Clipper 1.0

Finally a chosen name.   Anyway here's the break down on this project.

Here you can see the original ingnition coil and the new wires I have attached to it.  The old wires that were connected here were used to short the coil to ground and thereby kill the engine.  The new wires that I have installed on the two terminals are for the proccessor to monitor ignition cycles. As the flywheel comes around it has a strong permanent magnet on it and this induces current into the primary windings of the coil.  When the magnet passes out of range, and the magnetic field collapses, a high voltage is induced into the secondary windings of the coil, this voltage provides the spark to ignite the fuel mixture.  The coil is similar in function to a transformer.  The wires in the picture are connected to the primary coil terminals and provide a pulse to a 5 volt regulator which in turn reduces the voltage to a level the proccessor can work with.  The proccessor sees this pulse and realizes that an ignition event has occured so it checks the throttle position potentiometer and fires the fuel injector a specified period of time depending on the throttle opening.  The injector pulse is determined by going to a lookup table and finding the correct pulse for the current throttle opening. You may be asking, "Why fire the injector after the ignition event?".  What we are actually doing is providing fuel for the next ignition event before it needs it so that the fuel is setting on the back of the intake valve in a vacuum that helps it to atomize into smaller groups of molecules which makes for more complete combustion resluting in reduced emmssions, increased economy, etc.

In this picture you can see the fuel injector mounted to the orignal intake runner, the fuel pressure regulator and the fuel inlet and bracket.  The fuel inlet line from the pump has not been plumbed at this time (this weekends task).  The fuel pressure regulator helps to keep fuel pressure at a set level (in this case 2.5 bar or approx 32 pounds), without the regulator the electric fuel pump would continue to increase pressure until the lines burst or it ran into stall.  To the right of the injector and to the left of the fuel inlet bracket is a schrader valve attachment which allows for fuel pressure checks.  At the very left of the fuel pressure regulator is the vaccuum control line, this line must be plumbed to intake vaccuum to allow for increased fuel pressure when the intake is at atmospheric pressure.  This vaccuum line must be mounted behind the throttle plates and in this project will be mounted directly next to the injector on the right by drilling a hole in the manifold/intake runner and tapping in a tightly fitting metal tube approx 3 millimeters in diameter. Fuel pump control is done by the proccessor which turns on/off the Fuel pump relay. The throttle position will be controlled and monitored using a RF servo, the microcontroller will specify a postion between 0 and 255 which will relate to 0 to 100% throttle opening.

    More work has been completed on Clipper.  The inlet from the fuel pump to the injection rail has been plumbed to accept a standard rubber high psi fuel line.  The vacuum line to the fuel psi regulator has been plumbed to the intake manifold and the electronics for the throttle control has been finalized.  The next step will be to mount the servo and connect it to the throttle bellcrank (shaft).   Next step:  install fuel pump and tank and connect lines.

In this picture you can see the throttle control servo is mounted and connected to the throttle bell crank on the old 'carb'.  The servo is connected using a peice of wire (paperclip) and has a 'V' shape in the center of it.  This 'V' shape allows the wire to flex some when the servo goes slightly past the throttle bell cranks full opening or closing and keeps from overstressing the servo.  After this the only items remaining are the fuel pump and control electronics.  The elecronics that control the throttle and the fuel injection are mostly built and all the code has been written and tested.  The control 'stick' is pictured below and includes an RS232 port so the control via a PC through Hyperterminal is possible.  The Control PC also has a video capture card which will allow us to capture live wireless video that is broadcast from Clipper on 434Mhz (using the RF units from www.rentron.com) NOTE: 434Mhz is the same frequency as cable ready TV channel 58 so any TV tuned to that station could also pick it up if in range.

Pictured right is the joystick that controls Clipper.  It includes a PIC microcontroller, RF transmitter @ 418Mhz, RS232 port, and control switches and POT's.   The Joystick is the same one used on RUF bot with some new features.  The range has been improved by running a 12v power supply instead of only 9V.  Serial communication is still used and follows standard protocol, and an RF pump is used to help increase signal clarity.

In the picture below you can see the battery, starter and belt.  The starter turns the crankshaft via the belt and pully's and once started, through some diodes, becomes an onboard generator to recharge the battery and supply current to the electrical needs of the mower.  The top pulley on the crank shaft just happen to fit perfectly and I just used the original crankshaft bolt to hold it in place with a lock pin.