Catalytic Apparatus for Motorcycle Exhaust Pipe

Abstract

A catalytic apparatus is used for a motorcycle with an engine. The catalytic apparatus includes an engine exhaust manifold, a silencer, a front exhaust pipe positioned between the engine exhaust manifold and the silencer, a front supply pipe connected to the engine exhaust manifold and configured for supplying secondary air, and at least one catalytic converter positioned in the silencer. A catalyst is coated on an inner wall of the front exhaust pipe. The catalyst receives the secondary air supplied by the front supply pipe to clean engine exhaust gases. Particularly, when the motorcycle is started in a cold state, the present catalytic apparatus can enhance the temperature of the engine exhaust gases, and the at least one catalytic converter can be accelerated to reach its operating temperature.

Description

BACKGROUND

1. Field of the Invention

The present invention relates to an apparatus for cleaning exhaust gases and, more particularly, to an apparatus that utilizes a catalyst arranged in an exhaust pipe of a motorcycle engine to clean engine exhaust gases.

2. Description of the Prior Art

In order to satisfy the exhaust-gas discharge standard that is becoming strict more and more, manufacturers conventionally position a catalytic converter in an exhaust pipe of a motorcycle engine. The catalytic converter includes a metal tube and a catalyst coated on an inner surface thereof. Generally, the catalyst contains noble metal elements such as palladium (Pd), platinum (Pt), rhodium (Rh), and so on. The elements of Pd and Pt can advantageously oxidize harmful carbon monoxide (CO) and hydrocarbon (HC) contained in exhaust gases to harmless carbon dioxide (CO₂) and water (H₂O). The element of Rh can advantageously deoxidize harmful nitrogen oxide (NO_X) contained in the exhaust gases to harmless nitrogen (N₂) and oxygen (O₂). Therefore, engine exhaust gases can be cleaned, and an effect on air quality caused by the exhaust gases can be reduced.

As known in the art, the most ideal air/fuel ratio is controlled in a range of about 14.7, so that harmful substances in the exhaust gases can be oxidized or deoxidized by the catalyst arranged in engine exhaust pipe. Further, a motorcycle engine started in a cold state can generate over harmful exhaust gases because of an incomplete combustion of fuel. Therefore, in order to increase an exhaust-gas cleaning efficiency of the catalyst, a conventional technology usually induces secondary air in the catalytic converter at the front thereof when the motorcycle engine is started in the cold state. With the induced secondary air, the air/fuel ratio in the engine exhaust gases is equal to or larger than 14.7, so that the catalyst can acquire sufficient O₂ to oxidize CO and HC to CO₂ and H₂O. When a generating amount of CO and HC in the engine exhaust gases is reduced, the secondary air is stopped inducing, so that the air/fuel ratio in the engine exhaust gases is smaller than 14.7 and the catalyst can deoxidize NO_X to N₂ and O₂.

However, the catalyst in the engine exhaust pipe needs to be heated by the exhaust gases with a higher temperature. Only after the catalyst reaches its ideal operating temperature, a cleaning (including oxidation and deoxidization) reaction with the exhaust gases can be successfully carried through. Because the catalyst cannot immediately reach its operating temperature when the motorcycle engine is started in the cold state, the result is that a lot of harmful exhaust gases can be generated and discharged in the outer atmosphere.

In order to overcome the above-mentioned problems, an apparatus for cleaning engine exhaust gases has been disclosed in Taiwan Patent No. M287869. In this apparatus, a rear catalytic converter is arranged in a silencer, and a front catalytic converter is positioned in a front exhaust pipe arranged between the silencer and a motorcycle engine. When the motorcycle engine is started in a cold state, the engine exhaust gases firstly react with the catalyst in the front catalytic converter, so as to increase the temperature of the engine exhaust gases. Then, the front catalytic converter is thus accelerated to reach its operating temperature, so that the exhaust gases are effectively cleaned. However, the above-mentioned front catalytic converter is fixed in the front exhaust pipe in a welding manner. This welding manner is obviously difficult to be implemented on a front exhaust pipe with an aperture only ranging from 15 mm to 30 mm. In addition, the apparatus with a plurality of catalytic converters cost a lot.

What is needed, therefore, is an improved catalytic apparatus.

