JPH04171213A - Exhaust gas cleaning device for engine - Google Patents

Abstract

PURPOSE:To prevent heat dissipation from an exhaust air inflow section and enhance the coefficient of cleaning exhaust gas right after starting an engine by providing a flow passage control valve on the inlet side and the outlet side of a catalyser to change the flow direction of exhaust air to an opposite one near the outlet side of the catalyser and change it again near the inlet side of the catalyser. CONSTITUTION:In general, when an engine is in a warm-up condition, an exhaust air flow passage control valve 5 is opened by the force of a spiral spring 6 to allow uniform flow of exhaust air into a catalyser 2. When the engine is cool, a current flows in a solenoid 7 in accordance with signals from a water temperature sensor or an exhaust air temperature sensor to open a cutoff valve 8. As a result, lower pressure (negative) than atmospheric pressure in an inlet manifold is applied to a piston 10 to operate a lever 9 connected thereto for setting the exhaust gas flow passage control valve close. In such a state, exhaust gas flows through S1, S2 and S3 in sequence. It is thus possible to prevent heat dissipation to the outside and provide high exhaust gas cleaning coefficient.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention is an exhaust purification device for an engine such as an automobile, and is particularly suitable for removing harmful substances in the exhaust when the engine is cold and the exhaust purification rate of the catalyst is low. The present invention relates to a useful exhaust purification device.

(Prior Art) A conventional exhaust gas purification device is equipped with a catalyst container 1 equipped with an exhaust port 3 and an exhaust outlet 4 as shown in FIG. A catalyst 2 coated with a noble metal is fixed.

The normal exhaust gas is introduced from the exhaust port 3, comes into contact with the entire catalyst, is purified, and is discharged from the exhaust outlet 4. In the warm-up state when the engine exhaust temperature reaches 300°C or higher, the exhaust gas reaches 9
A high exhaust gas purification rate of several 0% has been obtained.

(Problem to be solved by the invention) However, in such an exhaust purification device, immediately after the engine starts, the heat of the exhaust gas is taken away by the catalyst, which is in a low temperature state, so the exhaust temperature is low. Therefore, the catalyst temperature does not rise until it is activated, and therefore the exhaust purification rate is extremely low.

Under such circumstances, a purification device for improving such a low exhaust gas purification rate was proposed in Japanese Patent Laid-Open No. 183511/1983. In this purification device, as shown in Fig. 5, a switching valve 15 is provided on the exhaust inlet side, and by allowing exhaust gas to flow only into the center of the catalyst immediately after startup, the volume of the catalyst heated by the exhaust gas is reduced. After the exhaust gas has sufficiently warmed up, the switching valve is switched to allow the exhaust gas to flow through the entire catalyst, improving the exhaust purification rate.

However, with the method shown in Figure 5, in which the exhaust gas flows only to the center of the catalyst, heat dissipation to the outside cannot be ignored because the catalyst at the outer periphery is cold. Due to the decrease in the volume of the catalyst and the shortening of the time during which the exhaust gas contacts the catalyst, improvements in the catalyst layer still remain to be solved in order to obtain a high exhaust gas purification rate.

(Means for solving the problem) This invention was developed as a result of research focusing on such problems.
Exhaust flow control valves or partitions are provided on the inlet and outlet sides of the catalyst to direct the flow of exhaust gas that flows in from the catalyst inlet side, which is located near the engine exhaust port, in the opposite direction near the catalyst outlet side. By changing the direction of the catalyst and redirecting it near the catalyst side, heat dissipation from the exhaust gas inlet is prevented, temperature rise is accelerated, and the volume of the catalyst through which the exhaust gas passes is utilized without being reduced, allowing for sufficient reaction. This is based on the discovery that time can be preserved.

Therefore, the first aspect of the present invention directs the flow of exhaust gas flowing from the catalyst inlet side located in the direction close to the exhaust port of the engine.
This invention relates to an exhaust purification device characterized in that flow path control valves are provided on the inlet and outlet sides of the catalyst in order to change the direction in the opposite direction near the catalyst outlet side and change the direction again near the catalyst inlet side. .

Further, the second aspect of the present invention is to change the flow of exhaust gas flowing in from the catalyst inlet side located in the direction close to the exhaust port of the engine to the opposite direction near the catalyst outlet side, and to change the direction again near the catalyst inlet side. , the exhaust temperature of the engine increases (approximately 200 to 30
The present invention relates to an exhaust gas purification device characterized in that a catalyst container used until the temperature reaches 0° C. is provided as an auxiliary catalyst container for a main catalyst container.

The present invention will be explained below based on the drawings.

FIG. 1 shows a catalyst container used in the exhaust purification device of the first aspect of the present invention.

