SECONDARY AIR INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINES

Field of the Invention

The present invention relates to " Secondary air injection system for internal combustion engines", and more particularly relates to a single cylinder, four-stroke internal combustion engine equipped with a secondary air injection system.

Background of the invention

In known internal combustion engines, additional air is supplied to the exhaust system of the internal combustion engines in order to effectively oxidize the oxidizable hydrocarbons and noxious constituents contained in the exhaust gases discharged from the engines, this additional air being generally referred to as "secondary air".

The secondary-air injection system is adapted to inject secondary air Into the exhaust gases in the exhaust system of an internal combustion engine. In the known secondary air injection systems, the secondary air is injected to the high temperature exhaust gases through a secondary air injection nozzle, which is installed in the wall of an exhaust manifold and projected into the exhaust port formed in the cylinder head.

In the known arrangements, the exhaust gases discharged from the combustion chamber are normally under certain pressure, also the secondary air injection manifold is connected to the air injection nozzle which is generally
placed in the exhaust manifold, and hence in most of the time the secondary air supplied to the exhaust port is insufficient with respect to the conversion requirements.

This insufficient air supply results in non-uniform mixing of the secondary air and the exhaust gases, and hence reduction in the conversion efficiency of the secondary air injection system of the Internal combustion engine.

The arrangements mentioned above have encountered difficulties such as non -uniform mixing of the exhaust gases and Ineffective conversion using the secondary air injection. Hence there exists a need for an improved secondary air injection system, which delivers higher conversion efficiency and increased durability in respect to secondary air injection to the internal combustion engine.

Object of the invention

The main objective of the present Invention is to provide an improved Internal combustion engine capable of providing higher exhaust gas conversion efficiency by effectively reducing the emission levels of the unburned hydrocarbons and noxious constituents of the exhaust gases from the internal combustion engine.

Another objective of the present invention Is to provide an improved secondary air injection system in which the unburned constituents contained in the exhaust gases of the engine are converted into purified gases in the presence of the secondary air supply.

Another object of the present invention is to provide an Internal combustion engine equipped with an improved air injection system, which allows for reducing jerks even at low speed operating conditions and thereby effectively promoting the drivability of the said engine.
Yet another object of the present invention Is to provide an internal combustion engine equipped with an improved air injection system, which can effectively promote the oxidation reaction of the unbumed hydrocarbon and noxious constituents In the exhaust gases of the engine.

Summary of the invention

In accordance with the present invention, an automotive Internal combustion engine Includes a power cylinder having an Inlet port and an exhaust port and an air-filter for feeding air mixture to the engine. The engine comprises an exhaust-gas passageway leading from the exhaust port of the cylinder.

The exhaust-gas passageway includes a secondary-air feed passageway formed in the exhaust manifold in the cylinder head of the intemal combustion engine. A check valve is arranged for providing control between the secondary-air that Is fed to the exhaust-gas passageway, such that the valve acts as a one way check valve in which, the air can only pass from the secondary air injection into the exhaust passage and no returning of gas from exhaust passage to secondary air injection passage is possible.

The secondary air Injection into the exhaust manifold includes a reservoir arranged in the secondary injection passage for storing the secondary air from the induction chamber. The reservoir in the secondary air injection passage accumulates the secondary air and expands with variable volume before the secondary air is injected into the exhaust chamber. This accumulation and expansion of the air in the reservoir allows improving the injection pressure and enables for uniform mixing of the exhaust gases and effective conversion of the exhaust gases from the combustion chamber of the internal combustion engine.

These and other features, aspects, and advantages of the present subject matter will be better understood with reference to the following description and appended claims. This summary is provided to introduce a selection of concepts in a simplified form. This summary is not intended to be used to identify key features or essential of the claimed subject matter, nor it is intended to be used to limit the scope of the claimed subject matter.

Brief description of accompanyinq drawings
The other objects, features and advantages of the internal combustion engine according to the present invention will be more apparent from the following description with reference to the accompanying drawing, in which:

FIG. 1 is a schematic left side view showing the engine along with the secondary air injection system mounted on the frame of a vehicle.

