Performance Design Verification in Automotive A/C

Malaysian automobile manufacturer Proton needed to test the air conditioning performance of its newly developed A/C system installed in their new Proton Persona 1.6 M-Line test car. During these rigorous tests, air conditioning performance was confirmed under several different test patterns measuring such factors as ambient temperatures and air pressure. Some of these tests were conducted in a specialized climactic test chamber and others on test courses or in special conditions. For example, cool down performance measured how effectively the newly-designed system could cool the car’s cabin from extremely hot conditions including parking in the sun on a hot day. Idling performance tests checked the air conditioning unit’s performance while the car was idling. Traffic jam tests checked the A/C unit’s effectiveness on the test course while the car was driven during heavy traffic conditions. Other tests such as engine cooling, high-speed runs and hill climbing were scheduled to contribute enough data to give engineers a complete picture of the A/C system’s effectiveness. Proton’s automotive engineers began searching for a flexible data logging solution for use in test setups to measure the temperature of every point on the test car to verify the effectiveness of the air conditioner’s performance and ensure that it worked within design requirements. A solution was also needed to measure the pressure of the air conditioning system cycle, the blower, radiator fan, compressor, and magnetic clutch voltage. Since frequent access to the logger wasn’t practical, the required device had to be a remote solution and needed a modem to access data on demand and send results via FTP and email to automotive plant management.

Proton engineers installed a dataTaker DT80M Intelligent Universal Input Data Logger inside the booth of the Persona test vehicle. The DT80M was then interfaced with 4 dataTaker CEM 20 Expansion Modules to expand the data logger’s universal channel capacity by 80 to accommodate the 128 universal thermocouple inputs needed for the tests. Each CEM20 connected to one analog channel of the data logger. The lightweight DT80M featured 12 flexible digital channels and 8 bi-directional digital channels as well as 4 SDI-12 channels and a serial ‘smart sensor’ channel. 4 high-speed counter inputs connected the DT80M to most data measurement sources and sensors including SDI-12 and Modbus. The stand-alone data logger measured most types of thermocouples to capture a broad sensor range.

The tests also required the use of the logger’s real-time data acquisition and communications capabilities, including the inbuilt 2G/3G cellular modem. During each test, the DT80M recorded temperature levels from every point of the test car, and was also used to capture other readings from the A/C system itself, including voltage, current, 4-20mA loops, resistance, bridges, strain gauges, and frequency. Integrated high and low pressure measurement based on strain measurement was performed using the appropriate sensor, while integrated engine speed pulse measurement (rpm) was done using the DT80M’s pulse count. The logger featured a built-in LCD display and 5 to 15 universal analog sensor channels recording across a ± 30Vdc input measurement range at 18-bit resolution. The logger operated at a broad temperature range of -45°C to 70°C (-49°F to 158°F). All measurements were stored on the data logger’s memory, holding up to 10,000,000 stored data points.

The DT80M data logger and its CEM expansion modules made for compact and low-power solutions in the small space of the test car, and their robust construction protected them against frequent jostling on the test course. Additionally, the DT80M’s sophisticated communications allowed connections to a PC from the test car either locally, remotely, or over the Internet using its Ethernet and USB ports. Test engineers set the modem’s automatic data delivery features to automatically email all recorded data to a specified inbox every day, with other schedules possible. The DT80M’s USB memory stick data collection further increased data accessibility.

The dataTaker logger’s user-friendly dEX software enabled quick setup and configuration directly in a web browser, and also performed live data analysis and post-treatment functions. Logged data could be remotely accessed by plant management and the software also allowed users to view the real-time data as mimics or charts in a Windows-Explorer-style interface. The logger’s internal modem came predominantly preconfigured enabling a rapid start to the project, and dEX also enabled remote reconfiguration over the Internet. After the completion of each test, a full report was then filed to management. In this role, the DT80M logger transmitted test result data and alarm messages to plant management PCs, emails, and mobile phones via the built-in cellular modem’s FTP and email SMS messaging.

The Proton plant’s test program immediately benefitted from installing the dataTaker DT80M data logger and its CEM20 expansion modules in several key ways. The DT80M accepted most types of thermocouples, and the CEM20 provided a convenient method of expanding the DT80M’s channels. Each channel of the CEM20 could be used for two isolated inputs or three common reference inputs, forming a very cost-effective solution to carry out the many data acquisition tests. Most importantly, the flexible DT80M handled all the different types of logging needed, monitoring air pressure, ambient temperature, voltage, and strain and pulse measurements. The data logger also served as a total remote monitoring solution, giving plant management the test report data they needed on demand through FTP and SMS messaging. The logger’s dEX software was included free of charge and suited both novice and experienced users in configuring and accessing its data. Finally, as an option for larger tests, a 5th CEM module could be added for the maximum of 300 analog inputs if required.