JPH07180541A - Exhaust emission control device for engine - Google Patents

Abstract

PURPOSE:To expedite a rise of catalyst operation during low speed operation of an engine and to prevent reduction of engine efficiency through prevention of the increase of the back pressure of an engine during high speed operation. CONSTITUTION:A catalyst plate valve 2 is pivotally supported in an exhaust pipe 1 and repulsively moved in a closing direction through the force of a spring 5. The catalyst plate valve 2 is formed of a catalyst metal adhered to a corrosion resistant steel and has an exhaust gas pass-through hole 4 formed in a position deviated to one side of a support axis 3. At an engine low speed running period at which an exhaust gas flow rate is low, a solid line position is kept to suppress a velocity of flow and through the increase of a reaction time, a reaction amount and the increase of temperature are increased. At an engine high speed running period at which a flow rate of exhaust gas is high, the catalyst plate is rotated in the direction of an arrow mark B by an exhaust gas pressure to increase a flow area and a back pressure is prevented from increaing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine exhaust gas purifying apparatus using a catalyst plate.

[0002]

2. Description of the Related Art A porous catalyst is fixed in an exhaust gas passage,
A device for purifying exhaust gas is well known (for example, Japanese Patent Laid-Open No. 4-303110). In this type of device,
Since the area through which exhaust gas passes does not change, there is the inconvenience that excessive back pressure is generated in the engine at high engine speeds and engine efficiency is reduced. The temperature rise tends to be delayed.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to accelerate the rise in catalyst temperature at low engine speeds and prevent the back pressure from rising at high engine speeds.

[0004]

A first means for solving the above-mentioned problems is to rotate a catalyst plate valve having exhaust gas passage holes across an exhaust gas passage as described in claim 1. It is characterized by supporting the shaft as much as possible and restricting the flow rate of exhaust gas at low engine speeds and reducing the throttle at high speeds.

Further, as described in claim 2, in the second means, in the first means, the catalyst plate valve is elastically urged in a direction to throttle the exhaust gas, and the turning angle is increased in response to the exhaust gas pressure. It is characterized by doing so.

[0006]

According to the first aspect of the present invention, when the engine speed is low, the flow rate of exhaust gas is reduced by the catalyst plate valve, the contact time with the catalyst plate valve is lengthened, the catalyst temperature rises quickly, and the purification action rises. early. When the engine becomes high speed, the opening of the catalyst plate is increased to reduce the increase of the back pressure of the engine and prevent the decrease of the engine efficiency.

According to the second aspect of the invention, the catalyst plate is automatically rotated by increasing or decreasing the exhaust gas pressure,
Automatically adjust the engine back pressure.

[0008]

Embodiments Embodiments will be described below with reference to the drawings. In FIGS. 1 and 2, 1 is an exhaust pipe, 2 is a catalyst plate valve in which a precious metal is adhered to a corrosion-resistant steel plate, and the catalyst plate valve 2
Is rotatably supported on the exhaust pipe 1 by a support shaft 3, and a passage hole 4 is provided asymmetrically with respect to the support shaft 3. As is clear from FIG. 2, the passage hole 4 is provided in the upper half portion so as to be offset.

The spring 5, one end of which is connected to the support shaft 3, is locked to the exhaust pipe 1 via pins 6 and 7, and the catalyst plate valve 2
In FIG. 1, an elastic force in the clockwise direction is applied to bring the stopper 8 into contact with the stopper 8 to maintain a posture in which the exhaust gas flows in the direction of arrow A.

FIG. 3 shows an example of an exhaust system having two exhaust pipes 1, 9 is an exhaust manifold, 10 is a catalyst case containing a fixed catalyst, 11 is a muffler, and the catalyst plates shown in FIGS. The valve 2 is provided on both exhaust pipes 1, 1.

At low speeds such as when the engine is started, the pressure of the exhaust gas is low, and the catalyst plate valve 2 maintains the vertical position shown in the figure, and purifies the exhaust gas by the catalytic action while suppressing the flow velocity of the exhaust gas. At this time, the purifying action is also performed on the fixed catalyst in the rear catalyst case 9.

Next, when the engine is driven at high speed, the pressure of the exhaust gas rises, and the pressure acts largely below the catalyst plate valve 2, and the catalyst plate valve 2 resists the elastic force of the spring 5. It rotates in the direction of arrow B to prevent the back pressure of the engine from rising. In this case, the exhaust gas is hot,
Since the content of unburned components is also low, the purifying action is sufficiently performed even if the contact time with the catalyst is short.

FIGS. 4 and 5 are graphs comparing the operation of the present invention and the prior art. The curve a is the catalyst plate valve 2 of the present invention.
The curve b is not provided, and the catalyst plate valve 2 is provided. In FIG. 4, the flow rate of exhaust gas at low rotation is low, and in FIG. 5, the exhaust gas temperature rises quickly. I understand.

In the above embodiment, the exhaust pipe 1 is provided with one catalyst plate valve 2, but two or more catalyst plate valves 2 can be provided.
When the catalyst plate valve 2 alone can be used for purification, the fixed catalyst at the rear can be omitted.

Further, the rotating means of the catalyst plate valve 2 may be a bimetal or other thermal response device which operates at the exhaust temperature, or a device which responds to the engine speed. Further, the shape and the supporting means of the catalyst plate valve 2 are not limited to those in the above-mentioned embodiment, and it is sufficient that the minimum flow rate can be secured and the flow rate can be adjusted by being supported by an arbitrary shaft.

[0016]

As described above, according to the first aspect of the present invention, the catalyst plate valve suppresses the outflow rate of exhaust gas to increase the reaction when the engine speed is low with many unburned components, so that the catalyst temperature rises quickly. It also has an advantage that the purification action starts up quickly, and does not suppress the outflow of exhaust gas at a high speed, and thus has the advantage that back pressure is prevented from rising and engine efficiency is not lowered.

Further, the invention of claim 2 has an advantage that the catalyst plate valve is simply elastically bulged in the closing direction, so that the structure is simple and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical side view of an embodiment of the present invention.

[Fig. 2] Same as above, vertical front view

FIG. 3 is a perspective view of the same as above.

FIG. 4 is a graph for explaining the operation

FIG. 5 is a graph for explaining the operation

[Explanation of symbols]

 1 Exhaust pipe 2 Catalyst plate valve 3 Support shaft 5 Spring

Claims (2)

[Claims] 1. A catalyst plate valve having an exhaust gas passage hole is rotatably pivoted across an exhaust gas passage to adjust the flow rate of exhaust gas at a low engine speed and reduce the throttle at a high speed engine. An exhaust gas purifying device for an engine, which is characterized in that 2. The exhaust gas purifying apparatus for an engine according to claim 1, wherein the catalyst plate valve is elastically urged in a direction to throttle the exhaust gas to increase the turning angle in response to the exhaust gas pressure.