Wednesday, February 16, 2011

CrazyEngineers Forum - Mechanical & Civil Engineering

CrazyEngineers Forum - Mechanical & Civil Engineering


AutoCAD - Now online

Posted: 16 Feb 2011 08:54 AM PST

This is to inform all Crazy Engineers that the most hotly used software by Civil and Mech Engineers : AutoCAD has been developed into an online version - AutoCAD WS. Check this out : Autodesk - AutoCAD WS. The best thing about it is that a file can be edited in real time by multiple people at the same time. Also, you can access AutoCAD anywhere in the world, without the need of any software. It can also be accessed on the iPhone and iPad and iPod Touch, so now, AutoCAD has become totally mobile and you can access it on the go. Save it on your iPhone while you are holidaying and your colleague will automatically recieve a copy as soon as you save it sitting in the the office. Pretty neat, huh? Well, it has it's disadvantages :
No command line
No support for 3D content
You can select max 30 objects in a window
But still, it is quite useful for everyday drafting and for 3D, there's Google SketchUp available on the iPad, so who cares? :happy:

Crank-shaft sensor

Posted: 16 Feb 2011 02:29 AM PST

In case of a petrol engine,it is important to achieve a correct timing between piston and ignition system.So basically we require a sensor.
It is called as:
Crank-shaft sensor :
This sensor reports the crank-shaft speed and piston position to ignition system.The ignition system should know as to when to ignite spark.In other words it must be able to calculate the instant when piston reaches TDC in compression stroke.
It consists of a pulse ring which rotates with the crankshaft.Whenever a notch in the disc aligns with sensor,it produces a voltage pulse.Hence the spark ignites.

There are two such types of sensors.
1.Pick up coil crankshaft sensor:
This arrangement consists of a reluctor i.e; a slotted disc which rotates with crankshaft.As each shaft passes through magnetic field at the end of pickup coil, a voltage is induced in it.
So even if you increase or decrease the speed,The ignition system will know the position of piston as the voltage will also vary.

2.Hall effect crankshaft sensor:
It uses HALL effect:
Def:
The Hall effect is the production of a voltage difference (the Hall voltage) across an electrical conductor, transverse to an electric current in the conductor and a magnetic field perpendicular to the current.(source of definition is wikipedia)
This crank sensor uses a Hall effect switch to turn voltage on or off.

Please contribute more to this article.:cean:

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