Diesel-Driven Compressor, Torque Pulse, Transport Refrigeration Unit (TRU)
When an open drive compressor is directly coupled to a Diesel engine in a Transport Refrigeration Unit (TRU), the torque pulses between the compressor and engine can have significant effects on the TRU control strategy and compressor reliability. Understanding the torque interaction between the compressor and engine during transient conditions is also critical to ensure the power limitations of the engine are not exceeded. Although torque data is typically available from engine manufacturers, it is not fully representative of the torque signature seen in the engine’s final application. Due to emissions regulations and higher efficiency requirements, advances in Diesel engine technology have resulted in higher torque pulses. For these reasons, it is necessary to measure the torque interaction between the compressor and engine. To study the interaction between the compressor and engine, two torque measurement devices were applied to a TRU. The torque signature was studied during compressor part load operation, transient events, multiple speeds, and start/stop. The torque measurements were then made available as inputs for finite element analysis (FEA), compressor torsional analysis, reliability predictions, fuel consumption prediction and TRU controls development. This paper discusses the tradeoffs of the different measurement devices, the experimental test configuration, the experimental method and the test results.