BRIEF SUMMARY

A catalytic apparatus for a motorcycle with an engine according to an embodiment of the present invention includes an engine exhaust manifold, a silencer, a front exhaust pipe positioned between the engine exhaust manifold and the silencer, a front supply pipe connected to the engine exhaust manifold and configured for supplying secondary air, and at least one catalytic converter positioned in the silencer. A catalyst is coated on an inner wall of the front exhaust pipe.

The catalyst can receive the secondary air supplied by the front supply pipe to clean engine exhaust gases. Particularly, when the motorcycle is started in a cold state, the present catalytic apparatus can enhance the temperature of the engine exhaust gases, and the at least one catalytic converter can be accelerated to reach its operating temperature.

These features and advantages of the present invention will be fully understood and appreciated from the following detailed description of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the various embodiments disclosed herein will be better understood with respect to the following description and drawings, in which like numbers refer to like parts throughout, and in which:

FIG. 1 is a partial cross-sectional view of a first embodiment of the present invention.

FIG. 2 is an enlarged, partial view of FIG. 1.

FIG. 3 is an operating view of the first embodiment of the present invention.

FIG. 4 is a partial cross-sectional view of the first embodiment of the present invention, with an alternative feature.

FIG. 4a is a cross-sectional view of the first embodiment of the present invention, with an additional feature.

FIG. 5 is a partial cross-sectional view of a second embodiment of the present invention.

FIG. 6 is a partial cross-sectional view of a third embodiment of the present invention.

FIG. 7 is an operating view of the third embodiment of the present invention.

DETAILED DESCRIPTION

Reference will now be made to the figures to describe the present invention in detail.

Referring to FIG. 1, a catalytic apparatus for a motorcycle with an engine in accordance with a first embodiment of the present invention is shown. The engine can be a four-cycle engine 1. The catalytic apparatus includes an engine exhaust manifold 11, a silencer 2, and a front exhaust pipe 3 positioned between the engine exhaust manifold 11 and the silencer 2. A front supply pipe 41 is connected to the engine exhaust manifold 11, and is used for supplying secondary air. A catalytic converter 5 is positioned in the silencer 2.

When the engine 1 is in operation, an intermittent negative pressure can be generated in the front exhaust pipe 3 and the engine exhaust manifold 11. The intermittent negative pressure can function as a power source to continuously induce the secondary air in the front exhaust pipe 3 and the silencer 2 through the front supply pipe 41.

The catalytic converter 5 is connected to the front exhaust pipe 3 via a connecting pipe 31. A catalyst including Pd, Pt, Rh, and so on is coated on an inner surface of the catalytic converter 5. Referring to FIG. 2, a catalyst 50 with elements same with the catalyst of the catalytic converter 5 is coated on an inner wall of the front exhaust pipe 3 that is located at rear of the front supply pipe 41.

Referring to FIG. 3, when the engine 1 is started in a cold state, the secondary air can be continuously induced in the front exhaust pipe 3 so as to supply sufficient O₂ to the catalyst 50 in the front exhaust pipe 3. Thus, the air/fuel ratio in engine exhaust gases is equal to or larger than 14.7, and the catalyst 50 in the front exhaust pipe 3 can oxidize the exhaust gases. That is, the catalyst 50 can oxidize harmful CO and HC to harmless CO₂ and H₂O, and the temperature of the engine exhaust gases is also enhanced. The connecting pipe 31 can transmit the exhaust gases with quickly rising temperature in the silencer 2. When the exhaust gases with quickly rising temperature pass through the catalytic converter 5, the temperature of the catalytic converter 5 can be enhanced to its operating temperature. As a result, the catalyst converter 5 can deoxidize harmful NO_X of the exhaust gases to harmless N₂ and O₂.

Alternatively, referring to FIG. 4, a front supply pipe 40 can also be connected to the front exhaust pipe 3 to replace the above-mentioned front supply pipe 41. The front supply pipe 40 has the same function with the above-mentioned front supply pipe 41. Referring to FIG. 4a, the catalyst 50 can be further coated on an inner wall of the connecting pipe 31.

Referring to FIG. 5, a catalytic apparatus for a motorcycle with an engine in accordance with a second embodiment of the present invention is shown. The engine can be a two-cycle engine 1. The catalytic apparatus includes an engine exhaust manifold 11a, a silencer 2a, and a front exhaust pipe 3a positioned between the engine exhaust manifold 11a and the silencer 2a. A front supply pipe 41a is connected to the engine exhaust manifold 11a, and is used for supplying secondary air. An end of the front exhaust pipe 3a is arranged in the silencer 2a, and a catalytic converter 5a is positioned in the end of the front exhaust pipe 3a. A catalyst 50a is coated on a part of or whole of an inner wall of the front exhaust pipe 3a that is located at rear of the front supply pipe 41a. The second embodiment has the same function with first embodiment.

