EHPS (electro hydraulical power steering) control

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EHPS (electro hydraulical power steering) control

Postby 20B on Sun Jul 15, 2012 9:34 pm

Has anyone used a Mxx ecu or SDL output to control an EHPS pump for the steering ?
Been toying with the idea of adding an electro hydraulic pump (Toyota MR2 late model) to the steering since the belt driven pump was ditched.
Anyone done a similar project or thoughts and ideas on how to go about it ?
Was thinking of running an output signal to the pump control unit from a 3D table of my SDL to speed control the pump on the VSS signal it normally pIcks up from the gearbox speed sensor.
Here is the link to the conversion process -http://www.mazdaspeedy.com/2011/11/toyota-mr-s-electric-power-steering.html
Mazda 1993 RX7
20B N/A engine
Motec M800,CDI, SDL, SLM, LTC, DHB
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Re: EHPS (electro hydraulical power steering) control

Postby JamieA on Wed Jul 18, 2012 10:57 am

what inputs does the steering system require from the other items?

ie ground speed
RPM
etc
etc...
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Re: EHPS (electro hydraulical power steering) control

Postby 20B on Wed Jul 18, 2012 8:32 pm

Jamie,
The late model MR2 pump has a built in 'ecu' which does the speed control for the pump. It only takes a single wire VSS speed signal from the ABS or Gearbox speed output (not sure which one) for the amount of assist required for the pump.
This is why they are popular for electric vehicle conversions and retro fit conversions as it has the built in electronics for the pump control.
I am wondering if I can drive this VSS signal from my SDL to allow me to 'tune' the amount of assist on a 3D table for example.
The other idea is to use another manufacturers EHPS pump and just drive the power DC input ( 50 amps +? ) with PWM through a DHB or similar directly on a 3D table ( ground speed / steering angle ? )
Any thoughts or experience doing this ?
Mazda 1993 RX7
20B N/A engine
Motec M800,CDI, SDL, SLM, LTC, DHB
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Re: EHPS (electro hydraulical power steering) control

Postby Holmz on Wed Jul 18, 2012 9:51 pm

20B wrote:Jamie,
...
Any thoughts?
...


Nothing of value..

For a race car do you even need the power steering?
For a street car you may need a bigger alternator to facilitate the p/s along with A/C.
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Re: EHPS (electro hydraulical power steering) control

Postby 20B on Thu Jul 19, 2012 5:23 pm

For a race car do you even need the power steering?

Yes, plenty of people run them. My car is not a race car but it see's track time and has wide semi slicks up front, this gets old pretty quick especially when your starting to approach the age of 40 :lol:
The fact you can 'tune' the power steering means that you have a nice soft assist for everyday driving then load the SDL config that has the 'heavier' steering for track days ( best of both worlds really ).
P.S factory fitted OEM 100amp alternator and no aircon so all good there.
Mazda 1993 RX7
20B N/A engine
Motec M800,CDI, SDL, SLM, LTC, DHB
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Re: EHPS (electro hydraulical power steering) control

Postby AdamW on Mon Jul 23, 2012 5:49 am

20B, I cant answer your question whether you can generate the frequency signal with your ECU or dash however, there is a aftermarket controller available that you might not be aware of:
http://www.myraceshop.com/Power_Steerin ... oller.html
If you click the "legacy controller" link, you will find some instructions for his older controller that gives a bit more info than the webpage.
It can take a standard VSS signal from any car and multiply or divide it to give more or less steering effort using a 3d table, or you can use it without a VSS (pot mode) where the controller generates the signal based on the position of a pot that you would mount on the dash.
I havent used one but will probably go that way if I cant get my mechanical pump to do what I want.
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Re: EHPS (electro hydraulical power steering) control

Postby 20B on Mon Jul 23, 2012 9:33 pm

Adam,
Wasn't aware of that little controller, sounds like it would be just the solution.
Pretty much does what I want so might look into that.
The only other way is to directly drive a pump with a DHB or similar on a 3D table.
Thanks for the info.
Mazda 1993 RX7
20B N/A engine
Motec M800,CDI, SDL, SLM, LTC, DHB
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Re: EHPS (electro hydraulical power steering) control

Postby Martin on Wed Jul 25, 2012 5:23 am

20B

Ive used the Mini cooper Electro hydraulic pumps before and also the latest mini R56 powersteering pump that needs CAN data TXd to it to make it work. If you are interested in these pumps send me an email

Cheers
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Re: EHPS (electro hydraulical power steering) control

Postby chelspeed on Fri Jul 27, 2012 9:48 pm

Loads of people with rally cars in UK use the Corsa B electric assisted column (not EHPAS just electric PAS I guess). These are simple to backfit to many cars, just fit it between the steering wheel and the rack by juggling the splined fittings.

You can get after market pot driven control units similar to mentioned above for anywhere from £10 to £100 from a number of suppliers on "the bay". Guess it would be possible to replace the pot with a ECU or ADL controlled output.
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Re: EHPS (electro hydraulical power steering) control

Postby 20B on Sat Jul 28, 2012 9:58 pm

Chelspeed,
Yes I am aware of the corsa systems. I am looking at repowering an unpowered rack that had the belt driven pump removed.
As it is a road car I don't want to pull apart the column so it must be an EHPS system.
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