Functions and Sensors of the Bosch MEV 17.4 System D Occupancy detonation Purpose The knock sensor is a piezoelectric sensor. Information about the detonation in the engine, coming from the knock sensor, allows the engine control unit to correct the ignition timing (reduce). The knock is due to the detonation of the fuel-air mixture in one of the 4 cylinders. When a detonation occurs, the sensor transmits voltage peaks to the engine control unit. Having received information about the detonation in the engine, the engine control unit reduces the timing of the ignition and simultaneously enriches the fuel mixture. Placement Figure 12.2 (1) the detonation sensor. Peculiarities of electrical equipment Pin equipment Pin assignment of connector:
Channel 1: Signal (+) Channel 2: Signal (-)
Engine Speed Sensor Purpose It is a "Hall sensor". The engine speed sensor provides an electrical signal for each target tooth pass (Change in magnetic field). Teeth 58 allow you to determine the mode of operation of the engine. 2 missing teeth allow you to determine the engine speed. The role of the engine control computer, depending on the information received:
Check the engine speed Defines the angle of rotation of the crankshaft Calculates the ignition timing
Adjusts the idle speed
Placement Figure 12.3 (2) 12.3 (2) The target of the sensor. (3) Engine speed sensor. Peculiarities of electrical equipment Pin equipment Pin assignment of connector:
Channel 1: Power + 5 V Channel 2: "Mass" Channel 3: Signal
Position sensor: Camshafts Purpose It Purpose It is a "Ha ll sensor". The camshaft position sensors send a rectangular waveform t o the engine control unit. The role of the engine control computer, depending on the information received:
Synchronizes the injection of fuel with respect to the position of the pistons Recognizes the top dead spots Defines the misfire Determine the amount of lift of the intake valves
Placement Figure 12.4 (4) 12.4 (4) Camshaft Position Sensor. Peculiarities of electrical equipment Pin equipment Pin assignment of connector:
Channel 1: Power + 5 V Channel 2: Signal Channel 3: "Mass"
Emitted signal:
The presence of a metallic "mass" opposite the sensor: 0 Volts The absence of a metallic "mass" opposite the sensor: 12 volts
Ignition coils Purpose Static ignition with one ignition coil per cylinder (of the "pencil" type). The ignition coil allows high voltage to be applied to the spark plug. Placement Fig. 12.5 (5) Ignition coil. Features of electrical equipment Fig. 12.6 Pin assignment of connector:
"a" Channel 1: Command for ignition on "b" Channel 2: Power supply 12 V "c" Channel 3: "mass"
Spark plug Features:
Ignition coils with flat stop surface Tightening torque: 2,5 ± 0,1 da.Nm
Motor control computer Power cascades and ignition coils are i ntegrated in the engine control unit (there is no separate ignition unit). The engine control unit energizes each primary coil winding in the order of ignition (1-3-42). Synchronization of the moment of ignition is carried out by sensors of position of camshafts. Engine Coolant Temperature Sensor Function The coolant temperature sensor sends information to the engine control unit about the temperature in the engine cooling system. Placement Fig. 12.7 (13) Coolant temperature sensor. Features of electrical equipmentPurpose of contacts:
Track N ° 1: Coolant temperature signal Contact No. 2: "Mass" of the engine water temperature sensor
The magnitude of the resistance as a function of the temperature of the liquid Coolant temperature
Resistance
0°C
16325 Ohms
20 ° C
6245 Ω
40 ° C
2660 Ohms
60 ° C
1245 Ohm
80 ° C
630 Ohm
100 ° C
340 Ohm
Adjustable thermostat Purpose The adjustable thermostat allows:
A faster increase in the coolant temperature for faster start of exhaust gas neutralization Higher engine temperature to reduce friction and reduce fuel consumption
Placement Fig. 12.8 (14) adjustable thermostat. Description Fig. 12.9 "A": The thermostat is open (always if the temperature is above 105 ° C). "B": The thermostat is closed. (21) Wax. (22) heating element. The wax (21) in the thermostat is diluted at a temperature of 105 ° C. Usually the electronics do not interfere with the operation of the thermostat, it itself maintains the temperature at 10 5 ° C. Adjustment of the controlled thermostat is carried out by t he RCO signal from 75 ° C (100% control) to 105 ° C (0% control). If necessary, the 100 %% engine control unit controls the heated resistance (22) of the thermostat to add 30 ° C, which lacks a 75 ° C temperature for melting wax (21).
