The invention relates to a drive having an energy recovery function.
A drive having an energy recovery function is known from U.S. Pat. No. 6,712,166 B2. In the system proposed therein, pressure medium is conveyed on the one hand from a reservoir into a pressure store by a pump/motor arrangement as long as the pump/motor arrangement is driven by the mass inertia of the vehicle during a deceleration operation. In order to then also allow the vehicle to be braked by means of the hydrostatic drive, when the capacity limit of the pressure stores is reached, there is provision in the drive proposed therein to produce a flow resistance with the storage elements being bypassed and to convey pressure medium in a closed circuit by the pump/motor arrangement.
The system proposed therein has the disadvantage that a change-over is carried out from the store to the additional closed circuit when the storage elements have reached the capacity limit thereof and consequently can no longer be used for storing pressure energy whilst performing braking operations. The throttling is carried out in an additional circuit. However, it is not known from U.S. Pat. No. 6,712,166 B2 to provide a throttle valve unit which allows a throttle function in a store line between the pump/motor arrangement and the storage element. The provision of the two separate functions which must be linked to each other in a complex control system not only requires considerable adaptation work but also requires a significant level of structural complexity. This leads to high costs and the additional mechanical components which are required.