Team of BSE capstone students helps John Deere take air out of hydraulics problem
Calendar Icon Apr 17, 2017 Person Bust Icon By Karl Vogel RSS
A team of biological systems engineering students is taking inspiration from race-car engines to help John Deere prevent air bubbles from damaging an oil filter in of one of its tractors.
As part of their senior design capstone project, the team of Luke Johnson, John Nielsen, Aaron Steckly and Bennett Turner used 3-D printing to create a corkscrew-like device that uses centrifugal motion to remove air from the hydraulics and return clean oil through the system.
"The problem they were having is they wanted filtered clean oil coming from the transmission back to the clean-oil reservoir," Johnson said. "Out of that pump they were having that cavitation problem. There was air entrained inside the oil and it was going through that filter and impact loading that filter.
"When the air slams into the filer, it destroys the paper element inside. Our device increases the life of their filter."
From the early days of the fall semester, the team "locked on" to using centrifugal force to separate the fluids, Turner said.
"We knew the constraints – it couldn't be too big, it had to work at a certain incline, they didn't want us to use electricity to power it. In the end, it was the most practical thing we could apply," Turner said.
Johnson said it was the first step in bringing together the knowledge they had learned in their college classes with their experience from other areas.
"We kind of knew we wanted to do it this way because, when you think two fluids with different densities, you know you can separate them if you spin them," Johnson said. "
The device consists of a box into which tubes for intake and output are attached. The intake tube brings the "dirty" (mix of oil and air) fluid mixture into the top of the box, where it feeds into the 9-inch long, corkscrew device. The denser oil circulates around the outside of the spiral and into the output tube. The lighter air is sent up through a center tube and out of the box.
Because all existing devices were on a much smaller scale, the capstone team had to scale-up to meet the size demands of the John Deere tractor.
The team found success on a smaller-scale version of their device, using low flow rates and a similar but smaller centrifugal device used in race-car engines.
"We noticed that when we'd go up to higher flow rates, like the ones in the tractors, it wasn't nearly as effective," Steckly said.
Using calculation techniques they learned in fluid dynamics classes, the team realized that it had to make the centrifuge larger.
"The viscosity of the oil was not as much the problem as the flow rate, the volume we needed to push through it," Steckly said. "That's when we knew we had to make this larger in scale.
"It didn't take too many iterations. We scaled up the diameter of the new hole, the intake, and based on that we knew that we could increase the flow and it should work."
Working with a larger-than-usual budget for a senior capstone project – John Deere gave the team about $12,000 – keeping costs down was always a factor, Nielsen said.
"The budget we had to work with gave us a lot of freedom, but we have always been very cost-conscious," Nielsen said. "Machining a part would be very expensive."
Choosing to manufacture the part on a 3-D printer was the logical choice. Not only would they save hundreds of dollars, the team also could rely on Nielsen's experience in that field.
"I have an internship and that's my job – to design and 3-D print things," Nielsen said. "I have a printer at home, but I usually print small stuff, like handles for Yeti mugs.
"This part was a much larger scale than anything I've ever printed. It took close to 40 hours to print and we had to use my company's printer because it has a 1-cubic foot volume."
When the new, larger-scale device was assembled and tested, it was easy to tell that the decision to scale up was the right one.
"It's one thing to conceptualize it and design it and you can see pictures of it how it's supposed to be than having it made." Johnson said. "Not just having it be a physical thing that you can touch, but knowing that it works. That's pretty awesome."
And the experience of working for a real client and developing a real product is something the team members value.
"It most definitely gives us an edge because it's putting us in a more real-world scenario – we're actually working on a project that has deadlines, and we have to meet them. There's really no other option," Johnson said. "We have to complete the whole engineering process on one part, and that's something we hadn't experienced before."