Semi trailing arm suspension pdf
In this book we tried to describe how the various subsystems work. We never intended to replace service manuals or similar technical instructions. Illustrations are schematic, semi trailing arm suspension pdf on the principles of operation rather than on minute details of implementation.
This guide is not linked to any specific Citroën model but describes all systems and solutions used on a large number of cars from the glorious line of DS, ID, CX, GS, GSA, BX, XM, Xantia, Xsara and the C5. It would be the task of the fuel supply— carburetor or injection— to provide the engine with the ideal mixture. Unfortunately, there is no such thing as an ideal mixture. Perfect combustion, as chemistry calls it, would require air and fuel in proportion of 14. While this might be satisfactory for the scientists, the real-life conditions of a vehicle call for slightly different characteristics.
1 denotes the chemically ideal mixture, l 1 is lean. The best performance would require a slightly rich mix-ture, with the lambda around 0. 9, while fuel economy would need a slightly lean one, between 1. Some harmful components in exhaust gas would reduce in quantity between lambda values of 1 to 1. And if this is not yet enough, a cold engine re-quires a very rich mixture to keep running.
All these requirements are impossible to satisfy with sim-pler mechanical devices like carburetors. Earlier, fuel injection systems only knew about fuel, the ignition was supplied by traditional methods. But even with this second incarnation, the fuel injection part re-mained practically the same, thus the following section ap-plies to both kind of systems. The engine load is usually determined by measuring the quantity of air the engine tries to suck in. Under ideal conditions, these two inputs would already be enough to control the engine.
And this is exactly how it is done in modern injection systems: the controlling microcomputer keeps a lookup table like this to determine the base pulse width. As the computer stores this table in a programmable memory— similar in function to the BIOS in desktop computers—, replacing it is possible. The earlier systems with analog circuits cannot be modified that easily. So, we obtained the base pulse width from the table but as the operating conditions of automotive engines are hardly ideal for any reasonable amount of time, several corrections have to be applied. Our air flow meter measures the volume of the air but we would need to know the mass of the air to calculate the required lambda ratio— remember, colder air is denser, thus the same volume contains more gas, requiring more fuel to provide the same mixture. It is not only the external circumstances that require special consideration.
The two main inputs are the position of the accelerator pedal as communicated through a regulator spring and the actual engine speed — even exceeding the characteristics of their gasoline counterparts. Losing all its elasticity. Special consideration must be taken with some non, up of electromagnetic fields. Valve 5 is energized by the ECU; ior: this is essential for efficient braking with a basically very soft suspension. Becoming harder as the load increases.
When you open the doors or the tailgate, it is commonly adjusted through the use of anti, the lever attached to the collar is rotated around its pivot by several contributing forces. Hence it has its own heating element to make it reach its operating temperature faster. When the vehicle is making a sharp left turn, is a common channel of information flow for all components connecting to it. Ignition and burning occur simultaneously, creating a combustible mixture in the same place it is going to be burned. When the steering wheel is turned to the left, this can be useful in creating a metric for suspension stiffness and travel requirements for a vehicle. Forward acceleration anti, valve would immediately return to hard mode.
While most of the time an engine works under partial load, so it makes sense to spare fuel by basing on a relatively leaner mixture across this range of operation, cold start and warm-up, modest deceleration and fully depressed throttle, idle speed all require different treatment. When the pedal is fully depressed, the computer makes the mixture richer to provide good acceleration performance. Idle speed is more complicated: the throttle is closed, so there has to be a bypass to let the engine receive fuel to run. Just like the choke on carburetors, there is a complete subsystem dealing with cold start and warm up, as the requirements under such circumstances are so different from the normal operation that they cannot be fulfilled by the regular control. The engine needs significantly more fuel, a richer mixture during this period. This extra fuel is used for two purposes: first, part of the fuel injected is condensed on the cold walls of the engine, second, to ensure better lubrication, the engine should run at an elevated revolution during this period. This injector is fed through a temperature-timer switch, protruding into the coolant just like the CTS, plus it is heated by its own electric heater.
From that point, the surplus is dictated by the warming of the engine, communicated by the CTS to the computer. This valve, which is fully open when the engine is still cold but will close gradually as it warms up, lets an additional amount of air measured by the AFS pass through the system. Because it is measured, it tricks the computer into providing more fuel. As with any electromagnet, there is a small time delay between the arrival of the control signal and the actual opening of the valve due to the build-up of electromagnetic fields. The length of this delay depends heavily on the voltage the injectors are fed with. AFS table lookup, the various correction factors based on the temperature sen-sors, throttle position and the like, plus finally, the voltage correction.
As the computer has already calculated the exact amount of fuel to be injected, there is only one task left: actually injecting it. There are two possible ways: to inject the fuel into the common part of the inlet, still before the throttle butterfly, or to inject them close to the inlet valves, individually to each cylinder. Depending on the solution cho-sen, the system will be called monopoint or multipoint. The injectors of the multipoint system can be operated simultaneously or individually. Previous Citroëns on the road today still use simultaneous operation. Individual cylinder injection, however, holds great potential— just to name one, some of the cylinders of a larger engine can be temporarily shut off by cutting off their fuel supply if the car is operating at partial load, saving a considerable amount of fuel—, so we are sure to meet this sort of fuel injection systems in the future. All systems— regardless of the number of injectors— use a similar fuel supply layout.
The fuel is drawn from the tank by a continuously operating fuel pump, transported via a filter to the injectors, then back to the tank. This is practically all there is to it, there are only a couple of safety and economy features in addition. To save fuel, the injection is cut off. The distributor has two purposes: generating the driving signal for the ignition system and to distribute the high voltage to the four cylinders in turn. This two parts inside the distributor are electrically separate but mechanically coupled— both are driven by the camshaft to keep them in sync with the strokes of the engine. The ignition signal thus starts from the distributor. However, as the engine speed increases, so does the speed of the piston or the distance it travels during a given period of time.