JPS6042175Y2 - monolith catalytic converter - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) 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. 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.

In order for this secondary air to fully exhibit the purifying function of the catalyst in the latter stage, it is necessary to mix it sufficiently with the exhaust gas from the catalyst in the former stage and to uniformly flow into the catalyst in the latter stage.

Therefore, conventionally, such a monolithic catalytic converter has a cylindrical casing equipped with an exhaust gas inlet and an outlet at the front and back, and a plurality of monolithic catalysts are placed in the axial direction of the casing via spacers that maintain a predetermined interval. In addition to arranging them in series, a secondary air supply nozzle is arranged in a direction across the above-mentioned interval to supply almost the entire radial area of the exhaust gas flow from the monolithic catalyst in the previous stage, causing turbulence. A method has been proposed in which the air and secondary air are mixed well and uniformly supplied to the subsequent monolithic catalyst (see Japanese Utility Model Publication No. 55-135115).

(Problem to be solved by the invention) However, in the above conventional device, when supporting the secondary air supply nozzle, the secondary air supply nozzle is supported in a cantilever manner, but the secondary air supply nozzle is supported due to heat. There is a problem with the supply nozzle drooping.

In addition, if both ends of the secondary air supply nozzle are fixedly supported, thermal expansion cannot be absorbed and the secondary air supply nozzle is affected by heat. However, there are problems in that the structure becomes complicated and the cost becomes high.

In addition, in the conventional monolithic catalytic converter described above, if the inner circumferential surface of the spacer that maintains a predetermined distance between the monolithic catalysts has a venturi shape that gently slopes in the axial direction, the gas flow passing through the monolithic catalysts tends to become laminar. Combined with this, the exhaust gas flow from the monolith catalyst in the front stage flows smoothly to the monolith catalyst in the rear stage, and mixing with the secondary air is not performed sufficiently, resulting in the purification function of the monolith catalyst in the rear stage being impaired. There is a problem that they are not able to demonstrate their full potential.

The present invention has been developed in view of this point, and makes it possible to support the secondary air supply nozzle in restraint against thermal expansion with a simple structure by using a spacer that maintains a predetermined distance between the monolithic catalysts. At the same time, the purpose is to create turbulence in the exhaust gas flow from the monolithic catalyst in the front stage to ensure good mixing with secondary air, so that the purification function of the monolithic catalyst in the rear stage can be fully demonstrated. do.

(Means for solving the problem) In order to achieve the above object, the solution of the present invention is to install a plurality of monolithic catalysts in a cylindrical casing provided with an exhaust gas inlet and an exhaust outlet at the front and rear. A monolithic catalytic converter is assumed in which the catalytic converters are arranged in series in the axial direction of the casing via a spacer that maintains an interval of , and a secondary air supply nozzle is provided in a direction transverse to the interval.

Then, the spacer is integrally formed by press-molding a single plate member, and the spacer has a support portion that supports the end surface of the monolithic catalyst, and a part of the inner peripheral surface in the circumferential direction. A screen-shaped baffle portion extending vertically inward in the radial direction, and a tip portion and a rear end portion of the secondary air supply nozzle formed in a portion where the baffle portion is not formed on the inner peripheral surface where the baffle portion is located. and a support hole that supports the shaft while allowing its movement in the axial direction.

In this case, if the spacer is integrally molded by press-forming a single plate member, if the baffle portion is provided all around the inner circumferential surface of the spacer, the opening of the support hole is machined. Since this becomes difficult due to the existence of this baffle part, the baffle part is provided by leaving a part of the circumferential direction on the inner circumferential surface of the spacer, and the baffle part is not formed on the inner circumferential surface of the spacer where the baffle part is located. A support hole is provided.

(Function) With the above configuration, in the present invention, even if the exhaust gas that has passed through the monolithic catalyst on the front stage side and is purified flows into the interval maintained by the spacer in a substantially laminar flow state, the , the flow is immediately disturbed by a screen-like baffle section provided on the inner circumferential surface of the spacer that extends vertically inward in the radial direction, resulting in a turbulent flow, and the existence of a secondary air supply nozzle that crosses the above-mentioned interval and the secondary air supply. The turbulence is further promoted by the jetting of secondary air from the nozzle, so the exhaust gas and secondary air are vigorously agitated and mixed sufficiently and uniformly, and then flow uniformly into the monolithic catalyst at the subsequent stage. It turns out.