Linear pressure sensor for liquid refrigerant (8009) Function The linear liquid pressure sensor measures the pressure in the air conditioner circuit. The role of the engine control computer, depending on the information received; Pressure in the cooling system:
Allows the activation of the engine cooling fan assembly (cooling of the air conditioner condenser)
Enables the air conditioning compressor
Description Fig. 12.10 Linear pressure sensor of liquid refrigerant of piezoresistive type. The linear pressure sensor of the liquid refrigerant consists of voltage meters. Linear sensor for liquid refrigerant type generates a volta ge proportional to the pressure in the air conditioner circuit. Designation: Black connector. NOTE: The electrical information supplied by the sensor is transmitted via wire to the engine control computer and then sent to the intelligent switching unit via a multiplex network (CAN interconnection). Peculiarities of electrical equipment Pin assignment of connector:
Channel 1: Power 5 V Channel 2: Pressure information (0 - 5 Volts) Channel 3: "Mass"
The voltage supplied for a pressure of 1 bar: +0.5 volts. The voltage supplied for a pressure of 31 bar: + 4.5 Volts. Atmospheric pressure sensor The atmospheric pressure sensor allows the engine control unit to determine the a ir density. NOTE: Air density decreases as you go up to the altitude. The atmospheric pressure sensor is integrated into the engine management computer. ATTENTION: The atmospheric pressure sensor can not be removed from the engine control computer. Vacuum pump Function NOTE: On EP3 and EP6 engines, the vacuum pump is not part of the pneumatic system. Vacuum pump provides the discharge necessary for the operation of the brake booster. Discharge in the intake manifold is not enough to power the brake booster. The vacuum pump is driven from the camshaft of the exhaust valves. Placement Figure 12.11(15) Vacuum pump.
Intake manifold pressure and temperature sensor Purpose The pressure and temperature sensor allows you to determine:
Intake manifold air pressure Intake Air Temperatures
The temperature sensor informs the engine control unit about the temperature of the air supplied to the cylinders.Operating modes 1. Normal operation The engine control unit uses information about the air temperature. NOTE: The intake manifold air pressure information is not used. 2. Emergency operation mode If a fault is detected in the timing system, the engine control unit uses the information of the pressure sensor and the supply air temperature to perform the following operations:
The role of the computer fuel injection system, depending on the information received Determination of the amount of fuel for injection
NOTE: Air density decreases as you go up to the altitude. Placement Fig. 12.12 (5) Intake manifold pressure and temperature sensor. Features of electrical equipment The pressure and temperature sensor in the intake manifold is a piezoresistor. The pressure and temperature sensor in the in take manifold is supplied with a voltage of 5 V. The pressure and temperature sensor in the intake manifold sends a voltage signal proportional to the measured pressure. The temperature sensor is a resistance with a negative temperature coefficient (CTN). Electrical characteristics:
Resistance at 0 ° C: 588 Resistance at 20 ° C: 2510 Ω
Resistance at 40 ° C: 2000 Ω
Pin assignment of the connector: Channel 1: Intake air pressure sensor signal Channel 2: Power supply 5V Channel 3: Air flow temperature signal Channel 4: "Mass" Changing the phases of the rise of the intake valves Purpose The change in the intake valve lift allows you to vary the amount of air supplied, without affecting the throttle. This phase allows:
Reduce reaction time Reduce fuel consumption Reduce harmful emissions Ensure compliance with emission control regulations EURO4
Placement Fig. 12.13 (7) Variable valve lift actuator. (8) Valve position sensor. (16) Intermediate lever. (17) Intake manifold. (18) Return spring. (19) Camshaft (Intermediate part). (20) Gear wheel.
