Claims:We Claim:
1. A single cylinder internal combustion engine (100); comprising at least
a crankcase (102);
a cylinder block (103); and
cylinder head (104) located on said cylinder block 103;
characterized in that

a casing (106) rigidly fitted on said cylinder head 104, said casing 106 interfacing with an inlet (108) and outlet (110) of said single cylinder internal combustion engine 100; and

a plurality of flow control valves (112 & 114) provided within said casing 106 in a manner so as to control the flow of air charge flowing through said inlet (108) and said outlet (110) of said single cylinder internal combustion engine (100).
2. The single cylinder internal combustion engine of claim 1, wherein said flow control valves (112& 114) are reed valves.
3. The single cylinder internal combustion engine of claim 1, wherein opening and/ or closing of said reed valve is through pressure variation generated during suction and exhaust stroke of said single cylinder internal combustion engine.
4. The single cylinder internal combustion engine of claim 1, wherein said reed valve is electronically actuated.
5. The single cylinder internal combustion engine of claim 1, wherein said flow control valves (112& 114) are poppet valves.
6. The single cylinder internal combustion engine of claim 1 and 5, wherein said poppet valve is driven by a cam shaft.
7. The single cylinder internal combustion engine of claim 1, wherein the opening/ closing of said flow control valves (112& 114) is synchronized with respect to an engine valve (116) of said single cylinder internal combustion engine (100).
8. The single cylinder internal combustion engine of claim 1, wherein said engine valve 116 is used during both suction stroke and exhaust stroke.
9. The single cylinder internal combustion engine of claim 1, wherein said engine valve 116 is at least one of a single valve, twin valve or a multiple valve. , Description:Field of the invention
[0001] This invention relates to the field of internal combustion engines.
Background of the invention
[0002] Single cylinder engines are used in low cost applications in emerging markets, like vehicles used for transportation of goods, raw materials and other articles. In most cases, these vehicles operate under full load condition. Higher the load on the engine, more will be the emission from the vehicle. With the advent of stringent emission norms in vehicles, there is a need for a low cost solution to combat emissions. Techniques to reduce emission norms are known in the art. One such technique, is to increase the amount of air supplied to the engine through synchronous valve actuation. In the case of synchronous valve actuation, a single valve opens and closes both the inlet and outlet paths. However in case of synchronous valve actuation the timing of opening of inlet and outlet valve is of prime importance. Also, in order to increase the volumetric efficiency of the engine, there is a need to increase the availability of air during every engine cycle.
[0003] Prior art patent application US5331929 discloses a cylinder head for an internal combustion engine of either a two-cycle operation or a four-cycle operation is disclosed. The cylinder head includes an intake port, an exhaust port, a dual-function chamber, a poppet valve positioned within the dual-function chamber, and a flapper valve also positioned within the dual-function chamber, capable of sealing the intake port from the dual-function chamber, capable of sealing the exhaust port from the dual-function chamber. If the cylinder head is for a two-cycle engine, an injector may be positioned within the cylinder head so that fuel is injected either within the dual-function chamber, or directly injected within the combustion chamber. A process of operating the cylinder head in conjunction with an internal combustion engine is also disclosed.
Brief description of the accompanying drawing
[0004] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:
[0005] FIG. 1 illustrates a single cylinder internal combustion engine.
Detailed description of the embodiments
[0006] FIG. 1 illustrates a single cylinder internal combustion engine 100. The single cylinder internal combustion engine 100 comprising at least a crankcase 102, a cylinder block 103, and a cylinder head (104) located on the cylinder block 103. A casing 106 is rigidly fitted on to the cylinder head 104. The casing 106 interfaces with an inlet 108 and outlet 110 of the single cylinder internal combustion engine 100. A plurality of flow control valves (112& 114) are provided within the casing 106 in a manner so as to control the flow of air charge flowing through the inlet 108 and the outlet 110 of the single cylinder internal combustion engine 100. The flow control valve 112 corresponds to inlet 108, while the flow control valve 114 corresponds to outlet 110. The flow control valves (112& 114) are reed valves. The opening and/ or closing of the reed valve is through pressure variation generated during suction and exhaust stroke of the single cylinder internal combustion engine 100. Alternately, the reed valve may also be electronically actuated. The flow control valves (112& 114) may also be poppet valves. The poppet valve may also be driven by the cam shaft.
