5.14.1. Features of a design
Elements of the following systems are a part of a power supply system:
– the supply of fuel including the fuel tank, an electrogasoline pump, the fuel filter, the fuel pressure regulator, pipelines and a fuel stage with nozzles;
– airgiving which enter the air filter, throttle knot, the idling regulator;
– catching of vapors of fuel, consisting of an adsorber, the valve of a purge of an adsorber and connecting pipelines.
The system of catching of vapors of fuel is described in separate subsection (see. "System of catching of vapors of fuel"), as it serves only for implementation of ecological requirements for decrease in toxicity.
Functional purpose of a fuel supply system — ensuring giving of necessary amount of fuel in the engine on all operating modes. The engine is equipped with an electronic control system with the distributed fuel injection. In system of the distributed injection of function of a smeseobrazovaniye and dispensing of supply of fuel-air mix in cylinders of the engine are divided: air moves system of the airgiving consisting of throttle knot and the regulator of idling, and the amount of fuel, necessary at every moment of operation of the engine, is injected by nozzles into an inlet pipe. Such way of management gives the chance to provide optimum composition of gas mixture at each concrete moment of operation of the engine that allows to receive the maximum power at minimum possible fuel consumption and low toxicity of the fulfilled gases. The electronic block which is continuously controlling by means of the corresponding sensors engine loading, speed of the movement of the car, a thermal condition of the engine, an optimality of process of combustion in engine cylinders operates system of injection of fuel (and system of ignition too).
The system of catching of vapors of fuel prevents leaving the system of food in the atmosphere of the vapors of fuel which are adversely influencing environment ecology.
In system the method of absorption of vapors is applied by a coal adsorber. It is established on the basis of a body on the right behind and connected by pipelines to the fuel tank and an inlet pipe. On the arm established on an inlet pipe the electromagnetic valve of a purge of an adsorber which on signals of the control unit of the engine switches system operating modes is located.
Fuel vapors from the fuel tank on the pipeline constantly are taken away and collect in the adsorber filled with absorbent carbon (adsorbent). During the operation of the engine there is a regeneration (restoration) of adsorbent an adsorber purge the fresh air coming to system under the influence of the depression transferred on the pipeline from an inlet pipe to an adsorber cavity when opening the valve. The size of opening of the valve and consequently, and intensity of a purge of an adsorber depend on an angle of rotation of a butterfly valve and are defined by depression which arises in a cavity of an inlet pipe of the working engine.
Fuel vapors from an adsorber on the pipeline come to an inlet pipe of the engine and burn down in cylinders.
Malfunctions of system of catching of vapors of fuel involve instability of idling, an engine stop, the increased toxicity of the fulfilled gases and deterioration in road performance of the car.
Fig. 5.21. Scheme of a contour of management of composition of fuel-air mix: 1 – the sensor of concentration of oxygen in the fulfilled gases (lambda probe); 2 – final collector; 3 – engine; 4 – nozzle; 5 – control unit of the engine; 6 – catalytic converter of the fulfilled gases
The main sensor for ensuring optimum process of combustion is the sensor of concentration of oxygen in the fulfilled gases (lambda probe). It is established in a final collector of the engine and together with the electronic block and nozzles forms a contour of correction of composition of the fuel-air mix given to the engine (fig. 5.21). The control unit of the engine determines amount of not burned down oxygen in the fulfilled gases by sensor signals and respectively estimates an optimality of composition of the fuel-air mix coming to engine cylinders in each timepoint. Having recorded a structure deviation from optimum 1:14 (respectively fuel and air), the catalytic converter of the fulfilled gases ensuring the most effective functioning, the control unit by means of nozzles changes composition of mix. As a result the contour of management of composition of fuel-air mix is closed.
The fuel tank welded, stamped, is installed under a body floor in its back part and attached by four bolts. In order that vapors of fuel did not get to the atmosphere, the tank is connected by the pipeline to an adsorber. In a flange opening in the top part of a tank the electric fuel pump is installed. From the pump fuel moves in the fuel filter installed in podkapotny space on a front board and from there comes to the fuel stage of the engine fixed on an inlet pipe. From a fuel stage fuel is injected by nozzles into an inlet pipe.
