CAS DataLoggers recently provided the datalogging solution for a large manufacturer who needed to test its injection valves and pumps to be used in a wide variety of engines. These valves consisted of compact modules containing the magnetic circuit and the valve unit, controlled by a digital signal from the ECU (electronic control unit), which started the movement of the valve. Wear on the proportional valves also needed to record over millions of cycles. A proposed test target was to detect the timing of this movement in every injection spray cycle in a durability test stand, which meant 6000 RPM 50x per second, or every 2nd revolution of the crankshaft. However, a persistent problem was that the valve movement signal had noise on it. The manufacturer needed a data acquisition system able to record additional signals such as gasoline spray volume and others at a high sampling rate and in real time. The device would also need to feature powerful analysis software to calculate digital filters and interpolation in order to reduce the noise, as well as all relevant timings online in every continuous valve cycle.
The manufacturer installed an ADwin-Gold Real-time Data Acquisition and Control System in its test area and connected it to a series of valves and pumps. The system detected and evaluated the valve movement timing both online in real-time. To reduce the valve movement signal noise, a digital filter and online interpolation ran in real-time. In order to test the injection pumps, the ADwin-Gold controlled magnetic valves via digital signals. The pump’s rotating parts correlated to the angle of these rotating parts, so the ADwin opened and closed the valves just as in a real engine, simulating the ECU signals to test the pump in a flexible way. Valve movement was recorded at high sample rate of up to 1 MHz.
The ADwin-Gold provided deterministic operation for the testing program with response times of 1 microsecond or less, supporting parallel, individually controlled processes while running in real-time independently of a PC. The system featured 16 multiplexed analog inputs and 8 analog outputs with 16-bit resolution, along with optional counters enabling extremely low latency operation and CAN, SSI, and RS-232/485 interfaces. The CPU controlled signal acquisition and the system recorded all measurements in real-time onto 16 MB of external DRAM. Additionally, the system’s integrated Ethernet/USB interface offered flexible communication with a PC.
The wear on the proportional valves was recorded for millions of cycles, with some ramps per second; a ramp from the D/A output opened and closed the proportional valve. The analog inputs measured valve performance, and the system also used various boundary curves to make an online comparison and evaluation of the recorded values. A log was made to record the increasing wear and tear, and the raw measurement data was regularly saved at certain intervals depending on the degree of damage.
Running under Windows and LINUX, the software environment functioned as a stand-alone data acquisition system. Several PCs concurrently communicated with the system to help with program implementation and commissioning. It also had drivers for many common programming environments including VB, VC/C++, LabVIEW, TestPoint, and others. The software also enabled calibration of the system’s analog inputs and outputs.
The manufacturer benefited significantly from installing the ADwin-Gold real-time data acquisition system in its injection valve and pump testing program. The system calculated digital filters and interpolation for effective noise reduction, determined all relevant timings in real-time for each movement in the valve cycle, and also recorded other signals including gasoline spray volume and all other parameters. The ADwin-Gold system also utilized its own DSP processor to operate independently of Windows on the PC, allowing for reliable and predictable operation, while its flexible communications functionality simplified data transmission and accessibility.
CAS Data Logger Inc.
Filed Under: Test & Measurement Tips