10.3.1.7. Work of system of the central injection of fuel

The amount of the fuel given by a nozzle is regulated by an electric pulse signal from the electronic control unit (ECU). He traces data on a condition of the engine, counts the need for fuel and determines the necessary duration of supply of fuel by a nozzle (impulse duration). For increase in amount of the given fuel duration of an impulse increases, a for fuel supply reduction — is reduced.
EBU has ability to estimate results of the calculations and teams, and also to remember experience of recent work and to work according to it. "Self-training" of EBU is the continuous process continuing during all term of operation of the car.
Usually to a nozzle one impulse on one basic impulse of the sensor of provision of a bent shaft moves. Fuel moves or synchronously with basic impulses, or asynchronously, i.e. without coincidence to them on time. Synchronous injection of fuel — the most common way of supply of fuel. The asynchronous injection of fuel is applied when additional fuel at sharp opening of a butterfly valve is necessary about what the sensor of provision of a butterfly valve signals. This injection of fuel is similar to fuel supply by the accelerating pump of the carburetor at sharp opening of a butterfly valve.
Irrespective of an injection method supply of fuel is defined by a condition of the engine, i.e. the mode of its work. These modes are provided to EBU and are described further.
Mode of launch of the engine. At inclusion of ignition of EBU includes on 2 with the electrogasoline pump relay, and he creates pressure in the highway of supply of fuel to the unit of the central injection. EBU considers indications from sensors of temperature of cooling liquid and the provision of a butterfly valve and air/fuel for start-up defines a proper correlation.
After the beginning of rotation of bent shaft EBU will work in the starting mode until turns exceed 420 rpm, otherwise switching to the engine purges mode is possible. Duration of each impulse on a nozzle at start-up makes 4–6 ms depending on temperature of cooling liquid and the provision of a butterfly valve.
Mode of an engine purge. If the engine "it is filled in with fuel", it can be started by full opening of a butterfly valve at a simultaneous provorachivaniye of a bent shaft. EBU in this mode gives on a nozzle the impulses corresponding to a ratio air/fuel 26:1 (impulse duration about 2 ms) that "clears" the filled-in engine. EBU supports the specified duration of impulses until turns of the engine are lower than 420 rpm, and the sensor of provision of a butterfly valve shows that it is almost completely open (more than 85%).
If the butterfly valve keeps almost completely open in attempt of normal launch of "not filled in" engine, then the engine can not be launched since the ratio air/fuel 26:1 can be insufficient for launch of not filled in engine, especially if it is not heated-up.
The mode of an open cycle after start-up (without feedback). After launch of the engine (when turns more than 420 rpm) EBU will operate a fuel supply system in the mode of "an open cycle". On this EBU mode ignores a signal from the sensor of oxygen and counts impulse duration on a nozzle on signals from the sensor of provision of a bent shaft (information on rotation frequency), the sensor of absolute pressure of air, the sensor of temperature of cooling liquid and the sensor of provision of a butterfly valve.
In the mode of an open cycle the calculated duration of an impulse of injection can give a ratio the air/fuel differing from 14,7:1. Not heated-up condition of the engine can be an example, т.к at the same time ensuring high riding qualities requires the enriched mix.
The system will remain in the mode of an open cycle until all following conditions are satisfied:
— the signal of the sensor of oxygen changes, showing that it is rather heated-up for normal work;
— temperature of cooling liquid is more than 32 °C;
— the engine worked a certain period of time from the moment of start-up. Time can vary from 6 with up to 5 min. depending on temperature of cooling liquid at the time of launch of the engine. In case temperature was below 18 °C, the period makes 5 min. If temperature was above 75 °C, the delay makes 6 pages.
The mode of the closed cycle after start-up (with feedback). On the mode of the closed cycle EBU at first counts impulse duration on a nozzle on the basis of signals from the same sensors, as in the mode of an open cycle. Difference consists that in the mode of the closed cycle EBU still uses a signal from the oxygen sensor for adjustment and thin adjustment of a settlement impulse precisely to support a ratio air/fuel at the level of 14,6-14,7:1. It allows catalytic converter to work with maximum efficiency.
The enrichment mode at acceleration. EBU monitors sharp changes of provision of a butterfly valve (on the sensor of provision of a butterfly valve) and behind pressure in an inlet pipe (on the sensor of absolute pressure) and provides giving of additional amount of fuel due to increase in duration of an impulse at a nozzle.
If the increased need for fuel is too big because of sharp opening of a butterfly valve, then EBU can add asynchronous impulses on a nozzle in intervals between synchronous which during the normal work one is the share of each basic impulse from the sensor of provision of a bent shaft.
Mode of power enrichment. EBU watches a signal of the sensor of provision of a butterfly valve and frequency of rotation of a bent shaft for definition of the moments at which the maximum engine capacity is necessary for the driver. Achievement of the maximum power requires the enriched gas mixture, and EBU changes a ratio air/fuel approximately to 12:1. On this mode the signal of the sensor of concentration of oxygen is ignored since he will point to a mix obogashchennost.
The impoverishment mode when braking. When braking the car with the closed butterfly valve emissions in the atmosphere of toxic components can increase. Not to allow it, the electronic control unit monitors reduction of an angle of opening of a butterfly valve and size of pressure in an inlet pipe and in due time reduces amount of the given fuel by reduction of an impulse of injection.
The mode of shutdown of supply of fuel when braking by the engine. When braking by the engine with the included transfer and coupling of EBU can for the short periods of time completely disconnect fuel injection impulses. Shutdown of supply of fuel comes when performing all following conditions:
1. Temperature of cooling liquid is above 44 °C.
2. Frequency of rotation of a bent shaft is higher than 3150 rpm.
3. Speed of the car is higher than 42 km/h.
4. The butterfly valve is closed.
5. The signal of the sensor of absolute pressure shows lack of loading of the engine (pressure less than 24 kPa).
6. The table enclosed in constant memory of EBU and comparing the frequency of rotation of a bent shaft to car speed defines the included transfer of the transmission.
When braking the car the engine any of the following conditions will cause renewal of impulses of injection of fuel:
1. Frequency of rotation of a bent shaft is lower than 2100 rpm.
2. Speed of the car is less than 42 km/h.
3. The butterfly valve is open not less, than for 2%.
4. The signal of the sensor of absolute pressure in an inlet pipe shows existence of loading (pressure more than 25 kPa).
5. Coupling is switched off. It can be determined by bystry falling of frequency of rotation of a bent shaft.
Compensation of power failure. At power failure the system of ignition can give a weak spark, and mechanical motion of "opening" of a nozzle can take more time. EBU compensates it by increase in time of accumulation of current in the ignition coil at power failure lower than 12 V, and at power failure it is lower than 8 V — by increase in turns of idling and duration of an impulse of injection.
Fuel supply shutdown mode. At the switched-off ignition fuel a nozzle does not move, than spontaneous ignition of mix at the superheated engine is excluded. Besides, impulses of injection of fuel do not move if EBU does not receive basic signals of provision of a bent shaft, i.e. it means that the engine does not work.
Fuel supply shutdown also happens at excess of maximum permissible frequency of rotation of a bent shaft of the engine, equal 6500 rpm. Impulses of injection will renew after falling of frequency of rotation of a bent shaft lower than 5850 rpm.

