IZ3LSV

G8MNY  > TECH     27.02.10 02:23l 130 Lines 5024 Bytes #999 (0) @ WW
BID : 49909_GB7CIP
Read: GUEST
Subj: Diesel Generators
Path: IZ3LSV<IK6ZDE<OK0NAG<OK0PPL<DB0RES<ON0AR<GB7SYP<GB7CIP
Sent: 100226/2324Z @:GB7CIP.#32.GBR.EU #:49909 [Caterham] $:49909_GB7CIP
From: G8MNY@GB7CIP.#32.GBR.EU
To  : TECH@WW

By G8MNY                                  (New Aug 09)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)

Only had experience of onem a 6kW Clarke diesel generator, it weighed in at
150kg & has a 12BHP engine all in a weatherproof noise reducing box!

               Top Hatch 
      ÚÄÄÄÄÄÄÄÂÄÄ~~~~~~ÄÄÄÄÂÄÄÄ¿
      ³ Fuel  ³      Decomp|   ³
      ³  Tank ³       Valve|   ³
      ÀÄÂÄÄÄÄÄÙ  Injector ||   ³
Electric³ Fuel     |ENGINE||   ³
  Panel_³  Tap     |      ||Fan³
      ³Ú - - - - -¿| Inj- ||   ³
      ³|ALTERNATOR|| pump ||   ³
      ³|          ||      ||12V³
      ³|          || Sump ||Bat³
      ÀÄÄÂÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÂÄÂÄÄÙ
         ÀÄÙ              ÀÄÙ

It was a little used generator that had been stored for years, initially the
main problem was dead battery, on starting, we soon found rubbish in the fuel
tank blocked much of the fuel line system...

Plastic                                Electric   Injector   Cylinder  
tank----Tap------In line------Bleed----solenoid-----fuel-----injector---unused
      on case   fuel filter   Screw    fuel valve   pump                return

When this had been cleaned out & a new filter put in all seemed well for an 8
day radio summer camp with it.

However our wet British summers soon found that water got into the fuel tank.
The low fuel sensor was placed in the top of the tank in a large molded sunken
area, this of course filled up with water on a rainy day & went straight into
the tank!

ÚÄÄÄ¿   ÚÄÄ¿ Water capture area   ReturnÚÄÄÄ¿
³   ÀÄÄÄÅÄÄÅÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙÀÄÙ   ³
³       Low       PLASTIC                   ³
³       fuel       FUEL                     ³
³      sensor      TANK                     ³
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ÚÄÄÄÙ
                                     Tap Feed

Rubber seals & self taps into a thin plastic tank are a silly idea!  Draining
off 2L of fuel into an empty clear drinks bottle showed how much water was
getting into the red fuel. (bottle now part of the tool kit)

Diesels with hand start options, have an extra cylinder valve or open the
intake valve for one engine cycle to stop the high 22:1 compression
(decompression lever), this enables enough speed to be built up for a proper
compression start stroke.

The Solenoid Tap
Fairly straight forward plunger device.

ÜÜÜÜÜÜ             
±ÚÄÄ¿±Coil         ß Steel Case
±³ðð³±             ð  Return Spring
±³ðð³±             Û  Soft Iron Plunger
ß³ÛÛ³ß             ²  Attached Rubber Seal
 ³ÛÛ³              ³  Brass tube
 ³²²³___
 À´ÃÄÄÄÄInlet
Outlet

On testing one annoying problem was the electric fuel solenoid, this only
operated on starting > 11V & if the enging was running, not in the "ON"
position!

The Injector Pump
This is one of the most complex parts in a diesel, it gives variable volume at
very high pressure. e.g. 30 atmospheres or 450PSI at a few degrees before top
dead centre of the engine cylinder's compression stroke.

         Outlet
           Ã ´  Ball
         ÚÄÙðÀÄ¿Valve                 The timing cam trikes the follower
    Pump ÃÄÄøÄÄ´                      & the small piston moves fuel
 Cylinder³Þ ÛÛÛ³                      through the ball valve until the
         ³ÞÜ ßÛ³__                    diagonal slot aligns with the inlet
   Piston³ÞÛÛÜÞÚÄÄÄInlet              port when the output is stopped.
with fuel³ÞÛÛÛÛ³                      The throttle arm is a sliding key
    slot ³  ÛÈÍÍÍÍ Throttle Arm       on the piston that controls piston
         ÃÄ Û Ä¿  (Piston rotation)   angle & hence the fuel volume.
          ð Û ð
          ð Û ð Return
          ð Û ð Spring
          ð Û ð
         ÜÜÜÛÜÜÜ
       Cam Follower

The Injector
This takes the high pressure fuel pulse & injects it in an atomised form into
the engine cylinder.

     Clamp plate
      ÜÜÜÜÜÜÜÜÜ
PressureÚÄÄÄ¿_                  Difficult to draw here, the
   Valve³ÜÜÜÚÄInput             high pressure input causes
        ³ð ð³                   the pressure valve to let fuel
  Fuel _³ð ð³Spring             suddenly pass through to the
 ReturnĿ߱߳                   microscopic spray holes.
ÜÜÜÜÜÜÜÜÀ¿±ÚÙÜÜÜÜÜÜÜÜ           (Usually 4 of them).
ÜÜÛ Spray|±|Spray ÛÜÜ
ÜÜÛ      ÀVÙ      ÛÜÜ           Fuel that does not get through
ÜÜÛ      Pin      ÛÜÜ           the holes is returned back to the
ÜÜÛENGINE CYLINDERÛÜÜ           tank when there is combustion.

WARNING: High pressure sprayed fuel is very dangerous, it will easily go
through your skin or affect your eyes. So a cover must be used to test the
injector action. e.g. half a clear plastic bottle!

Generator Governor
These work in a similar way to that of petrol generators. Force from spinning
"Bob weights" is used to balanced against a preset speed (Hz/volts) spring &
the difference used to move the throttle arm. Note that a drop in revs is
needed to open the throttle!


See also my Tech bul on "Petrol Generators for /P SSB"


Why Don't U send an interesting bul?

73 de John G8MNY @ GB7CIP


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