JP2906623B2 - Exhaust purification system for marine propulsion units - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to an exhaust purification device for a marine propulsion device.

(Prior art) Outboard motors, such as outboard motors that propel the hull by adhering to the tail of the hull, do not have exhaust gas regulations, so they are included in the exhaust gas emitted from engines of conventional outboard motors. ing
No measures are generally taken to remove CO and HC.

However, recently, marine leisure has become widespread, and in view of the tendency to become more and more popular in the future, even for marine propulsion systems such as outboard motors, CO and raw gas blow-by due to incomplete combustion in exhaust gas To remove HC.

In the exhaust system of the outboard motor, an exhaust tube (pipe) 3 connected to an exhaust manifold 2 of the engine 1 is suspended in a drive shaft housing 4 of the outboard motor, as shown in a partial cross section in FIG. From inside the housing 4, it passes through a gear case 5 joined to a lower part of the housing 4, passes around a drive shaft of a propeller 6 supported by the gear case 5, and is exhausted into water.

In such an outboard motor, a honeycomb type catalyst is attached to the lower end of the exhaust tube 3 as an exhaust gas purifying measure, and the exhaust gas discharged from the exhaust tube 3 is brought into contact with the catalyst to purify the exhaust gas. Some have been made to do so.

(Problems to be Solved by the Invention) However, in the above-mentioned conventional exhaust gas purifying structure, a catalyst is provided at the lower end of the exhaust tube, and this catalyst has a honeycomb shape, so that the exhaust pressure in the exhaust tube 3 and the exhaust manifold 2 increases. In addition, there is a problem that the engine output is remarkably reduced. In addition, since the position where the catalyst is provided is near the water surface, the catalyst is moved by the exhaust motion in the drive shaft housing 4 during operation, and is affected by the wave during mooring. Water (brine) is applied to the catalyst, and the durability and purification performance of the catalyst are deteriorated early. To avoid this, if the catalyst is mounted above the exhaust tube, the effect of water is reduced but the exhaust pressure is further increased, resulting in a disadvantage that the engine output is greatly reduced.

The present invention relates to an exhaust gas purifying apparatus for a marine propulsion device, which does not increase the exhaust pressure of an engine, is not affected by water, and can prevent a decrease in engine durability and purification performance while preventing a decrease in engine output. The purpose is to provide.

[Configuration of the invention]

(Means for Solving the Problems) An exhaust purification system for a marine propulsion device according to the present invention, in order to solve the above-described problems, includes an exhaust system that discharges into water through an exhaust tube connected to an exhaust manifold of an engine. In a marine propulsion device having, a catalyst exhaust plate sprayed with a catalyst on the surface is disposed in a multilayer shape along a flow of exhaust gas in an exhaust manifold,
The catalyst exhaust plate has a large number of holes formed therein, while an exhaust passage is formed between the catalyst exhaust plates.

(Operation) The exhaust gas discharged from the exhaust port of the engine flows to the exhaust tube through between the catalyst exhaust plates arranged in a multilayered manner in the exhaust manifold. At this time, the exhaust gas flows along the surface of the catalyst exhaust plate, so that there are many opportunities to come into contact with the catalyst carried on the surface, and CO and CO in the exhaust gas are provided.
HC reacts with the catalyst to be reburned and purified. Since the catalyst exhaust plate is provided in the exhaust manifold, there is no corrosion damage due to intrusion of water, and the catalyst can be easily applied to an existing propulsion device.

(Embodiment) An embodiment of an exhaust purification system for a marine propulsion device according to the present invention will be described below with reference to the accompanying drawings.

The present invention is applied to a marine propulsion device such as an outboard motor or an inboard engine in which an engine is housed in a hull. FIG. 1 shows an example in which the present invention is applied to an exhaust system of an outboard motor.

In the drawing, reference numeral 10 denotes an engine mounted on the upper part of the outboard motor. An exhaust manifold 11 is formed around the engine 10, and the exhaust manifold 11 is connected to an exhaust tube 12. The exhaust tube 12 is accommodated in a drive shaft housing (not shown) and is suspended.

The exhaust manifold 11 is configured by attaching an exhaust plate 14 to a cylinder 13 of the engine 10. A boss 15 is formed on the inner surface of the exhaust plate 14, and a plurality of (three in the illustrated example) catalyst exhaust plates 16 are fastened to the boss 15 with bolts 18 at predetermined intervals via spacers 17. Be worn.