Fig. 10-28. Scheme of electric connections of system of injection: 1 — the engine cooling system fan electric motor: 2 — the assembly block; 3 — the idling regulator; 4 — an electronic control unit; 5 — an octane potentiometer; 6 — spark plugs; 7 — the ignition module; 8 — the sensor of provision of a bent shaft; 9 — an electrogasoline pump with the fuel level sensor; 10 — a tachometer; 11 — a control lamp of "CHECK ENGINE"; 12 — the car ignition relay; 13 — the speed sensor; 14 — diagnostics block; 15 — a nozzle; 16 — the adsorber purge valve; 17, 18, 19 — safety locks of system of injection; 20 — the relay of ignition of system of injection; 21 — the relay of inclusion of an electrogasoline pump; 22 — the relay of an electric heater of an inlet pipe; 23 — an electric heater of an inlet pipe; 24 — a safety lock of a heater of an inlet pipe; 25 — the sensor of concentration of oxygen; 26 — the sensor of temperature of cooling liquid; 27 — the sensor of provision of a butterfly valve; 28 — the air temperature sensor; 29 — the sensor of absolute pressure; And — to the plus plug of the rechargeable battery; In — to the ignition switch 15 plug; P4 — the relay of turning on of the electric motor of the fan

Control of the cooling system electric fan. The electric fan turns on and EBU depending on temperature of the engine, frequency of rotation of a bent shaft, operation of the conditioner (if it is on the car) and other factors is switched off. The electric fan turns on by means of the auxiliary P4 relay (see fig. 10-28) located in the assembly block.
During the operation of the engine the electric fan turns on if temperature of cooling liquid exceeds 104 °C or the request for turning on of the conditioner will be given. The electric fan is switched off after temperature drop of cooling liquid below 101 °C, after switching off of the conditioner or a stop of the engine.