New Geared Hubmotor variable-regen e-braking system that still freewheels, by ChargeBike

amberwolf

amberwolf

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In this Grin Tech video
They discuss a clever new way of engaging and variably controlling regen braking. There's not a lot of detail, but essentially:

There isn't an electronic control over the variable regen, it is entirely mechanical. The disc rotor connects not to the shell, but to the planet carrier. So when you engage the mechanical disc brake on that wheel, it prevents the carrier from rotating (or adds drag to it if you aren't fully engaging the brake), and causes the clutch to engage as if the motor was spinning, causing the wheel rotation to backfeed into the motor.

This image from their page shows the standee with the images too)
FullyCharged1[1].jpg FullyChargedBoothCorner[1].jpg

Stuff not covered in the video:

Since you wouldn't normally have the motor operating while you're braking, it would then just be creating voltage as a generator, feeding current back to the battery if the voltage is higher than the battery voltage, using the controller FETS as a 3-phase rectifier. The more force you apply with the lever (which you will get natural normal mechanical feedback for, as you are simply using a standard disc brake as-designed),

If a controller could be designed to be able to detect that braking is occurring via this generated voltage and then perform switching operations it could increase this braking force, or alter the curve it is applied with, etc. (you could install some form of position sensor on the caliper that provides a variable output to do this, but that defeats the point of the system not requiring any sensors or wiring for this, and changes the feedback to control the braking to electronic instead of mechanical).




It's an interesting system I wish I had thought of. :)



It should be possible to alter an existing geared hubmotor to work this way, although the ones I've personally opened up have the planetary carrier and clutch on the pedal drive side, not the brake side, so it would take some mechanical rearrangement of the casing and internals to do this that would be easier on a front motor than a rear.

I am going to take a look at the old bafang Jump Bike motors I've got to see if this is a possible mod with the capabilities I have here, when at some point in the future I have time/etc to try.
 
Last edited:
No idea, couldn't find one for sale yet. :(

They do have a good image of the disc mounted to the planetary carrier, and the whole motor, on the standee in the video right about where it starts in my link. (another version of that is attached in the first post)
 
I can't quite wrap my head around how it works, I feel like I'd probably need a 3d animation of the internals or something. The thumbnail implies the disc rotor is stationary relative to the brake caliper so how is any useful force generated by pads pressing into a stationary rotor? I assume I'm confused about something. Also does this mean that any force that is generated by the pads only goes to engaging the internal clutch and only electromagnetic forces from the motor actually slow down the wheel? Or is there still mechanical drag on the wheel itself from the brake?

Sounds like very cool tech and I'm glad they went to Grin to launch it. It's in good hands.
 
I wish there was a video that actually showed it in operation, but I couldn't find one. I can see it in my head based on their images and explanation but I can't put it into words any better than they did. :oops:

If I had time/etc I'd modify something like one of my old Fusin hubs not being used anymore (like the one with the broken clutch) just to show it...but that's unlikely to happen anytime even remotely soon. :(
 
That's quite alright! I'm mainly interested for curiousity's sake. I'm sure when they actually release it they or someone else will provide explanations/better footage.

Tried googling Chargebike, could only find the guys LinkedIn page and some other company with the same name. No more information there. Also couldn't get the QR code shown in the pic on grins page to work. Not that I tried particularly hard.
 
I'm trying to think of use-cases for this.

At first it seems to me that it only offers an advantage for 'dumb' electric vehicles - where an electric brake switch won't trigger regen braking.

Considering it seems it might also permit regen with a motor that has a forward freewheel feature (no locked clutch) - but that still requires that the motor be engineered to provide the mechanical connection and that the system can do something with the power generated. A very 'dumb' battery-to-motor connection will back feed power when the voltage from the motor is greater than the battery, but I think this also depends on what any controller decides to do about the situation. Any circuitry between the battery and the motor must abet this reverse flow - do they all?

My current system uses an electric switch to signal 'braking' to the controller, which has the electronics to use this to put joules into the battery and slow the machine. The controller is built to permit/use the reverse power flow.

An advantage to my current system is I can leave the cable loose enough to close the switch before engaging the physical brake and have no wear on my brake pads and rotor.

If Grin is on it, I would expect there is some benefit, but I don't see it yet. The system still requires the electronics, a trickle from the battery to overcome cogging (usually mentioned as the reason for a freewheel in the motor) uses less power than is regained from the resulting regen, and it's mechanically as or more complicated.

I suppose we'll see more information.
 
That's a pretty interesting idea!
 
Hi guys, we are working hard with Grin to get this product out soon, and of course a proper explanation will follow.
But let me just give a quick clarification -
The controller applies motor braking torque that matches precisely the mechanical braking torque applied by the user, this is done by measuring wheel speed and motor speed and allowing the disc to slip ever so slightly - keeping motor speed a bit below wheel speed.
So that when the user brakes harder the motor speed will increase and the controller will respond by increasing brake torque in order to maintain that wheel motor speed difference.
The opposite accurs when the user brakes lighter.
The result is a totally natural brake feel and enough brake torque to skid the wheel if necessary.
 
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You can find some sketches there and in the quoted patent ;)

US11801747B1 - Electrical motor transmission - Google Patents

Provided is a powertrain of a vehicle comprising an electric motor, a final drive, a gearing system with two-degrees-of-freedom configured to transfer power from the electric motor to the final drive, the gearing system comprising a one-way mechanism, and a mechanical friction brake connected to...
patents.google.com

regards
stancecoke
 
Last edited:
Alon-ChargeBike said:
The result
Click to expand...
Distinct from any discussion of how it works, what is the point?

Is it less expensive than something, is it more reliable than something, does it provide more regeneration benefit than something?

How is it in some way better than what is available now?

