shape at the center thereof, and a first monolithic catalyst 144 is placed on the upstream side via an annular elastic body 142, and a first monolithic catalyst 144 is placed on the downstream side via an annular elastic body 142. A second monolithic catalyst 148 is disposed via the monolithic catalyst 146, and cylindrical elastic holding members 150, 152 are disposed between the outer circumferential surfaces of both monolithic catalysts 144, 148 and the inner circumferential surface of the case body 116. has been done. Reference numeral 154 denotes an annular disconnection body interposed between the exhaust manifold 114 and the upstream end surface 156 of the first monolithic catalyst 144;
58 is the downstream end surface 160 of the second monolith catalyst 148
This is an annular elastic body interposed between the discharge pipe 118 and the discharge pipe 118.

The catalyst holding portion 140 includes a first composite passage 13
4 and the second composite passage 136, respectively.
A partition member 166 that forms a divided passage 162 and a second divided passage 164 is provided.

With the above configuration, the exhaust gas from the first and fourth cylinders is transferred from the branch pipes 124 and 130 to the first composite passage 13.
4, and is connected to the discharge pipe 118 through the first small passage group A of the first monolith catalyst 144, the first divided passage 162, and the third small passage group A' of the second monolith catalyst 148.
is discharged to. Exhaust gas from the second and third cylinders flows from the branch pipes 126 and 128 to the second composite passage 136.
and is discharged to the discharge pipe 118 via the second small passage group B of the first monolith catalyst 144, the second divided passage 164, and the fourth small passage group B' of the second monolith catalyst 148.

Therefore, the exhaust gas from the first and fourth cylinders is
Exhaust gas from the second and third cylinders is discharged to the exhaust pipe 118 independently without substantially interfering with each other, reducing interference due to exhaust pulsation from each cylinder, improving exhaust efficiency and increasing engine output. At the same time, it has the effect of improving fuel efficiency.

In addition, the case body 116 has each exhaust port 4, 6,
8 and 10, the first and second
Both monolithic catalysts 144 and 148 are supplied with high-temperature exhaust gas immediately after being discharged from the exhaust port, which promotes the oxidation reaction and improves the purification efficiency of the exhaust gas.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing a first embodiment of the present invention, FIG. 2 is a cross-sectional explanatory diagram of FIG. 1, FIG. 3 is a cross-sectional explanatory diagram of FIG. Fig. 5 is a schematic explanatory view showing the second embodiment of the present invention, Fig. 6 is an explanatory cross-sectional view of the exhaust system shown in Fig. 5, and Fig. 7 is an explanatory view of the exhaust system in Fig. 5. FIG. 2: Engine body, 4, 6, 8, 10: Exhaust port, 12, 112: Exhaust system, 14, 16, 1
8, 20, 124, 126, 128, 130: branch pipe, 28: catalytic converter, 36, 134: first composite passage, 38, 136: second composite passage, 5
8,144: First monolith catalyst, 60,148:
Second monolith catalyst, 74: First auxiliary passage, 76:
Second auxiliary passage, 88, 162: First divided passage, 9
0,164: Second divided passage.

Claims (1)

[Claims] 1. An engine body having a plurality of cylinders, an exhaust gas passage that discharges exhaust gas discharged from the plurality of cylinders into the atmosphere, and a plurality of exhaust gas passages interposed in the exhaust gas passage and arranged in series in the exhaust gas flow direction. The exhaust gas passage is divided at least upstream of the monolith catalyst into a plurality of passages, which are opened near the upstream end face of the monolith catalyst, and the downstream end face of the upstream monolith catalyst and the upstream end face of the downstream monolith catalyst are divided into a plurality of passages. An exhaust gas purification device characterized in that a gap between the two is divided corresponding to the plurality of passages.