Jump to content

Build Theme!

Replying to Understanding the 2012 Buick LaCrosse with eAssist System


Post Options

  or Cancel


Topic Summary

Posted Yesterday, 08:39 PM

What about the BMW Turbo-Steamer that boiled water off the exhaust heat to run.... something?


Posted 17 October 2014 - 11:21 PM

Also, if its technically too difficult to use exhaust gasses to generate electricity directly, would it be possible to setup some of these hybrids with a smaller engine and small turbo and run a miller cycle?  Are the small turbos still too slow to spin up to be of use for a miller cycle engine?

 

With every manufacturer so anxious to turbo everything (allegedly for CAFE reasons) I have wondered why they don't switch to miller cycle engines.  They're already spending the money on forced induction and they would get better fuel economy out of the system.


Posted 17 October 2014 - 08:16 PM

 


This seems like a great idea, what kind of cost and weight is associated with a 300 lb ft electric motor?  With the fuel economy numbers being released for the mid size truck twins this week and the general underwhelming reaction by the internet at large I wonder what a system like this could do when plugged into trucks like that.  Big torque from the get go would work well, and with no torque converter losses and some regenerative braking I would have to think fuel economy would really out do what they're currently going for.  Has anyone made a commercial alternator or generator that can run off of the exhaust stream?  If possible to implement it would seem like a good fit if the industry is going to keep heading towards electrification of vehicles.

 

 

(1) The weight will be significant, but not so much from the motor as from the battery itself. A 70hp motor itself will be in the order of 70~80 lbs, a battery powerful enough and which stores enough charge to support a 70hp motor however will be on the order of 200~400 lbs. Still that is about what the Prius lugs around and it will not offset the gains from regenerative braking and subsequent motor assist.

 

(2) There isn't much "steam" in the exhaust. Certainly not enough to drive anything. However, there is plenty of heat and plenty of pressurized gas. Another source of "free" power is to use half a turbocharger -- just the turbine section without the compressor -- to drive a generator. This way, the normally wasted energy in the exhaust is converted (at least in part) to electricity. The problem with that is that it is much more of an engineering challenge. Turbos run at up to 100,000~150,000 rpm. Generators generally don't work well at such high frequencies, meaning you have to gear it down to maybe 1/10th or 1/20th of that rotation speed. It's a similar challenge as say Pratt & Whintey faces in commercializing the Geared Turbofan except it is actually worse because the reduction ratio is much greater. Alternatively you can simply work with a very high frequency AC source... that's another challenge by itself (efficiencies aside).

 

 

What kind of duty cycle can these electric motors handle?  Would they be capable of putting out max torque output over and over in a short time, say while towing/hauling through a town with a stretch of lights, or would they begin to overheat?  Is there a need to liquid cool a large enough electric motor when integrated in with the transmission?  I still think a setup like this would seem (at least on paper) to have the biggest benefit in the new mid sized trucks.  The electric motor could give a huge boost to the low rpm area of the torque curve, and the mild hybrid setup could essentially use wasted brake energy to remove the parasitic drain of the power steering pump, alternator, water pump, and torque converter - since all of those things would be electrified.  Could make stop/start systems work better too I suppose.


Posted 17 October 2014 - 05:09 PM


This seems like a great idea, what kind of cost and weight is associated with a 300 lb ft electric motor?  With the fuel economy numbers being released for the mid size truck twins this week and the general underwhelming reaction by the internet at large I wonder what a system like this could do when plugged into trucks like that.  Big torque from the get go would work well, and with no torque converter losses and some regenerative braking I would have to think fuel economy would really out do what they're currently going for.  Has anyone made a commercial alternator or generator that can run off of the exhaust stream?  If possible to implement it would seem like a good fit if the industry is going to keep heading towards electrification of vehicles.

 

 

(1) The weight will be significant, but not so much from the motor as from the battery itself. A 70hp motor itself will be in the order of 70~80 lbs, a battery powerful enough and which stores enough charge to support a 70hp motor however will be on the order of 200~400 lbs. Still that is about what the Prius lugs around and it will not offset the gains from regenerative braking and subsequent motor assist.

 

(2) There isn't much "steam" in the exhaust. Certainly not enough to drive anything. However, there is plenty of heat and plenty of pressurized gas. Another source of "free" power is to use half a turbocharger -- just the turbine section without the compressor -- to drive a generator. This way, the normally wasted energy in the exhaust is converted (at least in part) to electricity. The problem with that is that it is much more of an engineering challenge. Turbos run at up to 100,000~150,000 rpm. Generators generally don't work well at such high frequencies, meaning you have to gear it down to maybe 1/10th or 1/20th of that rotation speed. It's a similar challenge as say Pratt & Whintey faces in commercializing the Geared Turbofan except it is actually worse because the reduction ratio is much greater. Alternatively you can simply work with a very high frequency AC source... that's another challenge by itself (efficiencies aside).


Posted 15 September 2014 - 05:21 PM

but where do you put the batteries?

That shouldn't be too difficult in a truck platform.  GM butchered the under seat storage for the back seat so badly in the new canyon/colorado that batteries could be mounted there.  Honda put a truck underneath the bed in the Ridgeline, there is no reason the similar void space in a colorado/canyon could not be converted to battery use, instead of empty space or a trunk like the ridgeline has.  I would be more concerned about the durability of the electric motors they use in automotive applications and what their duty cycles are.  I have never read one way or the other what these motors are capable of putting out before some sort of cooling would be needed. 


Posted 15 September 2014 - 11:42 AM

but where do you put the batteries?


