Engine Camshaft Research Articles

캠축의 구조 진동 응답 및 응력

캠축의 진동 응답을 구하기 위해 캠축을 불균형 다단계 로터 베어링계로 해석하였으며, 복잡한 형상과 하중조건을 고려하여 유한요소법을 사용하였다. 유한요소 방정식을 유도한 후에 Newmark 법을 사용하여 진동 응답을 구하였다. V-8 엔진 캠축의 회전 진동 응답을 구하여 측정치와 비교하였다. 캠축의 변동 응력을 구하고, 응력 집중 효과를 고려한 다음에 Goodmann 식에 근거하여 피로 해석을 수행하였다. 캠축의 회전 진동에서는 굽힘 효과가 지배적이며, 인접하는 베어링 간격에 가장 큰 영향을 받는다. 캠축에 가해지는 하중의 변화가 클 경우에는 하중의 변화에 상응하여 시간에 따라 변화하는 베어링 계수를 적용하여야 함을 알 수 있었다. To get vibration responses, a camshaft is modelled as an unbalanced multiple rotor bearing system. Because of complex geometry and complicated load conditions, the finite element method is used. After the finite element equation of the system is constructed, Newmark's method is used to get the vibration responses. Whirl vibration responses of a V-8 engine camshaft are estimated and compared with measured responses. After the fluctuating stresses are obtained, fatigue analysis is performed based upon the modified Goodman's equation. Stress concentration effects are considered. In the whirl vibration of camshafts, the bending effect is dominant, and the bending deformation is dependent upon the span length between the adjacent bearing journals. For high speeds, the fluctuations of excitation forces are large, and it is known that nonlinear time varying bearing coefficients should be used for analysis.

Analysis of Engine Camshaft Bearing Loosening Fault Based-on Model Simulation and Vibration Signal

Virtual technology is used for simulation analysis of engine camshaft bearing-loosening fault. Firstly, dynamic model of engine powertrain and its valve-train is established, and then the model parameters could be set to simulate the camshaft bearing loosening fault, so the vibration acceleration signals on engine cylinder head can be obtained by simulation calculation. Then by analyzing and comparing with the vibration signals in the normal state, camshaft bearing-loosening fault features are extracted. The analytical result based-on model simulation and vibration signal is used to guide the actual engine fault diagnosis.

Analysis of a Cracked Diesel Engine Camshaft

A truck diesel engine camshaft was found cracked following a straightening operation after the camshaft was carburized. The camshaft is made of 16MnCrS5 steel and was required to be surface-carburized. The cracking occurred just at the transition fillet root of a cam at a near middle position on the camshaft. This location bore the maximum tensile stress in the straightening process, a process involving three-point bending. The crack surfaces once exposed exhibit cleavage morphology, indicative of brittle fracture as the failure mechanism. Microstructural observation revealed an intergranular network of carbides and intergranular microcracks present in the carburized layer and a banded structure consisting of ferrite and pearlite in the core. These metallurgical defects decreased the deformation capacity of the carburized camshaft, in fact creating a “metallurgical stress concentration” that promoted the cracking of camshaft.

Restoration of combustion engine's camshafts with plasma welding

A technology of engine's camshafts restoration by plasma welding is brought. Structure and hardness of built-up metal are described. Comparative evaluation of results of the laboratory testing of samples is presented.

마그네틱 픽업 방식의 CPS 신호 해석 회로에 관한 연구

The basic signals for electronic engine control are velocity and degree of the engine cam shaft. The CPS sensor used for this signal and magnetic pick-up type CPS sensor is more popular. It is very important thing analyze this signal correctly. If there are some mistakes at the analysis, like a noise, The engine do not working at the best status, it will generate some noise, emit exhaust fumes and waste more gases. In general way to analysis this signal, you use zero-level detector circuit and in order to reduce the error you must use another sensor like a TDC sensor. In this paper, We proposed the analysis method using electronics circuits for magnetic pick-up type CPS sensor. We designed Comparison level detector circuit, Differential circuit and Full-rectifier circuit for detected the Long tooth and Short tooth level correctly without another sensor. We expected it is useful for more reliable engine control.

English

Camshaft is one of the key parts or components in the engines of automobile and other vehicles. Due to the cyclic impact loading on the contacting surfaces of the cam and the follower, it often gives rise to premature wear of cam profile and affects a routine run of the valve gear such as the rotational speed, valve displacement and the torque. The objective of this work was to study experimentally the residual stresses at the surface layer of induction hardened cylindrical specimens. The diesel engine camshafts are generally made by EN19 Steel material. However, EN19 steel material has low wear resistance and its service life is shorter. ReplacingEN19 steel with EN41B steel. The results obtained from hardness test indicated that the hardness of the Nitride steel EN 41B is 31% higher than EN19 Steel before induction hardening and the hardness of the Nitride steel EN41B is 45% higher than EN19 steel after induction hardening. Impact test indicated that the toughness of Nitride steel EN41B is 38% higher than EN19 steel.

