In this article, we’ll be discussing a Driving Device and Driving System by Shimano, US patent 11970237. The publication date is April 30th, 2024, and the filing date is May 20th, 2019. This was actually filed in Japan all the way back in 2018 and has been in prosecution in the US since 2019. The reason this is being published in 2024 is because it was granted.
To my readers: Well, after a long hiatus, I am back at it. After a fairly demanding full-time job and my first kiddo, I had to take a break from something and Wheelbased was that something. Just too much.
I was recently laid off, so my calendar opened up pretty dramatically. I’ll be giving this concept another honest shot. I’ve missed researching and writing for everyone, and I’m stoked to dive back in. I’m not sure if this is awesome or awful timing, but I’ll make the best of it and do me.
If you use this, or any article, on your website, all I ask is that you link the website, IG, or Facebook. I don’t think that’s asking much.
Brief Summary (tl;dr)
There are a few concepts here related to electric braking. The first is an either/or type braking system, where the system either uses a hybrid braking system, which uses both hydraulic and electric systems, or fully hydraulic/traditional braking. The hybrid system senses a user pressing hydraulic brakes, converts the hydraulic pressure into an electric signal, which then applies a hydraulic pressure to the pads using a little motor and gearset. Yes, it’s hydraulic fluid pressure → electronic signal → hydraulic fluid pressure.
A second concept is a fully electric, battery-powered braking system and should get some of you fuming. The brake lever sends an electric signal to the caliper, the caliper converts that electric signal into hydraulic pressure with the same motor and gearset, and the brakes squeeze. badabing.
Lastly, a third concept offers roughly the same thing as the first concept, but with a mechanical bowden cable rather than hydraulic fluid.
Background
I’ve seen a lot of documents where Shimano suggests some level of electric brakes. The vast majority are pretty high-level, saying something like “ayo, we got electric brakes at this part in the schematic” but that’s about it. They rarely delve deeper into the concept.
That being said, a few years ago, I wrote about another Shimano concept that showed some electric brakes. While this does show an electric braking concept, it’s a kind-sorta-almost electric brake. It still hydraulically powers the brake pads, but the lever is electric and includes a controller and actuator. The actuator compresses the brake fluid like a typical brake lever, which then compresses the pistons and pads. So, it’s a decent middle-ground between full mechanical to full electric.
Intended Novelty
I said this was being published because it was recently granted, and having read a lot of Shimano IP, when we get to five years of prosecution, claims are generally pretty neutered and don’t amount to much. That doesn’t seem to the be case here, as this is a pretty decent claim set.
The intended novelty here, and what has been granted, is a driving device (brake system) with an electric drive mechanism (motor, gears, etc.), fluid pathways, and a switch. The system operates in two modes, where the brake lever either moves the brake pads via an electric motor in response to the brake lever being pulled or directly moves the brake pads.
There’s a little more to it than that, but that’s the general idea. This is not legal advice if you get a nasty-gram from anyone, do your own research, or hire someone. Don’t trust anyone who can write with impunity on the internet.
Why
Like always, Shimano rarely ever say why they do the things they do, but I’m having a hard time with this part. Why would they want to switch from hydraulic to electric and vice versa? I have some theories at the end.
It is desired that a state of driving a movable member by the electric drive mechanism and a state of driving the movable member by human power should be switched.
@shimano
What
Hydraulic Hybrid system
The first concept is shown in FIGs. 3 and 4. Both of these images show the same caliper in two different modes, electric and hydraulic .
We’ll start with electricity in FIG. 3. The brake line at the top is connected to a brake lever and has typical brake fluid in it. Just like normal.
The switch 73 (red box) has two fluid channels, one straight and the other angled. It is moved far left so the fluid flow goes through the angled channel and ends at the pressure sensor 74. When the system is in electric mode, the person riding the bike hits the brakes, fluid pressurizes (blue arrow) in the brake line, the pressure sensor senses the pressure increase, and the system says “ayo, we see you’re trying to stop, let me figure some shit out”.
A pressure signal is then sent to the controller 76 from the pressure sensor. The battery-powered controller then send a braking signal to the motor unit 71, which tells it to go ahead and spin up. I’ll assume this ‘motor’ is not an explicit motor, but actually a servo that can spin in both directions. Semantics.
The image below shows the sequence of power movement through the motor 71a, gearset 71b/c, ball screw 71d, and piston 71e. The motor spins, which turns the gears, which moves the screw, which then moves the piston in and out. The piston forces the fluid through the pathways to the pads, and we have brakes.
