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Gerotors are a family of mechanical pumps used for cooling, lubrication and fuel transfer in aerospace, medicine, etc. Modern industry demands to shorten the development time of products. This means further integration between the different design stages. As in any hydraulic machinery, an important bottleneck in the design process is the simulation time to validate designs. This is due mainly to the fact that Computational Fluid Dynamics (CFD) remains the go-to tool to perform simulations of hydraulic phenomena. One way to reduce this bottleneck is to adopt approximate yet fast simulation routines to refine the design before entering a precise simulation stage. This manuscript presents an interactive design tool that estimates the efficiency response of gerotor pumps using fast simulation routines. The presented tool intends to shorten and accelerate the design cycles of Gerotor pumps by providing the engineer with an estimation of the effect of geometry changes in the pump's efficiencies in real time. The software tool integrates 2D and 3D design capabilities with real-time simulation response. The resulting efficiency estimations differ from the CFD models in maximum 8% in the case of volumetric efficiency. For mechanical efficiency the error ranges between around 20% and 45%, but the pump's internal forces is estimated within a 1% accuracy. Future work focuses on refining the accuracy of the efficiency estimations and further integration of the design tool with physical data. [ABSTRACT FROM AUTHOR]

The development of electric gerotor pumps is a complex multiphysical optimization problem. To develop optimal systems, accurate simulation models are required to increase digital reliability. An important challenge is the accurate prediction of the pump behavior for extreme temperatures in automotive applications from − 40 °C to 110 °C, where the viscosity of the fluid changes significantly. Therefore, simulation-based methods (numerical methods for calculating viscous friction) were developed and validated by measurements, including climatic chamber tests. The results show a strong correlation between simulated and measured performance characteristics, especially in terms of volumetric flow rate ( < 5 % ), pump torque and efficiency ( < 7 % ) at different temperature and viscosity conditions over a wide speed range (1000–5000 rpm) and different system pressures (0.5–5 bar). A novel method for simulating the cold start behavior of pumps (journal bearing approach for outer gear in pump housing) was introduced and validated by measurements. The methods presented significantly reduce the need for physical testing and accelerate the development process, as the pump behavior at each operating point can be accurately predicted before a hardware prototype is built. This improves the understanding of gerotor pump characteristics and provides insights to further improve the model-based development of electric oil pumps for the automotive industry. [ABSTRACT FROM AUTHOR]

The development of electric gerotor pumps is a complex multiphysical optimization problem. To develop optimal systems, accurate simulation models are required to increase digital reliability. An important challenge is the accurate prediction of the pump behavior for extreme temperatures in automotive applications from −40 °C to 110 °C, where the viscosity of the fluid changes significantly. Therefore, simulation-based methods (numerical methods for calculating viscous friction) were developed and validated by measurements, including climatic chamber tests. The results show a strong correlation between simulated and measured performance characteristics, especially in terms of volumetric flow rate (<5%), pump torque and efficiency (<7%) at different temperature and viscosity conditions over a wide speed range (1000–5000 rpm) and different system pressures (0.5–5 bar). A novel method for simulating the cold start behavior of pumps (journal bearing approach for outer gear in pump housing) was introduced and validated by measurements. The methods presented significantly reduce the need for physical testing and accelerate the development process, as the pump behavior at each operating point can be accurately predicted before a hardware prototype is built. This improves the understanding of gerotor pump characteristics and provides insights to further improve the model-based development of electric oil pumps for the automotive industry.

In this paper, a lumped parameter approach for predicting cavitation in fluid power systems is described. The modeling approach is based on the homogeneous mixture one fluid model for cavitation and takes into account the effects of compressibility of both the liquid phase and gaseous phase, related to aeration and fluid vaporization. By using the homogeneous mixture theory, equations suitable for lumped parameter models are derived, including the orifice equation to describe flow through hydraulic connections, the constitutive relations, and the pressure built up equations for hydraulic chambers. The proposed equations are then used in the paper to simulate a Gerotor pump under cavitating conditions. Results are validated experimentally for different operating conditions. [ABSTRACT FROM AUTHOR]

