2 APRIL 2012
It’s time for me to focus
on the motor and pump. For the guideline, first of all, I plan again my block
diagram. Here is my block diagram:
This
project requires motor and pump for the main operation. So, from the block diagram, when power supply
is switch on, it will activate air pump which will suck air from environment
and delivered it to the valve. Air pump is controlled by pressure controller. I’m
using variable resistor 50K to control the pressure of air pump. When variable
resistor is turn to the maximum, it will give high pressure of air through the
valve, to the mattress and vice verse.
Valve;
which the rotation is controlled by motor will delivered the air through two tubes
to the mattress. Here come the difficulties for me to choose the best motor to rotate
the valve. These valves have three chambers; which one of it is from the air
pump, and another two I connect to the mattress by tube. When the motor rotate, it wills also rotating
the valve. So, each time only one chamber to the mattress will open to deliver
air to the mattress. The other chamber will not delivered air. After half
cycle, the other chamber opens to delivered air, and vice versa. This will
generate alternating flow to the mattress.
 |
| Valve: after half cycle each valve will open to delivered air |
 |
| Three chamber valve. 1 from air pump; the other 2 to the mattress |
Finally,
I decided not to use Stepper motor, and choose synchronous brush less DC motor
to rotate the valve. It is because, the operation of both motor is similar; but
stepper requires programming for it to operate; which requires more time to
explore and troubleshoot. Later I’ll explain the specification of the
synchronous motor. =)