Description Fig 12.14 (7) The valve opening motor. (8) Valve position sensor. (16) Intermediate lever. (17) Intake manifold. (18) Return spring: Intermediate lever. (19) Camshaft (Intermediate part). (20) Gear wheel. (21) rocker arm. (22) The valve. "a" Shaft rotation: The valve opening motor. "b" Shaft rotation: Camshaft (Intermediate part). "c" Moving the intermediate lever. "d" Variable valve lift. A variable lift of the intake valves is effected by means of an electric motor (7) which drives the intermediate camshaft (19) by means of a worm gear (20). The intermediate camshaft acts on the intermediate arm (16) located between the rocker arms (21) and the inlet camshaft (17). The camshaft of the intake valves acts on the valve (22) by means of an intermediate lever and a rocker arm; The position of the intermediate lever determines the rise of the intake valve, which varies from 0.3 mm to 9.5 mm. The engine control unit controls the valve lift motor depending on the following information:
Information from the accelerator pedal position sensor Information from the intake and exhaust position sensors of the engine The position of the intake valves
The valve position sensor (8) measures the position of the intake valves and transmits information to the engine control unit.
The valve opening motor Purpose The valve lift motor changes the angle of the intermediate camshaft position by a command from the engine control unit. The valve lift motor allows the intake valves to be lifted from a minimum to a maximum value in 300 ms.Placement Fig. 12.15 (7) The motor for changing the lifting of the valves. Description When the ignition is switched off, the valve lift motor (7) re-learns the end stop, then sets the valve lift amount to about 1.7 mm (lift amount to start the engine). The position of the change valve motor all ows the engine to start. Peculiarities of electrical equipment Pin assignment of connector:
Channel 1: Power + 12 V Channel 2: "Mass"
The engine control unit converts the 12 V voltage signal into the RCO (cyclic valve lift) by means of the valve lift motor relay (1370), which controls the valve lift motor (7). WARNING: Do not directly apply voltage to the valve lift motor to avoid damaging it. Emergency operation mode If the engine control unit detects a malfunction in the valve lift (valve position sensor, raising the temperature of the valve lift motor (7) above 175 ° C, etc.), the motor control switches to emergency operation. Function: Motor control computer:
Produces the maximum valve lift Manages the air supply through the throttle valve with electric drive
NOTE: This emergency operation mode is almost invisible to the driver. If the engine control unit detects a malfunction of the valve lift motor (blocking, temperature exceeding 190 ° C, malfunction of the motor power relay (1370), etc.), the motor control is put into emergency mode. The engine control unit does not allow changing the position of the intake valves anymore, therefore the system remains in the last position. The engine control unit uses an electric throttle to control the amount of ai r supplied. In this case, the amount of air supplied depends on the position of the valves during the occurrence of the fault, which significantly affects the operation of the engine. NOTE: This emergency operation mode may make it impossible to start the engine.
