Assessment of Friction for Cam-Roller Follower Valve Train System Subjected to Mixed Non-Newtonian Regime of Lubrication

2012 ◽  
Author(s):  
A. Turturro ◽  
R. Rahmani ◽  
H. Rahnejat ◽  
C. Delprete ◽  
L. Magro
Keyword(s):  
Dynamic Model ◽  
Current Model ◽  
Fuel Efficiency ◽  
Valve Train ◽  
Design Parameters ◽  
Engine Fuel ◽  
Building Simulations ◽  
Model Combining ◽  
Cam Follower ◽  
Train System

The tribology of cam-roller follower conjunction is highly dependent on the engine type and working conditions. The interface experiences transient conditions due to variations in contact geometry and kinematics, as well as loading. These lead to instantaneous and capricious behavior of the lubricant through the contact, which determines the regime of lubrication. The resulting frictional characteristics are affected by the shear of the lubricant film and the interaction of rough surfaces themselves. Thus, specific analysis is required for any intended new engine configuration. Therefore, a tribo-dynamic model, combining valve train dynamics, contact kinematics and tribological analysis is required. An important issue is to develop a simple yet reliable and representative model to address the above mentioned pertinent issues. This would make for rapid scenario-building simulations which are critical in industrial design time-scales. The current model has been developed in response to the above mentioned requirements. A multi-body dynamic model for the valve train system based on the key design parameters is developed and integrated with an EHL tribological model for the cam-follower contact. To keep the model simple and easy to use and to avoid time-consuming computations, the analytical EHL model makes use of Grubin’s oil film thickness equation. Viscous and boundary contributions to friction are obtained as these account for the losses which adversely affect the engine fuel efficiency.

Dynamic Simulation and Test for the Valve Train Dynamics

2011 ◽  
Vol 117-119 ◽  
pp. 15-19 ◽  
Author(s):  
Cai Yun Guan ◽  
You Ming Chen ◽  
Wen Jie Qin
Keyword(s):  
Dynamic Model ◽  
Contact Stiffness ◽  
Quantitative Agreement ◽  
Measured Data ◽  
Valve Train ◽  
Parameter Determination ◽  
Cam Follower ◽  
Train Dynamics ◽  
Simulation Results

This paper presents the development of a dynamic model of the valve train of one engine. During the parameter determination of the model, finite element method is used to calculate the contact stiffness of the cam-follower . The simulation results of the model are compared with measured data of the valve train at same speed. Excellent quantitative agreement is found between the numerical and experimental results and the validity of the dynamic model can be verified.

A New Numerical Method for Developing the Lumped Dynamic Model of Valve Train

2015 ◽  
Vol 137 (10) ◽  
Author(s):  
Jie Guo ◽  
Yipeng Cao ◽  
Wenping Zhang ◽  
Xinyu Zhang
Keyword(s):  
Dynamic Model ◽  
Natural Frequencies ◽  
Valve Train ◽  
Frequency Range ◽  
Matching Method ◽  
Lumped Masses ◽  
Flexible Component ◽  
Train Vibration ◽  
Train System ◽  
Low Order

The dynamics of valve train is influenced by stiffness, size, and mass distribution of its components and initial valve clearance and so on. All the factors should be taken into consideration correctly by dynamic model and described qualitatively and quantitatively through mathematical variables. This paper proposes a new simplified method for valve train components, namely, mode matching method (MMM) for camshaft, pushrod, rocker arm, valve, and valve spring. In this method, the amount of lumped masses for each flexible component is determined based on its natural frequencies and the considered frequency range. As a result, the dynamic model of each component is required to match its low order modes within the considered frequency range. The basis of this method is that the contributions of each component to valve train vibration are mainly in the low order modes. The numerical model of valve train is verified by an experiment conducted on a motor driven valve train system.

A New Numerical Method for Developing the Lumped Dynamic Model of Valve Train

2014 ◽  
Author(s):  
J. Guo ◽  
Y. P. Cao ◽  
W. P. Zhang ◽  
X. Y. Zhang
Keyword(s):  
Dynamic Model ◽  
Natural Frequencies ◽  
Valve Train ◽  
Frequency Range ◽  
Matching Method ◽  
Lumped Masses ◽  
Flexible Component ◽  
Train Vibration ◽  
Train System ◽  
Low Order

The dynamics of valve train is influenced by stiffness, size and mass distribution of its components and initial valve clearance and so on. All the factors should be taken into consideration correctly by dynamic model and described qualitatively and quantitatively through mathematical variables. This paper proposes a new simplified method for valve train components, namely mode matching method (MMM) for camshaft, pushrod, rocker arm, valve and valve spring. In this method the amount of lumped masses for each flexible component is determined based on its natural frequencies and the considered frequency range. As a result, the dynamic model of each component is required to match its low order modes within the considered frequency range. The basis of this method is that the contributions of each component to valve train vibration are mainly in the low order modes. The numerical model of valve train is verified by an experiment conducted on a motor driven valve train system.

scholarly journals Conceptual Design of a Hydraulic Valve Train System

10.14311/248 ◽  
2001 ◽  
Vol 41 (4-5) ◽  
Author(s):  
J. Pohl ◽  
A. Warell ◽  
P. Krus ◽  
J.-O. Palmberg
Keyword(s):  
Integrated Approach ◽  
Valve Train ◽  
Design Parameters ◽  
Combustion Engines ◽  
Variable Valve Train ◽  
Critical Components ◽  
Variable Valve ◽  
Component Models ◽  
Train System

