Advancing motor performance with accurate torque measurement in-house
09 October 2017
The Edinburgh University Formula Student (EUFS) Team, was established in October 2014 and now consists of over 90 members across the university, with complementary skills in engineering, architecture, business and economics.
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For the first time in 2016, the team participated in the Class 1 of Formula Student, the world’s largest student engineering competition run by the Institution of Mechanical Engineers. The event took place with 130 teams from more than 30 countries, including Africa and Asia, where the EUFS team received the “Spirit of the Formula Student Award” for overcoming multiple challenges with limited resources to help other teams to overcome theirs.
Over the course of the year, the team has been building a new car from scratch, including the frame, body panels and even nose cones. This year they aimed to improve their performance at Silverstone with a new, and a better-designed formula racing car. They worked on improving vehicle dynamics, optimising its wheels, and secured a new Kawasaki four-cylinder inline Ninja ZX636R engine, which needed to undergo scrupulous testing.
In preparation for this year’s competition, the EUFS team desperately needed an incredibly accurate torque and horsepower data, which they lacked last year, for the design validation contest as a part of the Silverstone event.
As a part of her final year project, Meghan Brown, an Electrical/ Mechanical Engineering student, was tasked to design a state-of-art dynamometer to measure engine torque and horsepower. One of the most important aspects of this project was to build a high-spec customised powertrain, coupling the engine and pump, which perfectly supported the inline rotary torque transducer. The objective was to align the shaft of the M425 Torque Transducer with the torque, which needed to be driven through the centre line of the shaft. Unlike disk transducers that require very fine alignment tolerances when mounting, the M425’s longer shaft allows a greater degree of flexibility in terms of alignment.
The torque transducer fits into the drive train or test bed, using standard keyway shafts and coupling, holding them securely in place. This is mounted inline and bolted to a level plate, to ensure alignment, preventing damage to the transducer and guaranteeing optimal accuracy.
The built system is able to offer seamless power transmission with integrated sensors for monitoring and control. Using a hydraulic axial piston pump to load the engine, a Datum Electronics M425 rotary torque transducer is mounted securely inline, coupling the engine and pump, capable of measuring shaft speed and power.
When the engine is turning the shaft to pump hydraulic mineral oil through the chamber, the M425 sensor accurately acquires torque readings from the shaft. This data is shown in real-time on the display of the Datum Universal Interface (DUI) module, which is incredibly beneficial in gaining an immediate understanding of loads that the shaft is under during test runs, and illustrates how the system is performing. The voltage output signals are sent from the DUI to National Instrument’s (NI) LabVIEW interface to sample, log, and display the data.
Use of NI’s CompactDAQ enables the NI 9201 module to acquire the data, while the NI 9263 analogue output module establishes a connection to the engine control unit (ECU) for initiating shutdown when the system operating limits are approached, protecting both the equipment and users of this test system.
• Datum Electronics M425 Torque Transducer
• Datum Universal Interface (DUI)
• NI 9201 +/-10 V, 12-Bit, 500 kS/s, AI Module
• NI 9263 +/-10 V, 16-Bit, 100 kS/s/ch, AO Module
• cDAQ-9174, CompactDAQ Chassis
• NI LabVIEW Software
Competition rules demand that engines have a single air intake a mere 20mm in diameter, significantly reducing the torque and horsepower, which the engine can achieve, making it even more critical for the team to test and understand the response of the engine to implement changes in their drive strategy. Using the new-built dynamometer with an accurate inline torque transducer to test the engine gave the team a better understanding of its mechanical performance and determined the measures that could be taken to improve its performance.
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