The gauge of position of inlet valves Purpose The inlet position sensor informs the engine control unit of the angular position of the intermediate inlet camshaft. Based on this information, the engine control unit determines the amount of intake valve lift. The engine control unit compares this information with the accelerator pedal position information and with the information of the intake and exhaust position sensors of the engine. Accommodation
Figure 12.16 (8) The valve position sensor. (22) The target of the sensor. Description
Figure 12.17 (8) The valve position sensor. (19) Camshaft (Intermediate part). (22) The target of the sensor. "e" Angle of the intermediate camshaft. At the end of the intermediate camshaft (19), the sensor (22) with a permanent magnet is fixed. The valve position sensor (8) transmits 2 signals under the influence of the sensor's magnetic field. The first signal determines the value of the angle "e" from 0 ° to 180 °, the second signal is a confirmation showing the angle from 180 ° to 0 °. The engine control unit uses the angle information "e" o f the intermediate camshaft (19) to determine the amount of intake valve lift. Emergency operation mode If the valve position sensor is damaged; Function: Motor control computer:
Produces the maximum valve lift Manages the air supply through the throttle valve with electric drive
Accelerator Pedal Position Sensor Purpose The system for changing the lift of the intake valves does not require a throttle to dose the amount of air supplied. The throttle body with electric drive allows:
Discharging of 50 mbar in the intake manifold, necessary for the intake of fuel vapors from the fuel vapor adsorber system and oil vapors Emergency mode in the event of a malfunction valve lift change system
The accelerator pedal position sensor translates the driver's request into the engine control unit. The dual sensor integrated in the throttle valve allows the engine control unit to determine the exact position of the throttle. Placement Fig. 12.18 (4) Accelerator pedal position sensor. Emergency operation mode In the event of a malfunction in the valve lift change system, the engine control unit controls the air supply by means of the throttle valve with electric drive Fig. 12.19
"C": Rest position of the throttle (contact open) or emergency position in the event of a fault. "D": Throttle position with ignition on or idling. "E": Throttle position when fully submerged. (4f) Throttle actuator force. (4g) Spring force. With the ignition off, the emergency mode spring keeps the throttle in the open position (View "C"). When the ignition is switched on, the engine control unit moves the throttle to the idling position, overcoming the force of the emergency mode spring (Type "D"). At idling speed, the throttle is moved to provide the required amount of air to the engine (Replacement of the idling speed stepper motor). Starting from 1500 min-1, the engine control unit moves the throttle to the other side, helping the spring (View "E"). The throttle position is monitored by the engine control unit (potentiometer integrated in the throttle valve). The engine control unit turns off the power to the throttle body when certain faults occur. MANDATORY: Electric throttle valve block. Pin assignment of connector: The throttle position is monitored by the engine control unit (potentiometer integrated i n the throttle valve). The engine control unit turns off the power to the throttle body when certain faults occur. MANDATORY: Electric throttle valve block. Pin assignment of
connector: The throttle position is monitored by the engine control unit (potentiometer integrated in the throttle valve). The engine control unit turns off the power to the throttle body when certain faults occur. MANDATORY: Electric throttle valve block. Pin assignment of connector:
Channel 1: Power 5 V Channel 2: Signal 2 Channel 3: "Mass" Channel 4: Signal 1 Channel 5: "Positive" Team Channel 6: "negative" command
