E-Drive and PE-Drive

[Worldwide_build]

Hello all,

It's me again. I have been offline for a while. However. I am developing a worthy replacement for Power Functions and Powered Up! train tech. I am going to build all-new train trucks, two and three-axle with one motor for each axle, running at 12 volts or more. These train trucks are not compatible with PF or PU. Instead, they use a new system. This system, in theory, allows for more pulling power and more speed for your LEGO train. The standard LEGO traction motor creates 3.6 Ncm of torque. A three-axle of my own design could generate 10x more torque while running 4x as fast.

Sounds impressive, but man how are you going to power that?

Well, thanks for asking. Some people may know of a post I placed a while back which discussed larger and smaller Pneumatic Compatible engine pieces. Build a small scale pneumatic V20 and hook a slow turning electric generator to it. This should generate the electricity needed to power the train trucks. This would make for a Pneumatic-Electric Locomotive, hence the name PE-Drive. Another method is an overhead live-wire that receives power from your wall-plug.

But wait, doesn't that mean my train would run at 230v?

Nope, a transformer takes the voltage down to either 12 or 24 Volts AC (not sure which electric motor I'll use yet) and it's not like the classic 9-Volt system. Each train is remotely controllable, just like PF or PU, or SBrick, etc. You can use as many trains as you want as long as your electrical grid can handle it. The electric live-wire is the reason why the all-electric system is called E-Drive.

 

A long term plan is to make very advanced train trucks with real suspension in it.

 

I wonder how you think about it. 

[Thai bricks]

Sounds interesting and I look forward to read more about it. I don't understand the pneumatic part. Are you storing energy in compressed air bottles?

[Worldwide_build]

53 minutes ago, Thai bricks said:

Sounds interesting and I look forward to read more about it. I don't understand the pneumatic part. Are you storing energy in compressed air bottles?

The solution is beneath the frame of the locomotive; The fuel tank. If I can make an air-compressor small enough to fit it beneath the locomotive, the locomotive would have its energy-generating source on-board. I found 3V electric motors, I could potentially use those. It would run off the same electronics that power the controlling modules of the locomotive. Still researching this though.

[Thai bricks]

15 hours ago, Worldwide_build said:

Build a small scale pneumatic V20 and hook a slow turning electric generator to it. This should generate the electricity needed to power the train trucks.

 

13 hours ago, Worldwide_build said:

an air-compressor small enough to fit it beneath the locomotive, the locomotive would have its energy-generating source on-board.

So, is your V20 an air motor or a compressor? If it is driving a generator, then it is not a compressor, it's an air motor, i.e. it turns air flow into rotary motion, which the gen turns into electricity. But what is the primary energy source?

You are making my head spin... :)

[Worldwide_build]

5 hours ago, Thai bricks said:

 

So, is your V20 an air motor or a compressor? If it is driving a generator, then it is not a compressor, it's an air motor, i.e. it turns air flow into rotary motion, which the gen turns into electricity. But what is the primary energy source?

You are making my head spin... :)

You're nearly there. The V20 is an air-motor that drives an electric generator. The power that the generator generates goes to the rail trucks to drive the wheels. On-board there is a lower voltage system that powers the controller (think about a stepper motor to control the airflow) and a small electric motor that powers a very compact air-compressor located in the fuel tank area. These two systems are independent of each other, the only relation being to control the motor and the compressor. All-Electric trains are on a completely different level, as the effort required to design this compared to the Pneumatic-Electric system is much higher. It's still feasible though, but I'm going to focus on my expertise first, industrial pneumatic systems.

Feel free to ask more questions if you like, more than happy to answer them and to talk about this. :)

[Thai bricks]

So, el. motor => compressor => air motor => generator => el. motors. Then you need an auto-off switch on the compressor and a valve to regulate speed. Plus a pole reverser to change direction.

Why so complicated? It will be noisy, very inefficient and hard to control. Why not control the el. motors on the axles directly? If this was a "live steam" engine, i.e. with working pistons and valve gear this would make sense, but I don't think you can build that from Lego. But it sure will be an interesting project, just for the hell of it.

[Worldwide_build]

14 hours ago, Thai bricks said:

So, el. motor => compressor => air motor => generator => el. motors. Then you need an auto-off switch on the compressor and a valve to regulate speed. Plus a pole reverser to change direction.

Why so complicated? It will be noisy, very inefficient and hard to control. Why not control the el. motors on the axles directly? If this was a "live steam" engine, i.e. with working pistons and valve gear this would make sense, but I don't think you can build that from Lego. But it sure will be an interesting project, just for the hell of it.

