JPH04134117A - Exhaust emission control device for marine propeller - Google Patents

Abstract

PURPOSE:To improve the extent of emission control over a harmful component in exhaust gases by installing a catalyst exhaust plate, where a catalyst is thermally sprayed on the surface, in an exhaust manifold as in a stratified form along a flow of exhaust, in a device which discharges exhaust gases into the water through an exhaust tube. CONSTITUTION:An exhaust manifold 11 is formed around an engine 10 being mounted on top of an outboard motor, and this exhaust manifold 11 is connected to an exhaust tube 12 which is housed in a driveshaft housing (unillustrated herein) and hung down there. Here plural sheets of catalyst exhaust plates 16 are clamped to two boss parts 15 formed on an inner surface of an exhaust plate 14 of the exhaust manifold 11 by bolts 18 in keeping a specified interval via each spacer 17. This plate 16 is made up of installing plural holes in a plate serving as a base material and attaching a catalyst tight to the surface by means of thermal spraying, while it is formed into a trapezoid in side form so as not to hinder a flow of exhaust.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to an exhaust gas purification device for a marine propulsion device.

(Prior Technology) Since there are no exhaust gas regulations for marine propulsion engines, including outboard motors that are attached to the tail of a ship to propel the ship, conventional outboard motors do not contain any exhaust gas emitted from the outboard engine. C
Measures to remove O and HC are generally not taken.

However, in view of the fact that marine leisure activities have recently become popular and are expected to become even more popular in the future, even marine propulsion engines such as outboard motors can emit CO and raw gas due to incomplete combustion in the exhaust gas. It is necessary to remove HC due to

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

In such an outboard motor, a honeycomb type catalyst is attached to the lower end of the exhaust tube 3, and the exhaust gas discharged from the exhaust tube 3 is brought into contact with this catalyst to purify the exhaust gas. There are things that have been done to make it possible.

(Problem to be Solved by the Invention) However, in the conventional exhaust purification structure described above, 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 exhaust manifold 2 increases. In addition, since the catalyst is located close to the water surface, the catalyst may be damaged due to exhaust pulsation inside the drive shaft housing 4 during operation, and due to the influence of waves while moored. The problem is that the catalyst's durability and purification performance deteriorate early due to water (salt water) splashing on the catalyst. In order to avoid this, if the catalyst is installed above the exhaust tube, the influence of water will be reduced, but the exhaust pressure will further increase, resulting in a drawback that the reduction in engine output will be greatly increased.

The second invention is exhaust purification for marine propulsion engines that does not increase engine exhaust pressure, is not affected by water, prevents a decrease in engine output, and prevents a decrease in catalyst durability and purification performance. The purpose is to provide equipment.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention is characterized in that a catalytic exhaust plate whose surface is thermally sprayed with a catalyst is arranged in a layered manner along the flow of exhaust gas within the exhaust manifold. It is something to do.

(Operation) Exhaust gas discharged from the exhaust port of the engine flows into the exhaust tube through between the catalytic exhaust plates arranged in layers in the exhaust manifold. At this time, the exhaust gas flows along the surface of the catalytic exhaust plate, giving it many opportunities to come into contact with the catalyst supported on the surface, which removes CO and H from the exhaust gas.
C reacts with the catalyst to be re-burned and purified. Since this catalytic exhaust plate is provided within the exhaust manifold, there is no damage caused by corrosion due to water intrusion, and it can be easily applied to existing propulsion machines.

(Embodiment) An embodiment of the exhaust gas purification device 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 marine propulsion devices such as outboard motors and inboard motors in which the engine is housed in the hull, and FIG. 1 shows an example in which the present invention is applied to an exhaust system of an outboard motor.

In the figure, reference numeral 10 is an engine mounted on the top of the outboard motor, and an exhaust manifold 11 is installed around this engine 10.
is formed, and this exhaust manifold 11 is connected to an exhaust tube 12.

Exhaust tube 12 is housed and suspended within a drive shaft housing (not shown).

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

As shown in FIG. 2, the catalytic exhaust plate 16 has a plurality of holes 19 bored in a plate material serving as a base material.
As shown in FIG. 3, a catalyst 20 is fixed to the surface by thermal spraying or the like. Catalyst exhaust plate 16
The side profile is trapezoidal so as not to obstruct the flow of exhaust gas,
It is configured so that the exhaust gas discharged from the exhaust port 22 flows smoothly within the exhaust manifold 11 and is given more opportunities to come into contact with the exhaust gas.

It is preferable to make the cross-sectional shape of the catalytic exhaust plate 16 wave-like, zigzag, uneven, etc. as shown in FIG. 3 because the area to which the catalyst 20 adheres can be increased.

Therefore, the exhaust gas discharged from the exhaust port 22 of the cylinder 13 flows between the catalytic exhaust plates 16 as shown by the arrow in FIG.
C reacts with the catalyst 20 and is reburned and purified by the reaction heat. The purified exhaust gas flows to the exhaust tube 12, passes through the drive shaft housing 4 and the gear case 5 (see FIG. 4), and is discharged into the water. In addition, exhaust gas is handled by a laminated catalyst exhaust plate 16.
Since the exhaust gas flows along the gap between the exhaust gases and the catalyst 20, more contact is made between the exhaust gas and the catalyst 20, and the purifying action is performed well and reliably.

In the above embodiment, an outboard motor is used as the marine vessel propulsion device, but it goes without saying that the present invention is also applicable to propulsion devices other than outboard motors.

〔Effect of the invention〕

As described above, according to the present invention, the catalytic exhaust plate whose surface is thermally sprayed with a catalyst is provided in a layered manner in the exhaust manifold, so that while the exhaust gas flows along the catalytic exhaust plate, the catalyst and the exhaust gas are Harmful components in the exhaust gas are purified by contact. Additionally, the catalytic exhaust plate acts as a guide path for exhaust gas, allowing it to flow smoothly, without increasing exhaust pressure or reducing engine output. Since the catalytic exhaust plate is located in the exhaust manifold near the exhaust port, it is a location with high exhaust temperature, so not only during steady operation (from idling to full throttle), but also during acceleration and low speed operation. The oxidation reaction of the catalyst can be promoted. Furthermore, the exhaust manifold with the catalytic exhaust plate is located in a position where it is difficult for water to enter, so there is no damage to the catalyst due to water (salt water), and there is no deterioration in catalyst durability or purification performance, and it can be used not only in new engines but also in existing engines. It is also easy to implement and can greatly contribute to the purification of exhaust gas from marine propulsion systems in general in the future.

[Brief explanation of drawings]

Fig. 1 is a horizontal sectional view showing an embodiment of the present invention, Fig. 2 is a perspective view showing a part of the catalytic exhaust plate in Fig. 1, and Fig. 3 is a sectional view taken along line A-A in Fig. 2. ,
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, 1
2...Exhaust tube, 13...Cylinder,
14... Exhaust plate, 16... Catalyst exhaust plate, 17... Spacer, 1
8... Bolt, 20... Catalyst, 22... Exhaust port.

Claims (1)

[Claims] In a marine propulsion system that has an exhaust system that discharges water into the water through an exhaust tube connected to the engine's exhaust manifold, a catalytic exhaust plate with a catalyst sprayed on its surface is arranged in layers along the flow of exhaust inside the exhaust manifold. An exhaust gas purification device for a marine propulsion unit characterized by the following.