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Research activities
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Hybrid mobile hydraulics for excavators
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0D models of axial piston pumps/motors
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CFD studies on conical poppet valves
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CFD analysis of gerotor pumps
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Lumped parameter models of crescent pumps
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Lumped parameter models of vane pumps
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Lumped parameter models of gerotor pumps
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Coupled simulation of telehandler hydraulics
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Modelling of brake booster vacuum pumps
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Absorbed energy in ICE lubricating pumps
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Multi-body simulation of axial piston pumps
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Development of variable flow lubricating pumps
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Optimization of ICE lubrication gerotor pumps
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Publications
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Research projects
Optimization of ICE lubrication gerotor pumps (1999-2001)
The continuous evolution of modern automotive engines sets stringent requirements on lubricating pumps in terms of specific displacement, absorbed power and fluidborne noise. Tight packaging is an essential requisite on the design of lubricating pumps. Oil flow rate required at hot idle conditions arbitrates pump displacement and therefore its space envelope. On the other hand, at high rotational speed, incomplete filling of pumping elements originates intense delivery pressure oscillations, causing noise and foam generation. Several experimental and theoretical investigations have been carried out at FPRL aimed at optimizing gerotor gearings in order to maximize the pump displacement and improve the chamber filling.
A general procedure has been developed for the computerized design of gerotor pump profiles. Figure 1 shows how this approach has been implemented for gerotor gears with circular arc profiles (a similar procedure has been also developed for external gear machines). The geometrical parameters of the gears complying with design criteria, namely dimensional constraints and pump displacement, are provided as output in order to guide the designer in selecting gerotor profiles best suited for a given application.
Figure 1
The chamber filling at high speed can be improved by reducing the gears thickness at equal pump displacement. Fig 2 reports the filling improvement obtained by the decreasing of the number of chambers from 9 to 8 at equal external diameter of the outer gear.
Figure 2
Through use of simulation models developed at FPRL, the porting geometry on the delivery side can be optimized aiming at reducing the pressure ripple in case of incomplete filling. Figure 3 shows the pressure measured inside the delivery volume of two gerotor pumps with different port plate designs: the increment of the delay of the delivery port opening and the optimization of the pressure relief groove, allow a remarkable reduction of the pressure peaks.
Figure 3
More analyses and details are available in:
MANCO' S, NERVEGNA N, RUNDO M, 2000: Effects of timing and odd/even number of teeth ...
MANCO' G, MANCO' S, RUNDO M, NERVEGNA N, 2000: Computerized generation of novel gearings ...