Technical report on FAE sensors for engine management

19-09-2019 - Reports

Engine management. The 5 senses of the ECU.
 

If we think of the engine as the heart of the car, we could say the switchboard is the brain. And, ever since the emergence of electronics in the automotive industry, the electronic control unit or ECU (Engine Control Unit) has been responsible for controlling the operation of the engine. Increasingly so, as in its infancy it only controlled the fuel dosage, reducing consumption and emissions compared to its predecessors, like the carburettor and the injection pump.
 
1. What is the function of the ECU?
2. How does it control ignition and injection timing?
2.1 Crankshaft Position Sensor.
2.2 Camshaft Position Sensor.
2.3 Speed Sensor.
3. How does it control fuel injection?
3.1 Manifold Absolute Pressure Sensor.
3.2 Oxygen sensor.
3.3 Intake Air Temperature Sensor.
3.4 Refrigerant Temperature Sensor.
4. How does it control engine knocking?
5. How does it control engine temperature?
6. How does it control the recirculation of exhaust gases in diesel engines?
7. How does it control the pressure in a turbocharger?



1. WHAT IS THE FUNCTION OF THE ECU?

Currently, the ECU is responsible for the coordination and control of engine parameters, such as ignition timing, fuel injection, engine speed, idle speed and even temperature, to ensure optimal engine performance.
The ECU has the optimal parameters for motor operation and the adjustment guidelines preloaded into its programme, so that it always functions under the best possible conditions. The switchboards work by comparing these parameters with the signals they receive from the different electronic sensors installed in the engine, calculating any deviation by means of a simultaneous control system.
· FAE sensors involved in engine management.

 
Without the work done by these sensors, the switchboard could not control the operation of the engine. Just like we talked about the heart and the brain at the start of the report, we could also say that the sensors are like the 5 senses of the ECU. They are like our eyes, ears or skin. They detect any sensation, such as magnetic or electrical impulses, temperature change, air volume and quality, etc.
And, depending on the signals received by the control unit, it will act according to its internal memory parameters to regulate the operation of the engine, sending a signal to different parts of the engine to optimise, among others, the following functions:
 

2. HOW DOES IT CONTROL IGNITION AND INJECTION TIMING?

The ECU needs to determine the position of the pistons and valves before starting the ignition process, as well as determine when to send the spark and maintain the injection pulse to prevent the piston, connecting rods and valves from collapsing and seriously damaging the engine.
To do this, the ECU needs impulse sensors that control the position of both the crankshaft and the camshaft.
 

2.1 FAE Crankshaft Position Sensor (CKP).
The CKP is in charge of verifying the position of the crankshaft axis, and the ECU uses it to calculate the revolutions and the position of the crankshaft in order to control the injection or ignition timing.
 
 



 

2.2 FAE Camshaft Position Sensor (CMP).
The CMP controls the position of the first cylinder and determines when it's at top dead centre, to be able to start the ignition process.
 
 
 
 



2.3 FAE Speed Sensor.
The Speed sensor is responsible for controlling the rotational speed of the engine, as well as the transmission change points.
 
 
 
 



FAE manufactures these types of sensors in its factories, producing both plastic injection and housing injection using the best available materials, such as the sensor's interior coil, which has more restrictive inductance tolerances than competitors. FAE’s wide range of references makes it one of the best sellers on the aftermarket.
 

3. HOW DOES IT CONTROL FUEL INJECTION?

Combustion efficiency is significantly increased, thanks to this control, resulting in lower fuel consumption and a reduction in harmful emissions. To do this, it receives signals from many electronic sensors, such as:
 
3.1 FAE Manifold Absolute Pressure Sensor (MAP).
The MAP controls the intake air pressure.
 
 
 
 
 

 
3.2 FAE Oxygen sensor.
The Oxygen sensor controls the amount of oxygen present in the combustion and the operation of the catalyst.
 
 
 



 
3.3 FAE Intake air temperature sensor.
 
 
 
 
 



3.4 FAE Refrigerant temperature sensor.
 
 
 
 
 



In this section, which is so important for engine operation, FAE is fully committed to providing a wide range of products.
FAE manufactures MAP pressure sensors in an ESD Room (Electrostatic Discharge), which is electrostatically discharged and has a state-of-the-art advanced automated mounting and protection system.
The ceramic sensors that go inside the Oxygen sensor are manufactured in another of FAE's special rooms: the White Room. The White Room is a 700m2 room free of dust and particles, which ensures completely clean air with a constant temperature and humidity, to prevent the sensors from being contaminated during manufacturing.


4. HOW DOES IT CONTROL ENGINE KNOCKING?

Uncontrolled acyclic combustion results in high temperatures inside the cylinder. This phenomenon causes engine components such as pistons, valves or the cylinder head to be subjected to high stress. The FAE piezoelectric sensors optimise the maximum ignition point, in both petrol and diesel engines, and work as close as possible to the optimal point, varying the ignition advance according to the need of each moment, to avoid the knocking effect of engine pistons.
FAE manufactures Knock sensors using high quality housing materials so that the sensor is completely isolated from external signals, to provide high measurement accuracy.
 


· FAE Knock Sensor.


5. HOW DOES IT CONTROL ENGINE TEMPERATURE?

In order for the engine to run efficiently, and to ensure the long life of its materials, the switchboard prevents the engine from working cold as much as possible (e.g. when we start the car), by injecting more fuel to produce a richer combustion. It also ensures that the engine temperature does not exceed the ideal working temperature, which could cause overheating and the consequences that come with this.
This is all controlled by the refrigerant temperature sensor, a sensor that FAE has manufactured since 1952, with a wide range available on the market.
 
 

· FAE refrigenant
temperature sensor.


6. HOW DOES IT CONTROL THE RECIRCULATION OF EXHAUST GASES IN DIESEL ENGINES?

By doing this, the ECU ensures that the particulate filter is functioning correctly and regenerates it for proper operation. The EGPS (Exhaust Gas Pressure Sensor) controls the differential pressure between the gases entering the particle filter. FAE has been a manufacturer of these sensors since 2013, and is a pioneer of this type of sensor in the aftermarket. The EGPS are manufactured under strict quality controls in the aforementioned ESD Room.

 

· FAE exahust
gas pressure sensor.



7. HOW DOES IT CONTROL THE PRESSURE OF A TURBOCOMPRESSOR?

When the FAE turbocharger boost pressure sensor detects that the charging pressure has increased to the maximum value, the ECU regulates the pressure valve by sending part of the exhaust gas directly to the exhaust pipe, without passing through the turbocharger turbine, which limits the pressure in the intake manifold. The FAE boost pressure sensor measures pressure ranges of up to 400kPa and allows the control unit to measure and control the amount of compressed air in the intake pipe.
 

 
· FAE boost pressure sensor.