Brilliant Honda motor and gearbox combo

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a4x4kiwi
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Brilliant Honda motor and gearbox combo

Post by a4x4kiwi »

Here is an beautifully integrated motor and gearbox from a Hydrogen FC Honda FCX.

http://a4x4kiwi.blogspot.com/2010/06/ve ... -fuel.html

Now, to wait for one to come up at Pick and payless. Image
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procrastination inc
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Brilliant Honda motor and gearbox combo

Post by procrastination inc »

Saw that on the vid too, nice grab.

it is compact, but a little wide at the CV's for narrow vehicles I think
Squiggles
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Brilliant Honda motor and gearbox combo

Post by Squiggles »

procrastination inc wrote: Saw that on the vid too, nice grab.

it is compact, but a little wide at the CV's for narrow vehicles I think


OK for rear wheel drive maybe.
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Brilliant Honda motor and gearbox combo

Post by Electrocycle »

It's a pity it still has a diff in it (not that a diff loses much power when it's not a hypoid input) - but I'd like to see the same thing with two motors in it :)
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Brilliant Honda motor and gearbox combo

Post by 7circle »

Looks like 4:1 and another 4:1 for 16:1 ratio there-abouts.
Can any point to how you could estimate this gearing efficiency?

The first pinion gear metal material looks so thin. I guess they can get away with a hollow rotor shaft as the motor torque is reduced by the high gear ratio.

Also trying to see if there is a water cooling. The thin rectangle in the motor cutaway could be for water flow.
Is the forced air cooling?
You can really notice all the extra copper need to make the overlapps of the windings. All that I²R losses with no path for heat to go through.
Perhaps the whole rotor and armature are in coolant/oil.

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Brilliant Honda motor and gearbox combo

Post by T2 »


At first sight this seems quite an elegant single motor solution, if you can close your eyes to the overhang (side load) presented by the take-off gear to the motor pinion under full torque, considering the rpms involved. There has been criticism regarding the practicality of using motor rpms approaching 14k rpm, but with a drive shaft this short, overhang should be minimized.

At first sight..... however the more I look at it Honda seems intent on continuing a philosophy of complexity yet again. Manufacturing could have had two smaller items to handle but that wouldn't test Honda's prowess. This larger unit will increase handling costs as a major sub assembly from assembly to test to integration. I'm thinking that the test department will need a larger jig for checking both outputs and the differential operation.

Regarding internal cooling there are usually ears on the rotor end bars which act like a fan on the end windings. Only a few will be needed here because of the high rotational speed. However this motor will probably have quite a high 60min overload rating and I would be surprised if the average 13Kwhr pack could present enough charge to overheat the motor.

It is fairly universal for any machinery that as it warms up the viscosity of the lubrication oil lowers and frictional losses go down. For short trips in cold weather the machinery never gets to running temperature and will affect this Honda powertrain. The point being that some internal heating is beneficial.

BTW is this an induction motor ? Can't quite read the labels on my monitor.
And I also was thinking Is this FWD or RWD ??

IIRC a similar FWD gearbox was also used for a Ford design in the mid 90's.
For some reason designers seem to like this concentric hollow shaft concept probably for its compactness. I kind of doubt the 16:1 ratio as 7circle suggested, I suspect somewhere closer to 10 : 1. Contemporary thinking, and not so contemporary thinking, suggests ~10k rpm at 60mph/100km/hr, with motor base speed placed about 6600rpm.
That's with the wheel axle rotating 1500rpm @ 100mph.

Regarding gear efficiences in this double reduction I would say the motor pinion has the larger step down of the pair. That would give it a 93% efficiency and the final differential which looks to be a lesser ratio perhaps as much as 94 ~ 95% culminating in a total overall 88% effcy.

My source says to expect a 1:1 ratio to offer a maximum of 95% effcy but more details are needed, for all I know this may have been in reference to straight cut gears in nonsynthetic oils. Are there more reliable benchmarks out there of which anyone is aware ?

I bring this up only because EVers seem content to throw away quite a bit of power in existing mechanical transmissions while at the same time become fanatically concerned over the efficiences of a range of motors which differ by only 2 or 3%.

When I was first involved in EVs I remember being told, and I bought into it, that donor cars were sought with the manual transmission because they were 98% efficient compared to just 70% for the auto transmission ! At least today, anyone claiming that a multi-ratio gearbox with clutch has a 98% effcy would be accused of dreaming in technicolor. Many are now aware that a RWD diff. adds a loss of 30% which explains why a high temp lube oil sometimes known as Hypoid 90 is specified for it. Well it is either use that or fit an oil cooler. You sure don't get to turn all that shaft power through 90 degrees for free. A dyno measurement- an ASG motor - with the two types of transmission will tell you. Suffice it to say, been there done that.

The elimination of lossy hypoid gearing was another compelling argument towards the adoption of FWD which proceeded once the suitable metallurgy, for longevity with constant velocity joints, was perfected. Meanwhile to us constructors who are looking to implement a DD, the losses incurred by a RWD differential remain an inconvenient truth.

The golden rule is that anytime you transmit mechanical or electrical power there are going to be losses. Minimalism is the key. ( I wish I could write shorter posts too !) This Honda design is a good example, the Prius transaxle not so much.

As Electro-cycle suggested too bad they have to include a differential. I was thinking the same thing. Honda goes to a lot of trouble here yet still manages to include that one mechanical device which quite frankly ought to be abandoned. A motor with a hollow shaft coupled to a differential with a 2 stage step down are the ingredients here whereas the twin motor is simply the conventional motor with standard planetary but twice.    
That brings us to actual twin motor designs, the most well known being that of the Impact (1990) whose construction was subcontracted by GM to AeroVironment. This concept vehicle opted for twin motor FWD as proof of principle. Although RWD would always be less challenging, in this particular case the decision to go FWD may have been a space limitation because the rear wheels on that car were closer together to achieve the aerodynamic tear drop shape.

As I mentioned coming in you want to avoid the handling of large assemblies whenever possible. However if size is not a problem and a single motor without differential is required then they might have considered the twin rotor inside a single stator approach. I envisage one rotor equipped with a hollow shaft containing at each end two ball races attached inside the shaft. The other rotor has a solid shaft with a stepped diameter extension which allows it to enter the other rotor by threading through the centers of the two ball races for support. Maintenance of the ball races may be a problem in service though the infinitesimal relative motion between shafts, except when cornering, should incur minimum wear on these parts.
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Brilliant Honda motor and gearbox combo

Post by photomac »

T2 wrote:
( I wish I could write shorter posts too !)


Not too long! Your descriptions with side-points are great for someone like myself with dangerous half-knowledge, and the extra info' embilishes the challenges.
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