Valveless Oscillating Air Engine
Project description:
Design and manufacture a valveless oscillating air engine, under a specific goal.
My Design:
From the five design goals listed in class (max speed, max coast, max power, air efficiency, and cost efficiency) I chose to focus on air efficiency. The first conceptual designs I started with on my engine were having a small piston and cylinder, an oak flywheel in the shape of a bike tire, an acrylic valve plate and oak base, and a cylinder made of delrin. With that rough direction, I continued to play with the calculations and critical values of the engine, until I had something that was mathematically and practically decent. From there I made decisions on all the less critical components and hand drew the orthographic projections of each piece of my engine with its dimensions.
I took these dimensions and modeled them on SolidWorks, making a final assembly of all the parts. The design of the crank disk was modified through this process. After consulting an experienced engineering professor about my engine, I made my flywheel acrylic and made it two pieces, connected with three socket head cap screws, in order to add more weight so that momentum would carry the flywheel a little more. I also made the cylinder wider and added a threaded insert to its pivot hole because it was delrin, and made the piston one solid thickness instead of two. The final design is shown above.
Manufacturing:
From my designs and SolidWorks sketches, I started manufacturing each of the pieces in the school’s machine lab. At first, each part took a long time to make, but I became faster and more efficient the more time I spent
Through the manufacturing process, a few different problems arose. After milling the cylinder, the piston wasn’t fitting into its slip-fit hole, so I went in with the same size ream and drilled it three more times, but it still didn’t fit. I decided to go with a drill that was slightly larger than the hole I wanted and the piston fit right in, though the fit wasn’t as snug as a true slip-fit would be. I had to mill the valve plate twice because the calculations weren’t quite right the first time, but the second time it was much more precise and I made it much faster in general from all the experience I had gained since first starting in the machine shop.
After assembling all the parts, I added another bronze bushing between the crank disk and valve plate and filed it to the right length so that the piston was positioned at the optimal spot on the e-pin. There was also some friction between the piston and crank disk, so I filed the edges of the crank disk.
Overall, I spent approximately 19.5 hours in the machine lab, both for fabrication and assembly problem-solving. A picture of the final product is above.
Engine 2.0:
For my second engine, if my goal were still for air efficiency, there are multiple aspects of my engine that I would change. First, the distance between the crankshaft and e-pin needs to be greater than what it is currently, and that would change multiple other aspects of the design, but only slightly. A heavier flywheel would carry momentum better, and keep the engine lasting a bit longer, even after the air is cut off. I would make it slightly bigger and add brass inserts, which would add to both the aesthetic and practical aspects of the engine.
For the manufacturing process, I would be more careful while crafting the cylinder’s piston hole, so that the piston slip-fits on and less air would leak through.
Design and manufacture a valveless oscillating air engine, under a specific goal.
My Design:
From the five design goals listed in class (max speed, max coast, max power, air efficiency, and cost efficiency) I chose to focus on air efficiency. The first conceptual designs I started with on my engine were having a small piston and cylinder, an oak flywheel in the shape of a bike tire, an acrylic valve plate and oak base, and a cylinder made of delrin. With that rough direction, I continued to play with the calculations and critical values of the engine, until I had something that was mathematically and practically decent. From there I made decisions on all the less critical components and hand drew the orthographic projections of each piece of my engine with its dimensions.
I took these dimensions and modeled them on SolidWorks, making a final assembly of all the parts. The design of the crank disk was modified through this process. After consulting an experienced engineering professor about my engine, I made my flywheel acrylic and made it two pieces, connected with three socket head cap screws, in order to add more weight so that momentum would carry the flywheel a little more. I also made the cylinder wider and added a threaded insert to its pivot hole because it was delrin, and made the piston one solid thickness instead of two. The final design is shown above.
Manufacturing:
From my designs and SolidWorks sketches, I started manufacturing each of the pieces in the school’s machine lab. At first, each part took a long time to make, but I became faster and more efficient the more time I spent
Through the manufacturing process, a few different problems arose. After milling the cylinder, the piston wasn’t fitting into its slip-fit hole, so I went in with the same size ream and drilled it three more times, but it still didn’t fit. I decided to go with a drill that was slightly larger than the hole I wanted and the piston fit right in, though the fit wasn’t as snug as a true slip-fit would be. I had to mill the valve plate twice because the calculations weren’t quite right the first time, but the second time it was much more precise and I made it much faster in general from all the experience I had gained since first starting in the machine shop.
After assembling all the parts, I added another bronze bushing between the crank disk and valve plate and filed it to the right length so that the piston was positioned at the optimal spot on the e-pin. There was also some friction between the piston and crank disk, so I filed the edges of the crank disk.
Overall, I spent approximately 19.5 hours in the machine lab, both for fabrication and assembly problem-solving. A picture of the final product is above.
Engine 2.0:
For my second engine, if my goal were still for air efficiency, there are multiple aspects of my engine that I would change. First, the distance between the crankshaft and e-pin needs to be greater than what it is currently, and that would change multiple other aspects of the design, but only slightly. A heavier flywheel would carry momentum better, and keep the engine lasting a bit longer, even after the air is cut off. I would make it slightly bigger and add brass inserts, which would add to both the aesthetic and practical aspects of the engine.
For the manufacturing process, I would be more careful while crafting the cylinder’s piston hole, so that the piston slip-fits on and less air would leak through.