FIG. 2 illustrates the front view showing the automotive internal combustion engine provided with a secondary air injection system

FIG. 3 is a view showing an embodiment of secondary air injection system of an Internal combustion engine provided with a secondary air reservoir and a check valve,

FIG. 4 illustrates the front view showing the internal combustion engine provided with a secondary air injection system having secondary air reservoir housing perforated profiled secondary air Injection pipe.

FIG. 5 illustrates the construction of secondary air reservoir provided with perforated secondary air injection pipe.

Detailed description of preferred embodiments

The subject matter will be described with reference to the accompanying drawings.

The motorcycle as illustrated in Fig. 1 comprises of a frame (1), front fork (2)
attached to a pivot tube of the vehicle frame, a circle representing the front wheel (3) is attached to the front forks, a handle bar (4) connected to the front forks, a fuel tank attached so as to straddle an upper part of the vehicle frame, a seat attached to the upper rear portion of the vehicle frame, an engine unit (E) attached to the lower front section of the vehicle frame, a swing arm attached to a lower rear section of the vehicle frame, suspended by a rear shock absorber from the vehicle frame and a rear wheel attached to a rear end of swing arm. The intake system of the engine comprises of a carburettor, intake duct and an air cleaner. The exhaust system of the engine comprises of exhaust pipe and a muffler.

The motorcycle is also provided with a side cover for covering a side section of the vehicle frame, a seat cover for covering a rear section of the vehicle frame below the seat, a front fender for covering an upper part of the front wheel, and a rear fender for covering an upper part of the rear wheel.

As shown in Fig. 2, the present invention relates in to an internal combustion engine (E) for automotive use and more particularly to an automotive internal combustion engine (E), which Is equipped with a secondary-air injection system (100) for emission control purposes.

The present invention therefore contemplates elimination of ail the above described drawbacks of the known secondary-air injection systems incorporated in the automotive internal combustion engine (E). The present Invention is made to provide an automotive engine (E) featuring the secondary-air injection system (100) arranged to fully exhibit the potential performance efficiency in conversion of exhaust gas contaminants, viz.,nitrogen oxides, hydrocarbons and carbon monoxide in the exhaust emissions of an internal combustion engine (E).

In accordance with the present invention and as shown in Fig. 3, an automotive internal combustion engine (E) includes a power cylinder (101) having an inlet port (102) and an exhaust port (103), and an air filter (105) for feeding air to the cylinder (101) of the engine (E). The engine (E) comprises an exhaust-gas passageway (104) leading from the exhaust port (103) of the power cylinder (101).

The exhaust-gas passageway (104) includes a secondary-air feed passageway (200) formed in the exhaust manifold in the cylinder head of the internal combustion engine (E). A control check valve (201) means is arranged for providing control between the secondary-air feeding (200) and the exhaust-gas passageway (104), such that the valve (201) acts as a one way check valve in which, the air can only pass from the secondary air injection (200) into the exhaust passage (104) and no returning of air from exhaust passage (104) to secondary air injection passage (200) is possible.

The secondary air injection into the exhaust manifold includes a reservoir (203) arranged in the secondary injection passage (200) for storing the secondary air from the air filter (105). The reservoir (203) in the secondary air injection passage (200) accumulates the secondary air, which expands with the variable volume of the reservoir (203) before the secondary air is injected into the exhaust chamber.

This accumulation and expansion of the air in the reservoir (203) allows improving the injection pressure and thus enables the uniform mixing and effective conversion of the exhaust gases from the combustion chamber of the internal combustion engine (E).

The control check valve (201) which provides one-way passage of secondary air from air filter (105) to the engine (E) is placed in between the said air filter (105) and the secondary air reservoir (203). The secondary air reservoir (203) is connected to the engine (E) and the control check valve (201) such that the ratio of pipe length connecting engine (E) to the reservoir (203) and the pipe length connecting the reservoir to the control check valve (201) is 1:3.

In order to obtain better operating conditions and better drivability the secondary air reservoir (203) capacity is optimized and provided with respect to the requirements of the combustion capacity of the internal combustion engine (E). The ratio of the volume of the secondary air reservoir (203) to the volume of the combustion chamber (C) of the Internal combustion engine (E) is about 1:4.

In an embodiment of the present invention, as illustrated in Fig. 4, the secondary air injection system (100) includes the secondary air reservoir (203) which is constructed in such a way that the reservoir (203) housing houses the secondary air injection pipe (204) having perforated profile formed along the pipe profile covered in the area within the reservoir housing.

