Field of the Invention
The present invention relates to a drive system, in particular for a self-propelled construction machine, in particular a soil compactor, including:                a drive unit        at least one hydraulic circuit with a hydraulic pump driven by the drive unit,        a hydraulic drive support unit with a hydraulic pump/motor assembly and at least one pressure fluid reservoir, wherein the hydraulic pump/motor assembly is, or can be, drivingly coupled with the drive unit and/or at least one hydraulic circuit, wherein the hydraulic pump/motor assembly can be driven in a charge operating mode by the drive unit and/or at least one hydraulic circuit as a pump to charge at least one pressure fluid reservoir, and be driven in a drive support operating mode as a motor to provide a drive support torque for the hydraulic pump of at least one hydraulic circuit.        
Background of the Related Art
Such a drive system has been known from WO 2013/074164A1 as a drive system of a construction machine built as a wheel loader. In this known drive system a drive unit is drivingly coupled with various hydraulic circuits via a gear arrangement. The hydraulic circuits comprise a hydraulic driving circuit with a hydraulic driving pump driven by the drive unit and a hydraulic drive motor driven by the flowing fluid to drive the drive wheels of the wheel loader on operation of the hydraulic driving pump. In addition, one or several hydraulic working circuits are provided. These also comprise a hydraulic working pump driven by the drive unit via the gear arrangement. By means of the hydraulic pressure generated by these pumps, piston/cylinder units can be activated, in order to move a bucket on operation of the wheel loader. This drive system further comprises a hydraulic support unit. It comprises a hydraulic pump/motor assembly driven by the drive unit via the gear arrangement which loads a pressure fluid reservoir when the pump is operated, namely it increases the pressure of the fluid stored therein. The hydraulic pump/motor assembly of this hydraulic drive support unit can also be driven as a hydraulic motor in order to generate a torque on expansion of the pressure in the pressure fluid reservoir which can be conveyed via the gear arrangement to the various hydraulic circuits, namely to the hydraulic driving circuit and the hydraulic working circuit(s). The hydraulic drive support unit can thus provide a drive support torque.
USPTO Backgrounds
USPTO Backgrounds