The number of applications with rotational speed controlled fixed hydraulic pumps is increasing because they offer good controllability and efficiency compared to conventional fixed speed pump drives. Both electric motors and pumps are dimensioned according to maximum power/torque. Consequently, the electric motor is significantly larger than the hydraulic pump. This paper introduces a double pump system with connection to additional hydraulic supply creating a hybrid drive. The power/torque demand can be reduced making it possible to choose a smaller electric motor without sacrificing performance while increasing power density. The connection to two energy sources results in a flexible energy supply and makes it possible to recover either hydraulically or electrically. Simulated results show that the studied circuit enables electric motor size reduction as much as 50% when the bottom of the cylinder is the load side and the second pump is connected to the accumulator or pressure source. This is applicable in applications where the rod side loading is remarkably lower as well as in other applications that have a minor extending load.
|Title of host publication||The 14th Scandinavian International Conference on Fluid Power|
|Editors||Arto Laamanen, Kalevi Huhtala|
|Place of Publication||Tampere|
|Publisher||Tampereen teknillinen korkeakoulu|
|Publication status||Published - 21 May 2015|
|Publication type||A4 Article in a conference publication|