Air induction system for two and three wheelers

Field of invention

The present invention relates to an 'Air induction system for two and three wheelers" and more particularly to a set-up of intake manifolds of naturally aspirating internal combustion engines.

Background of the invention

A four stroke, naturally aspirated, carbureted SI engine consists of snorkel pipe, air filter assembly, air filter outlet pipe, carburetor and intake manifold connected to intake ports in the cylinder head assembly of engine (Figure 1). Intake manifolds are used to supply filtered air fuel mixture to the intake ports and combustion chamber of the engines. Similarly, the known type of air induction system for a four stroke, naturally aspirated, fuel injected SI engine consists of snorkel pipe, air filter assembly, air filter outlet pipe, throttle body and intake manifold connected to intake ports in the cylinder head assembly of engine (As shown in Figure 1-2). Whereas, typical induction system of four stroke, naturally aspirated C.I. engine consists of snorkel pipe, air filter assembly, air filter outlet pipe connected to intake ports of cylinder head assembly of engine (Figure 2).

In normal operation of SI engines, either carbureted or fuel injected engine and naturally aspirated CI engines, a negative gauge pressure is created in the intake manifold during the suction stroke, which is due to the piston movement. This makes the air to be sucked from the atmosphere in to engine via air-filter and intake manifold.

It is well known that the length of intake manifold impacts the volumetric efficiency of the engine. Generally, short intake manifold pipes results in better volumetric efficiency at higher engine speed and lengthier intake manifolds results in higher volumetric efficiency at lower engine speed.

The amount of incoming air through the manifold impacts the engine performances viz. power & torque, fuel efficiency and exhaust emissions. The amount of incoming air can be normalized with cylinder swept volume and generally represented using a parameter known as volumetric efficiency. The length of intake manifold impacts the volumetric efficiency of the engine. Generally, short intake manifold pipes, results in better volumetric efficiency at higher engine speeds and lengthier intake manifolds results in higher volumetric efficiency at lower engine speeds. However by using fixed length intake manifold the volumetric efficiency is compromised either at lower or higher engine speeds.

To overcome the above said problems, other automobiles such as four wheelers, have Variable Geometry Intake (VGI) systems (Figure 3). For improvement in volumetric efficiency of naturally aspirated engines, variable geometry intake manifold systems are used and their use in I.C. engines is well known. In a two stage VGI system, the length variation is carried out by closing or opening of a butterfly valve employed in shorter pipe by means of an electrical or electromechanical actuator (not shown in the Figure) controlled by an electronic control unit (not shown in the Figure).

Closing of short pipes (by means of closing butterfly valve in short pipe) results in filtered air traveling through longer pipe. This results in higher volumetric efficiency when the engine is running below a threshold speed. After crossing the threshold speed of engine, butterfly valve housed in short pipe, is opened by means of an electrical or electromechanical actuator (not shown in the Figure). In this configuration filtered air passes through the shorter pipe. This results in better volumetric efficiency when engine is running above the threshold speed. In such vehicles, the variable geometry intake units are placed in between air filter unit and intake port of the engine and consequently the space requirement is higher.

However in two and three wheelers, for reaping the advantages of the aforesaid principle, the presence of variable geometry intake units becomes a problem due to additional space required for such an arrangement. Hence in view of the aforesaid shortcomings of the prior art, the present invention aims to provide a compact air induction system with variable geometry intake for engines used in two wheeled vehicles as well as three wheeled vehicles.

Another objective of the present invention is to eliminate an independent variable geometry intake unit and to provide a compact air induction system for engines used in two wheeled vehicles as well as three wheeled vehicles.

Another objective of the present invention is to provide a variable geometry intake system with optimized volumetric efficiency of the engine at both high and low speed requirements.

Brief description of the invention

The present invention has been accomplished by altering the air filter outer wall itself for adding further geometry to the intake manifold, such that two air paths are formed within the air filter unit. The arrangement is made such that one air path would be shorter than the other. The switching operation is performed using a butterfly valve housed in the shorter pipe, operated by an electrical or electromechanical actuator (not shown in the Figure) and controlled by an electronic control unit (not shown in Figure). The air paths are switched using the electronic control unit depending on the engine operational conditions in order to optimize the volumetric efficiency of engine. Thus using a modified air-filter design and optimizing the volumetric efficiency of the engine at different operating conditions accomplish the rationale of variable geometry intake manifold.