It would likely be inefficient, but so is a modern-day diesel engine. The auto-off switch is most likely not required as the compressor won't get a high enough pressure at a high enough rate for any danger, the PE would consume the air too quickly. The pole reverser is a must though. As for being noisy, so is a Diesel-Electric locomotive and this system is designed to mimic that. Hard to control can be solved by using clever tricks. I will provide a manual with the final product that teaches the user how to use the system correctly.

I see a lot of potential in this, it's hard but when the right techniques are applied it would be decent enough to run a high powered LEGO locomotive. Remember, it's all theory. The compressor will likely be a turbine design, to minimize space used and to maximize the volume of the air tank.

P.S., Some models could have 'turbochargers' to reduce the amount of air lost by using the exhaust air to drive a turbine, which sucks in additional air. This would be experimental though, first need to get the proper equipment up and running.

[andythenorth]

This will be interesting.  Are you building a bench test rig first, or going straight to the final train?

[Worldwide_build]

20 minutes ago, andythenorth said:

This will be interesting.  Are you building a bench test rig first, or going straight to the final train?

I will build a test bench rig first, to see if it works correctly. If it pasts the test and confirms my theories, I'll build a locomotive around it to showcase the functionality. Everything will be prototyped first. Oh, and by the way, these systems are designed for 8-Stud wide trains. 6-Stud wide is simply too narrow. At least, right now it is.

[Worldwide_build]

Update:

The very first prototype is being 3D Printed. This prototype is part of Revision 1 on these trucks. It features three axles and all axles run on 7mm roller bearings. The trucks are tunable, meaning you can opt for more torque but slower speed or less torque but high-speed. Weight will play a role here, the weight of your train determines the maximum speed of your train. Making the wheels rotate at the same speed as those from LEGO (2000RPM) and your three-axle truck could generate nearly 40 times more torque compared to LEGO motors. (142.8Ncm compared to 3.6Ncm torque)

I'll keep everyone updated on this project. By the way, should I turn to Kickstarter for this project?

[Worldwide_build]

Update:

I decided to create a Kickstarter project. This project primarily covers my earlier idea of smaller and larger engine pieces. But as those pieces concern this idea too, I am posting an update in this thread as well. I will post a link when it is ready. :)

[Phoxtane]

I'm not sure I see the functionality/usefulness/effectiveness of PE-Drive, or the business case for E-Drive.

It sounds like PE-Drive takes compressed air and uses it to generate electricity to drive the train. I don't think compressed air will be energy-dense enough to allow for any meaningful amount of run time, especially once you run it through a tiny pneumatic V20 motor-generator unit with the efficiency losses there.

Examining the efficacy of PE-drive vs batteries:

Typically, our Lego trains run off of six AA or AAA batteries in series.

Say I use AAA batteries - Duracell Coppertops, part number MN2400 (Duracell because I can find a data sheet for these), and run my train around a track non-stop. It will use on average about 300mA* and thus get about 2.5 hours of run time out of one set of AAA batteries**. This means that at the load this test train is running at, we can extract ~750mAh from those batteries. The PF train motor uses a small brushed DC motor for power, and since it's not hugely expensive let's say it's 75% efficient***. Overall, that means we use 1000mAh for running the train for 2.5 hours (4). Using 1000mAh can also be expressed as having used 32.4 kilojoules of energy (5) (6) (7).

Lego pneumatic compressors tend to cap out at around 30psi in my experience, but you're (presumably) using a custom compressor, so let's say that's 40psi. To store 32.4kJ in air that's at 40psi, you would need a reservoir with a volume of 117.47 liters (8). Where in the megablocks does that fit into a Lego train? Even with a 60-gallon 175psi compressor from my local hardware store, that's still a reservoir size of 26.86 liters (9), and IMHO that's a really scary pressure for something the size of an office water cooler tank on my living room floor. That's at an impossible 100% efficiency! This research paper suggests that reciprocating compressed air engines will be, at most, 13% efficient. If your air reservoir is roughly the size of two Lego AAA battery boxes, you have at most .15 liters, and you'd have to compress your reservoir to over 31000psi...

In two battery box's worth of volume you could store 42J of energy at 40psi (with an impossible 100% efficient drive train - motor-generator and all). That's the same as a 1.3mAh battery, which will run your train for roughly 3-4 seconds. Even if this gives you a ton of torque in that time, your wheels would slip and most of that energy would be wasted. 

