6.5. Systems of release and decrease in toxicity of the fulfilled gases
System of release of OG
The system of production of the fulfilled gases consists of final collectors, reception pipes, catalytic converters, mufflers and an exhaust pipe.
Systems of decrease in toxicity of the fulfilled gases
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Components and the function chart of systems of release and decrease in toxicity of OG are presented on accompanying illustrations of the Sections Principle of Functioning of a Control System of Injection of Fuel and Power Supply System of the Diesel V6 Engine. |
The principle of functioning of a control system of the engine is constructed so that to receive the maximum return from the engine at the minimum fuel consumption and the maintenance of toxic components in OG. The system of catching of fuel evaporations (EVAP) installed on petrol engines prevents hit of the last of the fuel tank in the atmosphere.
Arrangement of components of the EVAP system
On petrol V6 engines also the system of admixture of air in OG (SAI) for the purpose of acceleration of a conclusion of not heated-up catalytic converter to operating level is used.
System of admixture of air in the fulfilled gases
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On all models also the system of ventilation of a case (PCV) is installed. Components of systems of decrease in toxicity of OG of the diesel engine and their arrangement are specified illustrations.
Components of systems of decrease in toxicity of OG of the diesel engine
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1 — the Back catalytic converter |
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On diesel engines the EGR system is used.
System of the operated ventilation of a case (PCV)
For elimination of leak of not burned down hydrocarbons in the atmosphere the engine is completely sealed. The gases and vapors of oil which are formed in a case move in the inlet pipeline and burn down in cylinders together with fuel.
Gases are removed from a case at the expense of pressure difference in a case and the inlet pipeline (pressure in a case is higher).
System of catching of fuel evaporations (EVAP)
The EVAP system is intended for decrease in emission in the atmosphere of not burned down hydrocarbons. The jellied mouth of the fuel tank is hermetically closed by a cover. In a coal adsorber the fuel vapors which are formed in a tank during the parking of the car gather and keep there until on a signal of the control unit the adsorber purge does not begin. During a purge of couple of fuel move via the purge valve in the inlet pipeline where they mix up with working mix and further burn down usually in combustion chambers.
For ensuring normal operation of the engine on single turns and during warming up the control unit holds the valve closed. Thus hit of not burned down fuel in the catalytic converter (is prevented at the raised idling turns mix of a pereobogashchen). After warming up of the engine the valve begins to open and be closed, regulating supply of vapors of fuel to the inlet highway.
Catalytic converter and lambda probes
For decrease in number of harmful emissions in the atmosphere three-functional catalytic converters are built in system of release. The control system of injection of fuel has feedback which included a lambda probes, OG which are constantly informing the control unit on structure. Depending on the obtained data, the control unit corrects quality of the mix given to combustion chambers and, thus, optimizes fuel combustion.
In a lambda probe, established behind catalytic converters, the heating element which is switched on by the control unit via the special relay is built in. The working surface a lambda probe is sensitive to change of content of oxygen in OG. Depending on its concentration the output tension of the sensor changes. If mix of a pereobogashchen (content of oxygen in the fulfilled gases very low), the lambda probe gives signals with low voltage. Tension increases in process of impoverishment of mix and increase in content of oxygen in gases. Most effectively the converter works at optimum composition of gas mixture (14.7 parts of air for 1 part of fuel). At optimum concentration of oxygen in OG there is a jump in tension on a lambda probe. This jump is a reference point for the control unit at correction of quality of mix.
System of admixture of air in OG (SAI)
This system is intended for acceleration of warming up of catalytic converters and, therefore, their conclusion in an operating mode. For warming up heat generated during reaction contained in the given oxygen air with the fulfilled gases (CO and HC) is used. Air moves in final collectors the special pump SAI which turns on if temperature of the soaked-up air and OZh makes from-9 to 30 hail, battery tension no more than 16 V, and the stream of the soaked-up air does not exceed 700 mg / a combustion step. Besides, before operation of the pump the engine has to make from 40 to 75 full cycles, depending on OZh temperature. For the purpose of prevention of sudden jump of toxicity of OG at switching off of the SAI system, the pump SAI continues to work during 15 cycles of the engine after the termination of need for air admixture. During the work of the SAI system for compensation of additional air the volume of injectable fuel also increases.
For prevention of leakage of OG through the SAI system the control valve which is closed at switching off of the pump SAI is installed in each block of cylinders.
System of recirculation of OG (EGR)
This system allows to reduce the number of NO x in the fulfilled gases. For this purpose a small part of OG moves in the inlet pipeline via the special valve. The valve of system of recirculation is controlled by the control unit.