Este documento describe los componentes básicos del circuito de alimentación de gasolina de un automóvil, incluida la electrobomba ubicada en el depósito de combustible, el filtro de gasolina y el regulador de presión. Explica que la electrobomba puede ser controlada por la unidad de control electrónico o por un relé tacométrico y que existen circuitos con y sin retorno de combustible. También cubre el mando de la electrobomba de tres velocidades y la técnica de modulación de ancho de pulso.
19. Regulador de presión
• SITUACIÓN:
– En la Rampa o tubo distribuidor
– En el interior del depósito de combustible
formando cuerpo con el aforador, la bomba y
el filtro (circuito sin retorno – returnless)
31. ¿En qué consiste esta técnica?
• Pulse-width modulation control works by
switching the power supplied to the motor on
and off very rapidly. The DC voltage is
converted to a square-wave signal, alternating
between fully on (nearly 12v) and zero, giving
the motor a series of power "kicks".
• If the switching frequency is high enough, the
motor runs at a steady speed due to its fly-wheel
momentum.
• By adjusting the duty cycle of the signal
(modulating the width of the pulse, hence the
'PWM') ie, the time fraction it is "on", the
average power can be varied, and hence the
motor speed.
32. Advantages are,
• The output transistor is either on or off, not partly
on as with normal regulation, so less power is
wasted as heat and smaller heat-sinks can be
used.
• With a suitable circuit there is little voltage loss
across the output transistor, so the top end of
the control range gets nearer to the supply
voltage than linear regulator circuits.
• The full-power pulsing action will run fans at a
much lower speed than an equivalent steady
voltage.