Date: Thu, 23 Jul 2015 19:38:14 -0400
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Electric Power Steering
In-Reply-To: <1294586747.16185777.1437692194305.JavaMail.zimbra@comcast.net>
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Hydraulic power steering has a continuous parasitic load even when not loaded. The need for p0wer steering assist is intermittent so going to an electric system makes a lot of sense. Electric water pumps are not just used to reduce engine load. A water pump has a limited range where it is efficient. Designed to pump at low speeds it will just become a mixer at higher speeds. Generally they spin at close to 1.5 to 2 times engine speed. What works at idle will not works as well at 16,000 rpm. Also for pump losses doubling the speed takes 4 times the power. Turn a pump fast enough and push enough water and you can actually add heat to the water. This is how many low end hot tubs heat the water, just pump it, no elements needed. As for an electric compressor this too is now common especially in electric and hybrid vehicles. For the Vanagon the compressor can probably take around 2 to 3 hp. At 746 watts/HP that is 2,236 watts. At 12 volts that 186.5 amps. Add the inefficiencies of using an alternator, (that fan removes a lot of heat) and you may need 4 to 5 hp to make the 3 the compressor is using. Add the fans and the vehicles other electrical requirements and you need a 250 to 300 amp alternator.
Just some thoughts,
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Todd Last
Sent: Thursday, July 23, 2015 6:57 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Electric Power Steering
The new Mini Coopers have electric power steering. (They are often cited for noise and require a fan to keep the motor from overheating.) Racers have used electric water pump drives to squeeze out the last ounce of horsepower from their engines. So why not electrically drive the water pump and power steering ? Just think, you could add a speed control for the water pump - have it pump based on the water temperature, not the engine RPM. The equation to figure out is if it costs more in drag on the alternator to generate the power needed to run the electric motor than you gain by not turning the pump with the fanbelt. That would make for an interesting experiment. Perhaps it would be worth running the A/C compressor on an electric motor drive....
Todd
'88 Westy
----- Original Message -----
From: "Alistair Bell" <albell@SHAW.CA>
To: vanagon@GERRY.VANAGON.COM
Sent: Thursday, July 23, 2015 11:58:12 AM
Subject: Re: Electric Power Steering
Yes, the UK guys have been doing it (Germans too).
What I liked about the one I saw was how inexpensive it seemed to be.
Alistair
> On Jul 23, 2015, at 10:16 AM, Neil N <musomuso@GMAIL.COM> wrote:
>
> http://www.ultimate-engineering.co.uk/powersteering.html
>
> and....
>
> http://www.thesamba.com/vw/forum/viewtopic.php?p=7150246&highlight=nsk+japan+famous+bearing+eps+manufactured++corsa++late+2000#7150246
>
> --
> Neil n
>
> Blog: Vanagons, Westfalia, general <http://tubaneil.blogspot.ca>
>
> 1988 Westy Images <https://picasaweb.google.com/musomuso/New1988Westy>
>
> 1981 Westfalia "Jaco" Images, technical <http://tubaneil.googlepages.com/>
>
> Vanagon-Bus VAG Gas Engine Swap Group <http://tinyurl.com/khalbay>