JPH10231721A - Exhaust gas purifying device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To expedite a purification starting timing for exhaust gas through extremely simple structure the number of parts of which is reduced as much as possible, in an exhaust gas purifying device to purify exhaust gas discharged from an internal combustion engine by a catalyst. SOLUTION: When temperature is below a preset set temperature, a guide means 16 formed of a two-directional shape memory alloy is deformable between a first shape wherein exhaust gas through an exhaust gas introduction port 10 is guided to a part of one end of a catalyst 6 and a shape wherein exhaust gas through the exhaust gas introduction port 10 is evenly guided to the whole surface of one end of the catalyst 6 according to a situation that the temperature exceeds the set temperature. The guide means is arranged at one end part of a casing 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for purifying exhaust gas discharged from an internal combustion engine with a catalyst.

[0002]

2. Description of the Related Art In such an exhaust gas purifying apparatus, the activation temperature of the catalyst is, for example, 300 to 800 ° C., and it is desired that the temperature of the catalyst be quickly raised to the activation temperature when the internal combustion engine is started. For this reason, Japanese Utility Model Laid-Open No. 6-1443
In the device disclosed in Japanese Patent Publication No. 2 (1995), a catalyst made of a shape memory alloy is used to move a catalyst between a position close to the internal combustion engine when the exhaust gas temperature is low and a position away from the internal combustion engine when the exhaust gas temperature is high. By moving the internal combustion engine, the temperature of the catalyst is quickly raised when the internal combustion engine is started, and when the temperature of the exhaust gas becomes high, overheating of the catalyst is prevented. Further, in the apparatus disclosed in Japanese Utility Model Laid-Open Publication No. 3-27822, a warm-up converter is provided upstream of the main converter, and a state in which exhaust gas is guided to the warm-up converter when exhaust gas temperature is low, A state in which exhaust gas is led to the main converter by bypassing the warm-up converter when the temperature is high is switched by a switching valve made of a shape memory alloy, so that the main converter exhibits a sufficient purification function when the internal combustion engine is started. At the same time, catalyst deterioration in the warm-up converter when the exhaust gas temperature becomes high is prevented.

[0003]

However, in Japanese Utility Model Laid-Open No. 6-14432, the catalyst moves in the casing, the structure for moving the catalyst is complicated, and the number of parts is large. In addition to this, the assemblability becomes poor. Further, the device disclosed in Japanese Utility Model Laid-Open Publication No. 3-27822 can be applied only to an exhaust gas purifying device including a combination of a warm-up converter and a main converter, and has a complicated structure.

The present invention has been made in view of the above circumstances, and has an exhaust gas purifying apparatus for an internal combustion engine which has a very simple structure with a minimum number of parts and can accelerate the start of exhaust gas purification by a catalyst. The purpose is to provide.

[0005]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a casing having an exhaust gas inlet at one end and an exhaust gas outlet at the other end, with one end facing the exhaust gas inlet. In an exhaust gas purifying apparatus for an internal combustion engine in which a catalyst is accommodated, a guide means formed of a two-way shape memory alloy is connected to a part of one end of the catalyst from an exhaust gas inlet when the temperature is equal to or lower than a preset set temperature. And a second shape for guiding exhaust gas from the exhaust gas inlet substantially uniformly over the entire surface of one end of the catalyst when the temperature exceeds the set temperature, and It is provided at one end of the casing.

According to such a configuration, when the temperature of the exhaust gas from the internal combustion engine is low, the guide means is below the set temperature, so that the exhaust gas is guided to a part of one end of the catalyst, and a part of the catalyst is exhausted. When the temperature rise is accelerated and at least a part of the catalyst quickly reaches the activation temperature, the start of substantial purification of exhaust gas is accelerated. Further, when the temperature of the exhaust gas from the internal combustion engine increases, the guide means guides the exhaust gas to the entire surface of one end of the catalyst substantially uniformly as the temperature exceeds the set temperature, and the exhaust gas is effectively purified by the entire catalyst, The flow resistance of the exhaust gas also decreases.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.

FIGS. 1 to 4 show one embodiment of the present invention. FIG. 1 is a longitudinal sectional view of an exhaust gas purifying apparatus when the exhaust gas temperature is low, and FIG. 2 is a sectional view taken along line 2-2 of FIG. FIG. 3 is a longitudinal sectional view of the exhaust gas purifying device when the exhaust gas temperature is high, and FIG. 4 is a diagram showing the temperature rising characteristics of the catalyst in comparison with the conventional one.

First, referring to FIG. 1, the exhaust gas purifying apparatus includes a catalyst 6 housed in a casing 5 and is provided in an exhaust system of an internal combustion engine.

The casing 5 comprises a casing main body 7 and flanges 8 and 9 which are welded and connected to both ends of the casing main body 7. The casing main body 7 is formed by mutually connecting a pair of half members divided along the longitudinal direction, and has a cylindrical portion 7a having a circular cross section and a large-diameter end at one end of the cylindrical portion 7a. Upstream taper 7 connected
b, and a downstream tapered portion 7c having a large-diameter end connected to the other end of the cylindrical portion 7a. The flange 8 forming the exhaust gas inlet 10 is connected to one end of the casing main body 7, that is, the upstream tapered portion 7b. A flange 9 which is coaxially welded and coupled to the small diameter end to form the exhaust gas discharge port 11 is coaxially welded and coupled to the other end of the casing main body 7, that is, the small diameter end of the downstream taper portion 7c.

The flange 8 is connected to the upstream side of the exhaust gas purifier by a plurality of bolts 12 in the exhaust system of the internal combustion engine, and the flange 9 is connected to the downstream side of the exhaust gas purifier in the exhaust system of the internal combustion engine. Multiple bolts 13
Combined by ...

