Claims:We claim:
1. An air distribution unit (100) for an engine, comprising at least:
an air charging device (102) located upstream from an engine (106); and
a flow control valve (104) located on cylinder head of said engine; characterized in that
said flow control valve (104) adapted to be operated in a first position and a second position of said air charging device, said first position corresponding to a suction stroke of said engine, and said second position corresponding to an exhaust stroke of said engine.

2. The air distributor unit of claim 1, wherein said air charging device is a supercharger 102.

3. The air distributor unit of claim 1 & 2, wherein said supercharger 102 drives said flow control valve 104.

4. The air distributor unit of claim 2 & 3, wherein a compensator volume 107 is provided in between said supercharger 102 and said flow control valve 104.

5. The air distributor unit of claim 1, wherein said air charging device is a pressure wave pump 200.

6. The air distributor unit of claim 1& 5, wherein said flow control valve 104 is driven by said engine.

7. The air distributor unit of claim 1, wherein said flow control valve 104 is a rotary slide valve.
8. The air distributor unit of claim 1, wherein in a first position said air charging device delivers air into said engine via said flow control valve 104.

9. The air distributor unit of claim 2 & 5, wherein in a second position said air charging device is adapted to receive exhaust from said engine 106. , Description:Field of the invention
[0001] This invention relates to the field of air distributor unit for engine.

Background of the invention
[0002] Air distribution mechanisms are well known in the art. These mechanisms are used for increasing the quantity of air charge supplied to an internal combustion engine. In the case of single cylinder engines, there is a need to increase air availability and also decrease NOx emissions to meet the stringent emission norms being implemented in emerging as well as developed economies. Hence, this presents a two pronged challenge in the automotive industry. Firstly increasing air charge supplied and secondly meeting the emission norms. Hence, there is a need for an air distribution mechanism that performs both of the above mentioned functions.
[0003] Prior art patent applicationEP0271130 discloses a four-stroke reciprocating piston combustion engine with supercharging and method for the operation thereof, whereby at the end of the driving out stroke flushing air is supplied under high pressure for the driving out of residual combustion gas in the exhaust pipe. The pressure in the exhaust pipe is kept higher than the pressure in the inlet pipe, and the flushing air is taken from a separate source of air under high pressure. A flushing air supply line is provided with a flushing air valve and connected with a source of air under high pressure, and control means for controlling the flushing air valve synchronously with the piston movement such that at the end of the driving out stroke the air valve is opened briefly while the exhaust valve is still just open.