Day-to-Day Challenges of a Shipping Company From the Technical Department’s Point of View: Lessons Learned

Working for one of the largest shipping companies in Greece is not an easy task. The challenges from the day-to-day vessel operation never stop and the maritime environment, which grows more challenging by the day, demands that the technical department is on a constant state of alert. The paper discusses the lessons learned from the many years of the authors' combined experience in the technical departments of a bulk carrier operator and of its tanker counterpart. The most interesting and diverse cases are outlined together with the conclusions and the necessary alterations to the procedures and work practices established as a result of the experiences gained. The following cases are examined:propeller damage on a Capesize bulk carrier from inherent casting defects,main engine camshaft problems originating from initial poor design,cracking of main engine bedplate bearing girders on a very large crude carrier (VLCC) attributed to unauthorized repairs and casting defects,failure cases of fitted bolts in marine applications,premature failure of main engine piston crowns, andsea chest ballast valve problems on a VLCC attributed to poor detail design.

Fatigue Failure of Sychronous Belts for Automobile under Fluctuating Torque.

Fatigue failure of synchronous belts is investigated under fluctuating torque conditions, because the driving torque fluctuates in the automotive engine camshaft drive-systems. There are two types of fatigue-failure modes. The first mode is de-bonding along the interfaces between the stranded glass filaments in cords. The initiation of the de-bonding is explained by the cyclic bending deformation when the belt is wound around pulleys and transmits the power. A simplified mechanical model is proposed to explain the failure mechanism. The second mode is crack initiation between the cords and the facing fabrics. Further investigation is necessary to reveal the second failure mode.

Restoring diesel engine camshafts by laser treatement

The reliability of parts of the gas-distributing mechanism and drives of fuel pumps determines to a great degree the operating conditions of cylinder-piston parts and the economic characteristics of diesel engines. Intense wear of the camshaft pair disturbs the distribution phases and the lead angle of fuel supply to the diesel cylinders and increases the rigidity of the operation of the connecting rod-piston group. This causes incomplete combustion of fuel and fuming, a rise in the temperature of exhaust gases, sticking of the rings in the piston grooves and their premature failure, wear cracks, and chips and failure of the parts of the cylinder-piston unit, decreasing the efficiency of the diesel. Laser surface treatment is used to restore cams. It makes it possible to increase substantially the wear resistance of cams and restore their worn surfaces. This paper concerns the characteristics of the cams after such a treatment.

Development of Remelted Alloying Technique for Automobile Engine Camshafts

Development of Remelted Alloying Technique for Automobile Engine Camshafts

On the Stability of Chain Drive Systems Under Periodic Sprocket Oscillations

Experimental observations have shown that periodic torsional oscillations of engine camshafts induced by powertrain loads can cause significant tension variation in the timing chain and magnify the chain transverse vibrations and noise level. This result indicates that the sprocket dynamic characteristics and the chain vibration behavior are closely coupled. The chain drive models to-date are not able to address these phenomena. This paper presents a nonlinear model of an integrated chain drive system which couples the sprocket motion with the transverse and longitudinal vibration of the axially moving chain spans. With this model, the effects of the sprocket shaft periodic loads upon the total system are investigated. It is concluded that the sprocket oscillations will cause chain longitudinal vibrations. This could destabilize the system and induce the chains to undergo large transverse vibration. Both the subharmonic and summation types of parametric resonance are found and the instability regions are derived. The effects of various system parameters, such as the sprocket inertia, the chain speed, and the speed dependent excitation frequencies upon the instability regions have been studied. The significance of the gyroscopic terms of the stability boundary has been shown.

Investigation into the effects of waviness present on the cam surface profile of an engine camshaft

The results of an investigation into the effects of wavy surface topography on the wear and oil retention characteristics of the bearing surface of an automobile camshaft are presented. The cam surfaces were traced in the pre-worn and worn conditions, using a Talysurf 5 measurement instrument which has been developed to enable both two and three-dimensional measurements. Examples are presented showing the effects of waviness on surface performance when under wear. It is shown that similar oil retention values can be achieved in a surface with waviness removed. Also, the unwavy topography presents an improved area of contact which, it is suggested, would give a more even wear pattern.

Device for the complete inspection of I-C engine camshafts

Now that this device has been made at the Central Tools Laboratory of the plant, only every 500th shaft is inspected instead of every 50th shaft as previously. Only 2–3 shafts are inspected in order to detect any possible defects in the manufacturing process of the camshafts, per shift.

Profile Turning

THE machining of profiles on such pieces as the cams of internal‐combustion engine camshafts presents a problem which can be solved in two ways. The original method was to attempt to machine these portions of the shaft in the normal way, providing a special rocking tool‐holder in order to ensure that the cutting angle of the tool remained constant. The diagram fig. 1 shows one example of German practice in this respect, from which it will be seen that the tool‐holder for each cam is of the rocking type, whose angle of tilt is under the control of a large master cam, timed to give one revolution for each revolution of the workpiece, and which during that revolution constantly varies the degree of tilt and consequently the angle of presentation of the tool to the piece. Apart from this, the profile of the cam also necessitates a series of advances and withdrawals of the tool for each revolution of the piece; this is controlled by a somewhat similar master cam at the rear of the tool‐holder. From the foregoing, it will be seen that although the difficulties of machining are overcome, it is only by somewhat cumbersome and extremely expensive methods on a very special machine.