JPS6113084B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a monolithic catalytic converter that is installed in the exhaust system of an engine and performs an exhaust gas purifying action, and particularly relates to a monolithic catalytic converter that is installed in the exhaust system of an engine and performs an exhaust gas purification function. The invention relates to monolithic catalytic converters arranged in series.

(Prior art) Generally, in a catalytic converter in which multiple catalysts are arranged in series in a casing as described above, it is necessary to supply secondary air between the catalysts to ensure the oxidation reaction in the subsequent catalyst. It is being done.

Therefore, as disclosed in Japanese Patent Application Laid-open No. 53-9915, conventional monolithic catalytic converters have been constructed using a plurality of monolithic catalysts in an elliptical cylindrical casing with exhaust gas inlets and outlets at the front and rear. are arranged in series in the axial direction of the casing, and a spacer fixed to the casing is interposed between the monolithic catalysts to maintain a predetermined distance between the monolithic catalysts, thereby improving the flow of exhaust gas and secondary air. A system has been proposed in which a mixing area is secured for mixing.

In addition, as shown in Japanese Patent Application Laid-open No. 55-139918, spacers have been conventionally attached to the elliptical cylindrical casing to maintain a predetermined distance between the monolithic catalysts arranged in series in the axial direction as a mixing area. In addition to integrally providing the secondary air supply pipe in the direction of the long axis of the ellipse in the interval, the distribution of the secondary air and the mixing of the secondary air and the exhaust gas in the interval (mixing area) are performed well. Monolithic catalytic converters are also known.

(Problem to be solved by the invention) However, the former mentioned above (Unexamined Japanese Patent Publication No. 53-9915
In this case, the ridge of the casing, especially the part where the spacer is provided, is located at the center in the axial direction, furthest away from the highly rigid inlet and outlet.
The rigidity in the radial direction, especially in the direction of the short axis of the ellipse, is weak.
As a result, the casing vibrates due to engine vibrations and exhaust pulsations, resulting in the problem of cracks occurring in the casing.

Also, the latter mentioned above (Japanese Patent Application Laid-Open No. 55-139918)
In this case, a secondary air supply pipe extending in the direction of the long axis of the ellipse is provided in the part of the casing where the spacer is provided, and although the rigidity in the direction of the long axis of the ellipse is slightly increased, the rigidity in the direction of the short axis of the ellipse, which is a particular problem, remains weak. However, no attempt has been made to increase the rigidity of the casing, which similarly causes the problem of cracks occurring due to membrane vibration of the casing.

The present invention has been made in view of these points, and its purpose is to reduce the rigidity of the space in the elliptical minor axis direction, particularly in the portion where the spacer is provided, of the elliptical cylindrical casing as described above. By focusing on this, the purpose is to increase the rigidity in the direction of the short axis of the ellipse at the spacer-interposed portion, thereby suppressing the conventional membrane vibration of the casing and preventing the occurrence of cracks.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention includes a plurality of monolithic catalysts in an elliptical cylindrical casing provided with an exhaust gas inlet and an exhaust gas outlet. The present invention is based on a monolithic catalytic converter that is arranged in series in the axial direction of a casing, and a spacer fixed to the casing is interposed between the monolithic catalysts to maintain a predetermined distance between the monolithic catalysts. Further, the spacer is provided with a reinforcing member that extends in the short axis direction of the ellipse of the space and connects the opposing inner peripheral portions.

(Function) With the above configuration, in the present invention, the inner circumferential parts extending in the direction of the short axis of the ellipse and facing each other are connected to the spacer that is fixed to the elliptical cylindrical casing and maintains a predetermined distance between the monolithic catalysts. By providing a reinforcing member, the elliptical minor axis direction of the spacer-interposed part of the casing, which is particularly weak in rigidity, is effectively reinforced and its rigidity is increased, which prevents the casing from vibrating due to engine vibration or exhaust pulsation. will be suppressed.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

