Publication

Abstract : In IC Engines, basically the oil pump is driven either by a drive gear integrated with camshaft or a gear mounted on the crankshaft. In the older engines the oil pumps were mostly camshaft driven with a skew gear arrangement which becomes unique and tailor made for the given engine as part of the engine cylinder block sub-assembly. This arrangement calls for complex machining and the number of parts involved are more compared to a crankshaft driven oil pump as being seen in the modern engines. A crankshaft driven oil pump basically calls for a study of the envelope constraints and boundary conditions and finalising the mounting and maximum envelope possible for accommodating the oil pump. The challenge lies in arriving at a very compact pump with the required delivery for the given engine within the envelope limitations. From the different oil pump types, the external spur gear type was selected for the design as it is the most popular and cost effective with manufacturing friendliness for mass production. The basic design computation was done based on the amount of heat carried away by the lubricating oil and the circulation rate of oil in the system. Through the step by step procedure the gear size and the power required to drive the pump was calculated. Based on the gear size and the some preselected parameters, all the important gear parameters were calculated. The pump discharge was computed and it was verified that the discharge increases in direct proportion with the increase in engine speed, by a plotting a graph of oil pump discharge against engine speed and obtaining a linear trend in it. The design of the relief valve for the pump was also carried out. The physical dimensions of the compression spring were chosen and all the other important parameters were calculated and ensured that the pressure in the lubrication circuit remains within the prescribed limit.