|
|
| Home -> Heater control module kit |
|
Regular Rocket stuff
Copyright
© 2002, 2003 by
|
What's
New!
 |
||
|
Available NOW! The HCM is not limited to operating the heater valve. It can just as easily operate a fresh air valve or another light duty mechanical device that needs controlling with a remote mounted knob. I expect that soon I'll be selling the HCM as a kit, including a high quality firewall mounted heater valve with stainless steel door and hinge. This will provide an easy installation and excellent fire protection. How it works The system consists of a small circuit board. On the circuit board, there is a microprocessor, power supply and other electronic components. The power supply creates the electrical power needed for the servo and the microprocessor. The microprocessor in turn monitors the position of the rotary encoder (knob control) and positions the servo (and thus the valve) as commanded. The HCM processor also monitors the aircrafts fire/overheat detection system if installed. For example, say your aircraft has a fire detection system that detects an overheat/fire condition in the engine compartment. When an overheat/fire is detected, a cockpit lamp is illuminated, thus alerting the pilot. By connecting the HCM fire sense port to the overheat/fire light, the HCM can immediately act on this event. In the event a fire event occurs, the HCM immediately slams the valve shut, locks it there (by going over center) and inhibits further movement for the duration of the flight. Re-powering the HCM resets this lockout feature.
The HCM requires 8-32 volts
of DC power at less than 1 amp. The fire sense line will trip the lockdown
mode if more than 3 volts is detected. The HCM should be connected to the
aircrafts'
essential DC bus ( via 1 amp fuse or circuit breaker) if equipped. This is
to provide the greatest occupant protection against smoke/fire in the
event of an electrical malfunction. The servo will slam the valve shut and
lock over center in a fraction of a second. Subsequent power loss to the
HCM should have no effect on the valves "locked shut" position.
The microprocessor is
programmed to allow the pilot fine control of the valve. The control knob
is detented with 16 clicks per revolution. The knob will spin endlessly in
either direction. To open the valve full, the pilot needs to turn the knob
several turns. The close the valve, the pilot only needs to turn the knob
a fraction of a turn. again, the allows the pilot to instantly close the
valve, yet open it gradually to achieve the desired airflow.
Depressing the control knob
(switch built in) turns the heater on and illuminates the LED. The valve
will be commanded to the last known position. For example, if you have the
heater set to 1/4 open when shut down the airplane, the valve will open to
that position. Now that the HCM is "ON" slowly turning the knob, one click
at a time opens or closes the valve to your taste. Every time you move the
valve, the current position is stored in the CPU memory for future
reference. There are 20 positions available (20 clicks) from full off to
full on. Turing the knob to attempt to exceed the limits gives you a
single quick flash of the LED to let you know you are already at max
limit.
This Photo shows the HCM hookup diagram. Note the simplicity of it. You'll need to connect power, ground, fire sense (if equipped) and the rotary encoder. This picture shows poorly. Print it for a better copy.
A note about rotary
encoders... With the advent of modern technology, the time proven input
device, a potentiometer, has slowly fallen by the wayside. With it's
death, goes noise and intermittent operation from dirty mechanical wipers
and short lifespan. The rotary encoder, which is present in almost all
modern devices from cars to handheld radios, replaces the potentiometer
with a programmable digital interface device. It's knob give a similar
feel to operators, yet gives the designer greater freedom in achieving the
desired result from operator input. They are noise free, last nearly
forever, and the knob spins freely in both directions without limits. Kt includes:
HCM board with CPU
Tools to install it
The servo and electronics
must always be mounted inside the firewall. They simply can' take the heat
from that engine cooking after shutdown, not to mention you want to keep
control of the heater valve in the event you actually have an engine fire.
Kind of hard to do it if the servo melted and burned up! |
|||
|
"Sadly,
artificial intelligence will probably never be a match for natural
stupidity." |
