Plastics are more and more frequently applied in the construction of hydraulic components and systems, and recently, in the building of microhydraulic assemblies. The basic unit of the microhydraulic systems is a micropump. It is an object which is quite difficult to design and manufacture, especially when using plastics. The paper is a presentation of challenges that must be met in the process of designing gear pumps, and, at the same time, of the theoretical grounds for the designing of those objects. The challenges include the geometry and the gears, the construction of the pump body, the hydraulics of the pump, and the material—the plastic of which the pump is made. The knowledge on those issues was applied to make and to successfully test a prototype of a micropump.
The paper presents the results of numerical calculations of stress distributions in the gear micropump body for applications in hydraulic systems, especially in the marine sector. The scope of the study was to determine the most favorable position of bushings and pumping unit in the gear pump body in terms of stress and displacement distribution in the pump housing. Fourteen cases of gear pump bushings and pumping unit locations were analyzed: starting from the symmetrical position relative to the central axis of the pump, up to a position shifted by 2.6 mm towards the suction channel of the pump. The analysis of the obtained calculation results has shown that the most favorable conditions for pump operation are met when the bushings are shifted by 2.2 mm towards the suction channel. In this case the maximal stress was equal to 109 MPa, while the highest displacement was about 15μm. Strength and stiffness criteria in the modernized pump body were satisfied.
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In this paper, results of the static mechanical analysis of a gear micropump body are presented. Numerical simulations using finite element method (FEM) were conducted using Ansys Multiphysics software. After analysis of stress and displacement distribution in the pump body, a mass optimization of construction was provided. In the optimized body, maximal value of stress reached 134 MPa. Safety factor was equal to 2.9. The highest value of displacement in the optimized body was about 0.02 mm. Maximal values of stress and displacement provide appropriate work of the micropump. Strength and stiffness criteria in the optimized pump body were achieved. For the construction of the pump body before and after optimization, energetic efficiency ratios (kef) were calculated. Optimized micropump body has more than 30% increase in kef ratio to the pump with the primary body.