Presented within is a synopsis of the working and conceptual development of a piezoelectric controlled hydraulic actuator. This actuator was developed for use as a replacement for the camshaft in an internal combustion engine (ICE). Its development results in a new device; called the camless engine (CLE).
The objective of the seminar is to study about the working, literature review, and conceptual development a device that proved the concept of a CLE. More specifically, it is an electro/hydraulic device capable of producing engine valve displacement at typical automotive demands. The goals for maximum displacement and frequency are 10 mm and 50 Hz, respectively. In general, the unit must be capable of varying engine valve displacement and valve timing.
The system design utilized a customized piezoelectric stack and hydraulic spool valve combined with an in-house designed hydraulic amplifier. Control is facilitated by a function generator, and feedback is monitored with an oscilloscope.
: Introduction to camshaft technology
Chapter Three: Working of camless engine
: Literature Review
: Conceptual Development
: Assembly of the Hydraulic System
Chapter seven: Conclusion
List of figures
Definitions and Abbreviations
Chapter One: Introduction
Automobile manufacturers have recognized the compromises associated with engines that are governed by the rotation of a camshaft. This rotation, the speed of which is proportional to the engine speed, determines the timing of the engine valves. For this reason, automotive engineers must make a decision early in the design process that dictates the performance of the automobile. The engine will either have powerful performance or increased fuel economy, but with the existing technology it is difficult to achieve both simultaneously.
In response to the needs of improved engines, some manufacturers have designed mechanical devices to achieve some variable valve timing. These devices are essentially camshafts with multiple cam lobes or engines with multiple camshafts. For example, the Honda VTEC uses three lobes, low, mid, and high to create a broader power band. This does represent an increased level of sophistication, but still limits the engine timing to a few discrete changes.
The concept of variable valve timing has existed for some time. Unfortunately, the ability to achieve truly variable valve timing has eluded automotive manufacturers. Most variable timing mechanisms were created as tools for the automotive engineer. Their use was limited to the laboratory as a means of testing multiple, “virtual” cam profiles. These early Camless engines allowed for the designers to choose the best cams for the engine under scrutiny, but were less than energy efficient. Furthermore, they were one laboratory machines and were not capable of being mass produced or utilized in an automobile
Chapter Two: Introduction to Camshaft Technology
Since the origination of the automobile, the internal combustion engine has evolved considerably. However, one constant has remained throughout the decades of ICE development. The camshaft has been the primary means of controlling the valve actuation and timing, and therefore, influencing the overall performance of the vehicle.
The camshaft is attached to the crankshaft of an ICE and rotates relative to the rotation of the crankshaft. Therefore, as the vehicle increases is velocity, the crankshaft must turn more quickly, and ultimately the camshaft rotates faster. This dependence on the rotational velocity of...
References: Dobson, N. and Muddell, G., 1993, “Active Valve Train System Promises to Eliminate Camshafts,” Automotive Engineer February/March 1993.
General Motors – GM and the Environment. May 21, 2001. General Motors. June 13, 2001.
Ladd, D; Camless Engine is Gaining Momentum. September 13, 1999. Siemens Automotive. July 4, 2000 .
Lexus – Variable Valve Timing a First in an SUV. Autoworld. June 18, 2001 .
Mori, Kaz. Honda’s High-Output LEV Engine Home Page. Honda. June 13, 2001 .
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