Recently, car pump market is positively growing in emerging countries as well as advanced countries. A increasing attention is recently drawn to electric vehicle but, still commercialization is expected to take a long time. This research is to study on the performance analysis for change in number of teeth of internal gear oil pump with three different numbers of teeth in the inner gear. After measuring real design features, modeling, velocity distribution and pressure distribution are conducted numerically. Pressure changes and volumetric efficiencies are compared with three different cases in order to analyze the performance for inner gears. Finally, optimum volumetric efficiency is determined with the sequence of case 1, case 2, and case 3.

This paper describes the development of precision gear pump for transmitting source material of chemical machinery. Gear pump design is carried out considering geometry of gear and strength of shaft by CAE program. Teeth of gear is machined by ultra precision grinding, and by inspection of profile and lead, JIS 0-grade gear is manufactured. Through the pump performance test, pump discharge volume per one revolution is in a good agreement with the target values when varying rotational speed and working temperature.

A gear pump is a type of pump that displaces a volume of fluid by physical or mechanical action, or positive displacement pump. Power is applied to one of the gears and transmitted to a second driven gear via meshing teeth. This paper describes the hydraulic gear pump for an elevator. In gear pump, since geometrically special forms of gear tooth, ‘ulsations’is always caused in the delivery pressure and quantity. In other words, it is found that the number of delivery pressure pulsation per each revolution is always equal to that of the gear-teeth of the gear, which is coincident with the pulsation of the ideal delivery quantity. Some experimental results are given to verify the effectiveness of the developed pump.

External gear pumps are the most widely employed source of power in hydraulic applications, allowing good performance and low manufacturing cost. Generally, pumps with involute external gears are most commonly used. The undesired large pressure overshoots or spikes could be excited by virtue of the sudden volumetric change of meshing pockets. In practice, the spikes cause the gear machines to be noisy, inefficient, and have fatigue problems. In order to improve above issues, relief grooves are adopted practically. In this paper, the meshing pressure and the effects of relief groove configurations are considered through CFD analysis.

This paper describes the results of the application of Cr-Diamond-like carbon (DLC) films for efficiency improvement through surface modification of spur gear parts in the hydraulic gear pump. Cr-DLC films were successfully deposited on SCM 415 substrates by a hybrid coating process using linear ion source (LIS) and magnetron sputtering method. The characteristics of the films were systematically investigated using FE-SEM, nano-indentation, sliding tester and AFM instrument. The microstructure of Cr-DLC films turned into the dense and fine grains with relatively preferred orientation. The thickness formed in our Cr buffer layer and DLC coating layer were obtained the 487 nm and . The average friction coefficient of Cr-DLC films considerably decreased to 0.15 for 0.50 of uncoated SCM415 material. The hardness and surface roughness of Cr-DLC films were measured 20 GPa and 10.76 nm, respectively. And then, efficiency tests were performed on the hydraulic gear pump to investigate the efficiency performance of the Cr-DLC coated spur gear. The experimental results show that the volumetric and mechanical efficiency of hydraulic gear pump using the Cr-DLC spur gear were improved up to 2~5% and better efficiency improvement could be attributed to its excellent microstructure, higher hardness, and lower friction coefficient. This conclusion proves the feasibility in the efficiency improvement of hydraulic gear pump for industrial applications.

We developed a new tooth profile designed for P/M internal gear pump rotors. The theoretical discharge volume of the new tooth profile internal gear rotors is more than 10% higher than that of the same size conventional rotors. Our new profile rotors can achieve a decrease in torque, and fuel-efficiency will also be improved.