First, to explain the structure, the structure is a catalyst container, and the catalyst 2 is fixed in this container. Gas flows into the catalyst container 1 from the exhaust inlet 3 side and flows out from the exhaust outlet 4 side. 5 is an exhaust flow path control valve, to which a spiral spring 6 is attached. A shutoff valve 8 at the tip of the solenoid 7 is located between a pipe 11 opening into the intake manifold of the engine and a piston 10 that moves a lever 9.

Next, the effect will be explained.

Normally, when the engine is warmed up, the exhaust flow control valve 5 is kept open by the force of the spiral spring 6, and the exhaust gas flows uniformly inside the catalyst 2. When the engine is cold, current flows through the solenoid 7 based on a signal from the water temperature sensor or the exhaust temperature sensor, and the shutoff valve 8 opens. As a result, a pressure (negative pressure) lower than the atmospheric pressure in the intake manifold is applied to the piston 10, which moves the lever 9 connected to the piston 10, thereby closing the exhaust flow path control valve. In this state, the exhaust flows from S1 to S2 to S3. The area of the flow path is 5
1', S2ζ83 is preferably approximately equal.

FIG. 2 shows an auxiliary catalyst container 12 used in the exhaust purification device of the second invention.

In this example, a partition wall is provided for a cylindrical catalyst, and the purpose is to allow exhaust gas to pass only immediately after startup, and the catalyst is placed separately from the main catalyst container. That is, the exhaust gas purification device of the second invention consists of a main catalyst container 1-1 and an auxiliary catalyst device 12, the arrangement of which is shown in FIG. Main catalyst container 1-
1 is a conventional catalyst container as shown in FIG.
5 is opened, and after the temperature of the exhaust gas rises to a desired temperature, the valve 15 is switched to allow gas to flow into the main catalyst container 1-1 for processing. The auxiliary catalyst container 12 has an annular partition wall 13 on the catalyst inlet side and a circular partition wall 14 on the catalyst outlet side, so that the exhaust gas flows in the order of S1→S2→S3. Since the outer peripheral part S2 is also warmed by exhaust gas,
Heat dissipation from the central portion S1 to the outside is reduced, and the temperature rise at the time of startup is promoted, making it possible to increase the exhaust gas purification rate at low temperatures. Here, 31, 32.3
It is effective to make the areas of 3 approximately equal, and the radius ratio is preferably about 1:1.4:1.7 from the inside.

(Effects of the Invention) As explained above, according to the present invention, the configuration is such that a catalyst container is provided with flow path control valves on the inlet and outlet sides of the catalyst, or a catalyst container is installed alongside the main catalyst container. By using an auxiliary catalyst container and using partition walls on the inlet and outlet sides of the catalyst in this auxiliary catalyst container, the temperature of the exhaust gas rises from the start of the engine and reaches a warm-up state of approximately 200 to 300°C or higher. This has the effect of preventing heat dissipation from the exhaust inlet, accelerating temperature rise, and increasing the exhaust purification rate immediately after engine startup by utilizing the volume of the catalyst through which the exhaust passes without reducing it. can get.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram partially cut away showing a catalyst container provided with an exhaust flow path control valve according to the first aspect of the present invention, FIG. 2 is a sectional view of an auxiliary catalyst container according to the second aspect of the present invention, and FIG. Figure 4 is a layout diagram of the exhaust purification device of the second invention of the present invention, Figure 4 is a sectional view of a catalyst container used in a conventional general exhaust purification device, and Figure 5 is a catalytic converter for exhaust gas immediately after engine startup. FIG. 3 is a cross-sectional view of a catalyst container in which the catalyst is allowed to flow only into the central portion of the container. 1... Catalyst container 2... Catalyst 3... Exhaust population 4... Exhaust outlet 5... Exhaust flow path control valve 6... Spiral spring 7... Solenoid
8... Shutoff valve 9... Lever 10... Piston 11... Vibrator 12... Auxiliary catalyst container 13... Annular partition part 14... Circular partition part 15... Switching Valve Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] 1. In order to change the flow of exhaust gas that enters from the catalyst inlet side located in the direction close to the exhaust port of the engine into the opposite direction near the catalyst outlet side, and change the direction again near the catalyst inlet side, An exhaust purification device characterized in that a flow path control valve is provided in the exhaust gas purification device. 2. The flow of exhaust gas flowing in from the catalyst inlet side, which is located in the direction close to the exhaust port of the engine, is reversed near the catalyst outlet side, and then changed again near the catalyst inlet side. An exhaust gas purification device comprising a catalyst container provided with a partition wall and used until the exhaust gas temperature of the engine rises as an auxiliary catalyst container of the main catalyst container.