METHOD AND DEVICE FOR CHANGING AND GOVERNING THE COMPRESSION RATIO, VALVE TIMING amp; VALVE OVERLAP PERIOD OF AN INTERNAL COMBUSTION ENGINE

摘要

A device for regulating and changing the compression ratio, valve timing & valve overlap period of an internal combustion engine which includes primary cylinders that are inverted on secondary cylinders and in every primary cylinder there is a movable primary piston that is connected to the first crankshaft and in every secondary cylinder there is a movable secondary piston that is connected to the second crankshaft. Both cylinders are connected by throat. Secondary cylinder is mounted such that swirl is developed in it by throat for reducing ignition delay as fuel is injected along the air motion to enhance the atomization. The primary and secondary crankshafts are connected to each other by means of a transmission with speed ratio of 1:2. They are synchronized such that engine capacity will not vary during suction stroke. The phase difference between crankshafts will vary the clearance volume of combustion chamber, with which the variable compression ratio is achieved. Device will change the compression ratio depending upon the fuel used, engine speed and load conditions. There is also a provision for setting compression ratio at any particular value consistently by disconnecting crankshafts and setting angular position of secondary crankshaft with respect to that of primary crankshaft. Device on secondary crankshaft for changing the phase difference have the flanges with helical surface and coil spring located axially exerts thrust on them. Axial movement of the flange changes the phase difference between crankshafts. Axial movement is achieved by overcoming the axial thrust developed by spring. Combustion pressure exerted on secondary piston overcomes the spring force through crankshaft. Secondary crankshaft shares the camshaft as valve train for either inlet valve or exhaust valve or both. Phase difference between crankshafts also changes the valve timing depending upon the valve train shared by secondary crankshaft. Secondary crankshaft and camshaft for exhaust & inlet valve coupled by gear revolves opposite to each other, by changing phase difference it will vary the valve overlap period. In case of multi-cylinder engine, firing cylinder will change the valve timing of rest of the cylinders including it. Ports located at the BDC of secondary cylinder will reduce pumping losses. Exhaust gases coming from these ports are used for turbo- charging to utilize thermal energy of exhaust gases. Suction port with reed valve for secondary cylinder is exposed earlier than exhaust port. At the time of suction stroke exhaust ports are covered by piston which will expose only suction port and due to vacuum richer mixture is inhaled inside the secondary cylinder. It forms heterogeneous charge for lean burn in SI engine.