[0007] The constructional details of the single cylinder internal combustion engine 100 will now be described in further detail. The crankcase 102 encloses the crankshaft, the cylinder block 103 is attached or integrated to the crankcase 102. The cylinder block 103 houses a reciprocating piston. The piston is connected to the crankshaft via a connecting rod. The cylinder head 104 is located on the cylinder block 103 and comprises at least an inlet 108 and an outlet 110. The cylinder head 104, serves to deliver air charge into the cylinder block 103. The piston together with a portion of the cylinder head 104 defines an area of combustion zone in the cylinder block 103. Additionally, a casing 106 is rigidly fitted on the cylinder head 104, the casing 106 interfaces with an inlet 108 and outlet 110 of the single cylinder internal combustion engine 100. The casing 106 may be in the form of a box or cover like structure. The casing 106 defines an enclosed space between the inlet 108 of the cylinder head 104 and outlet 110 of the cylinder head 104 and the cylinder block 103. The inlet 108 and outlet 110 are provided with a plurality of flow control valves (112& 114) respectively so as to control the flow of air charge. The flow control valves (112& 114) may be at least one chosen from a reed valve or a poppet valve. The inlet 108 and outlet 110 opens into an engine valve 116 that allows air charge to flow into the cylinder block 103 for combustion to happen. The engine valve 116 is located on the cylinder block 103. The engine valve 116 is used during both suction and exhaust strokes. The opening/ closing of the flow control valves (112& 114) is synchronized with respect to the engine valve 116 of the single cylinder internal combustion engine (100).The engine valve 116 is at least one of a single valve, twin valve or a multiple valve.
[0008] The working of the single cylinder internal combustion engine 100 will now be described in further detail. During suction stroke, a negative pressure will be generated in the single cylinder internal combustion 100 engine, due to traverse of the piston. The engine valve 116 will open, and a time lag will exists for opening of the flow control valve 112 that is located on the inlet 108. If the flow control valve 112 is a poppet valve, then the timing of opening of the poppet valve can be controlled by the cam shaft so as to provide for the time lag. When the flow control valve 112 is a reed valve, then the opening/ closing of reed valve will happen due to pressure variation created due to movement of the engine valve 116. As the flow control valve 112 opens, a pressure wave is generated, higher the magnitude of pressure wave higher is the amount of air charge that is sucked into the single cylinder internal combustion engine 100 via the air filter. The air charge that is sucked into the engine 100 mixes with the fuel received from an injector to form a combustible mixture for the combustion process to occur. As the combustible mixture explodes the piston moves downwards (that is away from the cylinder head 104). Upon completion of the combustion process the combustible charge also called as the exhaust charge needs to be expelled, in order to bring in a fresh volume of air charge and fuel. This will happen during the exhaust stroke, as the piston moves upwards, pressure is built up in the cylinder block 103, the engine valve 116 opens, and the exhaust then enters the casing 106. The opening of the flow control valve 114 (reed/ poppet valve) at the outlet 110 of the casing 106 is now delayed. This delay also helps to bring about the effect of exhaust gas re-circulation (EGR) by using the casing 106. This EGR is also called as internal EGR as this is achieved within the casing 106 itself. A part of the exhaust charge that remains within the casing 106 will now mix with incoming fresh air charge that enters the casing 106 through the inlet 108 during the next intake stroke. The fresh air charge along with a part of the exhaust will now enter the single cylinder internal combustion engine 100 through the engine valve 116. The remaining exhaust charge in the casing 106 is then expelled through the outlet 110. This process of partly re-circulating the exhaust charge within the casing 106, in order to reduce emission by using the casing 106 fitted onto the cylinder head 104 is cost-effective, and improves volumetric efficiency of the engine. Also by timing the opening and closing of the flow control valve (112& 114) with respect to the engine valve 116, the flow of air charge can be controlled so as to match the combustion and exhaust cycles in the single cylinder internal combustion engine 100.
[0009] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention in terms of type of valve used and the mechanism used to actuate the valve. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.