Steering Pump - Acura 1994 Integra Service Manual

System Description
Steering Pump (cont'dl
Flow Control
The flow control valve in the pump performs the follow-
ing steps @ through O to control the flow of fluid, i.e. to
increase the discharge volum€ wh6n engine speed is
low and to decrease it when the engine speed increases.
The assistance thrust of the steering gearbox changes in
compliance with the change in the discharge volume.
When the engine starts, fluid discharged from the
discharge port starts to run through the metering
orifice in the pump. The discharge volume increas€s
as the engine speed increases,
A s t h e f l o w h a s a l r e a d y b e e n r e g u l a t e d b y t h e
metering orifice when the engine speed is at or near
the idle speed, a constant and regulated amount ot
fluid is discharged until the engine speed reaches
t h e m i d d l e s p e e d r a n g e . A s t h e e n g i n e s p e e d
increases, the pressure difference between the ends
of the metering orifice increases. A pressure differ-
ence is created between the top and bottom ends of
the flow control valve, too, pushing the flow control
valve to open the by-pass passage. This allows the
excess fluid to return to the inlet pon preventing
pressure at the discharge port trom rising exces-
sively.
As the engine speed continues to increase, the tlow
c o n t r o l v a l v e i s p u s h e d b a c k f u r t h e r . W h e n t h e
engine speed reaches a given speed. the return pas-
sage outside the metering orifice is connected to
t h e i n l e t p o r t , a n d t h e o p e n i n g t o t h e i n l e t p o r t
w i d e n s i n p r o p o r t i o n t o t h e i n c r e a s e i n e n g i n e
speed. This makes pan of the fluid regulated by the
metering orifice return to the inlet pon of the pump;
t h e r e b y d i s c h a r g e d f l u i d f r o m t h e p u m p i s
decreased slowly by this amount.
T h e o r i f i c e i n t h e r e t u r n p a s s a g e r e g u l a t e s a n d
m a i n t a i n s t h e f l o w o f f l u i d d i s c h a r g e d f r o m t h e
pump at a given level until the engine speed reach-
es the high speed range.
. 5
I J
l o
t =
r o
FLOW CURVE
PUMP R.P,M.
o
@
VALVE
@
@
17-6