Design, Manufacture and Performance of Internal Gear Pumps : 2nd Report, Design Methods for Increasing Specific Delivery and Performance of Trial-Made Gear Pumps

Abstract

By allowing for a small amount o gearing errors, the authors established a new design method of internal gear pumps with an appreciably larger specific-delivery than that of the internal trochoid pumps, etc. Using this method, three kinds of internal gear pumps with numbers of teeth z₁ = 8 and z₂ = 11 and also with z₁ = 7 and z₂ = 10 were designed and made in the author's laboratory. The performance of the trial-made gear pumps was as good as supposed, and almost the same as that estimated from the theory. Endurance tests were conducted using one of the trial-made gear pumps because there was a possibility of tooth surface failure due to excessive contact stress between the meshing teeth. However, no failure occurred at all when the gear pump was operated at a delivery pressure of 1.0 MPa (≒ 10 kgf/cm²) for 5×10⁶ revolutions.