Table of Contents VALVETRONIC Subject Page VALVETRONIC.3 Introduction.3 Load Control .5 Function.6 Eccentric Shaft Sensor .9 VVT Motor and Relay.9 Phasing .10 MIN/MAX Stops.10 VALVETRONIC III .11 Phasing .11 Masking.11 Valve Lift Adjustment Overview .12 VALVETRONIC Servomotor .14 Function.14 Initial Print Date: 03/11 Revision Date: VALVETRONIC Model: ALL Production: ALL ■BIIBTHBS After completion of this module you will be able to: • Name the service functions for VALVETRONIC . • Explain how the VALVETRONIC system will function if faulted. Fail safe operation. • Explain the relationship between the EDK and the VALVETRONIC system. • Identify how the VALVETRONIC motor is powered using the appropriate SSP’ • Locate and identify the components used for VALVETRONIC operation. 2 VALVETRONIC VALVETRONIC Introduction With the introduction of the N52, the 6-cylinder engine incorporated the load control system based on the valve timing gear (VALVETRONIC II). The VALVETRONIC I sys¬ tem that was used on the 8 (N62) and 12 (N73) cylinder engines already achieved a sub¬ stantial increase in efficiency. BMW has further developed this concept with the VALVETRONIC II. The results of this further development are: • Increased engine dynamics • Increased efficiency • Improved emission values 3 VALVETRONIC These results underscore BMW specific standards. As an example of VALVETRONIC II, the N52 engine features the following optimizations which further enhances the Ultimate Driving Machine: • The top engine speed has been increased to 7,000 rpm. • The specific power output has been increased to 63.4 kW/l. • The specific engine torque is 100 Nm/I over a broad engine speed range. • Distinctly increased valve acceleration values and friction-optimized transmission elements result in an even more responsive engine. • CO emissions reduced. • The world's most stringent exhaust emission regulations are complied with. Valvetronic II - used on N52, N52KP and N51 4 VALVETRONIC Load Control Index Explanation Index Explanation OT Top dead center 4 Exhaust valve opens UT Bottom dead center 5 Firing point 1 Intake valve opens A Gain 2 Exhaust valve closes B Loss 3 Intake valve closes P Pressure The illustration on the left shows the conventional method with the slightly higher loss. The reduced loss can be clearly seen in the illustration on the right. The upper area represents the power gained from the combustion process in the petrol engine. The lower area illustrates the loss in this process. The loss area can be equated to the charge cycle, relating to the amount of energy that must be applied in order to expel the combusted exhaust gasses from the cylinder and then to draw the fresh gasses again into the cylinder. 5 VALVETRONIC Apart from the full load setting, the intake of fresh gasses in a throttle valve controlled engine always takes place against the resistance offered by the throttle valve to the inflowing gasses. The throttle valve is virtually always fully opened during intake on the VALVETRONIC controlled engine. The load is controlled by the closing timing of the valve. Compared to the conventional engine where the load is controlled by the throttle valve, no vacuum occurs in the intake manifold. This means no energy is expended for the purpose of producing the vacuum. The improved efficiency is achieved by the lower power loss during the intake process. A minimum vacuum in the intake system is reguired for the crankcase ventilation and evaporative purge systems. The throttle valve is slightly adjusted for this purpose. Function The VALVETRONIC II consists of the fully variable valve lift control combined with the variable camshaft control (double VANOS). The valve lift is controlled only on the intake side while the camshaft (VANOS) is adjusted also on the exhaust side. The throttle-free load control is implemented by: • variable valve lift of the intake valve, • variable valve opening timing of the intake valve and • variable camshaft spread of the intake and exhaust camshaft. System optimization includes modification of the valve gear kinematics, a modified actu¬ ator motor and the adapted spread range of the VANOS units. The main differences are: • The plain bearing on the intermediate lever to the eccentric shaft has been replaced by a roller bearing, thus reducing the friction in the valve timing gear. • Guidance of the intermediate lever is more precise. Only one spring is now reguired to guide and hold the intermediate lever. • The moved mass of the valve timing gear has been reduced by 13%. • The lift range of the intake valves has been improved. The maximum lift has been increased to 9.9 mm but more importantly the minimum lift has been further reduced to 0.18 mm. The overall result is supported by further improvements in the intake manifold and exhaust dynamics. 6 VALVETRONIC Valvetronic II - used on N52, N52KP and N51 Index Explanation Index Explanation 1 Actuator 9 Exhaust Valve 2 Worm Shaft 10 Roller Cam Follower 3 Return Spring 11 HVA, exhaust 4 Gate Block 12 Roller Cam Follower, Intake 5 Intake Camshaft 13 Intermediate Lever 6 Ramp 14 Eccentric Shaft 7 HVA, Intake 15 Worm Gear 8 Intake Valve 16 Exhaust Camshaft 7 VALVETRONIC The fully variable valve lift control is activated with the aid of an actuator motor (1), an eccentric shaft (14), an intermediate lever (13), the return spring (3), the intake camshaft (5) and the roller cam follower (12). The actuator motor is installed in the cylinder head above the camshafts. It serves the purpose of adjusting the eccentric shaft. The worm shaft of the electric motor meshes with the worm gear mounted on the eccentric shaft. Following adjustment, the eccentric shaft does not have to be locked in position as the worm gear is sufficiently self-locking. The eccentric shaft adjusts the valve lift on the intake side. The intermediate lever varies the transmission ratio between the camshaft and the roller cam follower. The valve lift (9.9 mm) and opening time are at a maximum in the full load position. The valve lift (0.18 mm) and opening time are set to minimum in the idling position. The roller