Phase failure in camshafts Changing the phases of the camshafts is based on information from the sensors of the position of the reference cylinder, the engine mode sensor, the valve position sensor. The engine control unit drives the camshaft timing solenoid valves to change the position of the camshafts. The mechanisms for changing the phases of the intake and exhaust have the same operating principle, but are controlled independently of each other. Placement Fig. 12.20 (12) Timing of the timing system (Exhaust system). (13) The mechanism of change of phases of an inlet cam-shaft. (11), (14) Solenoid valves of change of phases of cam-shafts. Purpose Function of the mechanisms of phase change:
The mechanism for changing the position of the camshaft in relation to its drive is made at certain times of engine operation (displacement of the inlet camshaft by a maximum of 35 °, and the camshaft of the exhaust valves by a maximum of 30 °) Adapts the filling with air depending on the load of the engine Facilitates the cleaning of the combustion chamber Improves engine output at partial loads Reduces harmful emissions into the atmosphere Improves the power characteristics of the engine (in particular, increases the motor torque at low engine shaft frequencies)
NOTE: The camshaft timing solenoid valves are not controlled at temperatures below -10 ° C. Emergency operation mode If the engine control co mputer detects a malfunction of the camshaft timing system (malfunction of t he reference
cylinder position sensor, malfunction of the solenoid valve, etc.), the engine control is in emergency mode. Function: Motor control computer:
Produces the maximum valve lift Manages the air supply through the throttle valve with electric drive It stops operating the solenoid valves of the camshaft timing changes
The camshaft timing solenoid valve (1268 and 1243) Function The engine control unit supplies power to the camshaft timing solenoid valve (1268), (1243), depending on the engine mode, the engine load and the position of the intake valves. The camshaft timing solenoid valves (1268), (1243) control the camshaft timing hydraulics. Description Figure 12.21
"F": Solenoid valve for changing camshaft timing. "G": Hydraulic diagram of the camshaft timing solenoid valve. "f": Feed or return engine oil from the "F" chambers of the camshaft timing change mechanism. "g": Supply of engine oil under pressure into the camshaft timing solenoid valve. "h": Feed or return engine oil from the "G" chambers of the camshaft timing change mechanism. "j": Return oil to the engine oil sump. Peculiarities of electrical equipment Pin assignment of connector:
Channel 1: Controlling the fuel tank drain solenoid valve Channel 2: 12 Volts Winding resistance: At 20 ° C: 7.2 ± 0.4 ohms
The timing of the engine
Fig. 12.22 "X": Time of overlapping of inlet and exhaust valves. "Y": Opening time of the intake valves. "Z" : Opening time of exhaust valves. "M": Anticipation of the opening angle of the intake valve (AOA). "N": Delayed closing angle of intake valve (RFA). "P": Anticipat ion of the opening angle of the exhaust valve (AOE). "Q" : Delayed closing angle of the exhaust valve (RFE). "R": Inlet phase = Piston stroke down. "U": Compression phase = Piston lift. "T": Combustion phase = Piston stroke down. "S": Release phase = Piston lift. "V": The inlet. "W": Graduation system. NOTE: The intake and exhaust valves overlap only between the exhaust stroke "S" and the intake stroke "R". If the mechanism for changing the phases of the intake camshaft increases the delay in closing the intake valves "N", the opening of the intake valves "M" accordingly decreases. If the mechanism for changing the phases of the exhaust camshaft increases the delay in closing the exhaust valves "Q", the anticipation of opening the exhaust valves "P" accordingly decreases accordingly. Timing adjustment system Description The mechanism for changing the phases of the camshafts is given by the engine oil pressure. The solenoid valves for phase control of the camshafts (1268), (1243) dist ribute engine oil under pressure into 4 chambers "F" or into 4 chambers "G". The camshaft is displaced by the oil pressure difference in the chambers "F" and "G". Fig. 12.23. "K": The camera ("F") of the camshaft timing mechanism. "l": The camera ("G") of the camshaft timing change mechanism. "m": The camshaft timing gear locking pin (when the engine is muffled). "n": Channel for the supply and return of the oil in the chambers ("F"). "p": Channel for the supply and return of the oil in the chambers ("G").