The perforations in the secondary air injection pipe (204) allow the secondary air to pass through the reservoir (203) for accumulation and expansion which is then injected. The accumulation and expansion of the secondary air through the secondary air reservoir (203) allows for uniform mixing of the exhaust gases and effective conversion of the exhaust gases from the combustion chamber of the internal combustion engine (E).

Fig. 5 illustrates the construction of the reservoir (203). A cup is formed with a flange perpendicular to its axis, around the periphery, having a width which is one tenth of its outer size at the top portion of the cup and a smaller opening at the bottom of the cup with a flange extending outside, parallel to its outer wall. Another cup is formed similarly with higher width flange along its periphery. The cups are placed one above the other facing the flange without a gap and the larger flange is folded over the smaller flange so as to form a parallel wall around the flange. A perforated tube is then passed through the joined cups, which forms a reservoir (203). The perforated tube is placed in such a way that the perforations open within the reservoir (203). The joint of the perforated tube with the reservoir is sealed by means of welding or brazing.

The secondary air enters into the reservoir (203) chamber for accumulation and expansion. This construction of secondary air resen/oir (203) allows for uniform mixing of the exhaust gases.

The construction of secondary air reservoir (203) also promotes the oxidation reaction of the unbumed hydrocarbons and noxious constituents in the exhaust gases of the engine (E), and hence improves exhaust gas conversion efficiency of the internal combustion engine as also the unburned constituents contained in the exhaust gases of the engine are converted into purified gases in the presence of the secondary air supply.

The present invention allows for providing an internal combustion engine equipped with an improved air injection system which allows for reducing jerks even at low speed operating conditions, and thereby effectively promoting the drivability of the internal combustion engine.

The present invention of secondary air injection reduces the after burn, and thereby eliminating engine exhaust noise at low speeds, and improving the engine smoothness and reducing the engine harshness.

Although the subject matter has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the subject matter, will become apparent to persons skilled in the art upon reference to the description of the subject matter. It is therefore contemplated that such modifications can be made without departing from the spirit or scope of the present subject matter as defined.

Claim:

1) A single cylinder internal combustion engine (E) having a cylinder (101) with an inlet port (102) and an exhaust port (103), an air filter (105) for feeding air to the engine, an exhaust gas passageway (104) leading from the exhaust port (103) of the cylinder (101), said exhaust gas passageway (104) is provided with a secondary air injection system (100) having a secondary air feed passageway (200) formed in
the exhaust manifold of the cylinder (101), a control check valve (201) for providing control between the secondary air feed passageway (200) and the exhaust gas passageway (104) said secondary air injection system (100) comprising:
a resen/oir (203) adapted to be provided in the secondary injection passageway (200) after the check valve (201) and ahead of the exhaust port (103) of the cylinder (101) for storing secondary air from the air filter (105).

2) The single cylinder internal combustion engine (E) as claimed in claim 1, wherein the said reservoir (203) is made of identical cup shaped halves joined at the ends to provide a leak proof arrangement.

3) The single cylinder internal combustion engine (E) as claimed in claim 1, wherein the said reservoir (203) is made of metal.

4) The single cylinder internal combustion engine (E) as claimed in claim 1, wherein a secondary air injection pipe (204) passes through the said reservoir (203), one end of the said pipe (204) is connected to the control check valve (201) and the other end is connected to the engine (E).

5) The single cylinder internal combustion engine (E) as claimed in claim 4, wherein the said secondary air injection pipe (204) passing through the reservoir (203) has plurality of perforations along its profile opening inside the reservoir (203).

6) The single cylinder internal combustion engine (E) as claimed in claim 1, wherein the said reservoir (203) is connected to the engine (E) and the control check valve (201) such that the ratio of the pipe length connecting engine (E) to the reservoir (203) and the pipe length connecting the reservoir (203) to the control check valve (201) is 1:3.

7) The single cylinder internal combustion engine (E) as claimed in claim 1, wherein the ratio of the volume of the secondary air reservoir (203) to the volume of the combustion chamber (C) of the internal combustion engine (E) is 1:4.

8) The single cylinder internal combustion engine (E) as herein substantially described and illustrated with reference to the accompanying drawings.