Gerotor pumps are widely used for fuel and lubricating oil distribution, since they provide an economic and compact solution for low-pressure fluid systems. Made of two internally coupled gears, their behavioral and operative performances are strictly tied to their geometrical designs. Traditionally, the external gear features circular lobes that give origin to a cycloidal profile for the internal rotor. In this paper, the use of profiles based on asymmetric lobes made of elliptic arcs is further explored and expanded. At first, a complete mathematical framework describing the pump geometry and its dynamic behavior is provided, while algorithms used to compute a selected number of performance indexes are presented and when possible, verified. Hence, a single-objective optimization procedure is applied to the traditional cycloidal profile, in order to minimize each of the following quantities: the flow rate irregularity, the expected wear rate, and the estimated rotor mass. Finally, a multi-objective optimization process based on evolutionary strategy is employed, to obtain several asymmetric profiles minimizing the combination of two or more performance indexes. The results are hence compared, and the merits associated with the use of asymmetric lobes are presented.

The Gerotor pumps have a vast number of applications in industries and automobiles. The flow rate irregularity and wear rate proportional factor influence on the lifetime of the Gerotor pumps. In this paper, the optimization problem cost functions and constraints have been developed according to volumetric, dynamic and geometric properties. In order to have general optimum solution and reduce number of design variables, all variables have changed to non-dimensional variables by using the outer rotor lobe center radius which causes the non-dimensional cost functions too. The multi-objective optimization problem has been changed to single objective optimization problem by using a multi-objective optimization classical method. The single objective optimization problem has been solved by using of a mixed integer nonlinear optimization algorithm. The optimization programming has been implemented for several values of number of the outer rotor teeth, non-dimensional displacement and rotors width. On the other hand the influence of varied parameter such as number of outer rotors teeth, the value of non-dimensional displacement and non-dimensional rotor width have been surveyed on each of cost functions. The results show in constant input torque, as using greater number of outer rotor teeth up to critical value improves the wear of teeth. Also optimum value of flow rate irregularity in odd values of outer rotor teeth is smaller than even ones. At last for having better comparison, two sample commercial pumps have been optimized. The results show both wear rate proportional factor and flow irregularity have been significantly improved. [ABSTRACT FROM AUTHOR]

The mechanism of induction of stresses and deformations in plastic cycloidal gears used in gerotor pumps has been analysed using the finite element method and the ABAQUS program. It has been found that the gear system remains under the influence of the mechanical load resulting from the torque on the pump shaft and the hydraulic load resulting from the activity of pressure in the intertooth displacement chambers. It has also been discovered that the intertooth forces and stresses are formed only in the part of the gear that can be referred to as 'active'. In the other part of the gear, forces and stresses do not occur, and the part can be referred to as 'passive'. Another finding of the research is that gear deformations occur such that the teeth of the external gear are deformed and moved in the direction of the active part of the mesh, and the teeth of the internal gear in the direction of the passive part. Thus, radial and axial intertooth clearances are formed, which result in internal leakages in the pump, as well as in lower working pressure and efficiency of the machine. A way of determining the load range for plastic gears used in gerotor pumps has been specified. It has also been observed that the loading of the pump should not result in reduced stresses [ABSTRACT FROM AUTHOR]

Gerotor pumps are widely used for fuel and lubricating oil distribution, since they provide an economic and compact solution for low-pressure fluid systems. Made of two internally coupled gears, their behavioral and operative performances are strictly tied to their geometrical designs. Traditionally, the external gear features circular lobes that give origin to a cycloidal profile for the internal rotor. In this paper, the use of profiles based on asymmetric lobes made of elliptic arcs is further explored and expanded. At first, a complete mathematical framework describing the pump geometry and its dynamic behavior is provided, while algorithms used to compute a selected number of performance indexes are presented and when possible, verified. Hence, a single-objective optimization procedure is applied to the traditional cycloidal profile, in order to minimize each of the following quantities: the flow rate irregularity, the expected wear rate, and the estimated rotor mass. Finally, a multi-objective optimization process based on evolutionary strategy is employed, to obtain several asymmetric profiles minimizing the combination of two or more performance indexes. The results are hence compared, and the merits associated with the use of asymmetric lobes are presented. [ABSTRACT FROM AUTHOR]