NOTE: The camshaft timing change mechanism "m" is locked at low oil pressure. The "m" finger releases the camshaft timing mechanism when the oil pressure in the "F" chamber reaches about 0.5 bar. Elements of the fuel supply system ( BOSCH MEV17.4 ) Elements of the gasoline vapor collection system (BOSCH MEV17.4 )
Fuel supply system BOSCH MEV 17.4 Scheme: Fuel supply
Figure 12.24. "A": Low pressure circuit. (1) Fuel tank. (2) Pump assembly with sensor and fuel pressure regulator. (3) Fuel rail of petrol engine injectors. (4) Fuel injectors. (5) (SCHRAEDER). The fuel pump integrated in the pump and sensor assembly (2) directs the fuel to the common ramp of high -pressure fuel injectors. The supply pressure is maintained at 3.5 bar by a pressure regulator integrated in the pump and sensor unit (2). Gasoline, under pressure in the injector ramp, is injected into the intake manifold by injectors receiving commands from the engine control unit. Assembly assembly fuel pump and fuel level (low pressure) sensor Purpose The pump / fuel level meter assembly allows fuel to flow into the low pressure circuit "A". A check valve integrated in the pump / fuel level meter assembly (2) in the filling circuit maintains the residual pressure in the motor power circuit. Description Pump / fuel level meter assembly (2) BOSCH EKP:
Immersed in the fuel tank Receives power 12 volts Controlled by the signal from the e ngine control computer via the engine switching unit (BSM); When the ignition is switched on Resistance of sensor depending on fuel level: Resistance between channels 50 and 350
Pump start-up time when the ignition is switched on without starting the starter:
1,5 s, if the car was without traffic less than 6 days 10 seconds if the car has a ball without traffic for more than 6 days
When the motor shaft rotates, the engine control unit constantly supplies voltage to the fuel pump. Fuel filter
The fuel filter is integrated into the pump / fuel level meter assembly (2). Features:
The fuel filter can not be dismantled from the module. The fuel level sensor / fuel pump: 8 - 10 micron Periodicity of replacement: No, maintenance-free Fuel pressure control
Figure 12.25 (2) Pump block with fuel sensor. (6) Fuel pressure regulator. The fuel pressure regulator is integrated in the level meter / fuel p ump module. The fuel pressure regulator allows maintaining the pressure in the supply circuit at a level of 3.5 bar. (SCHRAEDER) Purpose Valve SCHRAEDER. Functions:
Functions Fuel pressure check for after -sales service Pump performance monitoring for after-sales service
Placement Figure 12.26 (5) (SCHRAEDER).
Fuel rail of injectors of the petrol engine Purpose Purpose: Fuel rail of injectors of the petrol engine:
Store the amount of fuel required for the engine in any mode of operation Smooth the pulsations generated by the injectors To connect elements of system of injection
Elements assembled in the ramp of the injection system:
Fuel Tube Fuel injectors (SCHRAEDER)
Placement Figure 12.27 (3) The fuel rail of the injectors of the petrol engine.
Fuel burner The purpose of injectors for injection of gasoline allows you to dose the amount of fuel. Functioning injectors for gasoline injection at each electric impulse:
Operation The needle of the injector rises from its saddle
Injectors for petrol injection are controlled separately in the same order as the order of operation of the cylinders (1 - 3 - 4 - 2), just before the intake phase. Fuel is sprayed under pressure at the inlet to the valve seat. Placement Fig. 12.28 (4) Fuel injector. Features Fuel injectors SIEMENS VDO. Operated by: Motor control computer. Characteristics :
Supply voltage: 12 V Resistance: Approx. 12 ohm Supply pressure: 3,5 bar Consumption (Static): 135 ± 4 g / min Consumption (Dynamic): 4.9 ± 0.2 mg / cycle
Pin Assignment:
Contact N ° 1: Injector control (+) Contact N ° 2: Injector control (-) Injection time
The engine control unit determines the injection time according to the following parameters:
Intake air temperature Engine speed The position of the intake valves Position of a regulator of phases of cam-shafts Engine temperatures Vehicle Speed
The table below shows an example of how the injection time will vary depending on the engine mode with the maximum depressing of the accelerator pedal. Engine speed (rpm) 1300 2700 4000 5000 5500 Injection time (ms) 13 ± 1.5 14 ± 1.5 14.5 ± 1.5 14.5 ± 1.5 15 ± 1.5 Flow control
