Finally got around to do this,
So I worked at TRW from 2000 until 2010 where I had some wonderful years. This is me in the centre, when we first started manufacturing of FIAT (Blurred everyone else out as I did not want to put there picture out there)
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So TRW developed the concept of the EPS unit back Pre-2000 and it went into Production around 2001. TRW in Birmingham was the development centre and centre of excellent for EPS and the model was to develop and NPI (New Product Introduction) and then ship it to a sister plant to continue the manufacture.
Originally we did the Fiat Stilo system from around 2000 – 2001, then it was shipped to Livorno in Italy. Then we did the Renault Megane system (including Renault Modus) in 2001 - 2002 but this was quiet short and then shipped to Pamplona in Spain to continue.
Around 2002 we started manufacturing the Nissan K12 Unit (originally the Nissan March K12 (Japan version)). This was very advance for its day and a starting point for TRW to produce further technology. The system was designed for future technology like; steer by wire, assisted parking, lane assist etc.. I remember TRW creating a concept from the Nissan K12 unit to do lane assist and steer by wire. It was the foundation of what is being developed now. there was a comment above about the older eps units and it was more reliable, and potentially but without a more advanced EPS unit you would not have the current technology on a car now days.
I was lucky enough to be at the plant for the life cycle of the EPS units and the plant again was very advanced.
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Unfortunately I was also one of the last people on site when the TRW lost the contract to Nissan - Sad times.
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The system has 4 major components. ECU, Sensor, Motor and column. I have spoken about most of the ECU and fault handling previous in this thread so I am not going back over that. But something people probably do not realise the unit does; Active Steering Position. The system knows where straight ahead is, and assists the vehicle to straight ahead allowing less friction with the mechanical geometry on the vehicle and in-turn allowing increase fuel efficiency. This is why I get angry when I see people removing the column and selling just the gearbox of the system. The system is aligned from Column to torsion bar, to ECU. Any removal and mis-placing could cause the vehicle to pull to one side. The ECU has a reference point and if this is changed by removing the column or disassembling your just asking for problems.
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I have made my feeling clear about the re-man companies dis-assembling this unit and re-assembling, not having a clue how the system really works… it’s a crime! In my opinion this is such a dangerous process to reduce the unit down to this state and anyone should stay away from this.
I know we (TRW) had massive issues attaching the column to the gearbox and attaching the column without causing side load. You must understand that sideload may cause incorrect torque demand and the system might assist without being required. If one of these units start turning, there’s not much stopping it!
The unit has a revolutionary patented design of an optical torque sensor. The Optical Torque Sensor was on the Fiat, Renault and Nissan units. Again, people do not realise that any contamination in the torque sensor greater than 35 microns (I think – something like that) would cause a failure. The Optical torque sensor has 2 disc attached to a torsion bar allowing torque to be measure. The disc would more relative to the torque applied allowing assistance to be applied by the motor/worm wheel.
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This sensor was later removed on more recent models Fiesta, Bravo etc.. and they opted for an off the shelf sensor (Hella).
A hot topic always is the security. I can only imagine that Nissan decided in their DFMEA that if a unit from one vehicle was removed and put on a different vehicle potentially it could cause serious injury. I do agree with this as although the units are essentially the same (RH vs LH are different) they do have different tunes (assistant maps) for each vehicle type (Petrol, Diesel, Sports+, C+C). So therefore there is a software dongle. On first ignition if the ‘dongle’ is empty (not learnt) then the BCM would write a Dongle (Code) to the EPS, this is checked each time the vehicle starts and will immobilise starting if the code is different.
I have done some investigation on this and it seem that the Dongle is in the Meter (Cluster), USM (Fuse Module) and the EPS.
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I know people mess with the NVM chip but how do you know what engine type is mapped, boost curves, torque vs speed map, ECU Calibration data. The system was designed to showcase the functionality and at the time I believe TRW won awards for the system.
I could go on for ages talking about the EPS, I did enjoy working with it and spent a lot of years working there, but I bet a lot of you do not realise the Nissan K12 EPS unit was also fitted to the Renault Clio Cup vehicle and also the Renault Megane Rally Championship vehicle. It is and was a very good system with a lot of technology and benefits.
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Obviously, now days the EPS has gone to a new level with self park etc.. but a lot of this originated from the Micra K12 System. Unfortunately I do not work there anymore but I will never forget what I learnt.
Speak soon.
Jason.
