Go Back   EcoModder Forum > EcoModding > EcoModding Central
Register Now
 Register Now

Now available from EcoModder: ScanGauge II fuel economy gauge.  Click for details.  

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 11-14-2008, 10:42 AM   #1 (permalink)
aero guerrilla
 
Piwoslaw's Avatar
 
Join Date: Oct 2008
Location: Warsaw, Poland
Posts: 3,312

Svietlana - '05 Peugeot 307 SW
Diesel
90 day: 52.73 mpg (US)
Thanks: 887
Thanked 480 Times in 297 Posts
Spring-loaded engine starter

The alternator sucks up lots of engine power, producing more electricity than the car needs. The reason it produces so much is because it doubles as a high power motor for getting the engine started in less than a second. If the alternator could be less powerful, it would be less of a power drain while driving.
So would it be possible to start the engine with some kind of powerful spiral spring, which would be wound by the alternator? The alternator could be less powerful since it would take its sweet time winding the spring, say 5-15 seconds. The spring could also be wound when braking. The spring could be slightly more powerful than a regular alternator, making it ideal for stop-and-start at traffic lights. Also, if your battery dies, the spring might still be wound up making starting possible. Or if it isn't, it could be wound up by a good old-fashioned hand crank. Just take the handle out of the trunk, pop it in a hole in your bumper, turn it 20-50 times and that's that.
I haven't fooled around with springs enough to know whether they can handle the load needed to start an engine, or how large/heavy they would have to be. Any comments?

__________________
e·co·mod·ding: the art of turning vehicles into what they should be

What matters is where you're going, not how fast.

"... we humans tend to screw up everything that's good enough as it is...or everything that we're attracted to, we love to go and defile it." - Chris Cornell

Piwoslaw's Peugeot 307sw modding thread

  Reply With Quote
Old 11-14-2008, 11:22 AM   #2 (permalink)
EcoModding Apprentice
 
Bicycle Bob's Avatar
 
Join Date: May 2008
Location: N. Saskatchewan, CA
Posts: 1,279

Appliance White - '93 Geo Metro 4-Dr. Auto
Last 3: 42.35 mpg (US)

Stealth RV - '91 Chevy Sprint Base
Thanks: 44
Thanked 160 Times in 121 Posts
Per pound, steel springs store less than 1% of the energy in a car battery, but they have occasionally been used to start aircraft and small engines. The usual difficulty comes if it does not catch on the first try. Compressed-air starters are lighter overall, effective, but less efficient. However, they can be charged up "for free" by using an air pump as a shock absorber.
It is very unusual for a car to have a combined starter and generator. The alternators are sized to replenish the battery fairly quickly after a cold start while running most of the lights and other accessories. Starter motors are built too light for continuous duty at regular power.
  Reply With Quote
Old 11-14-2008, 11:26 AM   #3 (permalink)
Deadly Efficient
 
Tango Charlie's Avatar
 
Join Date: Jun 2008
Location: Northern Indiana
Posts: 1,231

Olivia - '03 Pontiac Vibe base
90 day: 36.01 mpg (US)

R2-D2 - '00 Honda Insight
90 day: 58.81 mpg (US)
Thanks: 123
Thanked 161 Times in 85 Posts
The alternator does not double as the starter. They are separate units. The alternator is a belt-driven item that hangs off of a bracket at the 'front' (opposite end as the transmission) of the engine and is driven by the engine. The starter is a smaller electric motor that bolts into an opening at the transmission end of the engine and engages with a large ring gear to spin the engine for starting.
I don't think you'll gain anything using alternator power to wind up a spring for starting. You're just adding another step, a.k.a. a source of loss. If you only wind up the spring manually, or through regenerative braking, then you're onto something.
__________________
-Terry





My Pet Threads: What's in a UserName? and YKYAEI and
Hitch-mounted boat tail; the CARGaerO t'ailer
  Reply With Quote
Old 11-14-2008, 12:20 PM   #4 (permalink)
MechE
 
Join Date: Dec 2007
Location: Bay Area
Posts: 1,151

The Miata - '01 Mazda MX-5 Miata
Thanks: 0
Thanked 17 Times in 14 Posts
Quote:
Originally Posted by Piwoslaw View Post
The alternator sucks up lots of engine power, producing more electricity than the car needs.
Incorrect - the alternator only produces as much electricity as is needed... No more, no less.

The power is sucks up from the engine is the amount of power needed plus alternator inefficiencies.

And as already stated, your alternator does not start your car Exceptions for a few vehicles that use starter generators...

-----
Spiral spring.... you probably mean power spring, like what's found in a seat belt or clock. You'd need one helluva spring - that's a lot of energy stored... And as said, it'd be quite heavy. Impossible? No... But as said, a battery has a much better energy density.
__________________
Cars have not created a new problem. They merely made more urgent the necessity to solve existing ones.
  Reply With Quote
Old 11-14-2008, 01:02 PM   #5 (permalink)
Master EcoModder
 
Join Date: Jun 2008
Location: Earth
Posts: 3,580
Thanks: 95
Thanked 426 Times in 308 Posts
Correct me if I'm wrong, but I think with a conventional alternator most of the loss is actually coming from the drive belt and the cooling fan on the alternator pulley, not the alternator itself. The starter motor of course just sits there when it's not in use.
  Reply With Quote
Old 11-14-2008, 03:14 PM   #6 (permalink)
EcoModding Newbie
 
