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Electric power steering
https://auszookers.com/forum/viewtopic.php?f=5&t=35057		 Page 1 of 1
Author:  TZAR [ Sat Aug 18, 2012 7:28 pm ]
Post subject:  Electric power steering
Now before you get all WTF, I mean some of the late model jap stuff has some very interesting I deas. Take this pic for example. It from a wagon R but aparantly it will fit a late model JA11 suzuki. I know you will all say get a vitarda box or something else but I dont ant that I want this for an LJ. My secret red LJ project. The LJ box is right up next to the firewall and this would be an excellent option for my particular project.

PROS and CONS please especially from you Royce as you would be helping me fit and wire it ( with payment of course)

Image
Author:  Scales [ Sat Aug 18, 2012 7:59 pm ]
Post subject:  Re: Electric power steering
SUBSCRIBED

very interested in this one, my missus' i20 has electric steering, no IDEA how it works but its very smooth and one less thing to worry about fluid wise. Dunno how they go in the long-term though.
Author:  alien [ Sat Aug 18, 2012 8:33 pm ]
Post subject:  Re: Electric power steering
how much current do they draw??? might need to upgrade battery / alternator etc... and how do they steer if the power "goes out" ? ie: imagine it blew a fuse on the highway or something... also, how waterproof are they?
Author:  missmyljdaze [ Sat Aug 18, 2012 9:18 pm ]
Post subject:  Re: Electric power steering
alien wrote:
and how do they steer if the power "goes out" ? ie: imagine it blew a fuse on the highway or something?


Any power steering set-up (hydraulic or electric) must have a safe system of redundancy- if the electrickery part fails, the vehicle must still be safe to drive.
Probably be a bit heavier to steer- thats all.
Author:  royce [ Sat Aug 18, 2012 10:21 pm ]
Post subject:  Re: Electric power steering
how does its ECU know what to do? IE what sensors?

Ignis has similar, Stekky never got around to getting details though
Author:  Plum [ Sat Aug 18, 2012 10:44 pm ]
Post subject:  Re: Electric power steering
The EPS in the current cars iv seen cut out at about the 2 minute mark. That's stationary steering lock to lock.
All real 4x4's are still fluid. Not sure when they will adopt it.
Author:  Gwagensteve [ Sat Aug 18, 2012 11:28 pm ]
Post subject:  Re: Electric power steering
I believe the late 660cc Sierras used a similar system, as did the late Suzuki Cappuccino

Pro - easy to fit, if not to wire.
Con - any "power assistance" is being transmitted down the steering shaft in the engine bay, so the unis/rag joint and steering box will be getting a work out.

Bear in mind 660cc sierras are very light and have very narrow tyres. The amount of total assistance will be NOTHING like hydraulic power steer. It's primarily intended as a parking aid. (And this is how it was used in the Cappuccino) the assistance switched out over 10km/h or something. The control unit will have a VSS feed to it to enable this. I think you'll kill it if you try and run it to steer big tyres offroad.

As an aside, In general, electric power steer is being used in more cars because it helps improve emissions. There's something like a 2% fuel economy improvement by not running the hydraulic pump constantly. However, nobody (including Porsche) has yet to build an electric power steer system that has comparable feel to a hydraulic system.

Steve.
Author:  Gwagensteve [ Sat Aug 18, 2012 11:31 pm ]
Post subject:  Re: Electric power steering
Oh, and some cars (previous shape Mini) have a hybrid system where an electric motor drives the hydraulic pump as required. This is fine (and has good feel) until the electronics packs up and the steering almost locks solid. This was a common problem with previous generation Mini's. In the case of the system you have posted, I believe it is transparent when not powered - i.e has no effect on steering weight.

Steve.
Author:  Rhinoman [ Sun Aug 19, 2012 4:33 am ]
Post subject:  Re: Electric power steering
We make a lot of those where I work (including the Mini units!) in various flavours - direct drive electric assistance, belt drive and electrically powered hydraulic (EPHS). They all fail safe but they do then take more effort to turn because of the lack of assistance, which isn't really any different to conventional power steering - none of them 'lock up'. The issue that you might have is that the motors are carefully matched to each application, big tyres in mud is likely to be way in excess of the design intent. I have a Wagon R unit that I got ages ago to fit to an SJ, as I recall it uses the ABS sensors for vehicle speed, other than that its pretty much all one unit.
As far as power is concerned the units we make can draw over 100A momentarily and I think some peak at 180A. Its not really a big issue many small cars have these set ups and a relatively small battery.
Author:  Rhinoman [ Sun Aug 19, 2012 4:36 am ]
Post subject:  Re: Electric power steering
Gwagensteve wrote:
However, nobody (including Porsche) has yet to build an electric power steer system that has comparable feel to a hydraulic system.
Steve.



