1. Definition of marine diesel engine failure

Marine diesel engine is a kind of complex thermal machinery. The working conditions are complex and harsh. Therefore, it is inevitable that faults occur in use. The accident that the marine diesel engine loses the specified function becomes the marine diesel engine fault.

The scope of marine diesel engine failure includes two aspects:

⑴ Destructive failure causing immediate loss of function of marine diesel engine. Such as bushing burning and cylinder holding of marine diesel engine.

⑵ The performance of marine diesel engine is reduced due to the performance degradation. For example, the marine diesel engine emits black smoke and the fuel consumption increases.

2. Classification of marine diesel engine faults

Marine diesel engines can be classified from different aspects.

⑴ Essential fault Under the specified service conditions, the fault caused by the inherent factors or defects of the marine diesel engine and its parts in the province becomes an essential fault. For example, the cylinder liner of marine diesel engine is corroded and the connecting rod is broken.

(2) Misuse fault refers to the fault caused by not using according to the specified conditions or external factors. For example, tile burning is caused by insufficient lubricating oil level.

(3) Dependent fault Derivative fault caused by a fault. Also called a related fault. For example, the engine body cracks caused by the fracture of connecting rod bolts.

2.1 According to the severity of the fault and the harm caused, the marine diesel engine fault can be divided into four categories: nominal fault, serious fault, general fault and minor fault.

⑴ Fatal fault Any fault that causes important parts to be scrapped and causes personal injury or major economic loss is called fatal fault. It is also called dangerous fault. For example, the connecting rod bolt is broken and the engine body is broken.

(2) Serious fault Where the main performance indicators of the marine diesel engine exceed the limit value, the fault can be eliminated only after the main parts are damaged or disassembled. For example, the fuel consumption of marine diesel engine is too high, and the piston ring is broken.

(3) General fault Where the marine diesel engine needs to be shut down for maintenance, and non major parts need to be replaced, the fault that can be eliminated with accompanying tools is generally called minor fault. Such as three leaks (air leakage, water leakage, oil leakage), cover plate damage, etc.

(4) Mild fault refers to the fault that generally does not cause the shutdown of the marine diesel engine, does not require the replacement of parts, and can be eliminated in a short time with accompanying tools. For example, the sealing part of marine diesel engine leaks, and the cover plate screws are loose.

2.2 Classification of marine diesel engines according to the time of failure can be divided into sudden failure and gradual failure according to the time of failure.

⑴ Sudden fault occurs suddenly in a short time and cannot be predicted by early diagnosis. For example, the connecting rod bolt is broken and the valve spring is broken.

⑵ Gradual fault occurs in a gradual process, which can be predicted through early diagnosis. Such as cylinder liner wear, valve leakage, etc.

2.3 Classification of marine diesel engines according to the location of the failure can be divided into two categories: overall failure and component failure.

⑴ Complete machine fault is also called comprehensive fault. It affects the performance of the whole machine for comprehensive reasons. Such as difficult starting, insufficient power, runaway, unstable speed, abnormal pressure, etc.

⑵ Component failure refers to the failure of a part. For example, the gear is broken and the pump capacity is too small.

2.4 Marine diesel engine faults are classified according to their causes and phenomena. Marine diesel engine faults can be divided into wear faults, misuse faults and weak faults according to their causes and phenomena.

(1) Wear failure The failure caused by excessive wear of friction pair is called wear failure. This kind of fault can be predicted in the normal wear process under normal use conditions. If the piston ring is excessively worn, resulting in serious air leakage, insufficient power, etc., such failures will not generally cause serious consequences.

(2) Misuse fault Under actual service conditions, the fault caused by the load exceeding the original design capacity is called misuse fault. For example, the overload use of marine diesel engine causes black smoke, shafting fracture, etc.

(3) Weak fault Under actual service conditions, the load generated does not exceed the design capacity, but the fault that causes some weak links and parts to lose their working capacity is called weak fault. This kind of fault often occurs on newly developed models. It is generally manifested as damage of parts, fracture of shafting and support, etc.