Cool concept. I've always had this idea that I could never realise. But what if a transmission would switch gears depending on how much force there's on the chain? In other words, it might be cool if the chain was going over a slack wheel that controls the CVT lever. Could be worth a try.
If the chain is also lubricated with oil, then friction losses will be even less than in a manual gearbox! I really want to see how such a variator will accelerate the car and pull it uphill! 👍
Frictional force depends on force per unit area. As contact area increase, the force per area decreases proportionally. And so, the width of the rubber band doesn't really effect the available friction. Instead, what matters is the spring force and unsprung diameter of the rubber band. As that will increase the force over the same area.
13:13 measure voltage and current going to the motor That's probably one of the easiest ways to see Cause you're getting more torque out as you're spreading the load over time So power should stay somewhat constant
i'm surprsed you didn't just wire up the time axis to a consistent speed source, makes the graph easier to read and removes your aliasing issues, i guess only issue is figuring out how to get a consistent speed without a motor
I wonder...could you theoretically have four CVTs for four wheels? Basically just a direct drive from the engine to each transmission? I know it wouldnt be too practical in a car, because of the amount of things you have to lubricate and maintain, but could it be possible?
I noticed that, when shooting multiple balls at once, the first one mostly hits the basket while the subsequent ones tend to miss. I think in this case it is related to the RPM of the motors dropping after each launch. A flywheel might help stabilize this. Other than that: Awesome build! You have another subscriber!
I was just having the idea for a variable wheel transmission after seeing the first design and then you pull it out 😂 This is a beautiful concept, i wish you luck on the adventure
Woah. I've been thinking about a similar chain drive idea for years for a bicycle, but never really actually attempted to make it. Good job for actually implementing this!
Please just use a differential to get CVT. This is over engineered. There are 3 points on a diff. You can use it as 1 input 2 outputs or 2 inputs 1 output. I think you can figure out the rest. They have been used as CVT for decades.
3 points: 6:30-ish: You could have used gears to drive the chain, you'd just need to fix them with a ratchet rather than fixing their axle. 0:27 I would have tried wrapping the rubber band around the cones more times. You couldn't wrap it around the same cone more than once, but you could make it wrap around 3 cones per side to complete the 180° turn: 225° around the first cone, 270° around the second one, and then 225° around the last one. The first and last cone can both be geared to the input/output shaft. And the second cone can be used to pinch the rubber band at the contact points of the first/second and second/third cones. 13:01 Route your output into a differential, hook one of the diff's outputs into a device where the drag can increase with speed (like a large fan), and hook the other side into a pointer whose deflection is proportional to the torque (working against a weight or a rubber band). The differential will make sure that both of it's outputs are at the same torque, the pointer will allow you to read off the torque, and the fan will make sure that the output of the CVT can move even though the pointer stays still.
14:20 That's not a problem that's a feature! You're taking the definite integral of the motor's speed over the sampling interval! This way, you can use it to literally just measure the actual speed of the motor over that time period, or you could use it to see how _far_ the motor has traveled (position), which is the integral of the motor's velocity. Very clever, even if that's not what you intended to use it for. edit: 20:25 lol
I wonder what kind of performance you could get with a pulley based CVT instead. Both the input and the output side have 2 pulleys that get closer or farther apart to change the diameter of the belt. If you do try it out, maybe see if there's some type of V-Belt you can use, it should provide the most friction. A round (instead of a flat) band may also work for a pulley based CVT specifically
if you put another of those auto cvts in series it should both multiply low end torque and high end speed and you could probably do this until the friction diminishing returns over take multiplier which should be quite a few if it has as little friction that appears in the video.
cruise control in automatic transmissions works by measuring the rpm and torque of the engine and the fuel economy it would provide, and adjusting the gear and throttle to that
I think you might be able to reduce the turning radius of the long one a bit by mounting the motor backwards and bringing the rear wheels closer to the center, leaving the motor cantilevered behind them
Stop playing with LEGO. Collect soda cans from the neighborhood. Start a fire in the backyard. Pour your own cast aluminum blocks and gear parts. Build a go-kart.
@@dwavenminer In keeping with the stereotype: Umm actually, I didn't tell him to not have a hobby. Just to change what the hobby worked with specifically. It's even still the same hobby: assembling and engineering. Touch dictionaries.
This puts the entire load on just those little hooks, and transmits power only one way which is not ideal for a car. Some slip is realistic for an automatic transmission anyways.
