Less downtime and an optimized combustion process is achieved by monitoring the combustion diagnostics. Several engine hazards are explained on this page that are monitored by the Combustion Pressure Based Control (CPBC). The figure below shows an example of a pressure trace given by a Combustion Pressure Sensor (CPS) during one combustion cycle. This data is used for the combustion diagnostics for ArenaRed’s CPBC.
Knock occurs when the air/gas mixture auto-ignites before the power stroke. The combustion process with engine knock develops much faster and much more violent than an ordinary combustion process, which causes the distinctive knocking sound. Knocking can cause severe damage to the engine, the rapid combustion process results in enormous pressure oscillations with high pressure peaks that induce more heat into the piston and on the valves and head. This will eventually lead to engine failure.
The CPBC possible with the ArenaRed CPBC chip and CPS detects knock in an early stage and eliminates knock per cylinder in every cycle.
Blowby is caused by a leak between piston and sleeve and can create a weld between the piston and sleeve, which is explained in the next section. Blowby can damage an engine beyond repair within a second. ArenaRed’s CPBC monitors blowby and when detected, the fuel feed is cut off to that particular cylinder to prevent damage. A message is send to the helm and/or the fleet maintenance service in order to plan maintenance and replace that particular piston and sleeve.
When a significant leak between piston and cylinder arises, the burning mixture starts flowing between piston and sleeve. The heat of this spray is similar to that of a cutting torch. The blowby will create a growing iron melt. As soon as this melt is too big to be kept above melting point by the blowby the melt will solidify. At that moment the piston is welded to the sleeve. This welding takes place within one stroke. When a four-stroke engine runs 1200 rpm there are ten combustion cycles per second. In the event of blowby, pressure loss in the compression stroke will be detected. If so, the fuel supply will be stopped instantly and can be fixed in a planned service without the loss of performance.
Thanks the monitoring systems such as blowby detection and CPBC in general, insurance companies could see a chance to lower its premium for engines equipped with ArenaRed's CPBC.
The peak combustion pressure is called the Pmax. When Pmax exceeds a certain value engine damage can occur. Exceeding Pmax will be detected by the CPBC and will be minimized by changing the injection strategy without the loss of performance.
When combustion starts too early, this is called pre-ignition. This can be caused by for example hot spots in the combustion chamber, such as an edge of the piston or glowing soot deposits. Another pre-ignition source is lubrication oil that slips into the combustion chamber and auto-ignites. This is a major concern in for example the EMD, where due to the two-stroke principle of the engine it has a higher chance of oil leaking into the combustion chamber than a four-stroke engine. This lubrication oil can auto-ignite and causes the gas charge to pre-ignite, which can lead to engine-damaging knock. ArenaRed’s CPBC monitors these events and makes sure that the appropriate measures are taken. The CPBC could for example advise to change that piston and sleeve and meanwhile let that cylinder run on diesel only to prevent engine knock.
Pressure Rise Rate (PRR)
Exceeding the rated Pressure Rise Rate (PRR) means that the pressure increase with respect to the crank angle is exceeding the engine specifications. Thermodynamically a high PRR is desirable but will also lead to excessive engine wear. The CPBC will monitor and control the PRR for obtaining an optimal efficiency with a controlled minimum amount of wear.
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