* https://www.philohome.com/ttrain/ttrain.htm

** https://www.duracell.com/en-us/techlibrary/product-technical-data-sheets (have a look at the constant current curve for 250mA on the Coppertop MN2400 AAA datasheet)

*** https://www.quantumdev.com/brushless-motors-vs-brush-motors-whats-the-difference/

(4) https://www.wolframalpha.com/input/?i=Solve+X*.75+%3D+750+for+X

(5) https://www.rc-electronics-usa.com/battery-electronics-101.html

(6) https://www.wolframalpha.com/input/?i=1000*9.0*3.6+Joules

(7) https://hypertextbook.com/facts/2001/KhalidaNisimova.shtml

(8) https://www.wolframalpha.com/input/?i=117.47+liters+at+40psi

(9) https://www.wolframalpha.com/input/?i=26.86+liters+at+175psi

Due to the above I don't think PE-Drive will be a good candidate for powering our trains any time soon. On the other hand, from a ridiculously cool steampunkish aesthetic and engineering standpoint I'd love to see this system in action!

E-Drive is more feasible in my mind because it propose an alternate all-electric power system. However, I don't think it will be economically viable, because it requires more infrastructure than even the old 12V and 9V systems - how are you going to keep the overhead cables from moving relative to the track? Most of us don't have the space or budget for a permanent layout where these things can be glued or bricked down. In addition this also requires new motors/electrical pickups, transformers, etc...

Also:

On 1/19/2020 at 1:21 PM, Worldwide_build said:
The V20 is an air-motor that drives an electric generator. The power that the generator generates goes to the rail trucks to drive the wheels. On-board there is a lower voltage system that powers the controller (think about a stepper motor to control the airflow) and a small electric motor that powers a very compact air-compressor located in the fuel tank area. These two systems are independent of each other, the only relation being to control the motor and the compressor. All-Electric trains are on a completely different level, as the effort required to design this compared to the Pneumatic-Electric system is much higher.

Where does PE-Drive get the electrical power to run the onboard compressor? Don't say it comes from the motor-generator unit because that's a perpetual motion machine and those don't exist. And if it comes from wall power via an overhead cable, why bother with the complexity and poor efficiency of a pneumatic motor-generator unit? Why not just use an on-board electric motor, like the 9V, 12V, RC, PF, and PU systems use? You can get a ton of torque out of an electric motor - if you want more than what Lego currently offers, you should see what electric RC racing has done for the availability of small high-torque brushless motors.

(Side note: if you do look into RC gear for cramming into Lego trains, please consider stuffing a nitro RC buggy engine into one too. It'll be hilarious.)

 

Edited January 25, 2020 by Phoxtane
didn't unbreak the editor

[Phoxtane]

(I don't like making double posts but I somehow managed to absolutely destroy the post editing system with my last one so here we are)

One final thought: I would avoid Kickstarter (or any crowdfunding platform) until you have an actual, physical, operating prototype.

https://www.kickstarter.com/rules

"Projects must be honest and clearly presented.
Our community is built on trust and communication. Projects can’t mislead people or misrepresent facts, and creators should be candid about what they plan to accomplish. When a project involves manufacturing and distributing something complex, like a gadget, we require projects to show backers a prototype of what they’re making, and we prohibit the use of misleading imagery." (Emphasis mine).

Please also keep in mind many of us are VERY skeptical of crowdfunding stuff for Lego trains due to the fiasco of the ME Models metal rails. Four (?) years later most people still haven't gotten anything, pledges haven't been refunded, and ME Models is, for all intents and purposes, out of business. As a result we're a very tough crowd when it comes to crowdfunding.

[Worldwide_build]

On 1/25/2020 at 1:35 AM, Phoxtane said:

I'm not sure I see the functionality/usefulness/effectiveness of PE-Drive, or the business case for E-Drive.

It sounds like PE-Drive takes compressed air and uses it to generate electricity to drive the train. I don't think compressed air will be energy-dense enough to allow for any meaningful amount of run time, especially once you run it through a tiny pneumatic V20 motor-generator unit with the efficiency losses there.

Examining the efficacy of PE-drive vs batteries:

Typically, our Lego trains run off of six AA or AAA batteries in series.

Say I use AAA batteries - Duracell Coppertops, part number MN2400 (Duracell because I can find a data sheet for these), and run my train around a track non-stop. It will use on average about 300mA* and thus get about 2.5 hours of run time out of one set of AAA batteries**. This means that at the load this test train is running at, we can extract ~750mAh from those batteries. The PF train motor uses a small brushed DC motor for power, and since it's not hugely expensive let's say it's 75% efficient***. Overall, that means we use 1000mAh for running the train for 2.5 hours (4). Using 1000mAh can also be expressed as having used 32.4 kilojoules of energy (5) (6) (7).

