New conjugate pair design: Theory and application

This dissertation presents two new design methods for conjugate pair generation: the Direct-Profile-Design (DPD) method and the Deviation-Function (DF) method. The DPD method is for generating identical noncircular pitch pairs with almost unlimited profile varieties and any number of lobes. The DF method is to use deviation functions to reshape the original pitch profiles so that the desired conjugate profiles can be obtained. A deviation function is defined as the distance from pitch points to generated profile. The concept of deviation function creates a new geometry-intuitive approach for the design and analysis of conjugate pairs. The DF method can generate conjugate profiles from both circular and noncircular pitch profiles without using numerical methods. In this dissertation, the DPD and DF methods are applied to the design of rotor profiles of new lobe pumps for high efficiency. Besides, additional noncircular timing gear pairs are used for controlling the flowrate and improving dynamic properties of lobe pumps. The main goal for timing gear design is to achieve constant flowrate and eliminate the effect of rotor mass, i.e., eliminate input torque ripple. The results show that high performance new lobe pumps are successfully designed to have high efficiency, constant flowrate, and no input torque ripple. Finally, a new driving method for noncircular gears (without teeth) is presented to solve the problems for current noncircular gears (with teeth). This technique is applied to the driving gears and timing gears of new lobe pumps.