Service, the device and Folksvagen Sharan repair - Section 2. Engine VR6

Fig. 15. The schematic image of three types of six-cylinder engines used in motor industry: a — the V-shaped 6-cylinder engine; b — engine VR6; c — рядный the engine

In this section the 6-cylinder engine under name VR6, having considerable differences from the usual design concept of engines "Volkswagen" or �Audi� is considered established for the first time in 1991 on car Volkswagen Passat. The engine in firm "Volkswagen" has received the name �AAA�, but it is more known as VR6. Its six cylinders are located V-shapedly at an angle 15 � unlike the traditional V-shaped engines having a corner 60 � or 90 �. Engine VR6 became so compact that has allowed to cover both of some cylinders with one general head, unlike the usual V-shaped engine. As a result engine VR6 has turned out less on length, than рядный, and it is less on width, than the usual V-shaped 6-cylinder engine. On (fig. 15) three types of 6-cylinder engines are schematically represented, and it is visible, on the basis of what engine VR6 has been developed.

At such acute angle of an arrangement of cylinders (15 �) problems with non-uniform rotation of a cranked shaft of engine VR6 do not arise, it works as exactly, as well as рядный. The engine has two camshafts which operate twelve vertically located valves (on 2 on the cylinder). Both camshafts of the top arrangement are placed in an aluminium head of the block of cylinders. The camshaft 1, 3 and 5th cylinders is established on four bearings, and a camshaft for 2, 4 and 6th cylinders – on three bearings. The surface of a head of the block of cylinders in an installation site of a sealing lining is ground. Combustion chambers are made at an angle to correspond to a V-shaped design of the engine.

Fig. 16. A drive of camshafts of engine VR6

The shod cranked shaft rotates on seven radical bearings and is supplied by twelve counterbalances and one гасителем крутильных fluctuations that allows it to rotate without radial palpation. Shatunnye necks of a cranked shaft for each number of cylinders are displaced on 22 �. Rather long rods (164 mm) connect a cranked shaft to lungs on weight the pistons having two компрессионных piston ring and one маслоотражательное ring. At the majority of the engines developed for the last few years by firm "Volkswagen" the camshaft drive is carried out by a gear belt. However in engine VR6 the drive of two camshafts is carried out by one general двухрядной a chain (fig. 16) which is set in motion from the asterisk of an intermediate shaft connected by a single-row chain with a gear wheel of a cranked shaft.

Two натяжителя with boots (unattended) provide a demanded tension of chains, and тарельчатые self-regulated hydraulic pushers actuate valves. The design приводного the mechanism has allowed to make more compact a head of the block of cylinders.

The special attention at designing addressed on a supply of an air-fuel mix as in one head of the block of cylinders by a gas mixture two numbers of cylinders should be provided. The engine has been designed with a cross-section purge — inlet channels settle down on one, and final channels on other party, and the gas mixture in it should get simultaneously to 3 cylinders on each party of the engine, and inlet pipes should be equal length.

For the decision of this problem the air inlet case have established on the top part of a head of the block of cylinders from which to each cylinder there is a separate inlet pipe. Three pipes go directly to cylinders in a forward part of the engine, and other three pipes pass over the engine and incorporate to cylinders on the back party of the engine. Each inlet pipe is supplied by an atomizer, and spark plugs are located on an outer side of cylinders.

In spite of the fact that designers tried to make inlet pipes how much it is probably equal on length, all the same there is a difference in speed of compression at two numbers of cylinders. However this difference is brought to nothing, thanks to system of injection of fuel made by firm "Bosch" �Motronic� which regulates an operating mode of injection and ignition depending on loading on the engine and conditions of its work. The electronic block of management (ЭБУ) defines quantity of fuel injected into cylinders and an exact advancing of ignition, thanks to the information received in the form of electric signals from gauges, namely: the data about temperature, position and frequency of rotation of a cranked shaft, the expense of air arriving in the engine, compression degree, advancing coal. The injection system �Motronic� is supplied by the detonation gauge in everyone to a number of cylinders that allows ЭБУ to co-ordinate precisely management of injection and ignition for cylinders in everyone to a number and accordingly to synchronise the compression moments.

Fig. 17. Engine VR6 General view in gathering

Today for �Volkswagen� is almost a commonplace to establish on the cars neutralizer and the gauge of oxygen which provide a feedback. The gauge traces concentration of oxygen in the fulfilled gases, and ЭБУ on its signals supports such parity air/fuel which provides the most effective work of neutralizer. Engine VR6 general view in gathering is presented on (fig. 17).

The prevention

To provide the engine under other normal conditions with a good air-fuel mix it should be used неэтилированный gasoline with октановым number not more low 95.