Referring to FIG. 6, a catalytic apparatus for a motorcycle with an engine in accordance with a third embodiment of the present invention is shown. The engine can be a four-cycle engine 1. The catalytic apparatus includes an engine exhaust manifold 11, a silencer 2, and a front exhaust pipe 3 positioned between the engine exhaust manifold 11 and the silencer 2. A front supply pipe 41 is connected to the engine exhaust manifold 11, and is used for supplying secondary air. A front catalytic converter 51 and a rear catalytic converter 52 are arranged in the silencer 2. The front catalytic converter 51 and the rear catalytic converter 52 are connected to the front exhaust pipe 3 in series via connecting pipes 31, 32. A rear supply pipe 42 is connected to the connecting pipe 33, and is used for supplying the secondary air. A catalyst 50 is coated on an inner wall of the front exhaust pipe 3 that is located at rear of the front supply pipe 41.

Referring to FIG. 7, because the secondary air can be continuously induced in the front exhaust pipe 3 through the front supply pipe 41, the air/fuel ratio in engine exhaust gases is equal to or larger than 14.7. Thus, the catalyst 50 in the front exhaust pipe 3 can oxidize the exhaust gases, and the temperature of the exhaust gases is also enhanced. The connecting pipe 32 can transmit the exhaust gases with quickly rising temperature in the silencer 2. When the exhaust gases with quickly rising temperature pass through the front catalytic converter 51, the temperature of the front catalytic converter 51 can be enhanced to its operating temperature. As a result, the front catalyst converter 51 can deoxidize harmful NO_X of the exhaust gases to harmless N₂ and O₂. Then, the exhaust gases are transmitted by the connecting pipe 33 and mix with the secondary air supplied through the rear supply pipe 42. When mixed gases pass through the rear catalytic converter 52, the rear catalytic converter 52 can oxidize residual harmful CO and HC to harmless CO₂ and H₂O again. Therefore, the cleaning efficiency of the catalyst is enhanced.

The above description is given by way of example, and not limitation. Given the above disclosure, one skilled in the art could devise variations that are within the scope and spirit of the invention disclosed herein, including configurations ways of the recessed portions and materials and/or designs of the attaching structures. Further, the various features of the embodiments disclosed herein can be used alone, or in varying combinations with each other and are not intended to be limited to the specific combination described herein. Thus, the scope of the claims is not to be limited by the illustrated embodiments.

Claims

1. A catalytic apparatus for a motorcycle with an engine, the catalytic apparatus comprising an engine exhaust manifold, a silencer, a front exhaust pipe positioned between the engine exhaust manifold and the silencer, a front supply pipe connected to the engine exhaust manifold and configured for supplying secondary air, and at least one catalytic canister positioned in the silencer; wherein, catalyst is directly coated on an inner wall of the front exhaust pipe, and the catalyst receives the secondary air supplied by the front supply pipe to clean engine exhaust gases.

2. The catalytic apparatus as claimed in claim 1, wherein the number of the at least one catalytic canister is plural, and the plural catalytic canisters comprise at least one front catalytic canister and at least one rear catalytic canister, and a rear supply pipe is connected between the at least one front catalytic canister and the at least one rear catalytic converter and is also configured for supplying secondary air.

3. A catalytic apparatus for a motorcycle with an engine, the catalytic apparatus comprising an engine exhaust manifold, a silencer, a front exhaust pipe positioned between the engine exhaust manifold and the silencer, a front supply pipe connected to the front exhaust pipe and configured for supplying secondary air, and at least one catalytic canister positioned in the silencer; wherein, catalyst is directly coated on an inner wall of the front exhaust pipe, and the catalyst receives the secondary air supplied by the front supply pipe to clean engine exhaust gases.

4. The catalytic apparatus as claimed in claim 3, wherein the number of the at least one catalytic canister is plural, and the plural catalytic canisters comprise at least one front catalytic canister and at least one rear catalytic canister, and a rear supply pipe is connected between the at least one front catalytic canister and the at least one rear catalytic canister and is also configured for supplying secondary air.