Citroen Xantia

Since 1993 of release

Repair and car operation

Systems of decrease in toxicity and release of the fulfilled gases

All petrol models are adapted for refuelling неэтилированным by fuel. Besides it, systems of their food are developed taking into account last rigid requirements to preservation of the environment and allow to lower effectively enough toxicity of the fulfilled gases let out in atmosphere. The standard complete set of all models includes ventilation system картера. The majority of petrol models are equipped catalytic by the converter and system of catching of fuel evaporations (EVAP) (see above in the present Chapter).

On all diesel models the strict control over structure of the fulfilled gases also is provided and the ventilation system картера is provided. On some models it is established каталитический the converter. Even more utter annihilation of toxic components is promoted by introduction on separate models of system recycling the fulfilled gases (EGR). On equipped with system of a turbo-supercharging cars EGR it can be used in steam by system of indemnification of changes of atmospheric pressure.

More low principles of functioning of separate systems and the devices which use promotes decrease in toxicity of the fulfilled gases are in more details described.

Petrol models

Ventilation system картера

The system allows to lower issue level in atmosphere containing in картерных gases of hydrocarbons. The engine block is executed tightly, breaking in it bypassing piston rings gases together with oil evaporations compulsorily are deduced from chambers of combustion from картера in the inlet pipeline, and destroyed in the course of normal functioning of the engine. Before to get to the inlet pipeline картерные gases are banished through a mesh oil separator.

At increase of depth of depression in the inlet pipeline (single turns, braking by the engine) картерные gases are exhausted from the engine. If depth of depression is low (an acceleration, movement with completely open throttle заслонкой), gases are pushed out at the expense of relative increase of pressure inside картера. If the engine is worn strongly out, pressure in it картере will be constantly raised (at the expense of more intensive blowing off of gases from chambers of combustion bypassing piston rings) that provides constant return of a part of a gas stream at any pressure in the inlet pipeline.

The Katalitichesky converter and l-probe

For the purpose of decrease in level of issue in atmosphere of toxic products of combustion in system of release of some models it is established каталитический the converter. Thus included in release system the oxygen gauge (l-probe) provides a feedback with ECU control systems of the engine. On the basis of the analysis of the information received from the gauge about maintenance level in the fulfilled gases of oxygen ECU carries out instant updating of structure of an air-fuel mix, constantly supporting optimum conditions for functioning каталитического the converter.
The l-probe is equipped by the built in electric heating element which functioning through the relay of the oxygen gauge carries out ECU control systems of the engine. The working tip of the gauge registers maintenance level in fulfilled gases О2 and functions effectively only at enough high working temperatures which maintenance provides a heating element. The gauge develops the pressure which amplitude is directly proportional to level of the maintenance of oxygen in the fulfilled gases. At injection in the engine of the reenriched air-fuel mix the oxygen maintenance in combustion products is insignificant enough, and the gauge develops a low-voltage signal. In process of pauperisation of a mix the amplitude of a signal developed by the gauge raises. To the fullest combustion of a mix with the minimum maintenance of toxic components in combustion products there corresponds a parity of the maintenance of gasoline to air 1 : 14.7, i.e. On one weight part of air one weight part of fuel should have. The given parity is called стехиометрическим as number. Near to the given point change of amplitude of a signal developed by the gauge occurs wide jumps, ECU thus immediately develops a command on corresponding updating of structure of an air-fuel mix at the expense of change of time of opening of injectors/atomizers.

System of catching of fuel evaporations (EVAP)

The given system allows to lower essentially issue level in atmosphere of not burnt down hydrocarbonic connections. The system is established on the models equipped catalytic with the converter. The cover of a jellied mouth of a fuel tank is closed tightly. Behind a radiator, on the left wall of an impellent compartment the coal adsorber accumulating in fuel evaporations, allocated in a tank is established during car parking. The purge of an adsorber after engine start is carried out at the command of ECU control systems. The special valve, opening, provides a conclusion of the fuel which has accumulated in an adsorber in an inlet path, whence it arrives in chambers of combustion and is burnt out in the course of normal functioning of the engine.

In order to avoid infringement of stabilisation of turns of idling and for protection каталитического the converter from effect of influence of the reenriched mix the valve of a purge of a coal adsorber opens only after the engine will not get warm to normal working temperature and it will not appear under loading. Further ECU develops commands on periodic inclusions-deenergizings of the electromagnetic valve. In the course of such modulations also there is a conclusion of the fuel which has accumulated in an adsorber in an inlet path of the engine.

Release system

The information on functioning of system of release is presented in section System of release of the fulfilled gases - the general information, removal and installation.

Diesel models

Ventilation system картера

The subsection "Petrol models - ventilation systems картера" see above.

The Katalitichesky converter

The Katalitichesky converter enters into a complete set of separate models and represents placed in the metal container мелкоячеистую a grid with inclusions каталитических metals. Through a grid the fulfilled gases of the engine are banished разогретые to a heat. The catalyst promotes the accelerated oxidation of such connections as монооксид carbon (WITH), not up to the end burnt down hydrocarbonic connections, soot, etc., allowing it is essential to lower toxicity of an exhaust.

System recycling the fulfilled gases (EGR)

The system provides рециркуляцию parts of the fulfilled gases in an inlet path of the engine and their inclusion in process of burning of an air-fuel mix. Maintenance level in products of combustion toxic оксидов nitrogen (NOx) thus decreases.

The volume recycling is supervised by the electronic block of management of system.

System function chart recycling the fulfilled gases (EGR)

The system functions at temperature of a cooling liquid 60°С and loading not above adjusting value of the switch (2) on ТНВД. The management block opens the electromagnetic valve (7) supervising functioning of all system. Created located on the camshaft end the vacuum pump depression forces to work valve EGR (5) established in a final collector, and this operation occurs only at the open valve of management (7).

In addition, the inlet pipeline is equipped lamellar заслонкой, allowing to correct a parity of structure of a mix of the fulfilled gases submitted to an inlet path with air soaked up in the engine. Besides, заслонка prevents giving in the pipeline of the fulfilled gases at working on single turns or under low loading the engine when the valve in a final collector is completely open.
The block of management of system develops commands on the basis of the analysis of the information arriving on it about temperature of a cooling liquid and frequency of rotation of the engine (gauge VMT).

System of indemnification of changes of atmospheric pressure

The system allows to suspend updating of an advancing of the moment of injection for the purpose of decrease in level of smoke content at certain parities of temperature of the engine and atmospheric pressure. The system functions together with preheat system (the preheat System see - diesel models), using the information arriving from the gauge of temperature of the cooling liquid and the gauge-switch of atmospheric pressure.

Release system

The information on functioning of system of release is presented in section System of release of the fulfilled gases - the general information, removal and installation.