Lego pneumatic compressors tend to cap out at around 30psi in my experience, but you're (presumably) using a custom compressor, so let's say that's 40psi. To store 32.4kJ in air that's at 40psi, you would need a reservoir with a volume of 117.47 liters (8). Where in the megablocks does that fit into a Lego train? Even with a 60-gallon 175psi compressor from my local hardware store, that's still a reservoir size of 26.86 liters (9), and IMHO that's a really scary pressure for something the size of an office water cooler tank on my living room floor. That's at an impossible 100% efficiency! This research paper suggests that reciprocating compressed air engines will be, at most, 13% efficient. If your air reservoir is roughly the size of two Lego AAA battery boxes, you have at most .15 liters, and you'd have to compress your reservoir to over 31000psi...

In two battery box's worth of volume you could store 42J of energy at 40psi (with an impossible 100% efficient drive train - motor-generator and all). That's the same as a 1.3mAh battery, which will run your train for roughly 3-4 seconds. Even if this gives you a ton of torque in that time, your wheels would slip and most of that energy would be wasted. 

* https://www.philohome.com/ttrain/ttrain.htm

** https://www.duracell.com/en-us/techlibrary/product-technical-data-sheets (have a look at the constant current curve for 250mA on the Coppertop MN2400 AAA datasheet)

*** https://www.quantumdev.com/brushless-motors-vs-brush-motors-whats-the-difference/

(4) https://www.wolframalpha.com/input/?i=Solve+X*.75+%3D+750+for+X

(5) https://www.rc-electronics-usa.com/battery-electronics-101.html

(6) https://www.wolframalpha.com/input/?i=1000*9.0*3.6+Joules

(7) https://hypertextbook.com/facts/2001/KhalidaNisimova.shtml

(8) https://www.wolframalpha.com/input/?i=117.47+liters+at+40psi

(9) https://www.wolframalpha.com/input/?i=26.86+liters+at+175psi

Due to the above I don't think PE-Drive will be a good candidate for powering our trains any time soon. On the other hand, from a ridiculously cool steampunkish aesthetic and engineering standpoint I'd love to see this system in action!

E-Drive is more feasible in my mind because it propose an alternate all-electric power system. However, I don't think it will be economically viable, because it requires more infrastructure than even the old 12V and 9V systems - how are you going to keep the overhead cables from moving relative to the track? Most of us don't have the space or budget for a permanent layout where these things can be glued or bricked down. In addition this also requires new motors/electrical pickups, transformers, etc...

Also:

On 1/19/2020 at 1:21 PM, Worldwide_build said:
The V20 is an air-motor that drives an electric generator. The power that the generator generates goes to the rail trucks to drive the wheels. On-board there is a lower voltage system that powers the controller (think about a stepper motor to control the airflow) and a small electric motor that powers a very compact air-compressor located in the fuel tank area. These two systems are independent of each other, the only relation being to control the motor and the compressor. All-Electric trains are on a completely different level, as the effort required to design this compared to the Pneumatic-Electric system is much higher.

Where does PE-Drive get the electrical power to run the onboard compressor? Don't say it comes from the motor-generator unit because that's a perpetual motion machine and those don't exist. And if it comes from wall power via an overhead cable, why bother with the complexity and poor efficiency of a pneumatic motor-generator unit? Why not just use an on-board electric motor, like the 9V, 12V, RC, PF, and PU systems use? You can get a ton of torque out of an electric motor - if you want more than what Lego currently offers, you should see what electric RC racing has done for the availability of small high-torque brushless motors.

(Side note: if you do look into RC gear for cramming into Lego trains, please consider stuffing a nitro RC buggy engine into one too. It'll be hilarious.)

 

Well, that's a lot of information. You are right about the efficiency stuff, it's inefficient. It's more of a prestige thing. But, due to the use of an electric motor per axle, it could achieve more pulling power.

I am looking into the source of the electrical energy required to create enough pressure for the pneumatic engine. PE-Drive is not supposed to be as efficient as electric or batteries. Mainly because it is based on Diesel-Electric systems. The idea is the same but executed differently. I am considering the use of a low-voltage system that powers a very small compressor, hopefully, capable of at least 30 PSI.

