SOGAV Passes a Billion Operating Cycles
Woodward designs and builds a variety of solenoid operated gas admission valves (SOGAV). They all operate on the same principle.
Two steel metering plates with a pattern of holes drilled in them are pulled apart by a solenoid exposing the maximum amount of opening to meter fuel gas into the cylinder of a reciprocating engine. The valve remains open as long as the solenoid is activated and closes again when the solenoid is deactivated. The engine’s electronic control module determines how long each solenoid is activated to admit the proper amount of gas fuel into each cylinder.
On November 1 of 2014 Woodward Engineering initiated an endurance test on an insert top load unbalanced SOGAV 105 valve as a control in a series of experiments. This valve is just one of many production valves and was simply pulled out of stock and placed in test.
These SOGAVs are typically used on Caterpillar GCM34 engines that usually drive gas compressors or are used for electric power generation. Compressed air was used instead of natural gas as the test gas during the endurance testing. The valve was operated at a 30 % duty cycle with a low pressure across the valve.
The test was concluded on October 7, 2015 after the valve had operated for 1,002,550,000 cycles in an accelerated durability test. The valve continued to operate without any problems when it was finally removed from test for examination.
It was subjected to the end-of-line production test and did not pass due to weakening of their return springs. Replacing these springs would allow the valves to pass the production test.
After cleaning the oil from the air compressor off the valve’s plates, the plates were only 2% out of new build specification. There was a lot of oil build-up on the plates from the air compressor and the springs were slightly fatigued which explained the slight increase in gas flow from specified rate.
The design life target for this valve is 360 million cycles before it would need to be rebuilt.
This corresponds to about 16,000 hours of operation on a 750 rpm engine. The industry continues to push for more and more operating cycles and additional work is needed to validate that we can consistently meet those challenges, but this testing shows that the
valve’s design is sound and capable of meeting those challenges.
The following photos show the condition of valve’s metering plates at the conclusion of the endurance testing. The photos show the condition of the moving plate that incurs an impact in both the opening and closing direction.
This update originally appeared in Woodward’s Energy Controls News email newsletter, Jan 2016 Edition.
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