T7 in a stirling engine dynamometer

This is a good example of how LabJack devices are used in the wild. Martin Beck, an engineer working with VE Engineers in Germany, employed the T7-PRO for data acquisition within a dynamometer. The dynamometer is used to measure the output from a stirling engine.

Signals Acquired

• Eight (8) temperatures through Type K Themocouples. Directly connected to T7-PRO´s CB37 board without further amplification. Sample rate = 1 Hz. CJ compensation via LM34CAZ.
• Torque, ±50 Nm. Output of torque-gauge ±10V. Directly connected to LabJack T7-PRO. Sample rate = 1 kHz.
• Absolute internal pressure, 0-20 bar abs. Output of pressure-transducer 0-10V. Directly connected to LabJack. Sample rate = 1 kHz.
• Crankshaft angle and velocity. Incremental encoder with quadrature output. 360 tics per rev max. 36 kEdges per sec. Directly connected to LabJack. Counter is quadrature-counter. Sampling of Counter-value with 1 kHz. Resetting of counter through inductive initiator.

A view of the electronics enclosure on the side of the engine/dyno.

The engine setup

Another view

Close-up of the engine

The heat source for the stirling engine exposed for viewing.

Much information is derived from the acquired data, such as thermal and mechanical power, efficiency, etc. Quite a few graphs are automatically generated, such as high speed data over time and over crankshaft angle; p-over-V diagram; Power, Torque, Efficiency over velocity, etc.

The application was programmed in LabVIEW using the LJM Library and LJM LabVIEW example code. Other active components are a frequency-inverter from SEW-Eurodrive and a temperature-controller from Watlow. Both with ModBus/TCP interfaces. This makes a very neat system-concept, with just one Ethernet-cable coming out of the machine, for the entire control and data-acquisition.