Brief description of the drawings

Figure 1 illustrating the outline arrangement of a typical apparatus in a three-wheeler vehicle having a typical conventional air induction system of a 4 stroke, naturally aspirated engine with reference to prior art.

Figure 2 illustrates a typical conventional air induction system of a 4 stroke, naturally aspirated engine with reference to prior art.

Figure 3 illustrates a typical VGI system utilized in a 4 stroke, naturally aspirated Compression ignition engines with reference to prior art.

Figure 4 illustrates a cross section of air induction system involving a VGI unit with reference to prior art.

Figure 5 illustrates the modified air filter induction system for 4 stroke naturally aspirated spark or compression ignition engines incorporating principle of VGI system.

Figure 6 illustrates another view of the proposed invention showing 2 different paths at air filter outlet and a butterfly valve.

Detailed description of the invention

The disclosure provides an air induction system for engines involving a set-up of intake manifolds of naturally aspirating internal combustion engines. Figure 5 shows the proposed air induction system for four stroke, naturally aspirated S.I. or C.I. engines incorporating the principle of two stage Variable Geometry Intake system. The present invention modifies the outer wall of the air filter itself for adding additional geometry to intake manifold, such that two air paths are created within the air filter unit. The arrangement has been made such that one air path is shorter than the other one.

As referred in Figure 6, air filter unit 'B3' has two paths at the outlet i.e. filtered air can travel to intake port of engine through a shorter pipe 'G3' or longer pipe 'F3' housed in 'B3'. A butterfly valve 'E3' has been assembled in shorter pipe. Butterfly valve is operated by means of an electrical or electromechanical actuator (not shown in the Figure) and controlled by an electronic control unit (not shown in the Figure) with respect to some of the engine operating parameters.

This proposed arrangement results in higher volumetric efficiency during engine operation under the threshold speed. Once engine crosses the threshold operating speed, butterfly valve 'E3' is opened and filtered air travels to intake port through the shorter pipe 'G3'. This gives better volumetric efficiency during the engine operation above the threshold speed. Hence using the modified air-filter design and optimizing the volumetric efficiency of the engine at both high speed as well as low speed accomplish the same purpose of variable geometry intake manifold. Thus the system embodying the invention is capable of controlling the amount of air entering the engine such that the variable geometry intake unit enables compact engine layout for two and three wheeled vehicles.

Moreover, the weight and part count reduction is also achieved when compared to the air induction system housing a two-stage VGI system shown in prior art. This system has resulted in approximately 3 to 6 % better volumetric efficiency during the engine operation where the engine speed was above a threshold speed, compared to volumetric efficiency of a naturally aspirated four stroke CI engine without variable geometry intake system, employed in a three wheeled passenger vehicle.

The invention being thus described is applicable to both two and three wheeler and would prevail under the same spirit of invention as described and, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the claims.

Claims: We claim:

1. An air induction system for four stroke naturally aspirating engines, comprising:

a set up of air intake manifolds G3,F3;

a snorkel pipe A3;

an air filter assembly B3;

an air filter outlet pipe C3;

a throttle body.

2. The air filter assembly as claimed in claim 1, wherein the outer wall of the air filter is modified such that two air paths are formed within the same air filter unit.

3. The two air paths as claimed in claim 2, wherein one air path is shorter than the other.

4. The air induction system as claimed in claim 1, wherein the switching operation of the air paths is performed using a butterfly valve.

5. The butterfly valve as claimed in claim 4, wherein the butterfly valve is housed in the shorter pipe.

6. The butterfly valve as claimed in claim 4, wherein an electrical or electromechanical actuator operates the switching operation by the butterfly valve.

7. The butterfly valve as claimed in claim 4, wherein an electronic control unit controls the switching operation of the butterfly valve.

8. The air induction system for a four stroke naturally aspirating engines substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.