cam followers and the associated intermediate levers are divided into four classes. A corresponding code number is punched on the components. They always have the same class per pair. Assignment of the roller cam followers and the intermediate levers at the production plant ensures that the cylinders are uniformly charged even at the minimum valve lift of 0.18 mm. Valvetronic II at minimum valve lift Valvetronic II at maximum valve lift 0.18mm 9.9mm 8 VALVETRONIC Eccentric Shaft Sensor The eccentric shaft sensor (3) signals the position of the shaft back to the ECM. This sensor operates based on the magnetoresistive principle: A ferromagnetic conduc¬ tor changes its resistance when the applied magnetic field changes its position. For this purpose, a magnetic wheel (1) that contains a permanent magnet is mounted on the eccentric shaft. As the shaft rotates, the magnetic field lines of the magnet intersect the magnetically conductive material in the sensor. The resulting change in resistance is used as a correcting variable for the signal for the engine control unit. The magnetic wheel must be secured on the eccentric shaft by means of a non-mag- netic screw (2) otherwise the sensor will not function. VVT Motor and Relay The VVT motor is controlled directly by the ECM. The motor receives power from a relay located in the E-Box. 2 6 XMN JCK7 40 HT Ilf * y\ WTr*jy l»_WTS 10 0* ActMttf. or at* ■ *j gear ABOOD 9 VALVETRONIC Phasing The new VALVETRONIC II, is a very fast and exact engine control system. So-called phasing is implemented to assist adjustment in the lower valve lift range. The intake valves of a cylinder are opened synchronously up to a lift of 0.2 mm. Valve 1 then begins to lead (advance). Therefore, valve 2 opens with a slight delay behind valve 1 and catches up to valve 1 again at a lift of approximately 6 mm. From here on they open synchronously again. This opening characteristic has a favorable effect on the inflow of gasses into the cylin¬ der. By keeping the opening cross section of the intake valves small this results in a dis¬ tinctly higher flow rate at a constant intake volume. In connection with the geometry in the upper area of the combustion chamber, this higher flow rate is used to mix the air/fuel mixture more effectively. This phasing eliminates the need for the turbulence ports used on the previous genera¬ tion six-cylinder engines. The phasing feature of the Valvetronic creates the necessary turbulence (swirl) in the combustion chamber. MIN/MAX Stops A stop routine can be implemented between the mechanical stops in order to detect the positions of the mechanical stops. For this purpose, the eccentric shaft is adjusted from zero lift to full lift. The stop routine is executed only when the motor electronics deter¬ mines implausible values during the engine start procedure. This routine can also be initiated by the diagnosis systems. Eccentric Shaft - MIN Stop Eccentric Shaft - MAX Stop 10 VALVETRONIC VALVETRONIC III The main differences between VALVETRONIC III and VALVETRONIC II are in the arrangement of the VALVETRONIC servomotor and the VALVETRONIC sensor. As in VALVETRONIC II, the turbulence level is increased at the end of the compression cycle for the purpose of optimizing the mixture formation with the use of phasing and masking measures. This movement of the cylinder charge improves the combustion during par¬ tial load operation and in catalytic converter heating mode. The guench areas also con¬ tribute to mixture formation. Phasing Phasing results in a lift difference between both intake valves of up to 1.8 mm in the lower partial load range. Conseguently, the flow of fresh air is distributed asymmetrically. Index Explanation 1 Valve Opening (mm) 2 Maximum Valve Opening (mm) 3 Load(%) 4 Intake Valve 2 5 Intake Valve 1 6 Minimum Valve Opening (mm) Masking Masking refers to the design of the valve seats. This machining ensures that the incom¬ ing fresh air is aligned in such a way as to give rise to the reguired cylinder charge movement. The advantage of this measure is that the combustion retardation is reduced by approximately 10° of crankshaft rotation. The combustion process takes place faster and a larger valve overlap can be achieved, thus considerably reducing NOx emissions. 11 VALVETRONIC Valve Lift Adjustment Overview As can be seen from the following graphic, the installation location of the servomotor has changed with VALVETRONIC III. Another new feature is that the eccentric shaft sensor is no longer mounted on the eccentric shaft but has been integrated into the servomo¬ tor. N55, valve lift adjustment Front View I Viewed from the | exhaust side Index Explanation 1 Valvetronic servomotor 2 Oil spray nozzle 3 Eccentric shaft 4 Eccentric shaft minimum stop 5 Eccentric shaft maximum stop 12 VALVETRONIC The VALVETRONIC III servomotor contains a sensor for determining the position of the motor and the eccentric shaft. The servomotor is lubricated with engine oil by means of an oil spray nozzle (1) aimed directly at the worm drive and the eccentric shaft mecha¬ nism. N55, design of valve lift adjustment 200 milliseconds. The Valvetronic servomotor is actuated by a pulse width modulated signal. The duty cycle is between 5% and 98%. Index Explanation Index Explanation 1 Socket 6 Rotor with four magnets 2 Worm shaft 7 Sensor 3 Needle bearing 8 Stator 4 Bearing cover 9 Housing 5 Magnetic sensor wheel 10 Bearing 14 VALVETRONIC The following graphic shows the design of the cylinder head on the N55 engine with Valvetronic III and direct fuel injection. N55, overview of valvetrain Notice the hollow, lightweight design of the camshafts (7) and the blow-by passages leading into the intake ports (15). 16 VALVETRONIC @ @ © ® S' (°°) 0 Index Explanation 1 VANOS unit, intake camshaft 2 VANOS unit, exhaust camshaft 3 Injector well 4 Spark plug well 5 Camshaft housing 6 Valvetronic servomotor 7 Inlet camshaft 8 Torsion spring 9 Gate 10 Eccentric shaft 11 Intermediate lever 12 Roller lever tappet 13 Valve head 14 Oil spray nozzle 15 Passages for introducing blow-by gas into the intake ports 17 VALVETRONIC