Posted 14 September 2014 - 04:15 PM

Even more could you take the current Chevy Colorado scheduled to come out in a month or two and give its 3.6L LFX an atkinson cam grind, then do something a la Acura's RLX sport hybrid with a larger electric motor bolted to the transmission and two smaller electric motors at each rear wheel?

 

This would result in a truck with full AWD functionality that would produce 300 lb ft from 0-6000 rpm.  With an ICE running with an atkinson cycle and no more drivetrain losses through a rear diff and transfer case a vehicle like this would be able to do something like 28/28 on the EPA cycle with a very healthy ability to tow and haul.  Electric motors would complement truck and sports car applications better than any others, it seems odd that mild hybrid setups like this one have not been implemented in any of them yet.


Posted 05 September 2014 - 11:16 PM

The effectiveness of a Hybrid system is directly proportional to the amount of regenerative braking it can provide. That is the ONLY source of free energy in a Hybrid. Charging the battery by running the engine or running it harder costs more fuel have than the stored energy will help you save when converted back to mechanical energy. That is because there is generation and motor losses along the way, not to mention a small amount of battery self-discharge. Everything else is secondary to this...

 

The Prius is a more effective hybrid than the 2nd Gen Insight because it can slow the car with a 67 hp motor. And (more importantly) it has 295 lb-ft of torque working to slow the car in lieu of the brakes and capture that kinetic energy into battery charge, whereas the Insight only has 13hp flywheel integrated motor-generator with 58 lb-ft of twist. Slowing a 3500 lbs Buick with a 15hp belt attached device which is torque limited by its means of attachment isn't much slowing and hence doesn't capture a lot of "free" energy for reuse. It's that simple. If GM is serious about eAssist it cannot be a bolt on Belt-Alternator-Starter. Is should be a motor integrated into the transmission or flywheel.

 

For a 3500 lb car... a hypothetical "Electramatic 6E75" will be ideal. Basically, it is a 6T75 6-speed automatic transmission with a 300 lb-ft input torque rating fitted with a 70hp/300 lb-ft synchronous motor in lieu of the torque converter. The car always pull away from a stop using just the electric motor with 300 lb-ft @ 0 rpm. At above 1000 rpm the internal combustion engine may start if needed. If the ICE is used the electric motor torque is electronically limited such that the combined torque going into the transmission never exceeds 300 lb-ft. During deceleration or below 1000 rpm the engine always uses the 2-stage Variable Valve Life system to shut-off all the valves and simply freewheel. This hybrid setup cannot idle the internal combustion engine; at rest the engine is always stopped and initial motion is always electric.

 

Hypothetical Electramatic 2.5L performance = 268 hp @ 4,700~6,300 rpm / 300 lb-ft @ 0~4700 rpm

 

This seems like a great idea, what kind of cost and weight is associated with a 300 lb ft electric motor?  With the fuel economy numbers being released for the mid size truck twins this week and the general underwhelming reaction by the internet at large I wonder what a system like this could do when plugged into trucks like that.  Big torque from the get go would work well, and with no torque converter losses and some regenerative braking I would have to think fuel economy would really out do what they're currently going for.  Has anyone made a commercial alternator or generator that can run off of the exhaust stream?  If possible to implement it would seem like a good fit if the industry is going to keep heading towards electrification of vehicles.


Posted 24 April 2014 - 12:16 PM

The effectiveness of a Hybrid system is directly proportional to the amount of regenerative braking it can provide. That is the ONLY source of free energy in a Hybrid. Charging the battery by running the engine or running it harder costs more fuel have than the stored energy will help you save when converted back to mechanical energy. That is because there is generation and motor losses along the way, not to mention a small amount of battery self-discharge. Everything else is secondary to this...

 

The Prius is a more effective hybrid than the 2nd Gen Insight because it can slow the car with a 67 hp motor. And (more importantly) it has 295 lb-ft of torque working to slow the car in lieu of the brakes and capture that kinetic energy into battery charge, whereas the Insight only has 13hp flywheel integrated motor-generator with 58 lb-ft of twist. Slowing a 3500 lbs Buick with a 15hp belt attached device which is torque limited by its means of attachment isn't much slowing and hence doesn't capture a lot of "free" energy for reuse. It's that simple. If GM is serious about eAssist it cannot be a bolt on Belt-Alternator-Starter. Is should be a motor integrated into the transmission or flywheel.

 

For a 3500 lb car... a hypothetical "Electramatic 6E75" will be ideal. Basically, it is a 6T75 6-speed automatic transmission with a 300 lb-ft input torque rating fitted with a 70hp/300 lb-ft synchronous motor in lieu of the torque converter. The car always pull away from a stop using just the electric motor with 300 lb-ft @ 0 rpm. At above 1000 rpm the internal combustion engine may start if needed. If the ICE is used the electric motor torque is electronically limited such that the combined torque going into the transmission never exceeds 300 lb-ft. During deceleration or below 1000 rpm the engine always uses the 2-stage Variable Valve Life system to shut-off all the valves and simply freewheel. This hybrid setup cannot idle the internal combustion engine; at rest the engine is always stopped and initial motion is always electric.

 

Hypothetical Electramatic 2.5L performance = 268 hp @ 4,700~6,300 rpm / 300 lb-ft @ 0~4700 rpm


Posted 18 April 2014 - 05:36 PM

1st, try a different dealer.
2nd, does the auto-stop work when the hvac system is powered off and the engine is at operating temp?

Review the complete topic (launches new window)