What problem are you solving, or what advantage are offering?

Thanks.
 
amberwolf said:
In this Grin Tech video
They discuss a clever new way of engaging and variably controlling regen braking. There's not a lot of detail, but essentially:

There isn't an electronic control over the variable regen, it is entirely mechanical. The disc rotor connects not to the shell, but to the planet carrier. So when you engage the mechanical disc brake on that wheel, it prevents the carrier from rotating (or adds drag to it if you aren't fully engaging the brake), and causes the clutch to engage as if the motor was spinning, causing the wheel rotation to backfeed into the motor.

This image from their page shows the standee with the images too)
View attachment 344327 View attachment 344328

Stuff not covered in the video:

Since you wouldn't normally have the motor operating while you're braking, it would then just be creating voltage as a generator, feeding current back to the battery if the voltage is higher than the battery voltage, using the controller FETS as a 3-phase rectifier. The more force you apply with the lever (which you will get natural normal mechanical feedback for, as you are simply using a standard disc brake as-designed),

If a controller could be designed to be able to detect that braking is occurring via this generated voltage and then perform switching operations it could increase this braking force, or alter the curve it is applied with, etc. (you could install some form of position sensor on the caliper that provides a variable output to do this, but that defeats the point of the system not requiring any sensors or wiring for this, and changes the feedback to control the braking to electronic instead of mechanical).




It's an interesting system I wish I had thought of. :)



It should be possible to alter an existing geared hubmotor to work this way, although the ones I've personally opened up have the planetary carrier and clutch on the pedal drive side, not the brake side, so it would take some mechanical rearrangement of the casing and internals to do this that would be easier on a front motor than a rear.

I am going to take a look at the old bafang Jump Bike motors I've got to see if this is a possible mod with the capabilities I have here, when at some point in the future I have time/etc to try.
Click to expand...
Have you found something else? The easy motor has a clutch in the left side.
 
amberwolf said:
In this Grin Tech video
They discuss a clever new way of engaging and variably controlling regen braking. There's not a lot of detail, but essentially:

There isn't an electronic control over the variable regen, it is entirely mechanical. The disc rotor connects not to the shell, but to the planet carrier. So when you engage the mechanical disc brake on that wheel, it prevents the carrier from rotating (or adds drag to it if you aren't fully engaging the brake), and causes the clutch to engage as if the motor was spinning, causing the wheel rotation to backfeed into the motor.

This image from their page shows the standee with the images too)
View attachment 344327 View attachment 344328

Stuff not covered in the video:

Since you wouldn't normally have the motor operating while you're braking, it would then just be creating voltage as a generator, feeding current back to the battery if the voltage is higher than the battery voltage, using the controller FETS as a 3-phase rectifier. The more force you apply with the lever (which you will get natural normal mechanical feedback for, as you are simply using a standard disc brake as-designed),

If a controller could be designed to be able to detect that braking is occurring via this generated voltage and then perform switching operations it could increase this braking force, or alter the curve it is applied with, etc. (you could install some form of position sensor on the caliper that provides a variable output to do this, but that defeats the point of the system not requiring any sensors or wiring for this, and changes the feedback to control the braking to electronic instead of mechanical).




It's an interesting system I wish I had thought of. :)



It should be possible to alter an existing geared hubmotor to work this way, although the ones I've personally opened up have the planetary carrier and clutch on the pedal drive side, not the brake side, so it would take some mechanical rearrangement of the casing and internals to do this that would be easier on a front motor than a rear.

I am going to take a look at the old bafang Jump Bike motors I've got to see if this is a possible mod with the capabilities I have here, when at some point in the future I have time/etc to try.
Click to expand...
Do you have more information about this topic?
 
hmm.. modified MAC?
 
OK, how did I miss this in Dec?

Regen with a specialized freewheeling SX2 using a Superharness and enabled via a simple brake sensor trigger so I can keep my hydraulics? ... perfect, I'll be waiting.
 
While I understand the enthusiasm, I'm not sure this is such a brilliant idea: instead of wearing down a couple of disc brake pads, braking with this freegen system will wear down a much more complex and expensive clutch. Also I can only image the number of added failure possibilities.
I think brake systems need to be as simple and maintenance free as possible, hence I love the redundancy of having a modular electrical braking force on a DD hub + 2 disc or rim brakes. Drag seems to be a negligible tradeoff, especially on 500w+ systems...
 
I don't think there is a clutch (besides the freewheel ratchet). The braking works by slowing down the planetary carrier through the brake disk attached to it, which in turn forces the motor to spin. And you still wear down the brake pads.
 
Gruesome said:
I don't think there is a clutch (besides the freewheel ratchet). The braking works by slowing down the planetary carrier through the brake disk attached to it, which in turn forces the motor to spin. And you still wear down the brake pads.
Click to expand...
True: watched the video again, and saw that all they add is a second bearing in the hub shell, a speed sensor to measure disc rotor speed and a brake sensor. Everything else is computed by the controller.

What change is that the rear brake now passes through the planet gears, so wear on those gears happens in both directions. So Should you strip the gears, say by pumping to high amps into a tiny geared motor you'd not only loose traction but also all rear braking. And since there is no way to assess the the state of those gears without opening the motor, there is a serious risk of unexpectedly loosing one braking system on the run so I'm not sure this system would pass ebike certification here in Europe.
 
It's a good thing that gears tend to strip gradually!
 
zinaambiorix32 said:
Do you have more information about this topic?
Click to expand...
Hey everyone, we've got the final cut of the explanation video about to be released shortly as a youtube premiere so that we can do a live question and answer session afterwards for all those who are curious about this concept. That's going to start today at noon pacific time, 3pm eastern time, and 10pm europe time.

So tune in to watch that if you are interested!

 
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