Recent internal combustion engines are gradually required to have high performance, high fuel efficiency, and reduced exhaust gas to meet the demands on the high oil prices and eco-friendly regulations. One of the technologies that can satisfy these requirements is Continuously Variable Valve Lift (...
Recent internal combustion engines are gradually required to have high performance, high fuel efficiency, and reduced exhaust gas to meet the demands on the high oil prices and eco-friendly regulations. One of the technologies that can satisfy these requirements is Continuously Variable Valve Lift (CVVL) mechanism, so that many engine researchers have been conducting the study of developing CVVL mechanism. However, the papers including the equations of the dimensional synthesis on CVVL mechanism have not been published until present day. In this thesis, new methods for the dimensional synthesis and analysis of the CVVL mechanism are proposed.
The CVVL mechanisms are divided into several unit mechanisms which can carry out an independent function, and then the kinematic equation for each divided unit mechanism is defined. The cam profiles are synthesized by substituting the given curve profiles into the defined kinematic equation.
In order to verify the validity of the synthesized cam profiles, the analysis of the radius of curvature and curvature for them were performed, and also a kinematic simulation for the synthesized model was performed using the commercial software. The peak valve lift of the CVVL mechanism with two cams is analyzed by using the pitch curve of the driving cam and the kinematic relation. In addition, a new method for the dimensional synthesis of the peak valve lift is introduced and applied to the new Four-bar CVVL mechanism, so that the peak valve lift can be set at the values that a designer wants.
The cam profile using conventional synthesis method on the CVVL mechanisms is expected to be obtained by iterative modifications, but the cam profile using the new dimensional synthesis method proposed in this thesis can be easily obtained once. Also, the characteristics of the CVVL mechanisms may be readily recognized using the new proposed analytical method of the peak valve lift. Furthermore, using the new proposed method for the dimensional synthesis of the peak valve lift, they can be set at the values that a designer wants, which is able to accurately control the amount of air intake and the advanced angle or retard angle. As a result, we can develop the internal combustion engine to have high performance, high fuel efficiency, and reduced exhaust gas by optimizing the air-flow motion depending on the engine operating conditions.
Recent internal combustion engines are gradually required to have high performance, high fuel efficiency, and reduced exhaust gas to meet the demands on the high oil prices and eco-friendly regulations. One of the technologies that can satisfy these requirements is Continuously Variable Valve Lift (CVVL) mechanism, so that many engine researchers have been conducting the study of developing CVVL mechanism. However, the papers including the equations of the dimensional synthesis on CVVL mechanism have not been published until present day. In this thesis, new methods for the dimensional synthesis and analysis of the CVVL mechanism are proposed.
The CVVL mechanisms are divided into several unit mechanisms which can carry out an independent function, and then the kinematic equation for each divided unit mechanism is defined. The cam profiles are synthesized by substituting the given curve profiles into the defined kinematic equation.
In order to verify the validity of the synthesized cam profiles, the analysis of the radius of curvature and curvature for them were performed, and also a kinematic simulation for the synthesized model was performed using the commercial software. The peak valve lift of the CVVL mechanism with two cams is analyzed by using the pitch curve of the driving cam and the kinematic relation. In addition, a new method for the dimensional synthesis of the peak valve lift is introduced and applied to the new Four-bar CVVL mechanism, so that the peak valve lift can be set at the values that a designer wants.
The cam profile using conventional synthesis method on the CVVL mechanisms is expected to be obtained by iterative modifications, but the cam profile using the new dimensional synthesis method proposed in this thesis can be easily obtained once. Also, the characteristics of the CVVL mechanisms may be readily recognized using the new proposed analytical method of the peak valve lift. Furthermore, using the new proposed method for the dimensional synthesis of the peak valve lift, they can be set at the values that a designer wants, which is able to accurately control the amount of air intake and the advanced angle or retard angle. As a result, we can develop the internal combustion engine to have high performance, high fuel efficiency, and reduced exhaust gas by optimizing the air-flow motion depending on the engine operating conditions.
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