Pump efficiency test bench
The efficiency test rig for closed-loop hydraulic pumps at ifas permits the recording of efficiencies in accordance with ISO 4409.
ISO 4409
Efficiency measurements are primarily used as a benchmark for different product series and between competing products. Furthermore, efficiency measurements are suitable as a customer argument with regard to the fuel efficiency of the hydraulic drive. Efficiencies are divided into volumetric and hydro mechanical efficiency. Volumetric efficiency is the sum of internal leakage (from the high-pressure to the low-pressure section) and external leakage (from the machine to the tank). All losses that reduce the torque, such as solid-state and fluid friction in the hydraulics and friction in seals and bearings, are referred to as hydro mechanical losses. The definition of the efficiencies depends on the operating mode of the engine. The standard includes regulations on the design of the hydraulic circuit, in particular on the placement of the sensors, as well as on the conduct of the test.
The test rig
The test bench consists of an asynchronous motor with an output of 160 kW, which can be operated with speed regulation via a frequency converter. Both the speed and the torque delivered via the shaft are measured by sensors. The maximum possible torque is 500 Nm, the maximum speed 3000 min-1. On the hydraulic side, the test rig has a high-pressure filter, which also allows critical material pairings with potential particle formation to be tested. The flow rate is measured in the high-pressure section by means of a gearwheel sensor. The maximum flow rate (HLP 46, 40°C) is specified as 160 l/min. The load pressure can be adjusted between 10 and 300 bar by means of an electrically controlled pressure relief valve. Furthermore, the test bench is equipped with a circuit cooler. This enables the hydraulic circuit to be operated under temperature control. The hydraulic circuit is fed from a 300l tank via a gear unit with an adjustable pressure between 5 and 30 bar. A separate control oil pump is available. The temperatures as well as the volume flows of all supply and feed flows can be recorded.
Special options
An external unit makes it possible to perform tribological tests with pumps at zero swing angle and to exclude the influence of the stroke. The test rig can run continuously at any pressure, speed and swivel angle. An integral fluid condition sensor can record the oil quality in the drive