Protean electric hub motors in 2014

[kach22i]

Originally Posted by thingstodo

On this topic ... is there a technical reason why car tires and suspension don't use support (and bearings) on both sides of the wheel? Or is it just that it makes the car look goofy?

Good question, and it made me think of the car below.

Took forever to find, looks like motorcycle wheels all the way around.

https://www.popsci.com/cars/article/...gallery#page-6

Streamlined Car: October 1934

As far as home-built cars go, this model is one of the more novel designs in our archives. Dr. Calvin B. Bridges, a biologist from California, designed his car for lightness and speed. Weighing just 700 pounds, his vehicle was powered by a motorcycle engine and was expected to run 60 miles per hour. A gallon of gasoline could power it through 50 to 70 miles of travel. Like the Velodye, Bridges' car reduced wind resistance to a minimum, while its light frame, which was made of welded chrome-molybdenum steel tubes, would help the vehicle attain more mileage than one would expect from a car of its size.

Popular Science

https://caseybergman.wordpress.com/2...otive-pioneer/




Short video clip in link above.

[redpoint5]

Originally Posted by thingstodo

On this topic ... is there a technical reason why car tires and suspension don't use support (and bearings) on both sides of the wheel? Or is it just that it makes the car look goofy?

Based on the images supplied by kach, I assume because it adds unsprung weight without providing much benefit.

Motorcycle wheels are supported on both sides, but they also require suspension on both sides.



It is interesting when they use single-sided swingarms on a motorcycle:

[kach22i]

I watched a couple of videos on unsprung mass, this one isn't too bad.

https://www.youtube.com/watch?v=9FZrJBWQ7-g

Oh, just found one on our very topic specifically.

UNSPRUNG MASS — MYTHS AND REALITIES, Protean Electric & Lotus Engineering

https://www.youtube.com/watch?v=MRkhXCs52Lo

Some of the comments are not buying it apparently.

The paper the video refers to is the first hit in Google using the search term:

UNSPRUNG MASS — MYTHS AND REALITIES, Protean Electric & Lotus Engineering

It is a PDF.

Last paragraph under "7-Conclusions"....................

While perceptible differences emerge with increased unsprung mass, on the whole they are small and unlikely to be apparent to an average driver. The nature and magnitude of the changes appears to be nothing that cannot be overcome by the application of normal engineering processes within a product development cycle. Conversely, the promise of individual wheel motor control shows good potential for substantial improvements in vehicle behaviour.

[niky]

From a consumer point of view, having suspension arms on both sides of the wheel makes changing tires much harder.

It also adds cost and complexity to the assembly. Sure, wheel bearings and CV joints and etcetera wear out over time, but it costs the consumer much less up front to have the wheel attached outboard in the simplest manner possible.

Also, wasn't heat an issue with inboard brakes?

[kach22i]

When I was a kid we always had to patch the inner-tubes on our banana seat bicycles, and started with turning our bikes upside down to do the change out.

Cannot do that with a car, would need a lift and do it from the underside.

One could design it so that when you cut/turn the wheels sharply they can be removed. From the website, looks like 4-wheel steering and 90 degree wheel turn access is incorporated. Perhaps these unique features could be used to address such concerns with a telescoping shock motorcycle suspensions.

A very simple explanation below of unsprung and sprung mass, nothing fancy.

https://www.youtube.com/watch?v=ohtXHWDOkEU

[thingstodo]

Originally Posted by niky

From a consumer point of view, having suspension arms on both sides of the wheel makes changing tires much harder.

It also adds cost and complexity to the assembly. Sure, wheel bearings and CV joints and etcetera wear out over time, but it costs the consumer much less up front to have the wheel attached outboard in the simplest manner possible.

Also, wasn't heat an issue with inboard brakes?

I can live with more trouble changing tires if an electric hub motor would last longer than the first set of tires

Not sure about simple mechanisms, but a bearing on both sides and an electric motor inside the hub seems like a pretty straight-forward interface. How to maintain the tight tolerances needed for an electric motor with no suspension .. I think much work has been done on that part ... and it is perhaps the more challenging area.

As for the brakes, directing air flow sounds like it is simpler than the bearing issue?

[cRiPpLe_rOoStEr]

Well, nowadays that most cars are fitted with power steering, it wouldn't surprise me if an average driver couldn't perceive any difference on riding characteristics of a car fitted with hub-motors.

[kach22i]

Originally Posted by cRiPpLe_rOoStEr

Well, nowadays that most cars are fitted with power steering, it wouldn't surprise me if an average driver couldn't perceive any difference on riding characteristics of a car fitted with hub-motors.

I think it is helpful to recall some of those magazine reviews of old when discussing the driving characteristics of a Rolls Royce or Bentley (in the 1980's).

The author/reviewer would always remark about the car handling being incredible despite the massive weight involved, and excellent by any standard.

Today the modern F-150 probably the same weight of one of those old luxury cars, and a phenomenal ride too.

I suspect with the proper engineering and technology many laws of physics can be tamed.

Lotus Engineer is the world expert on this topic, and they said it can be done.

[cRiPpLe_rOoStEr]

Originally Posted by kach22i

I suspect with the proper engineering and technology many laws of physics can be tamed.

Well, maybe some drivers could claim to still feel some difference on handling, but I'm sure the average Joe wouldn't really care.

[oil pan 4]

My leaf uses nissan electric power steering and it's pretty nice.