When any pyrotechnic element is triggered, the supply of th e high-pressure fuel pump is i nterrupted by the engine switching unit (BSM), based on the information received from the airbag computer. When restarting the engine:
Ignition OFF
Turn on the "+ from the ignition switch" Engine starting Proportional oxygen sensor at the input
Purpose The proportional oxygen sensor detects the amount of oxygen in the exhaust gases and on this basis calculates the exact air-to-air ratio of the air-fuel mixture. The front oxygen sensor allows you to better control the filling of the engine.Fig. 12.29
"a" Exhaust gas channel. (7) Pumping chamber. (8) Measuring chamber. (9) NERST cell. (10) The reference chamber. (11) Heating resistor. (12) Electrode. The oxygen contained in the oxygen sensor is pumped into the exhaust gases by means of the pump current and stored in the measuring chamber. The NERST cell compares the amount of oxygen in the measuring chamber with the amount of oxygen in the reference chamber. To ensure the value of the lambda (air excess ratio) 1, the amount of oxygen in the measuring chamber (8) should be equal to the amount o f oxygen in the reference chamber (10). The magnitude of the pump current is related to the flow of o xygen coming from the exhaust gases, necessary for oxygen regeneration in the measuring chamber (8) and obtaining an excess air coefficient 1. If the excess air ratio is higher than 1 in the measuring chamber (8), the pump current is positive, the excess oxygen in the measuring chamber is withdrawn and sent to the exhaust gases. If the excess air factor i s less than 1 in the measuring chamber (8), the pump current is negative, the missing amount of oxygen is withdrawn from the exhaust gases and sent to the measuring chamber. The value of the coefficient of excess air in the exhaust gases, depending on the pump current. If the excess air factor is less than 1 in the measuring chamber (8), the pump current is negative, the missing amount of oxygen is withdrawn from the exhaust gases and sent to the measuring chamber. The value of the coefficient of excess air in the exhaust gases, depending on the pump current. If the excess air factor is less than 1 in the measuring chamber (8), the pump current is negative, the missing amount of oxygen is withdrawn from the exhaust gases and sent to the measuring chamber. The value of the coefficient of excess air in the exhaust gases, depending on the pump current.
Figure 12.30 "B": Excess air factor in the exhaust gases. "C": Current (mA). The pump current is in the range of - 2.2 to 2.54 milliamps. The engine control computer determines, depending on the pump current necessary to maintain the excess air ratio 1, the exact value of the lambda signal in the e xhaust gases and, thus, calculates the excess air quantity in the air-fuel mixture. Example. Pumping current: = 0.2 milliamperes, which corresponds to a signal of 1.1. The lambda signal makes it possible to determine the e xact value of the excess air factor. The degree of enrichment of the mixture is 1 / lambda signal. The degree of enrichment of the mixture = 1 / 1.1. The degree of enrichment of the mixture = 0.91. The engine control computer regulates the excess air ratio, changing the duration of the injection, so that the composition of the mixture is as close as possible to the stoichiometric (Lambda signal = 1). The oxygen sensor has an internal heating system, allowing it to quickly reach the operating temperature (+ 650 ° C). Placement Figure 12.31 (13) Proportional oxygen sensor at the inlet. Peculiarities of electrical equipment Pin assignment of connector:
Contact N ° 1: Information on the pump current of the proportional oxygen sensor (at the input) Contact N ° 2: Signal (-): Proportional oxygen sensor at the input Contact N ° 3: Heating control by p roportional oxygen sensor at the input Contact N ° 4: +12 V supply: Heating control by proportional oxygen sensor at the input Pin No. 5: Proportional Oxygen Sensor Compensation Pin No. 6: Signal (+): Proportional oxygen sensor at the input To the oxygen sensor at the input (ON / OFF)
