10.3.1.3. Sensors

The sensor of temperature of cooling liquid represents a thermistor (the resistor which resistance changes from temperature). The sensor is wrapped in a final branch pipe of cooling liquid on a head of cylinders. At a low temperature the sensor has high resistance (more than 100 kOhm at –40 °C), and at high temperature — low (177 Ohms at 100 °C).
Counts temperature of the EBU cooling liquid on power failure on the sensor. Power failure high on the cold engine and low on heated-up. Temperature of cooling liquid influences the majority of characteristics which are operated by EBU.
The air temperature sensor wrapped in a bottom of the case of the air filter is also a thermistor. He constantly takes air temperature and monitors its change. At air fall of temperature its resistance increases, and at increase — decreases.
At fluctuations of temperature of EBU monitors power failure on the sensor and regulates amount of injectable fuel.

Fig. 10-15. Sensor of absolute pressure

Fig. 10-17. Unit of the central injection: 1 — the fuel pressure regulator; 2 — a nozzle; 3 — the fuel supply union; 4 — the sensor of provision of a butterfly valve; 5 — the union of removal of fuel in a tank; 6 — an adsorber purge branch pipe; 7 — a branch pipe of ventilation of a case of the engine; 8 — a branch pipe for connection of the sensor of absolute pressure; 9 — the idling regulator; 10 — the sector of the drive of a butterfly valve from a pedal in interior of the car

The sensor of absolute pressure of air (fig. 10-15) is fixed in a box of airinflow and connected by a hose to a branch pipe 8 (see fig. 10-17). He watches air pressure in an inlet pipe which changes as a result of change of load of the engine and the frequency of rotation of a bent shaft.
Sensitive element of the sensor — a tiny diaphragm with the resistor which is raised dust on it. Depending on pressure of air the tension of a diaphragm changes and respectively resistor resistance changes. The chip which is built in the sensor will transform this change of resistance to change of tension at the sensor exit.
Rather low voltage of a signal at the exit of the sensor (1-1,5 B) is idling created. And at completely open butterfly valve — the highest level of a signal (about 4-4,5 In), since in this case pressure in an inlet pipe equally atmospheric.
The sensor considers barometric pressure that allows EBU to make high-rise corrections to fuel supply automatically.
EBU uses information from the sensor of absolute pressure for management of supply of fuel and an ignition advancing. At increase in pressure in an inlet pipe (the output tension of the sensor increases) — supply of fuel increases. At pressure drop (the output tension of the sensor decreases) — supply of fuel decreases.
The sensor of concentration of oxygen is installed on a final collector. The oxygen which is contained in the fulfilled gases reacts with the oxygen sensor, creating potential difference at the sensor exit. It changes approximately from 0,1 B (high content of oxygen — poor mix) to 0,9 B (not enough oxygen — rich mix).
For normal work the sensor has to have temperature not below 360 °C. Therefore for bystry warming up after launch of the engine the heating element is built in the sensor.
Tracing the output tension of the sensor of concentration of oxygen, the control unit defines what team on correction of composition of working mix to give on nozzles. If mix poor (low potential difference at the sensor exit), then the command for mix enrichment is given. If mix rich (high potential difference) — the command for mix impoverishment is given.
The sensor of speed of the car is installed on the transfer case between the drive of a speedometer and a tip of a flexible shaft of the drive of a speedometer. The principle of operation of the sensor is based on Hall's effect. The sensor gives on EBU rectangular impulses of tension with a frequency proportional to the speed of rotation of driving wheels.
On the basis of information from the EBU sensor sets the idling mode, and also switches-off the cooling system fan at a high speed of the car.

Fig. 10-16. Octane potentiometer

The octane potentiometer (fig. 10-16) is established in a motor compartment on a wall of a box of airinflow and represents the variable resistor. It gives a signal of correction of a corner of an advancing of ignition in an electronic control unit. Adjustment an octane potentiometer is carried out only at service station with use of the diagnostic equipment.
The sensor of provision of a butterfly valve 4 (see fig. 10 — 17) is installed on the unit of the central injection of fuel and connected with an axis of a butterfly valve.
The sensor represents a potentiometer on which one end moves plus supply voltages (5 V), and other end is connected to weight. From the third conclusion of a potentiometer (from the toddler) there is an output signal to an electronic control unit.
When the butterfly valve turns (from impact on a pedal of management), tension at the sensor exit changes. At the closed butterfly valve it is lower than 0,7 Century. When the gate opens, tension at the exit of the sensor grows and at completely open gate there have to be more than 4 Century.
Tracing the output tension of the sensor the control unit corrects supply of fuel depending on the angle of opening of a butterfly valve (i.e. at the request of the driver).
The sensor of provision of a butterfly valve does not demand any adjustment since the control unit perceives idling (i.e. full closing of a butterfly valve) as a zero mark.
The sensor of provision of a bent shaft — inductive type, is intended for synchronization of operation of the control unit with the top dead point of pistons of the 1st and 4th cylinders and the angular provision of a bent shaft.
The sensor is installed on a camshaft drive cover opposite to the setting disk on a generator drive pulley. On a disk there are 6 cuts, ravnoraspolozhenny on a circle, and one cut located in 10 ° from one of them and the employee for generation of an impulse of synchronization. At rotation of a bent shaft of a cut change magnetic field of the sensor, creating tension impulses at the sensor exit.
EBU determines the frequency of rotation of a bent shaft by signals of the sensor and gives impulses on nozzles.
Signal of request for turning on of the conditioner. If on the car the conditioner is installed, then the signal arrives from the conditioner switch on the dashboard. In this case EBU obtains information that the driver wishes to turn on the conditioner.
Having received such signal of EBU at first arranges the idling regulator to compensate additional load of the engine from the conditioner compressor, and then turns on the relay operating operation of the compressor of the conditioner.