Now let’s get to the hydraulic mode (FIG. 4), which can be considered a traditional hydraulic brake system. It’s pretty simple; the fluid flow passes through the straight path in the switching mechanism 73 directly to the pads. Outside the switching mechanism, this isn’t much different than the brakes on your bike right now.
In the end, here’s a line explaining what the switch is doing. Simply put, the switch controls where fluid flows through the caliper; either to the pressure sensor or the pads.
The switching mechanism 73 is configured to switch the state of the driving device 70 between a first state in which the movable member 66 is driven by the power (hydraulic pressure) of the electric motor 71a and a second state in which the movable member 66 is driven by the power (hydraulic pressure) from the operating portion 42.
So, is this a manual or automatic process? How does the switch actually go from electric mode to hydraulic mode? The answer is: I’m not sure. Shimano use the word ‘selectively’ to describe where the braking power is transmitted. This is very purposefully vague. So, it could be automatic, where it’ll switch under predetermined conditions, or be manually selected by the rider. I wish I could give you a more solid answer because this seems important.
The switching mechanism 73 is configured to selectively transmit the power from the operating portion 42 to either one of the transmission 72 and the additional transmission 75.
Another question I’ve got here is charging. Are you going to have to regularly plug your brakes in? Fortunately, that does not appear to be how this system will work (though you probably could plug it in somewhere). The system can be charged via a dynamo (anti-motor) as you ride. Additionally, if we scroll back up, we can see the schematic showing an external battery. I’ll assume these will be powered by a central battery like the already-available Di2 battery.
The power generation mechanism 26 is a dynamo (hub dynamo) that generates electric power with the rotation of the front wheel 20. The power generation mechanism 26 supplies the generated electric power to the battery 24.
Fully Electric System
There is a second part to this concept, which is shown in FIG. 5. Now we’re getting to the real controversy. FIG. 5 shows a fully, no questions asked, electrically powered caliper. This has zero fluid flowing from a brake lever, only an electric signal. This is not wireless. Shimano don’t say it is, and don’t suggest it in the pictures.
The electric braking function works the same as the prior example in FIG. 3, but without the switch. Instead, the brake lever (additional operating device 40B), sends a signal to a controller, and the controller does its decision-making, sending a braking signal to the motor which plunges the pads.
Mechanical Hybrid System
FIGs. 6 and 7 are a continuation of the concept but are mechanical-to-electric rather than hydraulic-to-electric signal. These use old-school mechanical Bowden cables to transmit a force to the brake caliper controller, which signals the motor to apply the brakes. Fluid pressure sequencing follows the same concept as the prior concepts.
Conclusion
This seems a bit silly and overcomplicated, going from hydraulic fluid pressure → electronic signal → hydraulic fluid pressure to initiate braking pressure, but the use of that electronic signal between the two hydraulic fluids could open up possibilities that are difficult with only hydraulic fluid.
The first thing that comes to mind is something like ABS, where an electric signal from the controller may be able to modulate fluid pressure based on wheel slip quickly and easily.
What about brake adjustments? Would it be easier to adjust the pad location relative to the rotor with a little electric motor moving a piston? Expanding on that, would it be easier to adjust pads as they wear?
But the biggest, number one, mega-comment, whenever anyone writes about electric brakes, is “bUt WhAt If tHe BatTeRy DiEs”. Idk man, what if…? You go careening into a guardrail or a tree, pretty simple. It’s possible the electric braking mode would be standard, while the hydraulic braking mode would be the fail-safe. If batteries die, the system can also work in a traditional manner to get you home.
Shimano appears to be attempting to answer that exact question with the primary concept here. You have a backup system, where your lever works both electronically and hydraulically.
As far as the fully electric system, I anticipate this will be the norm in 10-15 years. It is the obvious next-step and as much as we want to naysay this concept, fly-by-wire are in planes, autos, and even some race cars. IMSA cars even have brake mapping, meaning an input braking signal can output different braking pressures/sequences based on other inputs (speed, steering angle, hybrid-happenings, etc.).
Lastly, I’m going to use this opportunity to shamelessly promote my wife’s new business called Bunkara Flowers. We’re getting into the cut-flower farming business. If this works decently this year, we’ll expand to the Colorado western slope where there’s better weather and more reasonable farmland. Please follow along if you’re in the Denver area and would like some awesome locally-grown flowers for your house or event.
Bunkara.com — Instagram— Facebook
Here she is looking stunning.
The post Driving Device and Driving System [Electric Brakes] by Shimano first appeared on WheelBased.