1998 ACURA INTEGRA valve

System Description
Steering Pump (cont'd) .

17-6
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
increase the discharge volume when 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
ori{ice in the pump. The discharge volume increases
as the engine speed increases.
As the flow has already been regulated by the
metering orifice when the engine speed ls at or near
the idle speed, a constant and regulated amount of
fluid is discharged until the engine speed reaches
the middle speed range. As the engrne speed
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
pressure at the discharge port trom rising exces-
As the engine speed continues to increase, the flow
control valve is pushed back further' When the
engine speed reaches a given speed, the return pas
sage outside the melering orifice is connected to
the inlet port, and the opening to the inlet port
widens in prooortion to the increase in engine
speed. This makes part of the fluid regulated by the
metering orifice return to the inlet port of the pump;
there by discharged Iluid lrom the pump rs
decreased slowlv by this amount
The orifice in the return passage regulates and
maintains the flow of fluid discharged from the
pump at a given level untilthe engine speed reach-
es the high speed range.
o
fd
lot3rotr
FLOW CURVE
PUMP R,P.M,
o-l
a,
II
,a\
METERINGORIFICE
an

Pressure Relief
Pressure outside of the metering orifice is directed tothe bonom of the flow control valve. When the pressure
builds up, the relief valve in the flow control valve opensto relieve the pressure. As the flow control valve ispushed back by the pressure difference this time. theflow of fluid in the bypass passage increases, controllingthe pressure outside the metering orifice. The aboveoperatrons are repeated to provide constant discharaepressure from the pump.
I
(Decresses excossivevibration in the valve.)
VALVE
(cont'd)
17-7

System DescriPtion
Steering Gearbox
it
The rack,and-pinion type steering gearbox has a Valve body unit incorporated with the pinion to control the steering fluid
pressure. steering fluid from the pump is regulated by a rotary valve in the valve body unit and is sent through the cylin-
derpipetothepowercy|inder,wherehydrauIicpressureisapp|ied.Thesteeringf|Uidintheothersideofthepowercy|in-
der returns through the cylinder pipe and valve body unit to the reservoir'
Valve Body Unit
Inside the valve body unit is the valve, which is coaxial with the pinion shaft, and controls the steering fluid pressure The
valve housing ls connected wirh the fluid pipe from the pump. return pipe to the reservoir, and the two cylinder pipes
from the respective power cylinder.
The pinion shaft is double - structured with the input shaft connected to the pinion gear, both of which are interconnected
with the torsion bar.
The pin inserted in the valve and the pinion shaft groove engage; this allows the pinion shaft to rotate together with the
Because of this construction. the difference in angle in the circumferential direction between the input shaft and the valve
becomes larger according ro the torsional strength ol the pinion or steering resistance. However. maximum torsion
between the shafts is regulated by the engaged splines of the shafts at the pin engagement section to hold the torsion bar
within the set value.
This allows the steering system to function as an ordinary rack-and-pinion type steering if the steering iluid is not pressur-
ized because of a faulty PumP.
VALVE
INPUT SHAFT
INPUT SHAFT
VALVE XOUSING
of
'I
lEng.ge with th€ Pinionshaft groove)
TORSION BARDift6rance in angle b6twe€n theinput ih.ft.nd pinion shalt
la-l
B
VALVE BODY UN]T
SECNON B.B
17-8

INPUT SHAFT
High assist at lower speedsl
When steering resistance is high, such as when driving at low speed, or when turning the wheel with the car stopped, the
diiference in angle created between the input shaft and the valve opens the tluid passage on one side, and closes the fluidpassage on the other side, at each pair of orifices. The fluid pressure lncreases in the side of the power cylinder fed by thelarger fluid passage. This increased pressure pushes on the rack piston, allowing the steering wheel to be turned with light
effon. On the other side of the power cylinder, the return passage opens allowing the steering fluid to return through theinput shaft to the reservoir. The fluid passages to the power cylinder automatically change in size, increasing as the steer-ing resistance increases. In other words, the passages become larger and power assist increases when the steering effort
would normally be high, (for example, when parking or making low speed turns), and the passages become smaller andpower assist decreases when the steering effort would normally be low, (for example, when driving at high speeds or
straight ahead).
FLUIO PASSAGE TOPOWER CYLINDER
Ce) r.r;
VK
Pressure Control
Low assist at higher speedsl
When steering resistance is low, such as when driving at high speeds, or when driving straight ahead. the lnput shaft is
near or in the neutral position, so there is liftle or no flow to any of the power cylinder orifices. Most of the feed pressure
from the pump is bypassed to the reservoir. Because of this, the pressure stays the same in both sides of the power cvlin-
der, resulting in low or no assist.
RETURN PASSAGE{To RESERVOIR)
POWER CYLINDERlHigh fluid pressurelI
ALVE FTom PUMP
RESERVOIR
SECTION A-A
17-9