The catalyst 6 has a circular cross section.
The catalyst 6 is accommodated coaxially in the cylindrical portion 7a of the casing main body 7 so that one end of the catalyst 6 faces the exhaust gas inlet 10, and between the outer peripheral surface of one end of the catalyst 6 and one end of the cylindrical portion 7a. A ring-shaped buffering member 14 is provided between the outer peripheral surface of the other end of the catalyst 6 and the other end of the cylindrical portion 7a.

2, a guide means 16 made of a bidirectional shape memory alloy is provided at one end of the casing main body 7 in the casing 5. The guide means 16 includes a cylindrical base 16a having one end coaxially connected to the exhaust gas inlet 10 and a plurality of bases connected at equal intervals in the circumferential direction at the other end of the base 16a. , And the base 16a is welded and connected to one end of the casing main body 7.

When the guide means 16 is at a temperature lower than a predetermined set temperature (for example, 400 ° C.), as shown in FIGS. 1 and 2, it has a first cylindrical shape as a whole. That is, each of the divided portions 16 of the guide means 16
b are slits 17 between the divided portions 16b.
Are formed, and the posture is along the extension of the cylindrical base 16a.

When the guide means 16 assumes the first shape, the exhaust gas introduced into the casing 5 from the exhaust gas introduction port 10 is supplied to the one end of the catalyst 6 by the guide means 16 at a substantially central portion. Will be intensively led to the department.

When the temperature exceeds the set temperature, the guide means 16 has a second shape with the catalyst 6 side open as shown by the chain line in FIG. 2 and the solid line in FIG. That is, each of the divided portions 16b of the guide means 16 is
6b are deformed so as to expand.

When the guide means 16 assumes the second shape, the exhaust gas introduced into the casing 5 from the exhaust gas inlet 10 is substantially uniformly guided by the guide means 16 over one end of the catalyst 6. Will be crushed.

Next, the operation of this embodiment will be described. When the temperature of the exhaust gas from the internal combustion engine is low when the internal combustion engine is started, the guide means 16 is at or below the set temperature, as shown in FIG. 1 and FIG. As described above, the first shape is substantially cylindrical, and the exhaust gas introduced into the casing 5 from the exhaust gas inlet 10 is intensively guided to a part of the substantially central portion of the catalyst 6. For this reason, the temperature rise in the substantially central portion of the catalyst 6 is accelerated, and at least a part of the catalyst 6 quickly reaches the activation temperature, so that the substantial start of purification of the exhaust gas by the catalyst 6 is accelerated.

When the temperature of the exhaust gas increases with the continuation of the operation of the internal combustion engine, the guide means 16 becomes the second shape in which the catalyst 6 side is expanded as shown in FIG. Exhaust gas introduced into the casing 5 from the exhaust gas inlet 10 is substantially uniformly guided to one end of the catalyst 6. For this reason, purification of the exhaust gas is effectively performed by the entire catalyst 6, and the flow resistance of the exhaust gas is reduced.

In this way, by changing the shape of the guide means 16 for guiding the exhaust gas from the exhaust gas inlet 10 to the catalyst 6 according to the temperature, the time until the catalyst 6 reaches the activation temperature is represented by the solid line in FIG. As shown in the figure, the catalyst 6 is activated earlier by the time ΔT than the conventional one shown by the broken line, and the exhaust gas can be effectively purified.

Furthermore, the start time of purifying the exhaust gas by the catalyst 6 can be advanced with a simple and small number of parts such that the guide means 16 made of a two-way shape memory alloy is fixed to one end of the casing 5.

The installation position of such an exhaust gas purifying device in the exhaust system is not particularly limited, and the present invention can be applied to a so-called direct type converter in which the catalyst is located immediately below the exhaust manifold. is there.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the appended claims. It is possible to do.

For example, the guide means may be constituted by a plurality of divided pieces divided in the circumferential direction.

[0025]

As described above, according to the present invention, the guide means made of a bidirectional shape memory alloy switches between the first and second shapes in accordance with the temperature to change the shape.
With a simple structure with a reduced number of parts, the start of substantial purification of exhaust gas can be expedited, and when the temperature is equal to or higher than the set temperature, the flow resistance of exhaust gas in the catalyst can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an exhaust gas purifying apparatus when an exhaust gas temperature is low.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a longitudinal sectional view of the exhaust gas purifying device when the exhaust gas temperature is high.

FIG. 4 is a diagram showing the temperature rise characteristics of a catalyst in comparison with a conventional catalyst.

[Explanation of symbols]

 5 ... Casing 6 ... Catalyst 10 ... Exhaust gas inlet 11 ... Exhaust gas outlet 16 ... Guide means

Claims (1)

[Claims] A catalyst (6) having one end facing said exhaust gas inlet (10) in a casing (5) having an exhaust gas inlet (10) at one end and an exhaust gas outlet (11) at the other end. In the exhaust gas purifying apparatus for an internal combustion engine in which the guide means (16) formed of a two-way shape memory alloy is provided, the guide means (16) is a part of one end of the catalyst (6) when the temperature is equal to or lower than a preset temperature. A first shape for guiding the exhaust gas from the exhaust gas inlet (10) to the exhaust gas, and the exhaust gas from the exhaust gas inlet (10) is substantially evenly distributed over the entire surface of one end of the catalyst (6) as the set temperature is exceeded. An exhaust gas purifying device for an internal combustion engine, wherein the exhaust gas purifying device is provided at one end of the casing (5) so as to be deformable between a second shape to be guided.