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Power unit – engine
Published in Andrew Livesey, Practical Motorsport Engineering, 2019
The inlet and the exhaust valves each open once every two revolution of the crankshaft. The mechanism for opening the valves is a camshaft, which is either direct acting on the valves; or operates them through a pushrod and a rocker shaft assembly.
Complex product configuration updating oriented by changing customer requirements
Published in Journal of Engineering Design, 2023
Na Zhang, Wei Gao, Yupeng Li, Qiuyue Wang
The above-coordinated model is solved using a nested GA above. The initial change intensity is set to 3, the cross-module penalty factor is 1, the upper population is 60, the number of iterations is 30, the lower population is 60, and the number of iterations is 80, and the upper and lower crossover and variation probabilities are 0.8 and 0.1. The adjustment factor for the propagation probability μ is set to 1.8. The optimal product configuration scheme is presented in Figure 12 and the layered iterative process is shown in Figure 13. The optimal change propagation path is [1 5 11 12 8 7 9 10], and the corresponding updated configuration scheme is [5 2 3 3 1 1 3 3]. Its objective function value f is 0.315, and the changing difficulty DI = 0.95. That indicates that the optimal configuration update path of this motorbike engine is cylinder block (v1) – camshaft (v5) – timing chain/belt (v11) – crankshaft gears and camshaft gears (v12) – valve spring (v8) – valve (v7) – rocker arm (v9) – pushrod (v10). And the optimal update scheme is stainless steel cylinder (u15), magnesium camshafts(u52), magnesium chain (u113), copper gear (u123), aluminum valve spring (u81), aluminum alloy valve (u71), copper rocker (u93), copper actuator (u103).
Mathematical modeling and optimization of transverse heat sealing and cutting mechanism
Published in Journal of the Chinese Institute of Engineers, 2022
Mi Li, Xu-Hui Zhang, Jian-Qiang Yan
In the cam mechanism, when a roller pushrod is used, the radius of the cam working profile is equal to the difference between the radius of the cam theoretical profile and the roller radius. If the minimum radius of the cam theoretical profile is equal to the radius of the roller, the minimum radius of the cam working profile will be zero. This means that the cam working profile will have a sharp point. What is more serious is that when the roller radius is greater than the minimum radius of the cam theoretical profile, the minimum radius of the cam working profile will be a negative value. This will cause the pushrod to fail to achieve the expected motion. Therefore, it is necessary to limit the minimum radius of the cam theoretical profile.
Experimental investigation of Te addition on chilled cast iron tappet manufacturing process
Published in Materials and Manufacturing Processes, 2021
The tappet, alternatively termed as cam follower or valve lifter, is the part that runs on the camshaft and is made to move vertically following the rotational profile of the cam. The tappet drives a long, thin pushrod that actuates the rocker arm, making the valves go downwards to open them. Being the most important functional part of an engine, the quality of the tappet has become a critical issue for engine performance. Typically the tappet surface undergoes many defects such as pointed pitting, desquamation, corrosion due to substantial surface contact, high sliding speed between the camshaft lobe and cam lifter, and high temperature caused by the mechanical movement. These defects result in the catastrophic failure of tappet material.[1]