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 an air distribution unit for an engine; and
[0006] FIG. 2 illustrates an air distribution unit for an engine with a pressure wave pump as the air charging device.
Detailed description of the embodiments
[0007] FIG. 1 illustrates an air distribution unit for an engine 106. The air distribution unit 100 for an engine 106, comprises at least an air charging device 102 located upstream from an engine 106, and a flow control valve 104 located on cylinder head of the engine 106. The flow control valve 104 adapted to be operated in a first position and a second position of the air charging device 102, the first position corresponds to a suction stroke of the engine 106, and the second position corresponding to an exhaust stroke of the engine 106. In the first position the air charging device 102 delivers air into the engine 106 via the flow control valve 104, and in the second position the air charging device 102 is adapted to receive a part of the exhaust from the engine 106. The air charging device 102 is a supercharger 102. The supercharger 102 drives the flow control valve 104. A compensator volume 107 is provided in between the supercharger 102 and the flow control valve 104.
[0008] The constructional features of the air distribution unit 100 employing supercharger 102 as the air charging device 102 will be discusses hereafter in further detail. As seen from FIG. 1, the supercharger 102 is located upstream from an engine 106. The air charge for the supercharger 102 is received from two sources namely, air from the atmosphere through air filter 103, and at least a part of the exhaust that is purified after passing through the exhaust filter 108. The exhaust path 110 is in flow communication with the supercharger 102. An exhaust gas re-circulation (EGR) valve 112 is provided to control the quantity of exhaust that reaches the air distribution unit 100. The air distribution unit 100 also comprises a compensator volume 107. The compensator volume 107 is provided in between said supercharger 102 and said flow control valve 104. The compensator volume 107 prevents the pressure surges from the supercharger 102 from reaching the engine 106. The flow control valve 104 is located on the cylinder head of the engine 106. The cylinder head of the engine 106 also comprises the inlet valve 109. The inlet valve 109 is common to both intake and exhaust strokes of the engine 106. The drive for the flow control valve 104 is received from the supercharger 102. The operation of the flow control valve 104 is synchronized with respect to suction and exhaust stroke of the engine 106.
[0009] The working of the air distribution unit 100 with supercharger 102 as the air charging device 102 will now be explained in further detail. The air from the atmosphere is sucked into the supercharger 102, and charged along with the exhaust charge (from the previous exhaust stroke of the engine 106). Pressurized air charge from the supercharger 102 flows into the compensator volume 107. The drive of the supercharger 102 and the flow control valve 104 are timed with respect to each other. In other words during suction stroke, the supercharger 102 will drive the flow control valve 104 to the first position, in a manner so that the supercharger 102 delivers air into the engine 106 via the flow control valve 104. Hence air is pressurized in between supercharger 102 outlet and flow control valve 104 inlet. Once, the air charge has been delivered into the engine 106, the fuel that is injected mixes with the air charge for combustion to happen. Upon completion of combustion process, the exhaust needs to be expelled out of the engine 106. For this to happen, the supercharger 102 will drive the flow control 104 valve to the second position. In the second position, the flow control valve 104 will block the flow of air charge into the engine 106, and will open the engine 106 to exhaust path 110 through the same inlet valve 109. The inlet valve 109 is common to both intake and exhaust strokes of the engine 106. The exhaust flows through the exhaust path 110, where a part of the exhaust is vented out to the atmosphere, while a remaining part of the exhaust is purified through the exhaust filter 108, before it is sent back to the inlet of the supercharger 102 via the EGR valve 112 for the next suction stroke to happen. The above mentioned air distribution unit 100 may also be used for engine 106 having multiple valves.
[0010] FIG. 2 illustrates an air distribution unit for an engine with a pressure wave pump 200 as the air charging device. The pressure wave pump 200 is located upstream from an engine. An inlet path 202 is provided for air from the atmosphere and exhaust received from the exhaust path 203 to enter into the inlet 204 of the pressure wave pump 200. A part of the exhaust is also used to provide pulsating charge to the pressure wave pump 200 through a path 206. The outlet of the pressure wave pump 200 is in flow communication with the inlet of the engine via the flow control valve 104. Hence, the air distribution unit, comprising the pressure wave pump 200 and the flow control valve 104, together regulate the flow of air charge into the engine, and the flow of exhaust out of the engine. The flow control valve 104 is driven by the engine. The timing of the flow control valve 104 matches with the suction and exhaust stroke of the engine 106.
[0011] The working of the air distribution unit comprising the pressure wave pump 200 and the flow control valve 104 will now be explained in further detail. The pressure wave pump 200 also called as exhaust charging pump is adapted to perform at least two important functions. Firstly, suck the exhaust gas from the exhaust path and fresh air by creating a pressure difference between the pressure wave pump inlet 204 and the inlet path 202. Secondly, compress the charge (comprising exhaust and fresh air), through pulsation of an internal diaphragm 208 located within the pressure wave pump 200, so as to deliver the charged exhaust and fresh air to the outlet 205 of the pressure wave pump 200 and through the connecting pipe to the inlet of the engine through the flow control valve 104. During working of the engine, the exhaust generated due to combustion flows through the exhaust path 203 to reach a first path 206 and a second path 207 to reach the inlet path 202 through the EGR valve (212). The internal diaphragm 208 is in the form of a flexible elastic membrane. This flexible elastic membrane is sensitive to the pressure pulsation of the exhaust that is present in the first path 206. This pulsation causes the flexible elastic membrane to suck the charge (comprising exhaust and fresh air) received from the inlet 204, and also cause the charge the is received in the pressure wave pump to get compressed and expel the charge through the outlet 205 of the pressure wave pump 200. In other words the flexible elastic membrane alternately sucks and compresses the charge present in the pressure wave pump 200. The exhaust present in the second path 207 mixes with air received from atmosphere via the air filter 203. The pressure available in exhaust mixed with air, along with the movement of the flexible elastic membrane, causes the inlet valve 204 of the pressure wave pump 200 to open and the space available in the pressure wave pump 200 is filled with the above mentioned exhaust and air. The exhaust mixed with air in the pressure wave pump 200 will now be referred to as an “air charge”. Now, in order to compress the air charge, a certain amount of energy has to be delivered. This is achieved through pulsation for compressing the pressure wave pump 200, the energy required for pulsation is also delivered with the help of exhaust received from the engine. The air charge that is pressurized will now flow into the engine during the suction stroke. The expulsion of the air charge from the pressure wave pump happens due to the movement of the flexible elastic membrane 208 that causes the air charge to open the outlet valve 205. During the suction stroke, the engine will drive the flow control valve 104 to the first position, this enables air charge from the pressure wave pump 200 to enter into the engine 106. The air charge mixes with the fuel and explodes to form a combustible mixture. Once the combustion process is completed, the engine will drive the flow control valve 104 to the second position. In this position the flow control valve 104 will open causing the exhaust charge to flow through the exhaust path. A part of the exhaust will now get re-circulate for charging the pressure wave pump 200 and also be used as an input to the pressure wave pump 200 for the next cycle of the suction stroke. The working of the pressure wave pump 200, the flow control valve 104 is synchronized with respect to the working of the engine 106.
[0012] 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 air charging device and the flow control valve used. 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.