Appointment The oxygen sensor determines the oxygen content in the exhaust gases and allows to determine the correct operation of the catalytic converter; correct the composition of the mixture due to changes in time characteristics of the fuel injection system and catalytic converter. The amount of oxygen contained in the exhaust gases is compared with the amount of oxygen contained in the oxygen sensor coming from the ambient air in order to determine on this basis the coefficient of excess air. If the exhaust gas contains less oxygen than the oxygen sensor, the fuel-air mixture will be "rich" if it contains more - the mixture will b e "poor". The oxygen sensor 1 compares the mixture composition obtained by injecting the current fuel dose with a value providing a stoichiometric composition (lambda = 1 ), to determine the output voltage on this basis. Lambda signal ratio = Mass of air entering the cylinder / mass theoretical. Information on the composition of the mixture (poor / rich) is expressed in a voltage: 0 - 1 V:
Poor mixture = 0.1 V (Lambda (air excess ratio)) = 1.05 Rich mixture = 0.9 V (Lambda (air e xcess ratio)) = 0.95
The engine control computer regulates the composition of the mixture, changing the duration of injection to obtain the composition of the mixture as close as possible to the stoichiometric (Lambda (air excess ratio)) = 1. The oxygen sensor has an internal heating system allowing it to quickly reach the operating temperature (+ 300 ° C) .Placement Figure 12.32 (14) The oxygen sensor at the inlet. Features of electrical equipment Purpose of contacts:
Contact N ° 1: +12 V supply: Heating of the oxygen sensor at the input Contact No. 2: Heated Oxygen Sensor Heating Control Contact N ° 3: Signal (-): Oxygen sensor at the input Pin No. 4: Signal (+): Oxygen sensor at the input
Fuel vapor collection system BOSCH MEV 17.4 The system of collecting fuel vapor (to BOSCH BOSCH MEV 17.4) Block diagram Fig . 12 . 33
(1) Fuel tank. (2) Absorber. (3) Purge gas absorber gas purge solenoid valve. (4) Motor control computer. (5) Accelerator pedal position sensor. Fuel tank
The air in the tank leaves the atmosphere through the adsorber tank of petrol vapors (when the engine is muffled). Absorber Purpose The petrol vapor absorber is connected to the fuel tank to catch gasoline vapors and allow them to enter the atmosphere (toxicity reduction system). The gasoline vapor absorber is a cylindrical tank equipped with an activated carbon filter. The gasoline vapors are a bsorbed by the activated carbon filter in t he absorber tank.Placement Figure 12.34 (2) Absorber.
Purge gas absorber gas purge solenoid valve (1215) Purpose The gasoline absorber purge purge solenoid valve, controlled by the engine control computer, provides recirculation of the vapor of gasoline stored in the absorber. Placement Fig. 12.35 (3) Evaporator vapor purge solenoid valve. Fig. 12.36
(4) Return spring. (5) Electromagnetic winding. (6) The valve. (7) Magnetic core. When the electromagnetic purge valve of the absorber receives power, the electromagnetic winding (5) draws in the magnetic core (7), which presses the valve (6). Gasoline, which is in the absorber, can then be sucked into the intake manifold. When the electromagnetic purge valve of the absorber stops receiving power, the return spring (4) pushes the valve (6), which stops the purge of the absorber.Phases of action When the engine stops, the absorber purge solenoid valve closes. The a dsorber tank collects gasoline vapor in the fuel tank. When the engine is running, the engine management computer evaluates the mass of gasoline contained in the absorber, gradually opening the absorber purge solenoid valve to determine the amount of air / gasoline mixture sent to the engine. W hen the engine control computer recognizes the airflow through the absorber purge solenoid valve, it determines the degree o f saturation of the absorber with p etrol vapors based on this. The engine management computer reduces fuel consumption through injectors and controls the absorber purge solenoid valve to get the total amount of fuel required to be injected into the engine cylinders. The control of the absorber purge solenoid valve corresponds to the percentage of the absorber's purge that varies with the engine speed and load. The motor computer controls the operation of the electric throttle to provide a reduced pressure in the intake air manifold. When the absorber's purge solenoid valve is op en, the vacuum in the intake manifold all ows the gasoline vapor entering the absorber to enter.Features of electrical equipment The control of the solenoid valve of the gasoline vapor absorber is carried out according to the RCO type (cyclical opening degree). Pin assignment of connector:
Contact N ° 1: Control by connection to earth Contact N ° 2: Power supply: 12 V
