Advanced simulation of fluid power components using DSHplus and ADAMS

摘要

Efficiency improvement of an axial piston pump or motor is an important part in the design and development process. The behaviour of an axial piston machine or other displacement machines is a complex interaction between tribology of sliding contacts, pressure gradient in hydraulic volumes and dynamics and kinematics. Simulation programs are useful development tools to design these fluid power units on digital computers. At present all these programs are stand-alone tools and specialised to calculate a specific behaviour or effect of an axial piston pump or motor. To reproduce and to solve all the physical effects numerically in one program is impractical. Since the opportunity exists to couple standardised products, this is a promising approach. The paper presents a simulation approach of a displacement pump or motor using two different kinds of simulation programs. The tribology, e.g. surface roughness, mixed lubrication and contact pressure, and the hydraulic, e.g. the computed pressure gradient and volume flows, are calculated numerically by means of DSHplus. The integration of all kind of forces and torques, e.g. mass moment of inertia and pressure forces, to solve the equation of motion is calculated with a multiple body simulation program, in this case ADAMS by Mechanical Dynamics. The modular structure of the approach allows all designs of displacement machines to be simulated and not only axial piston pumps or motors. The flexible modelling of mechanical structures in ADAMS makes it possible to create various simulation models of motion, such as cylinders and valves. The mechanical simulation program is coupled with the hydraulic simulation program DSHplus. Both programs run simultaneously on PCs and exchange data at discrete simulation time intervals. To compare simulation results with other results computed by various simulation programs an axial piston pump was chosen. Special attention is paid to simulation time and precision of the calculated results.