Troubleshooting
General Troubleshooting
Check the following before you begin:
o Has the suspension been modified in a way that would affect steering?
. Are tire sizes and air pressure correct?
. lsthe steering wheel original equipment or equivalent?
. ls the power steering pump belt properly adiusted?
. ls steering fluid reservoirtilled to proper level?
. ls the engine idle speed correct and steadyT
Hard steering (check the power assist, see page 17-18. It the torce is over 34 N (3.5 kgf, 7 7 lbf), proceed with this troubl*hooting l
Abnormalfluidpressur€ (lluid
pressure rs roohish)
Too low reliefpress{ire
Normal line and hos6
I
II
iFaulty valve body unit
Normal Abnormal
rlrl
l{
Faulty pump assembly Faulty tlow control valv6
Ch€ck the tegd and return circuit lines and hoso
between the gearbox and pump for clogging and
detormation.
Check pump fluid Pressuro {sespage 17'221.Mgasure stoady-stat€ fluid Pres_sure while idling with the both
valv6Iully opon.It should be 1,500 kPa (15 kgf/
cm,,213 psi) or below.
Normal
Check the flow control valve (seo page 17-37).. Check the valvs Ior smooth movemont in the hous-
Ing.. Check tho reliel valvo for leaks.
Measure pump reliet prgssure
while idling with the both vslveIully closed.It should b€ 6,400 - 7,400 kPa {65- 75 kgt/cm', 924 - 1,067 psi)
Normal reliel pressure
I
I
+
Go to pags 17-11
17-10

From page 17-10
Normal
Check lorce required to turn thewhool (see page 17-'18).Start the engine and measu16the force required to turn thewheel to the right and left.Difference of the force requiredto twn the wheel to the right andto the left should be 5 N (0.5 kgf,1 lbl) or below.
Deformed
I
iFaulty cylinder lines
Not bent
Adjustment OK
Faulty valve body unit
Abnormal --> Faulty gearbox
Ch€ck th6 pans other than the gearbox-related parts lorDrooer rolaton.
. . lmproper rotation ofthe steering column-related pan{s}----------------- . tau[y $eenng lornt. Faulty rack endtio-rod ond balljoints. Intgrferonce in the steering system
Normal -----> lmproperly adjusted rack guide
Check lor bent rack shaft.
Check pump fluid pressure (seepage 17-22).Turn the steoring wheel fully tothe right and l€ft while idlingwilh the pressure control valveIully open, and measure the Iluidpressure. lt should be 6,400 -
7,400 kPa (65 - 75 kgflcmr, 924 -
1,067 psi).
Normal
Ch€ck the gearbox.Remove the gearbox and mea-sure the pinion torque.The lorque should be;. 0.7 - '1.2 N.m (7 - 12 kgf.cm, 6 -
10 lbf.in) wjth the steering rackin the straight driving position.
Abnormal
Adjust the rack guide {see page17-211, and recheck the pinion
torque.
17-11

Unev€n or rough steering.Adjust rack guid€ (see page 17-21).
It the problem is not corrocted byadjusting the rack guid€, replacethe g€a.box.
Adjust b6ll tension. Ropl6ce theb6lt, it necossary {s€e p€ge 17-20).
lfth€ engine stalls when the wheelis turned while the vehic16 isstopped or moving at low speed.adjust idl6 sp6od (s€e s€ction 111.
ldle spoed low or €rratic.
Check powsr st6oring fuid lovel. lfthe lovel is exceggively low, ch6cktor leaks in the svstem. Add fluidto the sD6cilied l6v6l,
Air in r€gervoir, or check powsr
steering fluid lovel.
lf fluid level is OK, chock O-ringsand seals on both 6nds ot thepump suction hose. and the P/Spump housing mating surfacesand tho oumo shaft oil seal forsuction lgakr. Roplaco parts asn6c6ssary.
Pump b€lt slipping on pulloy(pump stops momentarily).Adiust b6lt t€nsion {s6e page '17-
20) or r6olac€ b€lt.
Chock if pump pressure is normaland the gauge needle trav€l is 500kPa (5 kgl/cm', 71 psi) or lesB.Ch€ck the flow control valvo if theno€dl€ trav€l oxco€ds 500 kPa {5kg7cml, 71 p6i). lf the flow controlvalve is normal. roplace the pumpas an assemDtv.
Install the power st66ring pr6s-
su16 gaug6. Close th6 prossure
control valve lully and m6asurethe pump prossure (see page'17-22t.
Ste€ring wheol kicks backduring wide turns.
7-13

Troubleshooting
Fluid Leaks
Check the gearbox assembly for oil leaks carefully, Oil can leak out of various points, depending on location of the
faulty oil seals/seal rings. Check the following before removing the gearbox from the frame.
Stoo.ing GearboxReplace the valv€ oil seal fromthe valvo houging.Leaking from the oil seal on thetop of the valve housing.
Roplace the valve oil seal fromthe pinion shaft.Leaking trom cylinder 6nd intol€ft ti6-rod boot,
B€place tho cylindgr ond seal onthe gear housing side.
Replaco th€ cylindor end seal onths cylinder end side.Leaking from cylinder end intoright tie-rod boot.
Leaking from the thaft upper endsection or pin ongagement sgc-tion ofth6 Dinion shaftRoDlace tho valve bodv unit.I
I
Tighten connector. lf it€ still leak-ing. replace th€ lin€, cylinder orvalve housing.
Leaking lrom cylind6r line A or Bconn6ction {Et flare nut).
Leaking caused by a damagedcylinder line A or B.Replace cylinder line A or B.
Tightgn tho connector. ll its stillleaking, r€place the hos€, joint
fitting or valv€ housing.
Leaking from outlet line andreturn line joint fitting on thevalv6 body unit (at flare nut).
17-16