Engine design process | Reliable and durable engine
Making sure that the product has adequate efficiency and performance is an integral part of the engine design process. Durability refers to the usable life of the engine. This is the life-to-overhaul average for the engine system. For most of the main engine parts, as the engine is overhauled, there is an assumption of reuse. Reliability also involves infant mortality and unexpected complications involving attention to the operating life of the engine.
To ensure that the standards of longevity and reliability are fulfilled, engine design and construction must involve validation procedures. For the performance of every engine construction, the success of this effort is crucial.
Consider the need for the reliability of the cylinder head as an example. Being major component of the engine, and for the useful life of the engine, it must perform its duties without problems. It is normally anticipated that the cylinder head will not be removed but will be reused if the engine is overhauled.
The cylinder head is a dynamic feature that is subjected to a number of loads at the same time, including friction, combustion temperature and high amounts of head bolt clamping loads and press-fit loads at valves seat. Cylinder head cracking can result in either of these loads, singularly or in combination. The engine would easily build a bad reputation among consumers if such cracking happens even as infrequently as once in 1000 heads.
tIt is incredibly difficult to eradicate a reputation for head cracking which can result in an ineffective product, it must be replaced or greatly redeveloped before the tooling expenditure is recovered. This example illustrates, ensuring that the design validation is confirmed is completely necessary. Before the engine is released into development, the procedure determines all acceptable possibilities for insufficient reliability or efficiency.
The complexity of a given engine component and the combination of loads to which it is exposed have been indicated in the example just presented. Complexity of development becomes more challenging by combination of control of material property, control of production processes, and the number of client violations that may or may not have been thoroughly expected.
Usually, the structural analysis method is focused on the nominal or planned properties of the material and on the presumption that the component will be produced as defined in the design drawings. either of these assumptions are fully correct, and the analysis method must contain deviations from the nominal conditions. Throughout the development process, this involves working together with the engineers and material vendors to ensure that process and specification regulation limits are chosen based on the actual requirements for durability and reliability.
Over-specifying and under-specifying limits of control both add expense to the product. Conservative decisions in engineering frequently lead to over-specifying limitations on both material and manufacturing control limits. This is always required due to remaining unknowns in the validation process, but it has become an increasingly valuable one. More available comfort. The engineer faces forecasting the innovative ways in which the client could use the product if the difficulties just mentioned are not adequate. In planning for efficiency and durability, this remains the biggest unknown, and also the cause of the greatest aggravation.
Many components of the engine need any attempt to remove any risk of failures. Cylinder blocks, crankshafts, and flywheels falls into same group as the cylinder head example mentioned earlier.
In the parts like connecting rods, pistons, camshafts and bearings exceptionally low failure rates are allowable and hence every effort must be made for this. At some point, however the cost of production and the price of parts become Compared to what the consumer is prepared to pay for the goods . Taking as extreme example , Engine which is completely assured to work with only limited care and no failures for the life of the product.
The engine should be over-designed enough to allow this promise, and before the price is announced, it will sound very enticing to the buyer. Nearly any buyer will then select the much less costly option sold by the competition, and will expect the possibility of needing any maintenance over the life of the car. Achieving the optimum balance between acceptable repair rate and acceptable initial price is very challenging task involving thorough consumer and market study and comparative review of repair rates.
An planned engine maintenance rate and a warranty accrual that is factored into the engine’s original sale price are the product of the process. The buyer initially pays a cheaper amount for the engine and then pays for an insurance scheme (warranty accrual) to help cover for the possibility of product issues. The “extended warranty” for several engines and cars currently sold at extra expense supports this idea.
Usually, the repair rate is recorded in “repairs per hundred,” the cumulative number of repairs per 100 engines made. This figure is also broken down further by individual components of the engine. Tracking repairs a hundred per individual part and allowing design adjustments to enhance components with high maintenance rates is a significant feature of the continued growth of an engine after it goes into production, while not raising or better yet further reducing the costs where necessary.