A small gear pump, which can compress low viscosity fluid up to high pressure, is necessary for some systems such as an electric braking system. However, designing a high-efficiency small gear pump is difficult because leakage due to clearance is relatively larger than that in a normal-sized gear pump. Therefore, to design a high-efficiency small gear pump for high pressure, we are developing an external gear pump having an L-shaped block made of resin. This L-shaped block is the biggest difference from other gear pumps. First, we show the structure and characteristics of this gear pump with an L-shaped block, and we explain its advantages. Second, we explain a method to predict the clearances that are needed for designing high-efficiency gear pumps. Clearances in a gear pump are made by deformations of the inner parts during high-pressure operation. Thus, we applied structural analysis to design the high-efficiency gear pumps. Using this analysis, we can understand the deformation of each part during the pump operation. Moreover, we can design parts taking deformations into consideration. The analysis examples, such as the deformation in the vertical direction to the gear rotational axis and the deformation of the sliding surface with the side of the gears, are shown in this paper. As a result of these analyses, we could design the structure and shape of the inner pump parts to achieve high sealing performance. Finally, the results of an experimental evaluation for the developed gear pump are described in this paper. We measured the volumetric efficiency of a prototyped pump and evaluated the performance using experimental equipment. The results of the evaluation show that the developed gear pump has high volumetric efficiency under high temperature and low viscosity fluid.

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