Secondary air injection system for an internal combustion engine
Field of the invention

The present invention relates to "Secondary air injection system for an internal combustion engine" and more particularly to an arrangement for a secondary air injection system for supplying air to the exhaust manifold of an internal combustion engine

Background of the invention

An air injection system is an apparatus for cleaning exhaust gases of an IC engine, wherein secondary air is supplied and fed into the exhaust manifold of an engine. Additional air is provided while exhaust gases are in a high temperature state so that detrimental components in the exhaust gases may be oxidized and made nondetrimental. Typically secondary air injection system for an IC engine comprises of an air filter having an inlet and outlet, the said outlet supplying air to the exhaust manifold through a one-way valve and the said inlet draws air from the atmosphere. In case of low floored two wheelers, the said air filter inlet is in direct contact of polluted atmosphere, dust as well as other impurities. The said air filter is fitted as close to the exhaust manifold as possible and as a result of this, the chances of coming across the path of impurities become more prominent since the engine is located substantially lower part of the vehicle. Consequent this, the said air filter requires frequent servicing. Moreover, this induction of air to the said air filter causes a noise nuisance. With a view to obviate prior art defects as pointed out above, it is a primary object of the present invention to provide a novel and improved secondary air injection arrangement which is suitable for purifying exhaust gases from the engine having a greater shelf life.

Another objective of the present invention is to provide means for reducing induction noise produced due to suction of air by said air filter.

Another objective of the present invention is to provide better life and serviceability to air filter for the secondary air injection.

Brief description of the invention

A secondary air injection layout with a one-way valve and an air filter mounted on the main frame of a motorcycle. Clean air from the air filter is injected on the exhaust pipe to reduce emissions. Moreover, this arrangement reduces the air induction noise. The said one-way valve is mounted on engine bracket with a provision for anti-rotation to inject air into the exhaust pipe. The air inlet that is taken from the main frame to reduce air induction noise also prevents dust and water entry.

Brief description of the drawings

Figure 1 illustrates side view of a motorcycle according to one embodiment of the present invention

Figure 2 illustrates the secondary air injection system according to one embodiment of the present invention

Detailed description of the invention

A selected illustrative embodiment of the present invention will be now described with respect to the accompanying figures 1 and 2. A motorcycle body frame 100 comprises a head pipe 101, at least a tube extending downwardly and then extends almost horizontally (not shown in the figure) and then at the posterior position extends upwards (not shown in the figure) and further backwardly and horizontally. The rear most part of the said tube is opened to the atmosphere. A front wheel 102 is carried through the intermediary of a front fork 103 that is rotatably mounted within the head pipe 101. A rear wheel 104 is carried on the rear end of a rear fork 105 that is swingably pivoted on the rearward lower position of the vehicle body frame 100. A seat 106 is disposed above the shock absorber 105. Forwardly of the seat, a fuel tank 107 is mounted over the mono pipe 101. Behind the fuel tank 107, a step through space 108 is provided between the fuel tank 107 and the seat 106. A two-stroke cycle engine 109 is mounted under a footboard 110 and behind the front wheel 102. The exhaust pipe 111 extends from the engine 109 to the rear portion of the vehicle.

A secondary air injection system 201, to feed secondary air, is provided in a position adjacent to exhaust manifold 111 of engine 109. The said secondary air injection system 201 comprises of a filter 202 having an inlet 203 and an outlet 204. The outlet 204 is connected with a secondary air-feeding pipeline 205 through a one-way valve 206 allowing only flow of secondary air into the exhaust manifold 111. The air induction inlet 203 of the said air filter 202 is mounted through a hose 207 onto a metal tube that is welded on to the hole drilled on the lower part of the said tube of the said motorcycle frame 101.

Since the rear most part of the said tube is opened to the atmosphere, entry of air is accomplished. The serviceability of the said filter 202 is increased because the dust entering into the filter 202 is reduced considerably, since the air comes from the frame 101 that is less susceptible to dust due to location of air inlet into the frame 101 on its upper part. The secondary air filter is mounted on the frame with the help of a bracket 208 supported on the engine crankcase. This prevents anti rotation through installation of a poka yoke structure.

Moreover, the secondary air injection inlet 203 from lower part of the said tube of the frame 101 improves noise reduction when compared to air injection from direct atmosphere as a result of a resonating volume created by the said tube of the frame 101. Also, due to this secondary air injection system 201, the emissions decrease considerably that could be observed from the following experimental information.

Although the subject matter has been described in considerable detail with reference to certain preferred embodiments thereof, other embodiments are possible. As such, the spirit and scope of the appended claims should not be limited to the description of the preferred embodiment contained therein.

Claims

We claim:

1. A secondary air injection system 201 for a motorcycle comprising
a filter 202 having an inlet 203 and an outlet 204;
an one way valve 206;
wherein the said filter inlet 203 is connected to a provision made on the
frame 101 of the said motorcycle by means of hoses.

2. A secondary air injection system 201 for a motorcycle as claimed in claim 1, wherein the said filter outlet 204 is connected with a secondary air feeding pipeline 205 through the said one way valve 206.

3. A secondary air injection system 201 for a motorcycle as claimed in claim 1, wherein the said secondary air feeding pipeline 205 is connected to the exhaust manifold 111.

4. A secondary air injection system 201 for a motorcycle as claimed in claim 1, wherein the said air induction inlet 203 of the said air filter 202 is mounted through a hose 207 onto a metal tube that is welded or mounted on the provision drilled on the lower part of the said motorcycle frame 101.

5. A motorcycle having a secondary air injection system 201 comprising a filter 202 having an inlet 203 and an outlet 204;
an one way valve 206;
wherein the said filter inlet 203 is connected to a provision made on the
frame 101 of the said motorcycle by means of hoses;
wherein the said filter outlet 204 is connected with a secondary air
feeding pipeline 205 through the said one way valve 206. A