Sign in to follow this  
Ti-Max

Kinetic energy recovery system (kers) using pull-back

Recommended Posts

Hello everyone!

I just thought of a way to use a differential to use a pull-back motor as a Kers while reading this topic.

This is how it looks :

 35657814810_f186cd069d_c.jpgKERS V1 by Maxime Santerre, sur Flickr

The orange axle is the motor input, it can go trough the entire assembly if need be (to the green side). The green axle is the input/output of the pull-back motor. The blue axle is the wheel output.

How it works :

  - When the car accelerate, the PF motor rotate the diff. The green output can't rotate due to the ratchet so all the power goes to the wheel with a 1:2 ratio.

  - When the car brakes, the PF motor stop and the wheels want to continue rolling (inertia) so all that power goes right through the differential and spin the green axle in the opposite direction, winding up the pull-back motor

  - The pull-back motor can't spin back because of the ratchet mechanism

  - To use the KERS you need to use the PF motor to spin the diff and release the ratchet. That will spin the blue axle to too time the speed of the motor plus whatever the speed of the pull-back motor. If you don't use the PF motor at the same time the car will reverse!

 

Sadly I can't find any of my pull-back motors so I can't fully test this setup. However I've already tested all the mechanical component and they works pretty well but you need a really weak rubber band for the ratchet or you loose to much energy. Feel free to test this setup!

Here is the LDD files : https://drive.google.com/open?id=0BxZ7fJtFVZ4HYTdnVlBfeGR0dWc

 

Share this post


Link to post
Share on other sites

This is so cool!!!

I will use this model in my Thermodynamics classes! First law and that.

Thank you very much. I guess I have even a pull back motor somewhere in the shelves.

Best
Thorsten 

Share this post


Link to post
Share on other sites

Would it work though? At least on my vechicles (I don't know if they are just too heavy or what) come to a complete stop as soon as the motor is turned off. 

I feel like this would only work if the vehicle was moving at a high velocity and when the motor was turned off, the vehicle also went into neutral. I don't know, what do you think? 

The mechanism you made looks like it would work, nice job! 

Share this post


Link to post
Share on other sites

Thanks guys!

Well I'v just made a prototype without the pull-back motor and the wind un mechanism works flawlessly. The little car weight only 220g and it has enough momentum to roll after i cut the m motor. Now We just need someone to do the same test with a pull-back to see if it works.

36013335956_a543ece4ab_c.jpgKERS Prototype by Maxime Santerre, sur Flickr

Here is a (really) short video of the test

35215848834_b97798d844_c.jpgKERS prototype by Maxime Santerre, sur Flickr

Share this post


Link to post
Share on other sites

We have to get the guys working on the 40+ kph record breaking cars to get on this.  Your mechanism truly works flawlessly.  

Share this post


Link to post
Share on other sites

Interesting concept, but I don't yet know if it will work with pull-back motors... I might try it myself if I find time for it. (I'm currently spending most of my time on my secret project)

2 hours ago, aminnich said:

We have to get the guys working on the 40+ kph record breaking cars to get on this.

You mean @TechnicSummse, @Marxpek, and me? Because I don't think it would help getting to 40km/h - I have tried pull-back motors, and found that they don't really do much at all.

Share this post


Link to post
Share on other sites
3 hours ago, mocbuild101 said:

Interesting concept, but I don't yet know if it will work with pull-back motors... I might try it myself if I find time for it. (I'm currently spending most of my time on my secret project)

You mean @TechnicSummse, @Marxpek, and me? Because I don't think it would help getting to 40km/h - I have tried pull-back motors, and found that they don't really do much at all.

I think he means more in terms of having you guys optimise the megabluck out of it. You are really putting loads of work into the 40 km/h competition, so you guys know your stuff in terms of engines etc..

 

I agree that it wont be of benefit to the 40 km/h thing, KERS is all about getting back up to speed as quick as you can on the race track, the only influence it has on top speed, is reaching it a bit quicker

Share this post


Link to post
Share on other sites
3 hours ago, vectormatic said:

I agree that it wont be of benefit to the 40 km/h thing, KERS is all about getting back up to speed as quick as you can on the race track, the only influence it has on top speed, is reaching it a bit quicker

It may allow a higher gearing, and as a consequence, a theoretical higher speed.  If you gear the motors beyond a point where they can start rolling the car from a standstill, a one-time boost from the pullback motor could help get the car to a speed where the motors could take over.

Share this post


Link to post
Share on other sites
11 minutes ago, BusterHaus said:

It may allow a higher gearing, and as a consequence, a theoretical higher speed.  If you gear the motors beyond a point where they can start rolling the car from a standstill, a one-time boost from the pullback motor could help get the car to a speed where the motors could take over.

That is unlikely though, electric motors have pretty much max torque from 0 rpm

Share this post


Link to post
Share on other sites

 

7 hours ago, mocbuild101 said:

You mean @TechnicSummse, @Marxpek, and me? Because I don't think it would help getting to 40km/h - I have tried pull-back motors, and found that they don't really do much at all.

Same story here, tried it and dumped it.

I very much like the KERS-system, but i wont be any help in our quest for 40km/h+, the pullbacks do not add any energy here, even worse; they take away energy from the motor and we need every little bit.. it helps with acceleration, but not with top speed. 

However, maybe the ratchet release system can work for a booster unit at the start for our racers, but it still does not help with top speed, just acceleration, but we always like a shorter track, less time to crash on a shorter track :o

 

Share this post


Link to post
Share on other sites
15 hours ago, mocbuild101 said:

Interesting concept, but I don't yet know if it will work with pull-back motors... I might try it myself if I find time for it. (I'm currently spending most of my time on my secret project)

You mean @TechnicSummse, @Marxpek, and me? Because I don't think it would help getting to 40km/h - I have tried pull-back motors, and found that they don't really do much at all.

I also like the concept... really clever.

But as @Marxpek and @mocbuild101 allready said... there wont be any benefit of the KERS-system at our purpose.

What we could do, also to increase top speed, would be something what will be released at top speed. For example wind up a few pullback-motors, and activate their power with a micromotor controlled by the auxillary output of the rc-unit, right before the top-speed with e-motors is reached.

The problem here is, to not loose any power while driving with the electrical motorpower... for example the use of a ratchet would not work.

It would work, for example if the rear axle (driven axle) can rotate freely by the e-motor-power, and the micromotor would move an arm (beam) with an additional gear, connecting the drivetrain to the pulback-motors and release them at the same time.

 

But im not sure, how much power they really have, compared to a buggy-motor.

Share this post


Link to post
Share on other sites

I've been experimenting with a similar setup long ago, back in 2015 . My results were the same as now, it is easier to backdrive the motor rather than drive the wind-up motor. The car simply brakes.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.