Direct drive with 20% reduction gear

Technical discussion on converting internal combustion to electric
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Thomas
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Direct drive with 20% reduction gear

Post by Thomas »


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My average speed around town (won't be going further than that) is 50kmh on a good day. Legal limit anywhere is 90kmh. Any need to bother with a gearbox? I'm wondering if the efficiency gained by only using a reduction gear would make it worthwhile.

It's a Kia minivan, so direct drive like this would allow me to move the motor to the diff:
- save 10kg of rotating weight off the driveshaft
- improve weight distribution
- eliminate mechanical losses through the gearbox

I guess the only way to really work it out is to install the motor this way and see how it pulls.
Last edited by Thomas on Mon, 03 Oct 2011, 10:29, edited 1 time in total.
Started AC55 into a Kia Pregio in August 2011.
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Johny
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Direct drive with 20% reduction gear

Post by Johny »

Do you have an estimate of your final vehicle weight with all batteries etc. installed?

Edit: Your not you
Last edited by Johny on Mon, 03 Oct 2011, 10:37, edited 1 time in total.
Thomas
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Direct drive with 20% reduction gear

Post by Thomas »

Hi Johny - it'll be 1950kg or so. The motor has rated torque of 140nm.
Started AC55 into a Kia Pregio in August 2011.
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Johny
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Direct drive with 20% reduction gear

Post by Johny »

It's a bit hard to find out but do you know what the peak torque might be for this motor. From the graphs it looks light it's up around 280nm.
I'm trying to get enough info to model your vehicle on Woody's spreadsheet.
Thomas
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Direct drive with 20% reduction gear

Post by Thomas »

Hi Johny

Thanks for your help, I've got the spec sheet. You're right, it is 280nm. Rated torque is 140nm.

Max power 59kw. Continuous shaft power 25kw at 1500 to 2500rpm.

Cheers
Thomas
Started AC55 into a Kia Pregio in August 2011.
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Adverse Effects
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Direct drive with 20% reduction gear

Post by Adverse Effects »

if you go down in Tyre radius would work
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woody
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Direct drive with 20% reduction gear

Post by woody »

I think you can get a Hilux Diff in 5.1:1 - might be a good way to go.
Adverse Effects wrote: if you go down in Tyre radius would work
Going down in tyre size by 20% is pretty major:

2.06 m * 80% = 1.648 m

Diameter = 1.648/3.141 = 0.5246m.

Example Tyres: Mini 155/75R10 = 0.4866m Diameter :-(
Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack
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Johny
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Direct drive with 20% reduction gear

Post by Johny »

Preliminary figures on:
1950kg vehicle
AC55 300 volt, 140nm with BD torque of 2 times (280nm)
Drive ratio 3.7
Tyres 205/65R16 (336mm radius)
Controller 500 Amps (AC side) (a guess - more controller current doesn't help).

It's not very good.
0-60km/h in 16 seconds
0-100km/h in 31 seconds.

The motor really has to spin at least twice as fast as this drive ratio allows to get reasonable performance.
However I do not know where the torque "knee" in the AC55 lies. What is it's real nominal speed?

Edit: Changed max contr. current to 500 Amps after correcting the pack voltage to 312 VDC nominal. Didn't help unfortunately.
Last edited by Johny on Tue, 04 Oct 2011, 07:08, edited 1 time in total.
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Johny
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Direct drive with 20% reduction gear

Post by Johny »

My opinion is that it's going to get stuck on hills unles you use a gearbox.
Thomas
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Direct drive with 20% reduction gear

Post by Thomas »

Looks like you're right Johny. If I keep the gearbox it'll probably pull nicely around 1:2 to start and 1:1.3 to cruise up to 90km/h. Maybe third and fourth.

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Started AC55 into a Kia Pregio in August 2011.
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