Oh and Porsche don't make their electric power steering units either :wink:
Author:  Gwagensteve [ Sun Aug 19, 2012 10:05 am ]
Post subject:  Re: Electric power steering
I'm aware of this, I'm not aware of any manufacturer that makes their own hydraulic steering systems either, but they will be involved in the tuning of the system, and it seems that, to date, electronic systems have a "different" (and typically worse) feel.

BMW "claim" the engineering of stop start with an automatic transmission as their own, despite the whole system being built by ZF. It's clear that manufacturers work side by side with suppliers to get the engineering outcome they want. It's a measure of the importance of reduced emissions that a manufacturer like Porsche is willing to compromise steering feel to achieve a better CO2 number.

Opel have fitted hydraulic steering to the new Astra OPC (VXR) whilst the rest of the range has electric steering because they can't get the electric system right for a sporting application.

That's interesting tech on the peak loads drawn of the electric systems. That's going to be hard to manage in an offroad application IMHO.

Steve.
Author:  superduki [ Sun Aug 19, 2012 3:25 pm ]
Post subject:  Re: Electric power steering
I got the opportunity to head over to Hyundai training in melbourne 2-3 years ago for a current model Elantra they'd made at the time. The model we studied had the same electric steering system fitted.

To answer a question asked in an above post to how it works, with the Hyundai unit it basically operated as follows.

Imagine a torque bar internal to the motor assembly on the column, (just like a torsion bar for example), and at both ends it has a wheel attached to it, with 1 degree increments cut into it. (for the older people playing at home, same as how a VL commodore dizzy works). At one end of the torsion bar it has a light emitted through the first wheel and down to the second wheel.

When the column is twisted by the driver, the light changes slots as the torsion bar twists, thus telling the control unit how much assistance is needed by it. Obviously as your driving speed increases, the less the torsion bar will twist, which lowers the amount of assistance the control unit produces.

Since Hyundai have ran it in their cars (approx 3-4 years on some models) I've seen only 1 fail. The steering just went heavy like a hydraulic system turned off.

Luckily it was under warranty, replacement cost retail was nearly 4k :shocked:

Cheers, Simon.
Author:  Rhinoman [ Mon Aug 20, 2012 6:40 am ]
Post subject:  Re: Electric power steering
Gwagensteve wrote:
That's interesting tech on the peak loads drawn of the electric systems. That's going to be hard to manage in an offroad application IMHO.
Steve.


If the The WagonR system is the same as the one that I have then its a very simple and rather crude system using a brushed motor and an optical encoder, more modern systems use a brushless motor and run a sensorless control strategy, its a surprisingly simple control unit too without the safety features of a modern unit. I haven't measured the current draw on the WagonR but the wiring isn't that heavy duty, as its a brushless motor you can measure the motor coil resistance which will give you the peak current, my set up has been in storage since I moved so I don't have easy access to it.
Author:  Rhinoman [ Mon Aug 20, 2012 6:52 am ]
Post subject:  Re: Electric power steering
Checking the FSM it states about 1 Ohm for the motor windings so thats around 14A - less than 200W which is rather a small motor for an EPS.
Author:  TZAR [ Mon Sep 03, 2012 4:30 pm ]
Post subject:  Re: Electric power steering
Okay have found a factory fitted version for a sierra. More info when I get more info. :-)
Author:  neofitou [ Mon Sep 03, 2012 5:28 pm ]
Post subject:  Re: Electric power steering
I dont know why they cant just run an electric clutch like aircons do for hydro PS systems..
Im sure they looked at it, but I dont know why it wouldnt work. Using an elecric motor to run a pump? pfft.
Author:  Trypt [ Mon Sep 03, 2012 11:12 pm ]
Post subject:  Re: Electric power steering
Electro-hydraulics are very efficient. Why do you think so much heavy industry uses electro hydraulic over direct electric
Author:  Rhinoman [ Tue Sep 04, 2012 6:05 am ]
Post subject:  Re: Electric power steering
Quote:
EPS is extremely efficient when compared to a power rack and pinion pump, using only 10 percent of the energy and only when the driver demands it. With no energy drag on the engine, EPS systems offer a fuel savings of up to 0.33L/100km, with a corresponding reduction in carbon dioxide emissions of approximately 8g/km.


From here:
http://www.trw.com/sub_system/electrica ... d_steering
Author:  mazdaspater [ Tue Sep 04, 2012 9:47 pm ]
Post subject:  Re: Electric power steering
Had an electric unit on a brand new (14Km old) Yaris fail when I was at Toyota, Full assistance left, Full resistance right. Effing hard to drive down the road.

Nearly half the price of the car to fix.
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