BMW’s recent patent filings shows an electric motorcycle with shaft-drive, which may be the first time for electric motorcycles.
The recent patent filings by the automotive giant, BMW, reveals plans to make a shaft-driven electric motorcycle. The patent sketches show two optional connection methods for the shaft drive and the electric motor, with different alignment. It did take us some time to go over the heap of patents and track down this specific one, to get confirmation.
BMW’s recent news were all about the Definition CE 04 electric scooter, that was spotted out and about, testing. With that, the flow of patents for battery related, drive and cooling systems – all point to the BMW DC, which is highly likely coming our way!
This is actually something that was clearly shown when you look at any image of the BMW DC-Vision prototype and sketches, where the shaft-drive specifically sticks out in the design. Now that the patent came in, it becomes clear that BMW proceed in this path of making an electric shaft-drive motorcycle, and most likely this will be the DC-Vision.
In the standard layout of electric motor bikes, the electric motor is aligned across the bike, with a sprocket or gearbox that will then power either a belt or a chain. In electric, the main method for mid-mounted motors (vs hub mounted) is a Belt, which makes the ride more quite than a chain. But in both these cases for mid-mounted motors, creating a shaft-drive with rear (wheel mounted) gearbox – will be a first time in the 2-wheel electric space.
With BMW’s layout, the electric motor is positioned on the longitude line of the bike, with the motor driving a shaft connector, that connects to a reduction gearbox located on the wheel.
The BMW patent filing also provides two methods of connection, either with a perfect straight alignment or with an offset connection, which allows for a more flexible position of motor, and possibly more flexibility with other bike components you may want to have more ‘wiggle room’ to move around.
The gearbox position on the wheel is another advantage for the design, where instead of the (common) On-Motor integrated gearbox, BMW use a planetary gearset, mounted directly behind the motor. The shaft uses a constant velocity joint, so there are two shaft arms connecting to the final gearbox driving the wheel.
So, BMW is setting up to bring the electric motorcycle space a first-time shaft-drive motorcycle. It’s a new design that we haven’t seen before, but does it really add any simplicity?
We won’t really go into the pros and cons of shaft-driven motorcycles, vs other drive methods like Chain or Belt, and even Hub mounted motors in electric. You can easily find more about those basics anywhere. But here’s where this comes into question in my personal opinion – electric motors run up to extreme RPMs, they hardly have any ware, and since they produce full torque from 0 RPM, they can power many diameters of wheel sprockets with ease.
Attaching a gearbox to your motor as an integrated unit, is the simple way to go. But as it appears, BMW have innovated here, but they also created an over complicated product, creating a machine that requires more maintenance than any other electric motorcycle (using any other drive method). This is one of the very known, but unspoken of, facts of ‘traditional’ vs ‘innovative’ electric motorcycle companies.
The more moving parts you have, the more ware and potential break downs you may have. The less maintenance you have on your motorcycle, and if you have hardly any parts to replace, the less life-time-value you have as a customer for traditional manufacturers. And this one point is where innovative companies make up for in profit margin and technology innovation (intellectual property).
Let me know if you agree (or disagree) in the comment section below.
Source: Cycleworld, WIPO