There should be a folding wheelchair with hub motors and batteries integrated into the structural tubing.
Then people with disabilities could haul a chair around in really small car.-- nomocrow, Mar 04 2008 Here's what your needing. http://www.youtube....watch?v=Iv_SfonG4w4 [2 fries shy of a happy meal, Mar 08 2008] New Electric Hub Motor http://www.electricbikessys.com/motor.htm"Motor Size: 7 1/2" dia., 3" wide, 6" L x 7/16" dia. shaft. Wt. 5.4kg." [half, Mar 08 2008] A kinda powered chair? For wheelchair users who can unload a folding chair but need more power? Seems like a poor compromise. How bout a folding wheeler that rides in a compartment undernieth the car and then presents itself for use when needed? If you need a power chair, you need a power chair. Maybe the idea would be better framed by presenting it as a travel chair for the disabled tourist or somthing. Hub motors for wheelers are baked.-- WcW, Mar 04 2008 No, interesting idea, bad title. Should be Hub battery wheelchair. The problem is that it adds a lot of rolling inertia.-- MisterQED, Mar 04 2008 Maybe I'm misinterpreting. I thought the idea was to have a compact, motororized wheelchair by putting the batteries and motors in spaces within other structures not already occupied by something else, e.g. battery cells slid into the structural tubing of the chair and motors in the middle of the wheels where space isn't otherwise useful. The intended result seems to be the saving of space by "removing" the external structures required to house and support the batteries and motors. Might this even result in a lighter unit?-- half, Mar 04 2008 What [half] said.-- nomocrow, Mar 04 2008 Like I said it compromises the basic concept. If you need a fully powered wheeler nothing else will do (and you will likely have trouble unloading a chair from a subcompact) whereas if you are able to use a manual chair (and unload one from a subcompact) you will not benift from adding a low range low power motor set to that chair. Its a neat idea, but I suspect that it would only apeal in a few situations such as travel and as a backup for a fully powered chair.-- WcW, Mar 04 2008 Is it necessarily true that a hub motor would be underpowered? I've never actually worked with any so don't have any gut level feel for their capabilities. But, given that they could have a relatively large diameter in this setting, they might be able to provide decent torque.
Now, whether or not you can shoehorn enough batteries into the frame to support a powerful motor is a different question.
I don't think you could get a power chair to fold into as flat a configuration as I imagine the goal here to be. I have seen some relatively teensy power chairs that fold small. I'm not really sure which form factor would be more appropriate for stuffing into a small car.
Hmm...what about a door within a door? A panel on the interior of the car door slides up to reveal a recess into which a wheel chair can be stowed. A few design issues to overcome, obviously. Maybe the power window motor could double as a lift?-- half, Mar 05 2008 Smart. Powered wheelchairs have an awful lot of fooferaw going on underneath, but if modern electric scooters have taught us anything (not the "mobility" kind, the ones at Toys R Us), it's that those electronic bits can be smaller and still work just as well.
Is it just me or are powered wheelchairs grossly overpriced for the level of sophistication?-- elhigh, Mar 06 2008 [elhigh], you have a market which is both small (so economies of scale are smaller) and captive (thus unable to opt out of the purchase).-- angel, Mar 06 2008 Sounds like a great idea, although my experience with wheelchairs is decidedly limited, and doesn't include having to cope with cars. But with this kind of practical idea, the devil is usually in the details of the engineering.-- DrCurry, Mar 06 2008 Practically speaking, instead of sticking batteries inside the tubes, it would be much better to make a separate battery pack. Aside from tube-diameter increases and metal corrosion, the fixed weight of the chair and batteries would increase over that of a plain chair, so you'd need a hoist to get the thing in and out.
A separate battery pack could be lifted out more easily than if built into the chair, and quite easily clipped into place. A battery pack could store in any odd area of the car. Extra packs would allow for simpler charging and for each pack to be smaller than one long-cycle unit.
Hub motors are not so simple as they may seem. Weight, expense and complexity all figure in to the reasons they aren't already being used.
Current designs of powered wheelchairs really suck. But this idea doesn't contribute anything other than an obvious 'should' to what should be done to make things better for wheelchair users. [ ]-- baconbrain, Mar 06 2008 I think machinery exists that loads your wheelchair onto the car roof.-- david_scothern, Mar 07 2008 I thought the focus of the idea was compactness.-- half, Mar 08 2008 Simply stated the chair has to be designed for a specific disability and application. This is the point of origin for any design. Most wheelchairs with wheels large enough to invite hub motors are designed to be powered by the rider, steered by the rider, and sometimes stowed by the rider. Adding power to such a chair compromises the design. A chair that is not powered by the rider has small wheels and requires vast battery capacity. Generally users with this style of chair have vehicles built specifically for the chair.
Although there is room for improvement (stair climbing chairs were a halfbaked idea a decade ago) you have to start by thinking about the user and how that person could be better served.-- WcW, Mar 08 2008 I think a 7.5" diameter hub motor would fit within the wheels of many of the powered wheelchairs I've seen. (link)
I would guess that conventional electric wheelchairs are probably not often stowed inside a car by the user of said chair due to the size and weight. Since the author doesn't claim that the chair would be light enough to be loaded by the user, the argument that such a compact chair would be impractically heavy seems somewhat out of place.
As I read it, the goal would be to allow the chair to be stowed in a car that wouldn't have the space to accomodate the traditional powered wheelchair. More than weight concerns, I fault the idea for leaving out details such as a desired target size to fit the available storage space in at least one example of a "really small car".
Having said that, getting the weight down is certainly a reasonable goal. Li-po batteries, while they don't hold a charge as well as Li-ion and others, are relatively light weight and lend themselves to being put into non-conventional battery shapes. If limited range is acceptable, maybe such batteries could be used to make a light(er) weight chair.
If it could be configured and lightened sufficiently to be loaded by the user, maybe this could be a specialty short range, recharge-in-the-car unit. I mean, there are plastic wheelchairs for use in the shower that are too weak to be used for every normal purpose, but they exist.-- half, Mar 08 2008 random, halfbakery