Acura Integra 1998 Service Manual page 655

System Description
Steering Pump (cont'd) .
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1 7 - 6
Flow Control
The flow control valve in the pump performs the follow-
ing steps O through aE ro control the flow of fluid, i.e. to
i n c r e a s e t h e d i s c h a r g e v o l u m e w h e n e n g i n e s p e e d i s
low and to decrease it when the engine speed increases
The assistance thrust of the steering gearbox changes in
c o m p l i a n c e w i t h t h e c h a n g e i n t h e d i s c h a r g e v o l u m e .
When the engine starts, fluid discharged from the
discharge port starts to run through the metering
ori{ice in the pump. The discharge volume increases
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 ls at or near
the idle speed, a constant and regulated amount of
f l u i d i s d i s c h a r g e d u n t i l t h e e n g i n e s p e e d r e a c h e s
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 r 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 port preventing
p r e s s u r e a t t h e d i s c h a r g e p o r t t r o m r i s i n g e x c e s -
As the engine speed continues to increase, the flow
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
s a g e o u t s i d e t h e m e l e r i n g o r i f i c e i s c o n n e c t e d t o
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 o 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 part of the fluid regulated by the
metering orifice return to the inlet port of the pump;
t h e r e b y d i s c h a r g e d I l u i d l r o m t h e p u m p r s
decreased slowlv 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
p u m p a t a g i v e n l e v e l u n t i l t h e e n g i n e s p e e d r e a c h -
es the high speed range.
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FLOW CURVE
PUMP R,P.M,
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METERING
ORIFICE
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