Since the invention of the internal-combustion engine, a Slider Crank mechanism has been used to transfer power from the combustion chamber through the piston to the connecting rod to the crankshaft. Over time, many changes have occurred in the combustion chamber to improve power and reduce emissions.
Most engine designers didnít pay much attention to the mechanical disadvantages in the reciprocating and oscillating connecting rod that contributes more than 30% of the engineís parasitic losses. The crankless engine Iím proposing offers many mechanical advantages.
Force (F) generated in the engineís combustion chamber is equal to combustion pressure times the cross-section area of the piston.
F2 will always be less than F because of the connecting rodís angular position and because of the decreasing pressure of the expanding burned gases.
In a conventional engine, at top-dead-center (TDC), F is at its maximum, but the torque created is zero because the effective radius (R1) is zero. At mid-stroke, when α is 90 degrees, R1 equals R and the theoretical torque F times R should be at its maximum. However, during mid-stroke, the burned gases expand and F would be less than at TDC. Therefore, the torque produced at mid-stroke would be less even though R is at its maximum.
In my design, the rack and pinionís effective radius remains the same during the power stroke. In a combustion engine, it varies due to the connecting rodís angular position. The end result is less torque.
Iíve come to a series of conclusions.
- Referring to Figures 1, 2, and 3, and the torque statement we discussed, itís evident that my design produces 30% more torque than the traditional engine.
- During a stroke, the conventional engineís crank pin travels 3.14 times d and my engineís crank pin travels only 2 times d. This means that my engine can perform more strokes per minute, resulting in more horsepower.
- Without an oscillating connecting rod and by producing uniform torque during 75% of the power stroke, my engine operates with less vibration and can idle at a lower rpm.
- My engineís piston travels faster with little dynamic resistance and oscillating motion. This helps the piston seal properly to the cylinder walls and reduces blow-by, contamination, and evaporation of oil.
- Engine with my design runs at a lower temperature because its piston travels faster, allowing the burned gases to escape quicker from the combustion chamber without transferring much heat to the cylinder walls. In addition, NOx is reduced because of the lower temperature and the burned gases arenít captured in the combustion chamber for a long period at high pressure. And because the piston travels faster and doesnít allow the combustion flame front to hit it, knock is reduced.
- Engine with my design provides a piston that moves without any oscillating motion, minimizing piston slap and piston-to-cylinder wall friction.
Rajan Paul is the president of RajTek Inc. Heís worked in the automotive, locomotive, and machine tool industries for 42 years, 23 with Ford Motor Company. He holds a Bachelorís degree in mechanical engineering from the University Of Calicut, India.