Fuel-supply lines of a power supply system represent the tubes connecting among themselves various elements of system.
It is forbidden to replace steel pipelines with hoses, copper or aluminum tubes as only steel pipelines meet working conditions at the elevated pressure and vibration.
Hoses of a power supply system are made on special technology of maslobenzostoyky materials. Application of the hoses differing on a design from recommended can lead to power supply system failure, and in certain cases and to the fire.
In connections of pipelines with elements of a power supply system apply round sealing rings. Use of consolidations of other design is forbidden
The module of the fuel pump includes the electric pump and the sensor of the index of level of fuel.
The module of the fuel pump provides supply of fuel and is installed in the fuel tank that reduces a possibility of formation of steam traffic jams as fuel moves under pressure, but not under the influence of depression.
The submersible fuel pump, rotor type, with the electric drive. The pump of a non-demountable design is not subject to repair, at failure it should be replaced.
The fuel filter of thin cleaning — full-line, is fixed in the arm established on a front board in podkapotny space. The filter is non-demountable, consists of the steel case with the paper filtering element.
The fuel stage
of 2 (fig. 5.22)
represents a cast hollow detail with openings for installation of nozzles 3, with a flange for installation of the regulator of pressure of fuel and with the union for accession of a fuel-supply line of high pressure. Nozzles are condensed in openings of a stage and in nests of an inlet pipe with rubber rings 4 and fixed by spring clamps 1. On a stage flange two screws attached the regulator 5 of pressure of fuel to which the fuel discharge pipeline is attached. The stage with nozzles and the regulator is assembled inserted by shafts of nozzles into openings of an inlet pipe and fixed by two bolts.
|Fig. 5.22. Fuel stage: 1 – nozzle clamp; 2 – stage; 3 – nozzle; 4 – sealing ring of a nozzle; 5 – fuel pressure regulator
Nozzles (fig. 5.23)
are attached to a stage from which to them fuel moves, and the sprays enter openings of an inlet pipe. In openings of a stage and an inlet pipe of a nozzle are condensed with rubber sealing rings 1 and 3. The nozzle is intended for the dosed injection of fuel in the cylinder of the engine and represents the high-precision electromechanical valve. Fuel under pressure arrives from a stage on channels in the nozzle case to the locking valve. The spring draws in a needle of the locking valve to a conical opening of a plate of a spray, holding the valve in a closed position. Tension given from the control unit of the engine through shtekerny conclusions 2 on a nozzle electromagnet winding creates in it the magnetic field involving the core together with a needle of the locking valve in an electromagnet. The conical ring opening in a plate of a spray opens, and fuel is injected via the spray case diffuser into the inlet channel of a head of the block of cylinders and further into the engine cylinder. After the termination of receipt of an electric impulse the spring returns the core and a needle of the locking valve in an initial state — the valve is locked. The amount of fuel injected by a nozzle depends on duration of an electric impulse.
|Fig. 5.23. Nozzle of system of injection of fuel: 1 – lower sealing ring; 2 – shtekerny conclusions of a winding of an electromagnet; 3 – top sealing ring
The fuel pressure regulator installed on a fuel stage supports the constant pressure of fuel in the central channel of a stage on all power setting. Regulation of pressure of the fuel given to nozzles is based on the principle of tracking value of pressure difference in a stage and an inlet pipe which under any conditions has to make not less than 300 kPa (3,0 kgfs/cm2). Giving of the electric fuel pump is more, than it is necessary for ensuring operability of system. Therefore during the operation of the engine by means of pressure regulator a part of fuel constantly merges via the return pipeline in the fuel tank. Depending on depression in an inlet pipe the regulator of pressure reduces or increases discharge of excessive fuel, supporting constant pressure in a stage.
The regulator of pressure represents the closed cavity divided by a diaphragm into vacuum and fuel chambers.
