Ford Motor Company has filed a patent for an EV with a solid axle and hub motors, Ford Authority has learned.
The patent was filed on August 5th, 2021, published on February 9th, 2023, and assigned serial number 0042713.
The Ford Authority Take
Ford has filed its fair share of electric vehicle-related patents in recent months, including one for an EV winch and winch operating method, an EV charging pad with wireless charging, and an upgradable vehicle system. Now, this new Ford patent introduces another interesting idea – one for an EV with a solid axle and hub motors.
Currently, Ford doesn’t sell an all-electric vehicle with either of these features, but this newly filed Ford patent shows that the automaker is at least considering doing precisely that. The idea here is to create an electrified vehicle axle with one wheel assembly and an electric motor powering one wheel, while another unit is configured to power another wheel.
Additionally, a beam is present with one end connected to both wheels, with an axle shaft supported for rotation within the hollow center of the beam that’s configured to transfer torque between each. Finally, one or more clutches couples the electric motors to the axle shaft.
The idea of using hub motors on an EV isn’t exactly new, but it is fairly uncommon, at least for now. Presumably, such a setup improves traction – including in off-road situations – allowing the vehicle to manipulate the output at each wheel as needed. Additionally, solid axles are commonly used in off-road-focused vehicles thanks to their simple, durable nature, though they’re also typically heavier than independent setups. Regardless, this patent may indicate that Ford intends to utilize both solid axles and hub motors in future EVs, possibly in some sort of off-road-focused model.
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Comments
I suppose that’s one hood way to clear the underfloor for more battery space but it comes with a penalty in unsprung mass.
But if you’re not looking for a performance handling machine (like a motorhome or delivery van) this would be a very good solution that would eliminate a ring and pinion gear set, axle shafts, hypoid oil, bearings, seals, etc and replace them with a simple beam with motors at the ends and the signal and power cabling to drive them.
Edit: as for service this brings most of the important wearable parts out to the end of the axles.
For fleet vehicles service might be as easy as swapping out a used module for a rebuilt one so the vehicle downtime is minimized by plug and play service.
I sketched this out on an envelope a couple of years ago. Technology isn’t there yet, but in my version the axle houses the battery. It may need to be a little thicker. Each wheel/motor would have something like a CVT in it. Since everything can get bluetoothed now, the axle/motors can physically be independent from everything save the bolts that connect it to the vehicle. As Robert points out, you can easily swap out the whole assembly. You’d swap the axle out like a propane tank at 7-11, so the vehicle has no down time. Repairs to the axle happen independent of the vehicle.
I would venture to guess this would be useful on say an EV Bronco that was trying to retain some amount of off-road credibility.
In my daydreaming, being able to swap out the entire powertrain had a few advantages. One was that you could have a smaller, thrifty powertrain for your day-to-day and then swap it out for more range or power when you want to have more fun. Your vehicle wouldn’t be tied to just one driving profile. It would be somewhat like making the current eco/normal/sport selections many modern vehicles have, but at a much more dramatic scale. Your commuter car could be a jacked-up off-road beast every weekend and then back to the office on Monday.
I don’t think a battery in or on a beam axle is likely. It would be major unsprung mass which would affect vehicle stability and comfort on rough surfaces.
Additionally it’s unlikely a battery with that kind energy density will be available any time soon.
I was daydreaming, and the density is not there. But it isn’t a live axle. It is a dead axle. All the motion is out at the wheel and the “axle” is just a pipe that houses the battery. I also though of the whole unit just being one wheel. Each wheel would be its own self-contained powertrain complete with battery. For small urban vehicles, you could probably get away with a 1-wheel drive vehicle. You could also have 4 independent (but coordinated) powertrains for off-roading. Or 6, or 8, or 10.
Oops, my mistake don’t know why I typed “live”. Thx for the catch.
I understand you were just noodling on the idea and respect that.
I’m not convinced that the tech is there to do what you propose, except for some small or limited range vehicles but I like the creativity of thought!
And who knows, the changeable axles would be a modern equivalent of what dropping in a small block used to be.
“Additionally, solid axles are commonly used in off-road-focused vehicles thanks to their simple, durable nature”
More for the traction benefits, one side pushed the other down to maintain contact patches of both tires. It is called Flex and IFS or IRS tend to hang a tire in the air versus flexing properly.
What’s the point of the live axle? It’s not needed. The torque is being generated at the wheel, why the need to transfer it to the other side, which is generating it’s own torque?