Failure analysis of an overhead valve train system in urban buses

Godiño, José Antonio Vélez; García, Miguel Torres; Aguilar, Francisco José Jiménez-Espadafor; Guerrero, Daniel Palomo

doi:10.1016/j.engfailanal.2018.11.003

Cited by 10 publications

(3 citation statements)

References 14 publications

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“…Overall, the wear behavior was independent of the type of cams used for assessment. Godino et al [8] analyzed the recurring major failure in the valve train system (engine valves opening/closing system) of 130 buses (out of 400 urban buses fleet) and reported excessive damage on the cam nose, especially after 500 thousand km. The reasons for the failures, after a systematic analysis, were declared to be a combination of wear (low hardness of the cam nose) and fatigue cracking in the cam subsurface.…”

Section: Introduction (Gi̇ri̇ş)mentioning

confidence: 99%

Ceramic Particle Reinforced Camshaft Lobes: A Performance Evaluation and Comparative Analysis

Cerit,

Nair,

Zafar

2024

Gazi Üniversitesi Fen Bilimleri Dergisi Part C: Tasarım Ve Teknoloji

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Ceramic reinforced metal matrix composite (CMMC) cams in engines could improve fuel efficiency and wear resistance compared to traditional steel cams but require absolute evaluation. However, ensuring safe CMMC cam operation demands extensive wear testing, mimicking real-world conditions over longer durations instead of limited lab evaluations. This study is an extension of the previously reported feasibility analysis of the ceramic particle reinforced Al matrix composite labs. The performance of the best selected (Al + 20, 30 vol. % SiC(2µm)) composites for a wear duration of 2.5, 5, 7.5, and 15 h is reported with various combinations of pressures and compared with the reference cam lobes. Results showed that the higher content of ceramic particles improved the wear resistance, however, the influence diminished at larger durations due to surface hardening of the composites. The wear performance of the composite (Al + 30 vol.% SiC) reaches 73% of the conventional cams but it also causes significant wear in the counterface due to initiation of three-body-wear by the dislodged ceramic particles.

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Section: Introduction (Gi̇ri̇ş)mentioning

confidence: 99%

Ceramic Particle Reinforced Camshaft Lobes: A Performance Evaluation and Comparative Analysis

Cerit,

Nair,

Zafar

2024

Gazi Üniversitesi Fen Bilimleri Dergisi Part C: Tasarım Ve Teknoloji

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“…Due to the physically interacting nature of the cams' operation, wear appears to be the primary functional issue that needs proper addressing. 3 Other than the postmanufacture in-place solutions such as appropriate lubrication, tolerant spring tension, compliant hydraulic lifting mechanism and clean oils; little attention is given to utilizing alternate materials to reduce the wearing of cams. 4 Conventional materials of choice for cam manufacturing are high alloy steels [5][6][7] and cast iron.…”

Section: Introductionmentioning

confidence: 99%

Comparison of the surface morphologies of ceramic reinforced metal matrix composite cams after wear tests under dry and wet conditions

Cerit

Nair

Zafar

et al. 2023

Journal of Composite Materials

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The integral engine parts, such as camshaft members, are usually not preferably made of ceramic-reinforced MMC because the margin of compromise on the engine performance is small. However, the lightweight and wear-resistant nature of the mentioned materials can benefit fuel consumption without necessarily compromising engine performance. In this study, Al (AA2124) matrix is reinforced with ceramic particles of two different types (SiC, B4C), size distributions (B4C: 1–7, SiC: 2 and 20 μm), and volume fractions (0, 10, 20, 30 vol.%) to manufacture camshaft cams (lobes). While MMC cams are manufactured by powder metallurgy (300 MPa, 615°C, 30 minutes), spherical graphite cast iron (GGG40) cams are prepared by casting, induction hardening, and machining. The wear behavior of MMC cams is compared with the reference unreinforced AA2124 and conventionally used cast iron cams under dry and virtually created engine-like wet conditions. It was attempted to correlate the percentage increase in the roughness and weight loss with the structure of the cams using SEM, EDX, and macroscopy analysis. Results showed that the initiation of a three-body abrasive wear mechanism for 30 vol.% of the larger SiC particles caused lower wear resistance in the cams under dry conditions. As for the wet conditions, although the cams’ wear resistance increased with increasing ceramic particles’ content, it resulted in enhanced wear in the counterface when larger ceramic particles were used as reinforcement. Overall, higher ceramic content and larger particle size encourage three-body abrasive wear between the interacting surfaces and assist in degraded wear resistance under wet conditions.

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“…The overhead-valve train system in the diesel engine consists of a camshaft, tappet, pushrod, rocker arm, upper retainer, valve spring, fixed retainer, valve guide, valve, and valve seat [1]. The camshaft is used to open and close the intake and exhaust valves of the diesel engine at certain intervals.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Surface Hardening on The HQ 705 Steel Camshaft Using Static Induction Hardening and Tempering Method

Nugroho

Fitriyana²,

Ismail³

et al. 2022

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Induction hardening (IH) is a popular choice for automotive components such as camshafts for its ability to harden portions of a component selectively. The camshaft will contact the tappet, connected to the rocker arm, to open and close the valve whenever the engine is running. This contact between the camshaft and the tappet causes wear on the camshaft surface. IH of the camshaft is required to improve wear resistance and service life, as well as core elasticity to absorb high torsional stresses. It is known that studies about IH on camshafts are still very limited. This study aims to determine the effect of the induction hardening and tempering treatment on the mechanical properties of the camshaft made of HQ 705 steel. The induction hardening carried out in this study uses different parameter settings such as heating time and output current. The camshaft specimen is hardened by static induction and then quenched in oil. The specimens are tempered after induction hardening with different temperatures and holding times to adjust the hardness level and reduce brittleness. Hardness, macro photographs, micrograph, and wear tests were conducted to determine the mechanical properties of the camshaft specimen after the induction hardening and tempering process. This study indicates that induction hardening with an output current of 747 A for 15 seconds followed by tempering at 150 °C for 15 seconds on specimen 1 produced the best mechanical properties. On the surface of these specimens found more martensite content while there was no microstructural change on the inside. The surface hardness of these specimens is 44 HRC (Rockwell C Hardness), while the inside is 26 HRC. Meanwhile, specific wear decreased by 45.45%.

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Failure analysis of an overhead valve train system in urban buses

Cited by 10 publications

References 14 publications

Ceramic Particle Reinforced Camshaft Lobes: A Performance Evaluation and Comparative Analysis

Ceramic Particle Reinforced Camshaft Lobes: A Performance Evaluation and Comparative Analysis

Comparison of the surface morphologies of ceramic reinforced metal matrix composite cams after wear tests under dry and wet conditions

The Effect of Surface Hardening on The HQ 705 Steel Camshaft Using Static Induction Hardening and Tempering Method

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