K
kell
- Jan 1, 1970
- 0
This is for a waste-vegetable-oil diesel conversion. Before shutting
down, you have to switch the engine over to "regular" diesel fuel and
run it for about thirty seconds to clear the wvo out of the injectors
and such, so they don't get gummed up. My buddy doesn't want to have
to sit in the car after parking it if he forgets to switch over to
diesel a block or two before parking and shutting off the engine; or
even worse, forget altogether and end up mucking up the engine. So he
wants a circuit that will cause the engine to switch over to the diesel
line automatically and run for an extra half minute or so after he
turns the ignition key off.
Here's a block diagram of my initial idea for the part of the circuit
that
will cause the engine to run on briefly after turning off the key:
keyed 12 volts
|
+------------------,
| |
| ___|___
| | |
| | relay |---->to engine
| |_______|
| |
| |
| c/
| |
'----+-----+-----| npn
| | |
--- \ e\
--- / |
| \ |
| / |
| | |
'-----'-------'-----gnd
And use cap and resistor values to give the right amount of run-on
time. Obviously it works by maintaining some voltage in the cap for a
while, until
the resistor (and base current) drains it low enough to where it won't
hold the transistor on.
As for causing the plumbing to switch from wvo to diesel when he turns
the key off, we can accomplish that by using a 12 volt solenoid in the
wvo plumbing line,
so that when the operator turns the key off, the solenoid drops out and
the engine's plumbing reverts to the diesel fuel line.
Any feedback? I think there might even be a simple circuit that would
do the job with just a relay and cap.
down, you have to switch the engine over to "regular" diesel fuel and
run it for about thirty seconds to clear the wvo out of the injectors
and such, so they don't get gummed up. My buddy doesn't want to have
to sit in the car after parking it if he forgets to switch over to
diesel a block or two before parking and shutting off the engine; or
even worse, forget altogether and end up mucking up the engine. So he
wants a circuit that will cause the engine to switch over to the diesel
line automatically and run for an extra half minute or so after he
turns the ignition key off.
Here's a block diagram of my initial idea for the part of the circuit
that
will cause the engine to run on briefly after turning off the key:
keyed 12 volts
|
+------------------,
| |
| ___|___
| | |
| | relay |---->to engine
| |_______|
| |
| |
| c/
| |
'----+-----+-----| npn
| | |
--- \ e\
--- / |
| \ |
| / |
| | |
'-----'-------'-----gnd
And use cap and resistor values to give the right amount of run-on
time. Obviously it works by maintaining some voltage in the cap for a
while, until
the resistor (and base current) drains it low enough to where it won't
hold the transistor on.
As for causing the plumbing to switch from wvo to diesel when he turns
the key off, we can accomplish that by using a 12 volt solenoid in the
wvo plumbing line,
so that when the operator turns the key off, the solenoid drops out and
the engine's plumbing reverts to the diesel fuel line.
Any feedback? I think there might even be a simple circuit that would
do the job with just a relay and cap.