As shown in FIG. 2, the catalyst exhaust plate 16 has a plurality of holes 19 formed in a plate material serving as a base material, and a catalyst 20 is fixed to the surface by thermal spraying or the like as shown in FIG. . The catalyst exhaust plate 16 has a trapezoidal side shape so as not to obstruct the flow of exhaust gas, and the exhaust gas discharged from the exhaust port 22 flows smoothly in the exhaust manifold 11 and provides more opportunities for contact with the exhaust gas. It is configured as follows. It is preferable that the catalyst exhaust plate 16 has a cross-sectional shape such as a corrugated cross section, a zigzag shape, or an irregular shape as shown in FIG.

Therefore, the exhaust gas discharged from the exhaust port 22 of the cylinder 13 flows between the catalyst exhaust plates 16 as shown by the arrow in FIG.
Reacts with 20 and is reburned and purified by the reaction heat. The purified exhaust gas flows into the exhaust tube 12, passes through the drive shaft housing 4, and the gear case 5 (see FIG. 4), and is discharged into water. Further, since the exhaust gas flows between the stacked catalyst exhaust plates 16, more contact between the exhaust gas and the catalyst 20 is performed, and the purification action is performed reliably and reliably.

In the above embodiment, an outboard motor has been described as a boat propulsion machine, but it goes without saying that a propulsion machine other than an outboard motor can be applied.

〔The invention's effect〕

As described above, in the exhaust emission control device for a marine propulsion device according to the present invention, a catalyst exhaust plate having a surface sprayed with a catalyst is disposed in a multilayer shape in an exhaust manifold, and the catalyst exhaust plate includes While a large number of holes are formed, an exhaust passage is formed between the catalyst exhaust plates, so that the catalyst exhaust plate having a multilayer structure can increase the surface area of the catalyst, and the exhaust gas can be exhausted along the catalyst exhaust plate. While the gas flows, the contact area between the exhaust gas and the catalyst is increased, and harmful components in the exhaust gas can be positively and effectively purified. In addition, since the space between the multi-layer plates of the catalyst exhaust plate serves as a guide path for the exhaust gas and flows smoothly, the exhaust pressure is not increased, the exhaust gas is smoothly discharged, and the engine output does not decrease. Since the catalyst exhaust plate is located in the exhaust manifold close to the exhaust port, it is a place where the exhaust temperature is high, so the catalyst can be used not only during steady operation (from idling to full open), but also during acceleration or low speed operation. Can accelerate the oxidation reaction of
The exhaust gas flow is agitated by a large number of holes drilled in each catalyst exhaust plate, so that the contact with the disturbed catalyst is effectively performed, and the removal of harmful components is effectively performed.

In addition, since the exhaust manifold where the catalyst exhaust plate is installed is located in a position where water does not easily enter, there is no damage to the catalyst due to water (salt water), there is little deterioration in catalyst durability and purification performance, and not only new engines but also existing engines Can be easily implemented, and can greatly contribute to the exhaust purification of ship propulsion systems in the future.

[Brief description of the drawings]

FIG. 1 is a horizontal sectional view showing one embodiment of the present invention, FIG. 2 is a perspective view showing a part of a catalyst exhaust plate in FIG. 1, and FIG. 3 is a sectional view taken along line AA in FIG. ,
FIG. 4 is a partially sectional side view showing an outboard motor as an example of a marine propulsion device to which the present invention is applied. 10 ... Engine, 11 ... Exhaust manifold, 12 ... Exhaust tube, 13 ... Cylinder, 14 ... Exhaust plate, 16 ... Catalyst exhaust plate, 17 ... Spacer, 18 ... Bolt, 20 ... Catalyst ,twenty two
…… Exhaust port.

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Claims (1)

(57) [Claims] In a marine propulsion system having an exhaust system for discharging water into an exhaust tube through an exhaust tube connected to an exhaust manifold of an engine, a catalyst exhaust plate having a surface sprayed with a catalyst is provided along an exhaust flow in the exhaust manifold. A plurality of holes are formed in the catalyst exhaust plate, and an exhaust passage is formed between the catalyst exhaust plates. apparatus.