1 to 3 show a first embodiment of the present invention, in which 1 is an elliptical cylindrical casing, and the casing 1 consists of a pair of press-formed shells 2 divided into upper and lower parts in the axial direction. , 2, the shell 2,
The casing 1 has a catalyst accommodating part 1a in the center thereof with an elliptical cross section that is flat in the vertical direction. The front and rear ends of 1a have inlet and outlet exhaust pipe connecting portions 1b and 1c each having a circular cross section. An exhaust pipe connection inlet flange 4 having an exhaust gas inlet 4a in the center is fixed to the tip of the inlet side exhaust pipe connection part 1b via a connecting ring 3 by welding, and an outlet side exhaust pipe connection part 1c At the rear end, there is also an exhaust gas outlet 6a in the center via the connecting ring 5.
An outlet flange 6 for connecting an exhaust pipe is fixed by welding, and stud bolts 7 and 8 for connecting the exhaust pipe are implanted in both flanges 4 and 6, respectively.

In the catalyst storage portion 1a of the casing 1, a reduction monolith catalyst 9 is arranged in the upstream front stage and an oxidation monolith catalyst 10 is arranged in the downstream stage in series in the axial direction of the casing 1. are held via a spacer 11 so as to maintain a predetermined distance S between them as a mixing area. The monolithic catalysts 9 and 10 are both formed by coating a catalyst such as platinum on an elliptical columnar carrier made of ceramic material, and have a large number of ventilation holes penetrating in the axial direction in a honeycomb shape.

The spacer 11 has support flange portions 12a and 13a having an L-shaped cross section and projecting outward from the outer peripheral edge of the tip.
Two oval dish-shaped press-formed members 1 having
2 and 13 are attached to each other at their bottoms in the front and back, and the outer circumferential surfaces of the support flange portions 12a and 13a of each of the press-formed members 12 and 13 are brought into contact with the inner circumferential surface of the casing 1, for example, by plug welding. The support flange portion 12a elastically holds the rear end surface of the reduction monolith catalyst 9 in the axial direction via an elastic body 14 such as a steel mesh, and the support flange portion 12a 13a presses and holds the front end surface of the oxidation monolith catalyst 10 in the axial direction, and thus both monolith catalysts 9 and 10
They are configured to maintain the predetermined distance S between them.

Further, on the bottom bonding surfaces of the press-formed members 12 and 13 constituting the spacer 11, a semicircular cross-section is formed, which extends in the short axis direction of the ellipse with the spacing S and is concave in the opposite front and rear directions. Concave groove portions 12b and 13b are formed, and a hollow reinforcing member 15 is integrally formed to connect the inner peripheral portions of the spacer 11 facing each other in the direction of the short axis of the ellipse.

Further, each of the press-formed members 12 and 13 is perforated to form a communication port 16, leaving bonding flange portions 12c and 13c of a constant width at the bottom peripheral edge and both side edges of the groove groove portions 12b and 13b. A screen-like buffle 17 extending vertically inward in the radial direction is formed by the bonding flange portions 12c and 13c.

Furthermore, on the long axis of the ellipse of one of the press-formed members 12 of the spacer 11, a bonding flange portion 12c is made to protrude forward in a U-shape, so that a tip portion 20 of a secondary air supply nozzle 20, which will be described later, is provided.
A pair of support holes 18 and 19 are formed to guide and support the rear end portion 20b and the rear end portion 20b.

On the other hand, 20 is a secondary air supply nozzle arranged so as to cross the above-mentioned interval S in the direction of the long axis of the ellipse.
from the flange parts 2a, 2a bonded part of the shells 2, 2 to one support hole 1 of the spacer 11.
9 and insert its tip 20a into the other support hole 1.
8, the leading end 20a and rear end 20b of the secondary air supply nozzle 20 are supported in the supporting holes 18, 19 in a restrained relaxed state, and the shells 2, 2 are supported on both sides. flange portion 2a,
It is fixed by welding at the bonded portion 2a. The tip end 20a of the secondary air supply nozzle 20 is closed, and the rear end 20a of the secondary air supply nozzle 20 is closed.
b is led out of the casing 1 and is connected to an air pump (not shown) via a connecting flange 21 to form a secondary air supply passage 22, and is further connected to the outer periphery of the secondary air supply nozzle 20. In the rear half of the surface, there are a large number of secondary air ejection holes 23, 23 that communicate the secondary air supply passage 22 with the space having the interval S.
. . . is bored, and the secondary air from the air pump is passed through the secondary air supply passage 22 (secondary air supply nozzle 20) to the secondary air jet holes 23, 2.
3. It is configured to eject and supply rearward within an interval S from .