The vacuum chamber is reported through a vacuum hose with an inlet pipe of the engine, fuel — via the channel in the regulator case with a cavity of a fuel stage. In operating time of the engine under the influence of a spring the valve of the regulator is closed if pressure difference in an inlet pipe and a fuel stage no more than 0,3 MPas. There is no return discharge of fuel — pressure in a fuel-supply line begins to increase. At pressure difference over 300 kPa (3,0 kgfs/cm2) the diaphragm of the regulator caves in and between the valve and its saddle the gap through which to other canal of the regulator connected to the drain pipeline excessive fuel merges is formed — pressure decreases. At increase in loading of the engine working at big opening of a butterfly valve, fuel consumption increases and pressure in a fuel stage falls. Along with it depression in an inlet pipe decreases. The spring presses pressure regulator valve to a saddle, the discharge of fuel in the fuel tank stops — pressure increases. These processes repeat continuously therefore in a fuel stage constant pressure is supported.
The air filter is installed in the right forward part of a motor compartment on an engine mudguard. The lower branch pipe of the filter is inserted into an air duct of the muffler of noise of the admission established under the right forward wing.
The filter is connected by the rubber corrugated airbringing sleeve to throttle knot.
The filtering element of the air filter paper, flat, with a big area of the filtering surface.
The throttle knot represents the elementary control device and serves for change of amount of the main air given to inlet system of the engine. It is established on an entrance flange of an inlet pipe. The formed rubber sleeve fixed by a collar and connecting throttle knot to the air filter is put on an entrance branch pipe of throttle knot.
In the case of throttle knot the opening for a supply of additional air to the idling regulator is executed.
|Fig. 5.24. Throttle knot: 1 – sensor of provision of a butterfly valve; 2 – idling regulator; 3 – butterfly valve; 4 – sector of the drive of a butterfly valve; 5 – case of throttle knot
The gate 3 turning on an axis is installed in the case 5 (fig. 5.24)
. On one end of an axis the sensor of 1 provision of a butterfly valve of a control system of the engine, on another — sector 4 to which the cable of the drive of a butterfly valve is attached is installed. On the case 5 the regulator 2 idlings dosing an air stream at the closed butterfly valve is fixed.
In the air filter there is no device of seasonal adjustment therefore the throttle knot is equipped with the system of heating preventing frosting of a butterfly valve in cold season and connected to the engine cooling system hoses.
In use the throttle knot does not demand service and adjustment, watch only a condition of rubber consolidations to avoid an air suction.
The regulator of idling supports the set frequency of rotation of idling of the engine at completely closed butterfly valve during its start-up, warming up and at change of loading at turning on of the service equipment.
The regulator changes amount of the additional air given to inlet system besides a butterfly valve and represents the electromechanical valve attached by two bolts to a flange of the case of throttle knot. The channels executed in a flange of throttle knot and a saddle of the valve of the regulator form system of supply of additional air, passing a butterfly valve.
Fig. 5.25. Idling regulator: 1 – valve; 2 – regulator case; 3 – stator winding; 4 – running screw; 5 – shtekerny conclusion of a winding of the stator; 6 – ball bearing; 7 – stator winding case; 8 – rotor; 9 – spring
The control unit of the engine, having processed signals from sensors, defines need of opening of the valve 1 (fig. 5.25) of the regulator and 3 stators of the regulator transfer impulses on a shtekerny conclusion of the 5th winding. At each operating impulse the rotor 8 turns on a certain corner, moving by means of the running screw 4 the valve 1 concerning a saddle. Additional air comes to an inlet pipe via channels in throttle knot. Defining depression in an inlet pipe of the engine, the control unit seeks to support him at the set level, periodically opening and closing the idling regulator valve. It gives the chance to provide giving of constant amount of additional air for maintenance of constant frequency of rotation of idling. Changing the size of opening and closing of the valve of the regulator, the control unit compensates the significant increase or reduction of amount of the given air caused by its suction through untight inlet system or, on the contrary, a contamination of the air filter.
Turning on of additional units causes the increase in loading of the engine which is followed by decrease in frequency of rotation of idling and change of depression in an inlet pipe that is also compensated by the control unit by means of the regulator.