Join Date: Apr 2008
Location: Southern Ontario
Posts: 284

Parachute - '03 Chevrolet Tracker LX
90 day: 28.55 mpg (US)

Peon - '95 Plymouth Neon Highline baby!
90 day: 31.39 mpg (US)
Thanks: 0
Thanked 2 Times in 2 Posts
Stihl has chainsaws with spring starters, you pull the cord winding up the spring and when its fully coiled it releases turning over the engine. I've played around with one in the showroom and it seemed to work quite well. I don't know if it incorporates an auto decompression system as well.
It doesn't add much weight or bulk either.
Although springs don't store as much energy as batteries they sure can release it quicker! A typical spring on a strut seems to have enough energy to turn over an engine a few revolutions faster than most starters. The trick is harnessing it and reloading it.
Maybe for 1.0L engines all you need is to fit decompression valves to all the cylinders and then use a kick start off a motor bike.
Ian
__________________


  Reply With Quote
Old 11-14-2008, 04:31 PM   #7 (permalink)
Pokémoderator
 
cfg83's Avatar
 
Join Date: Dec 2007
Location: Southern California
Posts: 5,863

1999 Saturn SW2 - '99 Saturn SW2 Wagon
Team Saturn
90 day: 40.49 mpg (US)
Thanks: 439
Thanked 510 Times in 343 Posts
IndyIan -

Quote:
Originally Posted by IndyIan View Post
Stihl has chainsaws with spring starters, you pull the cord winding up the spring and when its fully coiled it releases turning over the engine. I've played around with one in the showroom and it seemed to work quite well. I don't know if it incorporates an auto decompression system as well.
It doesn't add much weight or bulk either.
Although springs don't store as much energy as batteries they sure can release it quicker! A typical spring on a strut seems to have enough energy to turn over an engine a few revolutions faster than most starters. The trick is harnessing it and reloading it.
Maybe for 1.0L engines all you need is to fit decompression valves to all the cylinders and then use a kick start off a motor bike.
Ian
This makes me think there must be a regenerative braking solution that could be used for harnessing/reloading. You wouldn't use it for the "first start of the day", but you could use it for restarting from a stoplight. No idea how to do it, though.

CarloSW2
__________________

What's your EPA MPG? Go Here and find out!
American Solar Energy Society
  Reply With Quote
Old 11-14-2008, 05:12 PM   #8 (permalink)
MechE
 
Join Date: Dec 2007
Location: Bay Area
Posts: 1,151

The Miata - '01 Mazda MX-5 Miata
Thanks: 0
Thanked 17 Times in 14 Posts
Quote:
Originally Posted by IndyIan View Post
The trick is harnessing it and reloading it.
Naw, that's not the trick - there's plenty of mechanisms used every day for such purposes....

The trick is matching reliability.... How many cycles is a modern starter motor designed for? Half a million cycles? Maybe a million cycles? A former job of mine was inspecting/analyzing failed power springs connected to motors

Given the loads on a chainsaw (even a lawnmower) and how many cycle uses - it makes sense not to have an electric start - even moreso because the input is human power

__________________
Cars have not created a new problem. They merely made more urgent the necessity to solve existing ones.
  Reply With Quote
Old 11-14-2008, 06:29 PM   #9 (permalink)
DieselMiser
 
ConnClark's Avatar
 
Join Date: Jun 2008
Location: Richland,WA
Posts: 892

Das Schlepper Frog - '85 Mercedes Benz 300SD
90 day: 23.23 mpg (US)
Thanks: 39
Thanked 168 Times in 115 Posts
Springs aren't the way to go and neither is compressed air. You need gunpowder!!

Seriously, aircraft used to use the Coffman starting system because it was far lighter than the rest.

Coffman engine starter - Wikipedia, the free encyclopedia

Of course the neighbors might complain about you starting your car for a late night beer run. Of course the police might have a thing or to to say about you starting your car this way too.

However for the weight and thus efficiency a Coffman style starter and a box of blank shot gun shells will weigh far less than any other method except for push starting.
__________________
  Reply With Quote
Old 11-14-2008, 07:02 PM   #10 (permalink)
Deadly Efficient
 
Tango Charlie's Avatar
 
Join Date: Jun 2008
Location: Northern Indiana
Posts: 1,231

Olivia - '03 Pontiac Vibe base
90 day: 36.01 mpg (US)

R2-D2 - '00 Honda Insight
90 day: 58.81 mpg (US)
Thanks: 123
Thanked 161 Times in 85 Posts
Ha ha! I remember that scene from The Flight of the Phoenix. That was a great movie.

__________________
-Terry





My Pet Threads: What's in a UserName? and YKYAEI and
Hitch-mounted boat tail; the CARGaerO t'ailer
  Reply With Quote
Reply  Post New Thread

Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
1992 Metro sedan needs a new engine - What/Where/How - advice appreciated greatly! Crono EcoModding Central 26 11-18-2008 01:42 AM
Moving air intake into the engine compartment? pasadena_commut Aerodynamics 5 07-25-2008 03:24 PM
Coasting experiment: engine on VS engine off on a fixed route = 12.9% gain MetroMPG Hypermiling / EcoDriver's Ed 6 02-22-2008 08:38 AM
Basic EcoDriving Techniques and Instrumentation SVOboy Instrumentation 2 11-17-2007 11:38 AM




Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com