Reference numeral 24 denotes a cone-shaped pressure member, which includes a support portion 24a that presses and holds the front end surface of the reduction monolith catalyst 9 in the axial direction, and a support portion 24a that presses and holds the front end surface of the reduction monolith catalyst 9 in the axial direction.
The baffle portion 24b is integrally formed with a baffle portion 24b made of a perforated plate located a predetermined distance forward from the axial front end surface of the exhaust gas for rectifying the flow of exhaust gas, and is fixed to the casing 1 by, for example, plug welding. Also, 25
and 26 are connected to the outer circumferential surfaces of both the monolithic catalysts 9 and 10 and the casing 1 so as to elastically hold the outer circumferential surfaces of the reduction monolithic catalyst 9 and the oxidation monolithic catalyst 10, respectively.
27 is an elastic body such as a steel mesh interposed between the inner circumferential surface of the catalyst storage portion 1a of the casing 1;
The axial rear end surface of the oxidation monolith catalyst 10 is covered with an elastic body 28 such as a steel mesh.
This is a support member that elastically holds the material through the support member.

Therefore, in the above embodiment, the exhaust gas flowing into the casing 1 from the exhaust gas inlet 4a of the exhaust pipe connection inlet flange 4 first passes through the buff-full portion 24b of the pressure member 24, and then passes through the reduction monolith. It flows into the catalyst 9 and is reduced and purified by the catalyst 9. At this time, the exhaust gas is rectified by the buffing portion 24b and uniformly flows into the reduction monolith catalyst 9, so that the reduction purification performance is improved.

Next, the exhaust gas that has passed through the reduction monolith catalyst 9 and has been reduced and purified flows in a substantially laminar flow state into the interval S, which is a mixing area held by the spacer 11. The flow is immediately disturbed by the screen-like buffle 17 provided on the inner circumferential surface of the spacer 11 and extends vertically inward in the radial direction, resulting in a turbulent flow. Presence of secondary air supply nozzle 20 and reinforcing member 15 and secondary air jet hole 2 of secondary air supply nozzle 20
The turbulence is further promoted by the injection of secondary air from 3, 23, etc., and as a result, the exhaust gas and the secondary air are vigorously agitated and mixed sufficiently and uniformly. It flows uniformly into the monolithic catalyst 10.

In this oxidation monolith catalyst 10, the oxidation purification performance is significantly improved due to good mixing of the exhaust gas and secondary air and uniform flow into the oxidation monolith catalyst 10, and the exhaust gas is oxidized and purified well. be done. Thereafter, the exhaust gas thus reduced and oxidized and purified is discharged from the exhaust gas outlet 6a of the exhaust pipe connection outlet flange 6.

Here, in the monolithic catalytic converter of the above embodiment, the casing 1 (catalyst storage section 1
a center part) and both monolithic catalysts 9, 10
Spacers 11 that maintain a predetermined distance S between them.
In addition, by integrally forming the hollow reinforcing member 15 that extends in the ellipse short axis direction of the interval S and connects the opposing inner circumferential parts, the ellipse short axis direction at the intervening portion of the spacer 11 of the casing 1, which has particularly low rigidity, can be effectively adjusted. Since it is reinforced and its rigidity increases significantly, membrane vibration of the casing 1 due to engine vibration and exhaust pulsation is suppressed, and as a result, cracks are prevented from occurring in the casing 1 and the press-formed members 12 and 13 themselves. The monolithic catalyst 9,
Monolithic catalyst 9,10 with increased fixation holding force of 10
It is possible to prevent damage to the parts. In particular, a casing 1 having a catalyst storage portion 1a having an elliptical cross section.
Since the rigidity in the direction of the short axis of the ellipse is extremely weak, providing the hollow reinforcing member 15 extending in the direction of the short axis of the ellipse as described above is particularly effective and effective in terms of reinforcing effect.

