An energy efficiency measurement test bench for gearboxes

Over the last decade, forced regulations and a growing social awareness with respect to energy efficiency have resulted in a renewed interest in the research for high efficient electrical machines. When an electrical motor is coupled to a machine, in many cases a gear or belt is used. Research shows a lack of information on energy efficiency of these components. In comparison to electrical motors and drives, there is very few regulation and if efficiency values can be found in catalogues, there’s no regulated test procedure available to validate the data. As a result, the reliability of these efficiency values is low and comparison between manufacturers and technologies is impossible. Regulation on energy efficiency on the other hand evolves to a total system approach such as the new European fan directive 327/2011. Information on the efficiency of mechanical transmission components such as gearboxes and belt drives will be required to invest on which drive train part it is most recommended to invest in order to optimize the overall system efficiency. Due to the lack of reliable information on energy efficiency of these components, the need for a test bench emerged. This paper discusses the test bench build for testing gearboxes up to 15kW in their entire working area. In the first part of the paper the technical set-up and influence factors on measurements are discussed. Secondly a test procedure will be proposed to ensure reliable and reproducible results. Finally the first results obtained by this procedure are presented and discussed. Technical description and construction test bench The purpose of the test bench is to measure gearbox efficiency at different loads and speeds within the allowed working area of the gearbox. Industrial gearboxes come in various types and power ranges. With the gearbox test bench it is possible to test a large scope of these types for a power range until 15kW. Test benches for tests on gear sets are fairly common. In such cases it is just one gear wheel pair that is being tested (Figure 1). Wear, load capacity, oil level, seal friction and efficiency are subjects which can be tested with these test rigs. Figure 1: FZG back-to-back test rig with add-ons for efficiency tests [1]