On 1/25/2020 at 1:58 AM, Phoxtane said:

(I don't like making double posts but I somehow managed to absolutely destroy the post editing system with my last one so here we are)

One final thought: I would avoid Kickstarter (or any crowdfunding platform) until you have an actual, physical, operating prototype.

https://www.kickstarter.com/rules

"Projects must be honest and clearly presented.
Our community is built on trust and communication. Projects can’t mislead people or misrepresent facts, and creators should be candid about what they plan to accomplish. When a project involves manufacturing and distributing something complex, like a gadget, we require projects to show backers a prototype of what they’re making, and we prohibit the use of misleading imagery." (Emphasis mine).

Please also keep in mind many of us are VERY skeptical of crowdfunding stuff for Lego trains due to the fiasco of the ME Models metal rails. Four (?) years later most people still haven't gotten anything, pledges haven't been refunded, and ME Models is, for all intents and purposes, out of business. As a result we're a very tough crowd when it comes to crowdfunding.

The Kickstarter project is not for the PE-Drive and E-Drive systems, but rather for my Larger and Smaller engine pieces. These are specialized pieces for both show and pneumatic engines. Special valve heads allow for a different way of building LPE's, much more resembling actual ICE's. I have real prototypes of these pieces, excluding the valve head. Starting with the larger pieces, I'll work my way down to bringing the system to stud-wide cylinder bores if possible.

The Fiasco of ME Models metal rails? Haven't heard of it... Would you like to tell me a little more about this?

[Phoxtane]

ME Models used to sell plastic curved tracks in different sizes, made up like the old 12V system (individual rails connected with a basic 2x8 plate).

They planned on branching out into all-metal rails, and started a Kickstarter to get the project going. Four (?) years and $87,000 later, the community only ever saw prototypes at a handful of conventions. In fact, the prototyping and production phases went so poorly ME Models is no longer in business as best I can tell - both their website and Facebook page have vanished into the ether. If you look at the Kickstarter page, the comments are full of a bunch of disappointed enthusiasts who put their money on the line in the hopes that ME Models would bring metal rails to market.

I believe this to be why people in Train Tech, including myself, are very skeptical of crowdfunding campaigns for Lego Train-related items.

[Worldwide_build]

1 hour ago, Phoxtane said:

ME Models used to sell plastic curved tracks in different sizes, made up like the old 12V system (individual rails connected with a basic 2x8 plate).

They planned on branching out into all-metal rails, and started a Kickstarter to get the project going. Four (?) years and $87,000 later, the community only ever saw prototypes at a handful of conventions. In fact, the prototyping and production phases went so poorly ME Models is no longer in business as best I can tell - both their website and Facebook page have vanished into the ether. If you look at the Kickstarter page, the comments are full of a bunch of disappointed enthusiasts who put their money on the line in the hopes that ME Models would bring metal rails to market.

I believe this to be why people in Train Tech, including myself, are very skeptical of crowdfunding campaigns for Lego Train-related items.

Darn... That sure is a bad way to build a reputation... I hate it when businesses handle people like that. Now I understand why people would be skeptical about this...

Anyhow, I aim to not do it the way they did. It does make it harder for me to get the project going though. Especially as I do not have the funds to make many prototypes to show you. For me, I guess it would be good luck then if people start funding.

If people want me to tell them who I am in order to gain trust, I would happily do so. If people do fund, I will make sure it will not turn into a fiasco of its own.

Edited January 26, 2020 by Worldwide_build
Forgot the word "show"

[peterab]

On 1/27/2020 at 8:50 AM, Phoxtane said:

ME Models used to sell plastic curved tracks in different sizes, made up like the old 12V system (individual rails connected with a basic 2x8 plate).

They planned on branching out into all-metal rails, and started a Kickstarter to get the project going. Four (?) years and $87,000 later, the community only ever saw prototypes at a handful of conventions. In fact, the prototyping and production phases went so poorly ME Models is no longer in business as best I can tell - both their website and Facebook page have vanished into the ether. If you look at the Kickstarter page, the comments are full of a bunch of disappointed enthusiasts who put their money on the line in the hopes that ME Models would bring metal rails to market.

I believe this to be why people in Train Tech, including myself, are very skeptical of crowdfunding campaigns for Lego Train-related items.

This is a little inaccurate. The ME models kickstarter offered both plastic and metal track. They started selling the plastic track before they had fulfilled the kickstarter pledges because the cost of tooling had blown out. The plastic track gained a reputation for needing to be glued otherwise it would burst apart if being moved and even when being used. The metal track prototypes failed to conduct electricity well and were eventually replaced with a system that used model railway fishplates to connect the rails. The production costs blew out and many pledges (even all plastic track like mine) were never fulfilled.

Essentially it appears the availability of 3D printed single piece track overtook the ability of ME to trade their way out of the cost blow out.