Further, the hollow reinforcing member 15 has a spacer 1
Since the concave groove portions 12b and 13b are integrally formed in the spacer 11 by press-molding the respective press-formed members 12 and 13 constituting the spacer 1, the number of parts can be reduced and the manufacturing process can be easily performed. I can do it.

4 and 5 show a second embodiment of the present invention, in which the hollow portion 15a of the hollow reinforcing member 15 in the first embodiment (FIGS. 1 to 3) is used as a mounting hole for a stud bolt 29. This is what I did. That is, the stud bolt 29 is inserted into the hollow reinforcing member 1.
5 into the hollow part 15a of the stud bolt 2.
Flange-shaped mold portions 29 protruding from the upper and lower ends of 9.
a and 29b are engaged with the casing 1 and fixed by welding at the upper and lower ends thereof, and in addition to the hollow reinforcing member 15 as described in the first embodiment, this stud bolt 29 is Therefore, the reinforcing effect on the casing 1 is doubled, and the rigidity in the short axis direction of the ellipse is significantly increased, thereby making it possible to suppress membrane vibration of the casing 1 even more effectively. The rest of the structure is the same as that of the first embodiment, and the same parts as in FIGS. 1 to 3 are given the same reference numerals, and the explanation thereof will be omitted.

Further, FIGS. 6 and 7 show a third embodiment of the present invention (the same parts as in FIGS. 1 to 3 are denoted by the same reference numerals, and the explanation thereof is omitted),
A spacer 11' that maintains a predetermined distance S between both monolithic catalysts 9 and 10 is integrally formed with a secondary air supply passage 22' that crosses the distance S in the direction of the long axis of the ellipse. The hollow reinforcing member 15' is formed in the direction of the minor axis of the ellipse and is perpendicular to the air supply passage 22', and the hollow portion 15'a is also utilized as the secondary air supply passage 30.

That is, in FIGS. 6 and 7, a recess that has support flange portions 12'a and 13'a that support the end faces of monolithic catalysts 9 and 10, respectively, and forms a hollow reinforcing member 15' that extends in the direction of the short axis of the ellipse. An annular secondary air chamber 31 is formed between the inner circumferential surface of the casing 1 and a spacer 11' formed by bonding two press-formed members 12' and 13' having groove portions 12'b and 13'b. One end of a secondary air introduction pipe 32 arranged and fixed on the bonding surface of the flanges 2a, 2a of the shells 2, 2 in the casing 1 is opened in the secondary air chamber 31, and the secondary air introduction pipe 32 is opened in the secondary air chamber 31. The other end of 32 is led out of the casing 1 and connected to an air pump (not shown) via a connecting flange 21. On the other hand, on the bottom bonding surfaces of each of the press-formed members 12', 13', there are concave groove portions 12'b, 13' constituting the hollow reinforcing member 15'.
Concave groove portions 12'd, 13'd extending in the long axis direction of the ellipse perpendicularly to b and having semicircular cross-sections are formed by concave molding in opposite front and rear directions, and both concave groove portions 12'd, 13 A secondary air supply passage 22' whose both ends communicate with the secondary air chamber 31 through 'd' and which crosses the interval S in the direction of the long axis of the ellipse is integrally formed with the spacer 11'. ′
The hollow portion 15'a communicates with the secondary air supply passage 22' at its center, and communicates with the secondary air chamber 31 at both upper and lower ends, so that the An air supply passage 30 is also formed. Furthermore, the secondary air supply passages 22', 30 are provided on the outer circumferential surfaces of the concave grooves 13'd, 13'b in the major axis direction and minor axis direction of the ellipse on the downstream side, respectively.
A large number of secondary air ejection holes 23', 23'... and 33, 33...... are bored to communicate the space S with the above-mentioned space S, and the secondary air introduced into the secondary air chamber 31 is Secondary air injection holes 23', 23', 33, 3 through both secondary air supply passages 22', 30
3. It is arranged to eject and supply the gas toward the rear within the interval S. Furthermore, 12'c, 1
3'c are the bonding flange parts of the press-formed members 12' and 13', and together they form a screen-like butthole 17' that extends radially inward and vertically and has a turbulent flow generating effect. It is something. In the case of this embodiment, in addition to the hollow reinforcing member 15', the reinforcing effect on the casing 1 is further increased by the concave groove portions 12'd, 13'd (secondary air supply passage 22') extending in the direction of the long axis of the ellipse. At the same time, the secondary air supply passages 22' and 30 that cross the interval S in the major axis direction and the minor axis direction of the ellipse improve the distribution of the secondary air into the interval S, and the secondary air and exhaust gas are separated. This has the advantage of being able to mix evenly and evenly.

