Ny mät-trigger i Scanias motorprovning
Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
One of the main functions of Scania CV’s engine testing facility in Södertälje is to make sure that the quality of every produced engine is guaranteed before delivery to its customers. All of the engines are driven in a brake test bench where their power is measured at a low and a high rpm specified for every single different engine. In the existing process, start of the measurement is determined by the temperature of the oil in the engine sump. It is desirable to gather data after the point where the engine has reached thermal stability. However, this is not possible because of time constraints and the data must be collected during warm up. As the engine’s power varies during this phase it is important that data gathering for every separate run takes place on the very same point if repeatability is to be guaranteed. In the present situation it is uncertain if so is the case partly because of the different oil pan designs that could affect the measurement position. In this thesis a study was made at Scania CV AB on how well the current method of measuring the engine’s power works in comparison to potential replacements. By investigating how the thermal state of an internal combustion engine can be measured in different ways a number of concepts were chosen as possible substitutes. Based on an investigation of prevailing problems and procedures a set of requirements was established that clarified the demands that a solution had to meet to be accepted as a new measurement trigger. On this basis a larger amount of runs took place in which data were collected for analysis. The collection of data was carried out in a total of three sets; one with repeated measurements on two analysis engines to investigate the repeatability concepts in between, then one with engines from regular production in order to verify the results obtained from the first round and finally a set where data was collected from all of the engine test cells to study the influence of external factors.The collected data were evaluated statistically by the median, interquartile range and range for the difference in power between runs in terms of percentage of the current engine’s nominal maximum power. By performing this analysis in each point throughout the warm up phase, for every concept and engine model separately, detailed graphs showing the spread of measured power were received.The analysis showed that there seemed to be no significant difference between the different concepts in terms of repeatability. A slightly higher repeatability could be achieved by changing the measurement trigger, but not without the risk of various problems emerging. At the same time no indication that the alleged problems with the current measurement trigger actually exists could be found. All the pros and cons of each concept were put together in a so-called concept scoring matrix where a ranking was created. The current method was ranked highest and was recommended for continued use in the engine test facility.
Place, publisher, year, edition, pages
2011. , 101 p.
Teknik, Bilsystemteknik, Motorprovning, Scania, Automotive, Engine testing
IdentifiersURN: urn:nbn:se:ltu:diva-55805Local ID: ca0d22e2-8f9b-4cf4-a944-2a6da98fda51OAI: oai:DiVA.org:ltu-55805DiVA: diva2:1029189
Subject / course
Student thesis, at least 15 credits
Automotive Engineering, bachelor's level
Validerat; 20110430 (anonymous)2016-10-042016-10-04Bibliographically approved