In the kind of system analysed in this work the possibility for energy saving lays on the fact that dissipative
distributors are used to manage flows and maintain control of multiple loads. The alternative architecture here
studied and compared with the traditional one uses independent metering valves (I.M. valves) instead of single spool
distributors. The I.M. valves are electronically controlled by an E.C.U. which can adopt different control strategies.
The variable displacement pump can be controlled with a traditional flow compensator or with a dedicated E.C.U.
From the perspective of energy analysis this architecture offers potential energy savings compared with a traditional
single spool valve architecture. However, this must be verified for a real tractor operation because the amount of
energy saved strongly depends on the kind of duty cycle involved in the analysis, the required performance and the
expected level of reliability. It is noted that the remote valves circuit can serve a wide range of actuators, depending
on the equipment connected to the tractor at any given time, for example a seeder, or a loader or a harrow. The
actuators can be either single or double effect cylinder and motors. Standardized duty cycles for this kind of circuit
do not currently exist, hence more careful analysis must be dedicated to the experimental measurement of the main
hydraulic variables during a tractor work cycle using different equipment. For this purpose, a duty cycle for remote
utilities is applied, obtained from experimental measurements on a tractor equipped with a front loader. The adopted
duty cycle involves two pairs of linear actuators working together with different loads and requiring different flows.
The traditional and alternative architectures are modelled using a lumped parameter approach with particular detail
dedicated to the modelling of traditional and independent metering valves, to the variable displacement pump and
finally to the definition of the control strategies. A comparison of efficiency of the systems is then made with
reference to the front loader duty cycle.
In the kind of system analysed in this work the possibility for energy saving lays on the fact that dissipativedistributors are used to manage flows and maintain control of multiple loads. The alternative architecture herestudied and compared with the traditional one uses independent metering valves (I.M. valves) instead of single spooldistributors. The I.M. valves are electronically controlled by an E.C.U. which can adopt different control strategies.The variable displacement pump can be controlled with a traditional flow compensator or with a dedicated E.C.U.From the perspective of energy analysis this architecture offers potential energy savings compared with a traditionalsingle spool valve architecture. However, this must be verified for a real tractor operation because the amount ofenergy saved strongly depends on the kind of duty cycle involved in the analysis, the required performance and theexpected level of reliability. It is noted that the remote valves circuit can serve a wide range of actuators, dependingon the equipment connected to the tractor at any given time, for example a seeder, or a loader or a harrow. Theactuators can be either single or double effect cylinder and motors. Standardized duty cycles for this kind of circuitdo not currently exist, hence more careful analysis must be dedicated to the experimental measurement of the mainhydraulic variables during a tractor work cycle using different equipment. For this purpose, a duty cycle for remoteutilities is applied, obtained from experimental measurements on a tractor equipped with a front loader. The adoptedduty cycle involves two pairs of linear actuators working together with different loads and requiring different flows.The traditional and alternative architectures are modelled using a lumped parameter approach with particular detaildedicated to the modelling of traditional and independent metering valves, to the variable displacement pump andfinally to the definition of the control strategies. A comparison of efficiency of the systems is then made withreference to the front loader duty cycle.
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