Note that the present invention is not limited to the above-mentioned embodiment, and includes various other modifications. For example, in the above-mentioned embodiment, the spacers 11, 1
1' into two press-formed members 12, 12', 13,
13', but it is also possible to use an integral type formed by press molding and provided with a reinforcing member extending in the direction of the short axis of the ellipse and connecting the opposing inner circumferential parts. Although similar effects can be achieved, the split mold as in the above embodiment is more advantageous because the reinforcing member can be easily formed by press molding.

Further, in the above embodiment, two reduction monolith catalysts 9 are arranged in series in the front stage and two oxidation monolith catalysts 10 are arranged in the rear stage in the casing 1, but the present invention also provides three or more monolith catalysts arranged in a predetermined manner relative to each other. Of course, the same can be applied to those arranged in series with an interval of .

Furthermore, in the above embodiment, the casing 1 is a bonded type consisting of a pair of upper and lower shells 2, 2 divided in the axial direction, but it may also be a rolled type in which the casing 1 is integrally formed into a cylindrical shape. Needless to say.
In addition to welding as described above, various known fixing means can be used as means for fixing the spacers 11, 11' and other members.

(Effects of the Invention) As explained above, according to the monolithic catalytic converter of the present invention, the monolithic catalysts arranged in series in the axial direction of the elliptical cylindrical casing are fixed to the casing so as to maintain a predetermined distance between them. By providing the spacer with a reinforcing member extending in the short axis direction of the ellipse of the above-mentioned interval and connecting the opposing inner peripheral parts,
In particular, it is possible to effectively increase the rigidity in the direction of the short axis of the ellipse at the part of the casing where the rigidity is weak, where the spacer is interposed. It is possible to prevent the occurrence of cracks and improve durability.

[Brief explanation of the drawing]

The drawings illustrate embodiments of the invention.
3 to 3 show the first embodiment, FIG. 1 is a cross-sectional view, FIG. 2 is a cross-sectional view taken along the line -
The figure is a sectional view taken along the line -- in FIG. 2. 4 and 5 show a second embodiment, in which FIG. 4 is a longitudinal cross-sectional view of a main part, and FIG. 5 is a cross-sectional view taken along the line -- in FIG. 4.
6 and 7 show a third embodiment, in which FIG. 6 is a longitudinal cross-sectional view of a main part, and FIG. 7 is a cross-sectional view taken along the line -- in FIG. 6. 1...Casing, 4a...Exhaust gas inlet,
6a... Exhaust gas outlet, 9... Reduction monolith catalyst, 10... Oxidation monolith catalyst, 11, 11'...
...Spacer, 12, 13, 12', 13'...Press molded member, 15, 15'...Hollow reinforcing member, 2
2, 22'... Secondary air supply passage, S... Spacing.

Claims (1)

[Claims] 1 A plurality of monolithic catalysts are arranged in series in the axial direction of the casing in an elliptical cylindrical casing equipped with an exhaust gas inlet and an outlet at the front and rear, and a spacer fixed to the casing is interposed between the monolithic catalysts. In a monolith catalytic converter in which a predetermined distance is maintained between monolith catalysts,
A monolithic catalytic converter characterized in that the spacer is provided with a reinforcing member that extends in the short axis direction of the ellipse of the space and connects opposing inner peripheral parts.