This paper describes the numerical modeling of the hydraulic
circuit of a self-moving boom lift. Boom lifts consist of several
hydraulic actuators, each of them performs a specific movement.
Hydraulic systems for lifting applications must ensure consistent
performance no matter what the load and how many users are in
operation at the same time. Common solutions comprise a fixed or a
variable displacement pump with load-sensing control strategy.
Instead, the hydraulic circuit studied in this paper includes a
fixed displacement pump and an innovative (patented) proportional
valve assembly. Each proportional valve (one for each user) permits
a flow regulation for all typical load conditions and movement
simultaneously. The study of the hydraulic system required a
detailed modeling of some components such as: the overcenter
valves, for the control of the assistive loads; the proportional
valve, which keeps a constant flow independently of pressure drop
across itself.
The model of the hydraulic circuit has been implemented in
AMESim® simulation environment, integrating also a mechanical model
for loads, in order to evaluate the instantaneous forces acting on
the actuators and depending on the position of mechanism in the
machine. The aim of this study is to find the best way to control
the prime motor, in order to obtain the optimal controllability
reducing the energy losses in the system by varying the speed of
the pump by means of an Electronic Controller (EC).