To learn more about iVT, please read through this presentation first given at Aachen in October 2017

iVT Overview

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What is iVT

  • iVT is a full authority, purely electro-mechanical, variable valve actuation system for piston engines
  • Unprecedented level of control – valve by valve
  • Full, fast feedback control throughout the event
  • Can be used on both inlet and exhaust valves, double events possible – an HCCI enabler?
  • Digital control of gas exchange, the last controllable combustion variable

Intelligent Valve Technology

  • Uses an individual, electrically actuated desmodromic mechanism per valve or valve pair
  • No mechanical drive from the crankshaft
  • No conventional valve (or “helper”) spring
  • Compliance to allow for seating loads, expansion etc. is built in to the drop link
  • Operates on 12 or 48 volts

Operating Modes

  • Full lift = full rotor rotation
  • Part lift = part rotation + return
  • Rotor velocity never constant
  • Rotor “parks” between most events
  • Every event is independent of both its predecessor and its successor

What does iVT Offer?

  • Complete, infinitely variable, phase control
  • Complete, infinitely variable, period control
  • Complete, infinitely variable, lift control
  • Event shape control – and not just MOP shift
  • All virtually independent of each other
  • Multiple event, no event

iVT Installation

  • Actuator axis perpendicular to crankshaft
  • Electronic control unit compliantly mounted over or alongside the mechanicals
  • Packages within normal N-S and E-W layouts with conventional bonnet clearances

Electro-mechanical Layout

  • Mechanically, the linkage contains nothing unfamiliar or of unusual precision
  • Each actuator is an 8-pole, permanent magnet machine
  • The stator is segmented and shared between actuators, maximising torque capacity and efficiency
  • Asymmetry further improves performance/unit package volume and weight

Control

  • Master controller requests the required valve event
  • Each actuator is under independent position control
  • Local actuator controller determines the target rotor trajectory for minimal energy consumption
  • The target trajectory is dynamically adjusted, compensating for transient engine behaviour during each valve event

Testing

  • Testing has been conducted both on test rigs and on the dynamometer
  • The first iVT modules have been designed for the inlet valves of a Jaguar Land Rover Ingenium engine

Engine Performance

  • Max valve lift reduced to 7.8mm
  • 1D analysis suggested similar performance- timing/period  compensating for reduced lift
  • The dynamometer results confirmed the predicted performance
  • Eliminates piston interference

Dynamometer Testing

  • 10 “minimap” steady state points defined
  • Large DoE experiment completed (Inlet only)
  • CO2 improvements up to 7.5% recorded
  • Optimised events established
  • The VVT capability required is greater than any other available system
  • Even greater iVT dynamic capability is now in development and will provide further benefit

Results Analysis

  • CO2 results achieved with iVT power sourced from the alternator – opportunity for smart charging?
  • The CO2 benefits come from 3 sources:
Pumping loss reduction
Heat release rate and knock sensitivity increase
Parasitic loss reduction

Event Consistency

  • Valve position was measured on the fired engine for 300 consecutive events
  • An example of the control achieved is shown
  • Measurements of event quality have been established in order to ensure that other development improvements, e.g. power consumption, can be measured against a common standard

Optimised events

  • Throttle wide open in all cases, including idle
  • Single valve mode often best
  • Both EIVC and LIVC capability needed for different conditions
  • Late MOP useful for some events
  • Only steady state and the simplest iVT strategies have been explored so far – there is much more to come

Other Aspects of Note

  • VERY low mechanical noise
  • Transient valve response: 0-100% in one cycle
  • Significant detonation sensitivity improvement
  • Cranking torque reductions of ~30% through reduced pumping loss have been demonstrated
  • There are hybridisation synergies yet to be explored but deletion of the timing drive is an obvious benefit
  • Demo car available now
  • Single cylinder R&D programme support possible

Cost and Affordability

  • On-costs have been estimated as a joint effort – a Tier 1, Jaguar Land Rover and Camcon
  • The CO2 benefit, even on the basis of today’s steady state results alone “pays for” the system
  • There is much more to come in terms of CO2 benefits

Next Steps

  • The next generation iVT prototypes are being procured now.
  • The new actuators will be smaller, lighter, cheaper, >40% lower electrical power demand
  • Improved dynamic performance will mean further improved CO2 results
  • Exhaust actuators and 16V engine testing included in the next stage of the programme 
  • And then: diesel, including heavy duty

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