Variable valve train systems have been brought into focus during recent years as a means to decrease fuel consumption in tomorrow's combustion engines. In this paper an integrated approach, called simulation driven experiments, is utilised in order to aid the development of such highly dynamic systems. Through the use of systematic design methodology, a number of feasible concepts are developed. Critical components are subsequently identified using simulation. In this approach, component behaviour is simulated and validated by measurements on prototype components. These models are unified with complete system models of hydraulically actuated valve trains. In the case of the valve trains systems studied here component models could be validated using comparably simple test set-ups. These models enable the determination of non-critical design parameters in an optimal sense. This results in a number of optimised concepts facilitating an impartial functional concept selection.

scholarly journals Modeling and NVH Analysis of a Full Engine Dynamic Model with Valve Train System

2020 ◽  
Vol 10 (15) ◽  
pp. 5145
Author(s):  
Xu Zheng ◽  
Xuan Luo ◽  
Yi Qiu ◽  
Zhiyong Hao
Keyword(s):  
Dynamic Model ◽  
Cylinder Head ◽  
Power Level ◽  
Valve Train ◽  
Depth Study ◽  
The Difference ◽  
Engine Dynamic ◽  
Noise Vibration ◽  
The Impact ◽  
Train System

The valve train system is an important source of vibration and noise in an engine. An in-depth study on the dynamic model of the valve train is helpful in understanding the dynamic characteristics of the valve train and improving the prediction accuracy of vibration and noise. In the traditional approaches of the dynamic analyses, the simulations of the valve train system and the engine are carried out separately. The disadvantages of these uncoupled approaches are that the impact of the cylinder head deformation to the valve train and the support and constraints of the valve train on the cylinder head are not taken into consideration. In this study, a full engine dynamic model coupled with a valve train system is established and a dynamic simulation and noise vibration harshness (NVH) analysis are carried out. In the coupled approach, the valve train system is simulated simultaneously with the engine, and the complexity of the model has been greatly increased. Compared with the uncoupled approach, more detailed dynamic results of the valve train can be presented, and the subsequent predictions of vibration and noise can also be more accurate. The acoustic results show that the difference from the experimental sound power level is reduced from 1.8 dB(A) to 0.9 dB(A) after applying the coupled approach.

A Dynamic Model for the Design of Methanol to Hydrogen Steam Reformers for Transportation Applications

2004 ◽  
Vol 126 (2) ◽  
pp. 149-158 ◽  
Author(s):  
Gregory L. Ohl ◽  
Jeffrey L. Stein ◽  
Gene E. Smith
Keyword(s):  
Response Time ◽  
Dynamic Model ◽  
First Principles ◽  
Initial Conditions ◽  
Design Parameters ◽  
Physical Parameters ◽  
Steam Reformer ◽  
Powerful Means ◽  
Steam Reformers ◽  
Transportation Applications

As an aid to improving the dynamic response of the steam reformer, a dynamic model is developed to provide preliminary characterizations of the major constraints that limit the ability of a reformer to respond to the varying output requirements occurring in vehicular applications. This model is a first principles model that identifies important physical parameters in the steam reformer. The model is then incorporated into a design optimization process, where minimum steam reformer response time is specified as the objective function. This tool is shown to have the potential to be a powerful means of determining the values of the steam reformer design parameters that yield the fastest response time to a step input in hydrogen demand for a given set of initial conditions. A more extensive application of this methodology, yielding steam reformer design recommendations, is contained in a related publication.

Analytic Optimization of Cost Effective Thermoelectric Generation on Top of Rankine Cycle

2013 ◽  
Author(s):  
Kazuaki Yazawa ◽  
Yee Rui Koh ◽  
Ali Shakouri
Keyword(s):  
Steam Turbine ◽  
Fuel Efficiency ◽  
Cost Effective ◽  
Rankine Cycle ◽  
Energy Conversion Efficiency ◽  
Design Parameters ◽  
Steam Temperature ◽  
Combined System ◽  
Fuel Consumption Rate ◽  
The Impact

Thermoelectric (TE) generators have a potential advantage of the wide applicable temperature range by a proper selection of materials. In contrast, a steam turbine (ST) as a Rankine cycle thermodynamic generator is limited up to more or less 630 °C for the heat source. Unlike typical waste energy recovery systems, we propose a combined system placing a TE generator on top of a ST Rankine cycle generator. This system produces an additional power from the same energy source comparing to a stand-alone steam turbine system. Fuel efficiency is essential both for the economic efficiency and the ecological friendliness, especially for the global warming concern on the carbon dioxide (CO2) emission. We report our study of the overall performance of the combined system with primarily focusing on the design parameters of thermoelectric generators. The steam temperature connecting two individual generators gives a trade-off in the system design. Too much lower the temperature reduces the ST performance and too much higher the temperature reduces the temperature difference across the TE generator hence reduces the TE performance. Based on the analytic modeling, the optimum steam temperature to be designed is found near at the maximum power design of TE generator. This optimum point changes depending on the hours-of-operation. It is because the energy conversion efficiency directly connects to the fuel consumption rate. As the result, physical upper-limit temperature of steam for ST appeared to provide the best fuel economy. We also investigated the impact of improving the figure-of-merit (ZT) of TE materials. As like generic TE engines, reduction of thermal conductivity is the most influential parameter for improvement. We also discuss the cost-performance. The combined system provides the payback per power output at the initial and also provides the significantly better energy economy [$/KWh].

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