EnginSoft - CAE Conference Abstracts

EnginSoft International Conference 2011
CAE Technologies for Industry

Optimization of the Valveplate Geometry for a Variable Displacement Axial Piston Pump in Case of Multiple Design Constraints

Lettini Antonio - Casappa

Abstract

The design of hydraulic pumps is always a balance between a set of different constraints and between several conflicting targets. In particular, the most important part in the design of an axial piston pump is the valveplate, that has a major influence on both hydraulic and mechanical behaviour of the pump. The valveplate indeed, by defining the pressure transients, directly affects the noise of the pump, that has to be reduced, and the pressure pulsations in the hydraulic circuit, to be reduced too. These goals have to be matched with the hydraulic efficiency of the pump, that also depends, among other parameters, on the valveplate geometry. Another constraint is the maximum speed of the pump, that has to be reached without occurrence of cavitation. If the pump is a variable displacement swashplate type, an additional effect is present on the regulation system of the pump. In fact, the main forces acting on pump internal components are produced by the pressure in the variable chamber, therefore the valveplate geometry affects the forces acting on the swashplate. This effect is thus to be taken into account when designing the valveplate, in order to get an optimal regulation behaviour in the entire range of pump working conditions. All these phenomena are well predicted by a simulation model developed by Casappa.
In a recent project, the behaviour of the standard pump, a variable displacement axial piston pump with torque control, was not acceptable on a particular application. In fact, the noise emission of the machine was too high and an improvement of pump in terms of noise reduction was required. The result of a first multi-objective optimization of pump valveplate was satisfactory, but an unacceptable drawback was shown: the pump torque regulation was bad, because at low speed the pump showed an increase of the regulated torque, leading to kill the engine. In order to minimize the noise, taking into account the constraint of a good torque regulation, a new optimization has been performed using Esteco modeFRONTIER. An optimal balance between all the variables has been found. Experimental measurements on a test bench have confirmed the optimal behaviour of the pump. After the final validation directly made on the machine, the customer has decided to adopt the improved version of the pump, eventually showing the complete success of the project.