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Old 11-26-2012, 02:03 PM   #1 (permalink)
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Default Insight EV Pumpkin Drive

The drive axle differential carrier assembly is often referred to as the "pumpkin". A casual comparison of the output specs.of the Toyota 2004 Highlander Hybrid 4WD/Lexus RX400H electric rear wheel drive units (pumpkins) and the output of Gen1 Insight show similarities that suggest interchangeability: Why not use one of these Toyota pumpkins as an EV drive for the Insight? On paper, at least, it appears that this approach should yield an adequate/equivalent EV Insight.

These units are compact, self contained and weigh less than 100 lbs. The outputs are flanged and a simple adapter could allow direct connection to existing Insight drive shafts. A rigid three point framework using Insight motor mount locations would be fabricated with a suitable platform for resilient rubber mounting of the pumpkin. The mechanical aspects of this conversion are simple and straight forward enough because there is plenty of space available.

The real difficulties for this conversion are adapting a suitable Toyota Synergy Drive. These motors operate at 650 volts and would require inverter drives from the Lexus, Highlander, Camry, or other similar models. There has been a lot of work done by the ORNL with these drives but there is little information available to the public. Previously, Mike Dabrowski has suggested the "Insight with the Prius Heart". The Prius machinery is quite bulky and fitting it under the hood of an Insight presents some difficult to solve challenges. The pumpkin drive, while milder, would be much simpler to accomplish quickly and satisfactorily.

Hacking the Toyota Synergy Drive can be avoided if a commercial Inverter were used, however, I have hopes that with the talent available here on IC, the mysteries of utilizing existing Toyota drives will be solved and this type of conversion may be made workable soon.

Last edited by Hugh-Falls; 12-09-2012 at 12:27 AM. Reason: Spelling
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Old 11-26-2012, 03:08 PM   #2 (permalink)
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650 volts?!?!?!?! Maybe it can be rewound for less? Thats a lot of damn voltage to get from a pack with potentials for lots of losses along the way.

Ive never seen the lexus or highlander drives, Ive assumed it was one and the same which would be a beefed up version of the prius synergy power splitter but mounted in a tradational manner in the engine bay.
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Old 11-26-2012, 04:32 PM   #3 (permalink)
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Quote:
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650 volts?!?!?!?! Maybe it can be rewound for less? Thats a lot of damn voltage to get from a pack with potentials for lots of losses along the way...........
Toyota has been raising the operating voltages and RPM's of their motors over the years with higher voltage boost in their motor controllers and have kept the battery voltages relatively low. This allows them to use less copper, lighter magnets and smaller motor mass to achieve similar performance at lower cost. In our conversion, the inverter could be mounted close to the motor, perhaps less than a foot or two mostly for concerns about safety.
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Old 11-26-2012, 07:07 PM   #4 (permalink)
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Higher voltage means less amperage. You'd get less losses and less heat with higher amperage as well as higher RPM with the same setup. I wouldn't think of rewinding.

Best of luck with the conversion, you've got a good idea with a software challenge of getting the existing equipment to work.
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Old 11-27-2012, 11:28 AM   #5 (permalink)
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I wouldnt mind seeing some photos if there are any to link to.
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Old 11-27-2012, 11:56 PM   #6 (permalink)
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Default Part drawing

Quote:
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I wouldnt mind seeing some photos if there are any to link to.
I don't have any photos available at this time. If you check a Toyota parts dealer you will find drawings of the part. The easiest to find may be: 2006 Lexus RX400H, rear axle, drive motor.
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Old 11-28-2012, 06:40 AM   #7 (permalink)
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Quote:
Originally Posted by Cobb View Post
650 volts?!?!?!?! Maybe it can be rewound for less? Thats a lot of damn voltage to get from a pack with potentials for lots of losses along the way.

Ive never seen the lexus or highlander drives, Ive assumed it was one and the same which would be a beefed up version of the prius synergy power splitter but mounted in a tradational manner in the engine bay.
The whole point of boosting the voltage is to reduce the losses.
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Old 11-28-2012, 09:27 AM   #8 (permalink)
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The 220lb synergy drive should fit nicely in the insight engine bay.
I have had feelers out trying to find one of those rear wheel drives from the Hylanders, but they are pretty scarce.

Since they are the full rear end, not designed for CV shafts the process of putting it in the front and adapting the CV shafts so one can steer the car makes it a very tough adaption .
The very common gen 2 Prius synergy drives are readily available as are the inverters.
The inverter can boost the voltage of the 200V pack to over 600V, and the modified (welded planet gears) drive should hit 95 MPH without exceeding the design RPM.
Only need time, as I have all the parts in hand.
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Old 11-28-2012, 01:40 PM   #9 (permalink)
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Default CV joint flange adapters

Mike: The Toyota Lexus/Highlander electric pumpkin does drive CV joints which are flange mounted to it. I propose machining flange adapters and inserting the splined internal output gears from an Insight differential carrier to mate with existing Insight drive shafts. The width across the pumpkin flanges is close to 10.750 inches which should enable use of two of the short Insight shafts if the Toyota unit is centered and the thickness/width of the adapters is correctly machined.

Last edited by Hugh-Falls; 11-28-2012 at 01:56 PM.
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Old 11-28-2012, 03:12 PM   #10 (permalink)
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Never got a look at one, but that sounds like a nice possibility.
Like my approach, it all hinges on being able to make the inverter work.
I would imagine that the read drive would not need all complexity of the planetary power split device, as it just needs to drive the rear end with only one geared electric motor?
Have you found any photos diagrams?
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