AUTOMOTIVE EMBEDDED SYSTEMS

SEMINAR REPORT

VALVE-BY-WIREINTELLIGENT VALVE ACTUATION (IVA)

Submitted by:ARJUN HAREENDRAN (CB.EN.P2.ATE.13003)

INTRODUCTIONThe optimization of Internal Combustion Engines are one of the most active area of research and development. Several technologies were implemented to improve the engine in different aspects. The advancements in automotive electronics and embedded systems have enabled much sophistications in the engine and its working. Valve-by-wire is a new technology in this series that is capable of taking the engine optimization to a higher level. This technology deals with the electronic and intelligent valve actuation, timing, period etc.Valves are one of the main components of an Internal Combustion Engine which can play a pivotal role in the optimization of it. The conventional or the existing technology of the valves are based on the mechanical connection or linkage of the cam shaft to the engine crank shaft. This mechanical connection in most case, is in the form of a belt called timing belt or using chains. A detailed study on the valve actuation, timing, period etc. by the existing cam shaft driven technology can clearly expose the limitations and disadvantages of it. Valve events are one of the few remaining major constraints on internal-combustion engine optimization. Eliminating those constraints is the aim of a new technology called Intelligent Valve Actuation (IVA), developed byU.K.-basedCamcon. According to the company's Technical Director, Roger Stone, Intelligent Valve Actuationwill play a major role in allowing OEMs to meet 2020 requirements for fuel consumption and emissions.Intelligent Valve Actuation system (IVA) brings engine valve control into the digital age, removing one of the most significant remaining barriers to the optimisation of combustion efficiency. By providing full-authority by-wire control of timing, duration and lift for each individual valve, IVA provides continuous, high-precision mechanical control of the valve at every point in its movement and at every combination of engine speed and load.The basis of the system involves control technology that eliminates the mechanical connection between valve operation and crankshaft rotation, allowing valve events (lift, timing, and period) to be optimized for every speed and load combination and even varied from one cycle to the next. Intelligent Valve Actuation is the combination of a new Multi-stable Actuator Technology (an evolution of the companys proven Binary Actuation Technology) with an innovative mechanism that uses desmodromic cam pairs and rockers to translate the actuators rotary movement into fast, high-precision linear movement of each valve. In effect, it is the creation of valve-by-wire technology.BINARY ACTUATION TECHNOLOGY (BAT)Binary Actuator Technology has been developed to push the boundaries of actuator speed, efficiency and integration. Like most profound ideas, the underlying principle for BAT is simple its job is to provide actuation faster, more efficiently and with greater ease without increased costs.By utilising a simple combination of permanent and electro-magnets combined with an integrated electronic control system, a unique new way of accurately controlling a 2 way spindle at speed is achieved. Packaged within a compact and simple-to-manufacture housing, accompanied by the sealed and integrated electronic control module, the actuation uniquely requires zero power to maintain engagement. This fast acting, high efficiency, low power design provides the foundations for a multitude of applications to which BAT can be applied.With a design that lends itself to a far more durable and quiet solution than worm and wheel geared systems, and more efficient than solenoid based arrangements, the benefits quickly begin to become apparent. Integrated control negates the need for complex installs with additional control units and programming allowing an actuation unit to almost become plug and play. Ranging across many industries, BAT is already established in the Oil and Gas sector. Recent successful testing and development programs have enabled Camcon Automotive to be established to develop products based on this proprietary actuator concept purely for the automotive sector.

WORKINGLeft stable PositionRight stable Position

The actuator intrinsically has 2 stable positions where it will lock with zero power required to hold position. In the stable position, the actuator is locked in place by the magnetic circuit formed by the permanent magnet and the steel case. Locking force of the actuator is the difference between the magnetic clamping force and the spring force trying to push it away. No external power is required.SWITCHING THE VALVETo change the actuator force, we need to break the magnet clamp. This is done using a pulse of magnetism from the electromagnets (a quick injection of current) with opposite polarity to the permanent magnet. The coils at the other end are also energised, attracting the permanent magnet towards them. The stored spring force accelerates the magnet away from its lock position and the electromagnet boosts this acceleration.Balance of magnetic and spring forces clamp actuator without power.

