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Discussion Starter #1
Hello

What do you guys think of the Insight's CVT compared to that of the Prius design.

Why did Honda choose to use a mechanical CVT rather than a more efficient one like that of the Prius?

Will Honda switch to using a Hybrid Drive like that of the Prius? rather than it's current IMA system?

What benefit/disadvantage of each do you see?

Thanks
 
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Hi Hou_ge2000:

What do you guys think of the Insight's CVT compared to that of the Prius design.

___I don’t really have a strong opinion either way. I like the HSD in its simplicity and probably longevity but I don’t like that it needs 2 MG sets and the ICE to transfer power through it (HSD as a system, not just the CVT).

Why did Honda choose to use a mechanical CVT rather than a more efficient one like that of the Prius?

___Probably cost? The CVT of the Prius itself is a marvel in simplicity but add up the surrounding components and it probably costs far more then the simple dual sheaved pulley and belt system of the Honda based CVT.

___As for efficiency, the Prius’ are darn efficient for the weight that they were designed at but as far as real world fuel economy is concerned, a CVT based Insight would probably far exceed the Prius’ real world mileage capabilities. The CVT however would not be a major factor in this. The 50% drop in weight and smaller frontal area of the Insight with a CVT would be. A closer match would be the CVT in the HCH vs. the CVT in the 01-03/04 Prius’. You can see the fuel economy battle heating up between the HCH’s and 01-03 and 04 Prius’ over at GreenHybrid’s Real Hybrid Mileage Database. An HCH w/ CVT is currently on top of the list with a host of Prius drivers following closely behind. All fall behind the 5-speed Insight’s by some distance and more then likely would fall behind the CVT based Insight’s as well. A particular 2000 5-speed Insight driver (Rick Reese) well known for his superb Insight fuel economy driving skills will probably soon surpass all of them with his used 01 Prius however.

Will Honda switch to using a Hybrid Drive like that of the Prius? rather than it's current IMA system?

___Probably not. The 2005 Accord Hybrid will supposedly use the IMA as is albeit even more powerful overall.

What benefit/disadvantage of each do you see?

___About the same as described above. The steel belt on sheaved pulleys is about as low cost an automatic transmission as you could probably find. The Prius’ CVT however appears on paper to be more bulletproof. The cost of the Prius’ CVT appears to be very cost effective in its own right as well but not when you have to have 2 MG-Sets and an ICE to propel the Prius as a system. I am not sure what kind of transmission the 05 Accord Hybrid will be using but since it is using the same 240 HP V6 as its EX counterpart, I would probably say it will use a std. bulletproof automatic that we have all come to know and love w/ the IMA attached at the front drive shafts somehow?

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:1289u8eq][email protected][/email:1289u8eq]
 

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Discussion Starter #3
Thanks.

Does anyone know how efficient is Honda's powertrain compared to that of the Prius?

I have some very specific question that I hope you experts can answer.
First of all, let me make sure I got these fact right, so please correct me if I'm wrong.

1. Both the Prius and Honda have the regenerative braking feature which adds to the fuel economy

2. The Honda Insight depends on the engine more while depending on the motor to a lesser extent than the Prius. This means less energy conversion (between gasoline to electric) is needed and also weight saving can occur due to a smaller motor/generator.

3. Both Honda and Prius allows the engine to work at its optimum range by using CVT. The Honda uses a mechanical CVT. ( does anyone know the efficiency of it?) The Prius uses an ECVT by 2 motors and the power split mechanism. It's unclear how much more efficient the Prius's ECVT is than the Honda's mechanical. I'd really appreciate it if anyone can tell me.

If I'm wrong on anything please correct me and also feel free to add anything. Any comment would be appreciated.
 

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See if this link is of any help. I don't know of any numbers for efficiency (work input / work output) for either transmission.
 

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Discussion Starter #5
Thanks, does anyone know the weight of the Honda motor?

The Insight doesn't have a generator, unlike the Prius. Also, the battery pack and the motor is also much lighter.

Overall, I think Honda is primarily trying to get mileage by reducing weights. I think those reduced weight from the motor/generator/battery makes the Insight at least a few percentage more efficient from a weight point of view.

Does anyone know how much those motor/generator/batteries weigh? compared to the Prius.

Thanks.
 

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Wow, you ask a lot of questions :wink:

But you seem to have the facts straight. As for you initial question of why a "conventional" CVT versus a planetary "CVT" like the Prius: In addition to xcel's info is the simple fact that the planetary system would not work with the IMA arrangement.
 

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The Toyota sysnergy drive trades gear simplicity for electrical complexity. Understanding how it actually works is about as easy as describing electron orbitals. Many patents have been aplied for by Toyota on just the computer software that controls the torque and speed ratios of the two electric motor/generators versus the ICE. The Honda system is very simple as the electric motor/generator and ICE are conected to the drive shaft, rotating at the same speed and sharing the same bearings. The IMA occupies the same space as a traditional flywheel and performs the same function as well as assisting the ICE. A standby 12 volt starter for the ICE does add to the complexity of the IMA system but is only used for extreme cold weather starting.

Toyota's system is more efficient in stop and go traffic as the ICE is only on for a small portion of the time. Furthermore because the majority of the torque is provided by the electric motor a quasi Atkins cycle motor can be used to increase combustion efficiency. Honda's IMA is inherently more efficient in steady speed conditions such as highway comutes as it is inherently lighter and does not have the electrical losses associated with the Synergy drive. Honda uses lean burn and/or cylinder idling to achieve high combustion efficiencies.

Honda is on record for saying that they will not abandon the IMA technology. Two major advatages of the IMA system are:
1. It allows drop in engine choices without having to design the vehicle around the engine.
2. For hauling heavy loads and climbing long hills it provides about 40 percent more power to the wheels as it derives less of its torque from the electric motor.

It is my impression that the Toyota system efficiency is more effected by cold weather as it is more dependant on battery power. The efficiency of all batteries goes down dramatically at low temperatures so the more battery dependant the system the more accentuated the efficiency variations. In time all manufacturers will have to deal with this by finding better batteries or developing a system for keeping them warm.

Hope this helps.

:D :D
 
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