As a result, the purification performance of the downstream monolith catalyst is significantly improved due to good mixing and uniform inflow of the exhaust gas and secondary air.

Furthermore, the secondary air supply nozzle arranged across the gap between both monolithic catalysts is supported on both sides by a pair of support holes provided in the spacer so as to allow movement of the nozzle in the axial direction. , even if the secondary air supply nozzle thermally expands,
It is possible to reliably support and relieve restraint without causing sagging.

Moreover, in this case, the support holes are formed in the spacer that maintains a predetermined distance between the monolithic catalysts, so it is possible to perform restraint relaxation support with a simple structure without providing a separate complicated restraint relaxation structure. can.

Specifically, in the above spacer, the screen-like baffle portion that performs the turbulent flow generating action as described above is not provided all around the inner peripheral surface of the spacer in the circumferential direction, but is provided leaving a part of the circumferential direction, and the position of the baffle portion is By providing the support hole in the non-formed portion of the baffle on the inner peripheral surface of the baffle, when the spacer is integrally formed by press forming a single plate member, the support hole does not need to be processed. , can be easily carried out without being hindered by the baffle section.

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

1 to 3, 1 is a cylindrical casing, and the casing 1 has a pair of press-molded shells 2, 2 which are vertically divided in the axial direction.
, 2 are attached to each other at flanges 2a, 2a formed on the outer peripheral edges of the casing 1, and the central part of the casing 1 has a catalyst storage part 1a with an elliptical cross section that is flat in the vertical direction. The front and rear ends of the portion 1a have inlet and outlet exhaust pipe connecting portions 1b, lb 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. An exhaust pipe connection outlet flange 6 having an exhaust gas outlet 6a at the center is fixed to the rear end of the portion 1c via a connecting ring 5 by welding. Stud bolts 7.8 for connection are installed.

In the catalyst storage portion 1a of the casing 1, a reduction monolith catalyst 9 is arranged in the upstream front stage, an oxidation monolith catalyst 10 is arranged in the downstream downstream stage in series in the axial direction of the casing 1, and both monolith catalysts 9.10 are held via a spacer 11 so as to maintain a predetermined distance S between them as a mixing area.

Both monolithic catalysts 9 and 10 are formed by coating an elliptical cylindrical carrier made of ceramic material with a catalyst such as platinum, and have a large number of ventilation holes penetrating in the axial direction in a honeycomb shape.

The spacer 11 is integrally molded into an elliptical cylindrical shape by press-forming a single plate member, and protrudes outward from the outer peripheral edge of the front end, and the rear end surface in the axial direction of the reduction monolith catalyst 9 is made of elastic material such as steel mesh. It has an L-shaped flange-shaped front support part 11a that is elastically supported through the body 12, and
An L-shaped flange-shaped rear support portion 1 protrudes outward from the outer peripheral edge of the rear end and presses and supports the axial front end surface of the oxidation monolith catalyst 10.
1b, and the outer peripheral surfaces of the supporting parts 11a and llb are brought into contact with the inner peripheral surface of the casing 1 and fixed to the casing 1 by, for example, plug welding. It is provided to maintain a predetermined distance S between the catalysts 9 and 10.

Further, the spacer 11 has a screen-shaped baffle portion 11c extending vertically inward in the radial direction, leaving a part of the circumferential direction, that is, a part on the long axis of the ellipse, at the center of the inner peripheral surface of the spacer 11. A tip portion 15a and a rear end portion 15b of the secondary air supply nozzle 15, which will be described later, are attached to the non-baffle portion (the portion on the long axis of the ellipse) on the inner circumferential surface where the baffle portion 11c is located. A pair of support holes 13, 14 are formed to allow movement and support.

