A Study On Camshaft Technology Engineering Essay

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The aim of all efforts is liberation from a constraint that has handcuffed performance since the birth of IC Engines more than a century ago. The majority of conventional automotive engines run on a valvemotion fixed to the crankshaft rotation through the mechanical linkage of the rocker, pushrod,camshaft, and the timing chain. It likes very simple manually developed programme contains only a set of guidance, the cam always open and close the valves at the same precise moment in each cylinders constantly during the strokes. In this whole case rotating steel shaft with Cams are “brain“of the system.

The friction loss of cams, dependent and inflexible valve train operation, wearing of cams its inefficient and noisy operation were some of the parameters which everyone has to compromise until a new approach of Camless engine was developed. In today's era, the growing need to improve fuel economy and reduce harmful exhaust emissions forced the engine designers to seriously consider alternative methods of valve operation.

Camless engine is an engine replaced with a fully variable camless actuation system which allows complete control of mass transfer into and out of the engine cylinder .the engine uses actuators, sensors and microprocessors to control the lift of valves according to operating conditions. it gives programmable flexibility in controlling the engine events. The system offers a continuously variable and independent control of virtually all parameters of valve motion control this permits optimization of valve events for each operating conditions without any compromise.

1.2 Aim:

To research the application of CAMLESS ENGINE

1.3 Objectives:

  • To analyse different Camless technologies
  • Quantify the benefits of Camless operation

2. Research Conducted:

2.1 What is Camshaft Technology?

The primary means of camshaft is controlling the valve actuation and timing, and therefore, influencing the overall performance of the vehicle.

The camshaft is attached to the crankshaft of an internal combustion engine and rotates relative to the rotation of the crankshaft. Therefore, as the vehicle increases its velocity, the crankshaft must turn more

quickly, and ultimately the camshaft rotates faster. When camshaft rotates, cam lobs which attached with the camshaft, link with the engine's valve. This displacement works through out of mechanical linkage. And as a result of it inlet and outlet valve can be changed in to closing and opening position.

2.2 What is Camless technology?

In camless technology valve is operated with the help of different types of mechanism or combination of different technologies includes different field of engineering sector. In camless operation inlet and outlet valve are not depended on camshaft, crank shaft, timing chain etc. In different types of camless operation need different mechanism which powered by different source includes electrical energy, combination of hydraulic and mechanical energy, combination of electronic and hydraulic energy etc.

2.3 Different Mechanism of Camless Technology:

2.3.1 Valve Spring Mechanism

  • Valve springs, though used in all conventional valve systems, are the primary limiting factor on engine speeds, and generate many unpleasant effects, such as harmonics and valve float. Without them there is relatively little friction in the valve train.

2.3.2 Electro Mechanical Mechanism

  • Electro magnets are used to open and close the valve and hold it in position once moved and after that valves assume their original position by mechanical mechanism.

2.3.3 Hydraulic Mechanism

A piston driven by hydraulics is used to open the valve and compress a conventional valve spring. The valve is closed by the spring. The valve open and close is affected by valve mechanisms controlling the flow of hydraulic fluids to and from the hydraulic cylinder.

2.3.4 Electro Hydraulic Mechanism

It uses neither cam nor spring. It exploits the elastic properties of a compressed hydraulic fluid, which acting as a liquid spring, accelerates & decelerates each engine valve during it's opening & closing motions. This is the principle of the hydraulic pendulum controlled by electronic computer microprocessor and sensors.

2.3.5 Stepper Motor Mechanism

  • Stepper motors are used to open and close the valves.
  • This methodology of valve control has previously not been successful in camless engine design due to the limited RPM range inherent in the design.

2.3.6 Pneumatic

  • Systems utilizing pneumatics to drive the engine valves. In all probability not be feasible because of it contains large space for the device and their complexity and the very large amount of energy required to compress the air.

2.4 Benefits of Camless Technology :

  • Camless operation controls Valve timing ,lift and velocity easily.
  • Camless mechanism reduces head height and improves packaging.
  • Most of above mechanism contributes low consumption of energy.

3. Future Plans

Future plans include continuing to refine the technology for prototype camless CIDI (Compressor Ignition-Direct Injection) engines driven by an electronically controlled camless valvetrain:

  • Refine the system and component design for higher efficiency and consistency
  • To derived electronic control algorithms, software, and hardware for valve timing, lift, soft seating, and closing control
  • Integrate the variable valve timing system with small CIDI engines
  • Characterize performance envelope, energy consumption, open- and closed-loop repeatability, and sensitivity to environmental conditions of the camless valvetrain system through both simulation and experiment
  • Develop a system and control dynamic model of CIDI engines and investigate the control configurations and strategies by using the proposed actuating system
  • To derive more and more efficient way to increase performance of engine

4. Appendices

4.1 References


* http://www.sturmanindustries.com/main/hydraulicValveActuation.htm

* http://www.valeo.com/automotive-supplier/Jahia/pid/1317

Images References

* http://img217.imageshack.us/img217/8605/pushrod2ht6.png-Image 1.1

* http://subscribers.wardsauto.com/microsites/images/editorial/valeo_camless_engine_1105.gif-image-1.3

* http://us1.webpublications.com.au/static/images/articles/i30/3089_7lo.jpg-Image-1.2