The Importance of Exhaust Sense and Control in Engine Management

Exhaust Sensors

Exhaust related sense and control components showing rapid increase in demand.

Increasingly stringent Euro Emission Standards have had a profound effect on aftermarket engine management demand as sales of exhaust related sense and control components show significantly faster growth than their EMS counterparts.

Vehicle manufacturers now rely on a host of electronic components to achieve cleaner combustion but as these components have to operate in some of the most hostile environments of the vehicle, they are highly prone to failure.

As a supplier with a complete engine management product portfolio, ELTA Automotive has seen a definite shift in the product pareto as exhaust sense and control components climb the ranks.

The EGR (Exhaust Gas Recirculation) Valve product group for example is now the second biggest and continues to show the fastest growth.

Here is a brief overview of our most popular exhaust related sense and control components.

 

 

EGR Valves

EGR Valve with Cooler

Fundamentally the EGR valve reduces harmful nitrogen oxides (NOX) emissions from our exhausts. This helps vehicle manufacturers to meet increasingly stringent environmental targets set by European Regulations.

NOX is produced when combustion temperatures exceed 2500°F and nitrogen begins to react with oxygen.

The EGR valve helps keep temperatures below the NOX threshold by recirculating a small amount of exhaust gas back through the combustion process.

This dilutes the incoming air/fuel mixture and cools combustion temperatures resulting in reduced NOX emissions.

The most common cause of EGR valve failure is carbon deposits that cause clogging or sticking. The valve may stick open or closed.

Lambda Sensors

Lambda O2 Sensor

Lambda sensors were first fitted to cars in 1977 to improve the efficiency of combustion engines and help to reduce harmful exhaust emissions such as carbon monoxide.

Lambda sensors operate by measuring the amount of oxygen in the exhaust. An efficient engine requires a specific amount of air and fuel in its cylinders at combustion. The perfect ratio being 14.7:1 (14.7 parts air to 1 part fuel). This perfect mixture is called Lambda and this is where the unusual name originates.

The levels calculated by the Lambda are sent as data to the ECU which then calculates and determines how best to achieve the ideal mixture of air and fuel at combustion.

Many will simply fail due to age. The lifespan tends to be 45,000 miles for an unheated sensor, a heated sensor can typically last closer to 100,000 miles.

EGTS

EGTS Sensor

The Exhaust Gas Temperature Sensor (EGTS) is simply a thermistor element fixed in cement to protect from vibration and housed in stainless steel to withstand extreme temperatures of up to 900°C. Changes in temperature result in changes in resistance of the sensor and this is communicated to the ECU as a voltage.

Exhaust Gas Temperature sensors protect vital exhaust components from overheating and help to control emissions. They are also used in several combustion control processes in both diesel and petrol engines including Selective Catalytic Reduction (SCR), Turbo Boost, Exhaust Gas Recirculation and Diesel Particulate Filter (DPF) Regeneration.

The Exhaust Gas Temperature sensor can be subjected to intense heat of up to 900°C so it’s no surprise that they may start to suffer over time.

EBP Sensor

EBP Sensor

The Exhaust Gas Pressure Sensor or Exhaust Back Pressure Sensor (EBP) is a key component in the Diesel Particulate Filter (DPF) regeneration process.

The DPF traps Particulate Matter (PM) and soot, preventing it from harming the environment.

The EBP monitors the pressure before and after the DPF to identify a difference in pressure caused by a build up of PM (soot). It then instructs the ECU to initiate DPF regeneration.

The range also includes 10 Exhaust Gas Pressure Sensors covering over 3.5 million vehicles on UK roads. The EGPS plays a vital role in the regeneration of the Diesel Particulate Filter and so all sensors are built to original equipment specifications to ensure maximum longevity of the DPF.

 

 

Fuel Vaporizer

Fuel Vaporizer

DPF regeneration requires extremely high temperatures for soot to be removed from the DPF by combustion. When normal driving conditions do not allow for this temperature to be reached in the exhaust system additional processes must be introduced to raise the heat. Traditionally, post injection of unburned diesel fuel into the combustion chamber provides the catalyst and raises temperatures. However, this has been found to cause oil dilution leading to premature engine wear or more frequent servicing.

Fuel Vaporizers go some way to solving this problem, lowering emissions whilst prolonging engine life. Rather than being injected directly into the combustion chamber, fuel is directed to the Fuel Vaporizer. The Vaporizer then uses an integrated, electrically heated glow plug to evaporate the fuel before injecting it into the exhaust gas stream ahead of the catalytic converter/ diesel oxidation catalyst. Vaporized hydrocarbons are then burnt on the catalytic converter, releasing energy from exothermal chemical reactions and raising the temperature before the DPF allowing for regeneration to occur without oil dilution or the need for additional cooling.