On the other hand, reference numeral 15 denotes a secondary air supply nozzle disposed so as to cross the center part in the longitudinal direction of the above-mentioned interval S in the direction of the long axis of the ellipse. Secondary air is supplied to both support holes 13 and 14 by inserting one support hole 14 of the spacer 11 from the flange parts 2a and 2a bonded part and fitting the tip 15a into the other support hole 13. Tip part 1 of nozzle 15
The flange portion 2a of the shells 2, 2 is supported on both sides by supporting the rear end portion 5a and the rear end portion 15b in a restrained relaxed state to allow movement in the axial direction.

It is fixed by welding at the bonded portion 2a.

The tip end 15a of the secondary air supply nozzle 15 is closed, and the rear end 15b is connected to the casing 1.
It is led out and connected to an air pump (not shown) via a connecting flange 16, thereby forming a secondary air supply passage 17.

Further, in the rear half of the outer circumferential surface of the secondary air supply nozzle 15, a large number of secondary air ejection holes 18, 18, . Therefore, the secondary air from the air pump is ejected rearward within the interval S from the secondary air injection holes 18, 18, etc. through the secondary air supply passage 17 (secondary air supply nozzle 15). configured to supply.

Reference numeral 19 denotes a cone-shaped pressure member, which includes a support portion 19a that presses and holds the axial front end surface of the reduction monolith catalyst 9 in the axial direction, and a support portion 19a located a predetermined distance forward from the axial front end surface of the reduction monolith catalyst 9. A baffle portion 19b made of a perforated plate for rectifying the flow of exhaust gas is integrally formed with the baffle portion 19b, and is fixed to the casing 1 by, for example, plug welding.

Further, 20 and 21 are steels interposed between the outer circumferential surfaces of the monolithic catalysts 9 and 10 and the inner circumferential surface of the casing 1 so as to elastically hold the outer circumferential surfaces of the monolithic catalysts 9 and 10, respectively. Elastic body such as mesh, 22
is a support member that elastically holds the axial rear end surface of the oxidation monolith catalyst 10 at the axial rear end of the catalyst storage portion 1a of the casing 1 via an elastic body 23 such as a steel mesh.

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 baffle portion 19b of the pressure member 19, and then passes through the reduction monolith catalyst 9. and is reduced and purified by the catalyst 9.

At this time, the exhaust gas is rectified by the baffle portion 19b and uniformly flows into the reduction monolith catalyst 9, so that the reduction purification performance is improved.

Subsequently, 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 an interval S as a mixing area held by a spacer 11. The presence of the secondary air supply nozzle 15, which is immediately disturbed and becomes turbulent by the screen-like baffle portion 11c provided on the inner circumferential surface of the air and which extends vertically inward in the radial direction, and furthermore, crosses the above-mentioned interval S in the direction of the long axis of the ellipse. The turbulence is further promoted by the ejection of secondary air from the secondary air ejection holes 18, 18... of the secondary air supply nozzle 15, and as a result, the exhaust gas and the secondary air are violently agitated. well and evenly mixed,
Thereafter, it flows uniformly into the oxidation monolith 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. .

Thereafter, the exhaust gas thus reduced and oxidized and purified is transferred to the exhaust gas outlet 6a of the exhaust pipe connection outlet flange 6.
is discharged from.

Here, in the monolithic catalytic converter of the above embodiment, the secondary air supply nozzle 1 is arranged so as to cross the interval S between both the monolithic catalysts 9 and 10 in the direction of the long axis of the ellipse.
5 is supported on both sides by a pair of support holes 13 and 14 provided in the spacer 11 to allow movement of the nozzle 15 in the axial direction, so even if the secondary air supply nozzle 15 expands thermally, It is possible to reliably support and relieve restraint without causing sagging.

Moreover, in this case, the support holes 13, 14 are formed in the spacer 11 that maintains the predetermined distance S between the monolithic catalysts 9 and 10, so a simple structure can be achieved without providing a separate complicated restraint relaxation structure. Restraint relaxation support can be performed.

