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Distribution systems

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Distribution systems

  1. 1. distribution systems Introduction This paper intends to explain the operation of the variable distribution of BMW (VANOS). To understand this article you must first have an inkling of operating a multi-valve engine (with dual overhead camshafts) of the basic components and how they interrelate. I refer primarily to the crankshaft, connecting rods, pistons, chain / timing belts, camshafts and valves. Without such prior knowledge will be difficult to understand what you explain. The idea The set of pieces of the "distribution" is responsible for moving the valves in sync with the crank to open and close at the right time.In this variable valve timing engines without synchronism is fixed, by that I mean that the valves always open and close at the moment with respect to the position of the piston, where the piston reaches a certain position, the valve opens, always happens the other, the valve closes, no matter what rpm take the engine, always occurs at the same time. The point is that for each r.p.m. Engine is an optimal time of opening / closing of valves, an optimal standard, an optimum opening time ... This means that if the distribution is fixed it only optimizes the synchronized pistons and valves for a rpm point, and out of there we have a performance could be improved. The definition of serious VANOS, variable valve timing system for BMW which is responsible for changing the times of opening / closing the valves with respect to the position of the piston according to rpm engine. What it does is sync continuously optimize for better performance at all times. Its operation is based on the camshaft and the distribution chain are not linked directly, but there is an intermediate piece which is responsible for changing the relative position of the camshaft with respect to the sprocket on the chain passes . Honda VTEC System Acronym for Variable Valve Timing and Lift Electronic Control System. Honda presented in 1989 a system for varying the time of
  2. 2. distribution, in which the camshaft is not twisting. Not only regulates the opening phase, but also time and the same section. The objective of this measure are laws designed to measure the opening of the valves for different speed regimes. For a number of revolutions average, shorter opening times and a lower valve lift raise the gas velocity and thus also the filling and the torque in this range. For a higher speed number, the longer opening times and a larger valve lift intensify engine breathing, which in turn has an effect on power. The method by which this effect can be achieved, requires up to 4 valves per cylinder, 6 and 6 rocker cam lever. External cams, which are assigned directly to the valves, carry profiles and cam soft core has the longer delivery times and running bigger cam. At low rpm, just outside the cams are active, while the central cam is driven, as it were somehow empty, ie has no effect on the valve rocker lever of power. An additional spring prevents the loss of the contact between the cam and the rocker lever. There are some pins that can be moved hydraulically, and that between 5000 and 6000 rpmmake a mechanical connection between the rocker lever 3. Since that time the largest central cam which marks the opening of the valve. Delivery pressure required to move the circuit provides the engine lubricating oil. For the coupling of the rocker lever works well, it is necessary that the base circle cams are all equal, so that when the valves are closed accommodation and the pins are aligned. Honda has demonstrated the ability of system performance VTEC (DOHC) having two camshafts located at the top Summarizing the variable distribution system employed by Honda in cars is based on third cam in each cylinder which comes into operation at high rpm. The swing of the cam does not work at low revs, while at speed, oil pressure moves a rod between other camshaft rockers and central cam, leaving the whole ensemble together. At this point the rockers are opened by the higher profile cam (the middle) and increasing the valve lift and the moment of opening and closing. When the engine reduces the engine speed picks up the stem and the rocker panel is loose. The profile is now active external cam. This system is coupled to the intake and exhaust valves in the engine with twin overhead camshafts (DOHC) and only the intake valves of an engine camshaft (SOHC). Depending on the locking pins or bolts are available in the following states of operation. State 1: Under the 2500 rpm and the engine at low load, the three pins
  3. 3. are unlocked so that arms can rotate relative to each other.The left over is supported by a machined ring on the camshaft, so that the height of the corresponding valve is void, remaining closed. The engine then will be running in either 12 valves (3 valves per cylinder). The intermediate swing not be located not operate any valves. The swing to the right is driven by the cam profile smoothing, individual valve actuation, which results in a distribution diagram of an engine itself elastic with a high combustion efficiency. State 2: When you have exceeded the 2500 r.p.m. or accelerate, the bolt is inserted higher pressure and isolation, with the rocker ends are forced together. Thus the two intake valves are driven by the milder cam profile, so running the engine 16 valves. The engine operates in this state from around 2500 rpm to 6000. State 3: When the engine exceeds 6000 rpm pressure is sent to the lower bolt, making the three rocker solidarity, which become activated by the cam profile of greater height. This results in a higher power, typical of a fast motor.

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