I found an error in the video! Due to tolerance stackup (which is a topic not covered that is worth Googling if you're unfamiliar), only one tooth of a sprocket takes most of the reaction force of the chain. You still use steel for driving, aluminum for driven, since you still have a long lever arm on the larger sprocket. The wheels will turn before the aluminum tooth yields.
Absolutely Incredible video. As the High Voltage Electronics lead on a first year team, this made a lot of things more clear and made everything seem more achievable. Keep doing great things man.
My seals knowledge was underdeveloped when I recorded this. The rubber seals on the Drexler differential are more for keeping dust out of the needle bearings than anything. They especially do not "help keep the axle straight," that's the needle bearing's job. Contamination can impact the efficiency and longevity of any moving part, be aware of this when designing and use rubber boots over CV joints as well. Contamination includes both metal shavings in your shop and the debris of the road during testing.
I'd love to help, but unfortunately I do not know enough about suspension design to teach others at a competitive level. Now that I work full-time in the automotive industry maybe I'll learn enough to make a video in the future. For now, there are plenty of great videos and books already out there. I'd learn everything you can about "vehicle dynamics," focusing on suspension geometry, tire data, spring rates, and damping. I'm sure you've already done this; I'm commenting for future readers. I recommend Bosch's Automotive Handbook. It is a great tool for detailed and high-level understanding of all kinds of automotive systems. You can also follow the advice in this video regarding learning the FSAE rules, organizing your team, research, brainstorming, and narrowing down options, and apply it all to suspension design.
Another update: Lots of motors have a built-in gearbox so they can directly connect to the axles while still achieving reduction. This is sometimes referred to as an Electronic Drive Unit, or EDU. EDUs sometimes integrate high-voltage components as well, like an inverter.
Hi Oliver! I believe I fixed the link, let me know if it still doesn’t work. Otherwise you should be able to find it on my channel, the most recent video
@calebsengineeringprojects6202 This video is fantasic. I want to know more about the controller aspect. Emrax motors seem to be paired with Bambocar D3, but I see they arent really available. Sevcon Gen4 Size 8 is in stock in various places. What about making a controller myself? Another question would be the battery for the build. I am choosing cells of 3.6v at 5000mah from Samsung. How do I build the battery to my specs (considering running at low volt config of 180v)? After all, the only way to calculate the kWh that I want the battery pack to have ,is to figure out how much power it will draw over the 2 hour span I want it to have. How would such a thing be calculated? Thank you so much!
Im wanting to go to purdue for automotive engineering. currently Im currently perfecting my math at community college, because its cheap, but once i get though past diff eq, and stats as well as get further into science, but this is awesome stuff and id love to collaborate on a design.
Hey man, amazing dream!!! I also went to community College before University. Honestly the small college profs are often better because they care about education more than research, so you'll have a solid foundation to stand on. Definitely make sure you go to a school with cool competitions/projects, whether it's SAE or otherwise. It's totally worth it, I'm rooting for you!!!
Incredible video ! Concerning the EMRAX 228, you don't speak about the different converter of electrical energy that are needed, could you indicate what kind of component were used between the battery and the motor ? Thanks again
Hello @Tttt-mz5ly When I was in FSAE we split our powertrain team into two halves, electrical and mechanical. After working in industry I realize this is atypical, but I therefore don't remember what components the EE team chose. In the automotive industry, motors are AC not DC, so the only components (besides safety disconnects) are the HVPDU (high voltage power distribution unit) and the inverter which doubles as a motor controller by changing the AC frequency. In your case I'd assume you only need some kind of HV motor controller/voltage regulator, and if your output battery voltage is different from your motor input voltage, a DC/DC converter. An HVPDU is also necessary if you have multiple HV components (for example, multiple motors). To recommend specific components I'd just be googling what other teams have done, which you can do yourself and I'm sure you've already done since your question is 3 months old. I wish I could help more, and best of luck.
To get the optimal gear ratio, should I consider measuring the maximum traction of the tires, and use that force divided by the radius of the wheel to get the output torque coming out of the final drive? Because in my brain, any torque greater than that value would be wasted through wheel slippage. Is that true in the practice?
Yes, that's absolutely true! The friction force at the wheels has an upper limit depending on your tires. When doing your math, remember that your traction increases with downforce, so this upper limit moves up as the vehicle accelerates. This will also depend on the number of powered wheels. Hence why 4wd and awd cars are better for launching, although they're heavier and more complex so maybe not ideal overall.
Hello guys, thanks for the great video. We are an FS team attempting to design our first EV. Could you please tell us if you used a table power supply for testing, instead of a battery pack?
Hi @evangelosbountioukos401, either approach should work in theory, though I definitely think a table power supply is ideal schedule-wise. Battery is the hardest part of the project, and you don't want testing to be held-up if battery falls behind schedule or requires maintenance.
Hey, thanks a lot for the video. At 29:00 there is a statement that appears incorrect to me. The force of the chain does not divide evenly amongst all of the teeth of a sprocket. You can see this for yourself by applying force to the chain and then wiggling the chain links in the middle of a sprocket. You will notice that they are loose. In fact only the first couple teeth take all of the force.
I agree with you, I'll be honest my knowledge on tolerance stackup was tragically limited when I made the video. With tolerances in mind I'd be surprised if any teeth besides the first one or two saw load. It would be interesting to do a study to see exactly how the load is distributed.
Its been 3 years since I graduated so I do not remember the rules, but I think you'd run into weight or spaceclaim problems. Both of the vehicles you mentioned are much larger than an SAE racecar and 8X the weight since they have comfort, durability, & range in-mind. A motor built to last 10+ years and haul 4,000 lb will be much heavier than that in a 500-lb 1-season racecar. The Leaf's drive unit integrates several other HV components such as the onboard charger, DC-DC converter, inverter, etc. All together this gets quite tall, not sure if they're separable. I do not know whether you can buy Chevy Volt battery cells individually, but buying the entire battery would be larger than your entire car and almost weighs by itself what your car should weigh upon completion. This is because the heavy vehicle with longer range and onboard accessories (such as cabin heating) draws significantly more watts/hour than your vehicle should. But do the research, compare rules, weights, sizes, and specs, and let me know what you think! Personally I think using OEM electric motorcycle parts would be a closer fit if its legal and if they're powerful enough. And sourcing your battery so you don't have to build it yourself could save time.
Thank you so much for this. This is extremely helpful but at 14:34 you make a reference to another video with a link, would it be possible to get that link again? the one in the video doesn't work
@@yuriykovalov2936 There is a link in the description as well as what is embedded in the video. (ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-pkwBeQO-0A8.html)