Further, in the spacer 11, the screen-like baffle portion lie that performs the turbulence generating action as described above is provided in the spacer 11.
It is not provided on the entire circumferential circumference of the inner circumferential surface, but is provided leaving a part of the circumferential direction (a portion on the long axis of the ellipse), and the baffle portion is not formed on the inner circumferential surface where the baffle portion 11c is located (ellipse). By providing the support holes 13.14 in the portions on the long axis, when the spacer 11 is integrally formed by press-molding a single plate member, the front and rear support portions 11a, 11.
b and the baffle portion 11c can be integrally molded at the same time.
This can be done easily without being obstructed by the baffle portion 11c, and therefore, the support portions 11a, llb, the baffle portion 11c, and the support hole 13.14 can be It is possible to simplify the manufacturing process of the included spacer 11 and, in turn, to reduce costs.

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 reduction monolith catalyst 9 is placed in the casing 1 at the front stage and the reduction monolith catalyst 9 at the rear stage. Although a case has been described in which two oxidation monolith catalysts 10 are arranged in series, it goes without saying that the present invention can be similarly applied to a case in which three or more monolith catalysts are arranged in series with a predetermined distance from each other.

Further, in the above embodiment, the casing 1 is a bonded type consisting of a pair of upper and lower shells 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 to fix the spacer 11 and other members.

(Effects of the invention) As explained above, according to the monolithic catalytic converter of the invention, a single spacer is installed to maintain a predetermined distance between a plurality of monolithic catalysts arranged in series in the axial direction of the cylindrical casing. a support part that is integrally molded by press-forming a plate member and supports the end face of the monolithic catalyst; and a screen-like part that extends vertically inward in the radial direction, leaving a part in the circumferential direction on the inner peripheral surface. and a baffle portion formed in a non-baffle portion on the inner circumferential surface where the baffle portion is located to support the tip and rear end of the secondary air supply nozzle while allowing movement in the axial direction. Since the secondary air supply nozzle is equipped with a support hole, it is possible to reliably support the restraint relief with a simple structure without causing the secondary air supply nozzle to sag, thereby reducing costs and improving durability. At the same time, it is possible to create turbulence in the exhaust gas flow from the monolithic catalyst on the front stage side to achieve good mixing of the exhaust gas and secondary air, thereby improving the purification performance of the monolithic catalyst on the rear stage side. This has the effect of making it possible to improve the performance.

Furthermore, the integrally molded spacer has the advantage that the turbulent flow generating function of the baffle portion can be sufficiently ensured, and the support hole can be easily formed.

[Brief explanation of the drawing]

The drawings illustrate an embodiment of the present invention, and FIG. 1 is a cross-sectional view, FIG. 2 is a cross-sectional view taken along the line ■-■ of FIG. 1, and FIG.
It is a sectional view taken along the line ■-■ in the figure. 1...Casing, 4a...Exhaust gas inlet, 6a...Exhaust gas outlet, 9...
... Reduction monolith catalyst, 10 ... Oxidation monolith catalyst, 11 ... Spacer, lla ...
Front support part, llb... Rear support part, 11C.
... Baffle part, 13.14 ... Support hole, 15 ... Secondary air supply nozzle, 15a ...
... Tip part, 15b... Rear end part, S...
··interval.

Claims (1)

[Scope of utility model registration request] A plurality of monolithic catalysts are arranged in series in the axial direction of the casing via spacers that maintain a predetermined interval in a cylindrical casing equipped with an exhaust gas inlet and an exhaust outlet at the front and rear, and two monolithic catalysts are arranged in the axial direction of the casing through spacers that maintain a predetermined interval. Next, in the monolithic catalytic converter provided with the air supply nozzle, the spacer is integrally formed by press-forming a single plate member,
The spacer includes a support part that supports the end face of the monolithic catalyst, a screen-shaped baffle part that extends vertically inward in the radial direction leaving a part of the circumference on the inner peripheral surface, and a position where the baffle part is located. A support hole is formed in the non-baffle portion on the inner circumferential surface of the secondary air supply nozzle and supports the tip and rear end of the secondary air supply nozzle while allowing movement thereof in the axial direction. Features a monolith catalytic converter.