Un-checked the actuator will be driven by the spring/electromagnet acceleration to a realm where the magnet circuit on the left hand end draws the permanent magnet into contact with the bobbin at that end. The spring is compressed during this action, absorbing actuator inertia and storing it as potential energy to be released next time the actuator is fired. This ensures a soft landing for the magnet, eliminating wear and giving long life.In the second stable position, the actuator is locked in place by the magnetic circuit formed by the permanent magnet and the steel case. Locking force of the actuator is the difference between the magnetic clamping force and the spring force trying to push it away, no power is required to maintain the locked position, so no heat is produced or power dissipated.BENEFITS OF BAT Zero power latching power is only required to engage and disengage the mechanism and then remains locked in position until a current is applied again. Fast action switching (c. 0.2 seconds loaded actuation) Integrated electronics eliminate the need for new vehicle/transmission controllers to be developed to provide the actuation. Inbuilt Health Checking monitor temperature, positional feedback, and current and automatically takes corrective action Quiet operation a fast, damped actuation ensures minimal noise pollution Scalability from micro to mini to macro applications, the BAT technology can easily be made to measure. Compact design small, simple design aids packaging and integration to existing systems or future solutions. Customisable available as a completely standalone package, with a remotely mounted control unit or just the actuator, the design can be tailored to each individual application

INTELLIGENT VALVE ACTUATION (IVA)IVA is a full authority, electro-magnetic, poppet-valve actuation system which can actuate inlet, exhaust or both inlet and exhaust valves on an internal combustion engine. Advanced, multi-stable, electronically controlled, BAT based actuators drive individual desmodromic valve trains for each valve. Energy recovery spring (ERS) assists to drive or slow the actuator when boost is required. IVA has 3 system operating modes that provide an unbeatable control range of valve lift, timing and period; irrespective of crank angle and almost independent of each other thus the mechanical link to the crank is not needed. The system is controlled via a Valve Control Unit (VCU) that operates considerably faster than conventional engine controllers used for ignition or fuel injection. A typical fuel or ignition ECU only has to calculate an output once every other revolution for each cylinder but IVA monitors the valve position up to 100 times per event, requiring a 100 ms computing cycle.MODES OF OPERATION1. Full Rotation ModeThe electronically controlled actuator rotates though a full 360 degrees. The actuator always starts from a stationary position. It initially builds up speed before the individual cam pair reaches the point where it begins to lift the follower. The desmodromic mechanism drives the valve all the way to full lift before continuing down the other side of the cam lobe and back to the valve closed position. The ERS spring assists in accelerating the actuator and in slowing it down again storing and then recycling energy and reducing the power required.

2. Oscillation ModeThe actuator does not rotate fully. It is driven to a controlled angle, part way around the cam profile. In this way the valve is driven to any lift required so long as it is less than the maximum value. The actuator rotational velocity is controlled so that it reaches zero at the point where the target lift is achieved. Then the actuator will be stationary for some moment but still working, applying a torque to accelerate the cam back in the other direction. The cam then returns back to the parked position, closing the valve as it goes. The actuator will stop, returning to its datum condition.3. Oscillation and Dwell ModeThe mode is very similar to the oscillation mode except that the target position is an actuator angle rather than a specific lift. The lift at this point is a function of the cam profile design and an appropriate value will be selected. As the mechanism approaches the target position both actuator velocity and acceleration are reduced to zero. The natural detent torque of the actuator maintains the valve at a fixed lift. This position is stable and can be maintained until the actuator controller decides to drive the cam back the way it came just as for oscillation mode, closing the valve and re-parking the actuator.

ADVANTAGES 12V Capability for full system Bi-stable (No current) Operation Bi-stable Variable Lift Energy efficiency Full speed range to 8000rpm & beyond (eqvlnt to 4000rpm of cam shaft) Multiple opening per cycle subject to 7 ms cycle time Advanced engine start strategies are possible Optimised Emissions Optimised fuel efficiency Optimised Performance Reduced idle speed Most effective engine braking Effective traction control 2-stroke/4-stroke capability and beyond Advanced Swirl Control Advanced turbo control Engine weight reduction and hence improved power to weight ratio Increased low-end torque which allows higher gearing Low power consumption..etc.DISADVATAGES Dependency on the electrical systems including battery and alternator Vulnerable in strong external magnetic fields.

CONCLUSIONThe Intelligent Valve Actuation System (IVA) is a highly potential valve-by-wire technology that provides independent control of valve lift, timing and period for all engine speed and load conditions. IVA can overcome the deficiencies of conventional and existing technology. It brings engine valve control into the digital age and frees it from the restrictions of the mechanical system in the control of the combustion process. IVA can also make the engine more environmental friendly due to its capabilities in optimizing the emissions. All these facets of IVA makes it a promising technology of the future.

REFERENCE Automotive Engineering international SAE Magazine, July 2013 edition. http://www.sae.org/mags/aei/12246/ http://articles.sae.org/12246/ www.camcon-automotive.com www.car-engineer.com/a-valve-by-wire-technology-for-a-full-valve-actuation-control/ www.automotivedesign.eu.com/automotive-design-news/valve-by-wire-technology-breakthrough-from-camcon/52047/ www.automotiveworld.com/news-releases/new-valve-by-wire-technology-removes-one-of-the-final-restrictions-on-combustion-design/