Design and performance of gear pumps with a noninvolute tooth profile

This paper describes the design and performance of external gear pumps with a tooth profile based on the cycloid tooth profile. A method has been developed to calculate accurately the displacement volume of external gear pumps having a non-involute tooth profile and an involute tooth profile. Using this method, the displacement volumes of external gear pumps with an involute tooth profile, a cycloid tooth profile, an involute– cycloid composite tooth profile and a modified cycloid tooth profile are calculated. Then, the merits and the demerits of these tooth profiles are discussed with respect to the displacement volume. In addition, a gear pump with an involute–cycloid composite tooth profile was designed and manufactured, and the displacement volume of the pump was measured. Consequently, it was confirmed from both the calculated and the experimental results that the displacement volume of the gear pump with an involute–cycloid composite tooth profile is about 20 per cent larger than that of the conventional gear pump with an involute tooth profile.