CLSS - Hydraulic Pumps Section 2.2
Hydraulic Pump HPV95+95 VARIABLE ISPLACE!E"# PIS#$" P%!P &&2 CC PER P%!P !A' ISPLACE!E"# Controlled (y 2 LS )al)e* and 2 PC )al)e* it, an LS EPC and PC EPC mounted on t,e *ide o- t,e pump (ody
Hydraulic Pump HPV95+95 VARIABLE ISPLACE!E"# PIS#$" P%!P &&2 CC PER P%!P !A' ISPLACE!E"# Controlled (y 2 LS )al)e* and 2 PC )al)e* it, an LS EPC and PC EPC mounted on t,e *ide o- t,e pump (ody
Hydraulic Pump.
/ront Pump
Rear Pump
#et
#,e t0o pump* can 0or1 independently or toet,er a* one.
Hydraulic Pump.
/ront Seal
Input *,a-t 3-ront4 Input S,a-t 3-ront4
S,a-t Couplin
Input *,a-t 3rear4
Hydraulic Pump. Rod. 3Connection (et0een *er)o 6 *0a*, plate4
Ser)opi*ton
Roc1er Cam
Input S,a-t 3-ront4
Hydraulic Pump.
Val)e Plate
S,oe*
Input S,a-t 3-ront4
Pi*ton
Cylinder Bloc1
Hydraulic Pump. Control o- i*c,are Amount. Ser)o pi*ton mo)e* in a reciprocal mo)ement7 accordin to t,e *inal pre**ure -rom t,e LS or PC )al)e*. #,i* mo)ement i* tran*mitted t,rou, t,e rod to t,e roc1er cam to increa*e or decrea*e *0a*, plate anle.
Hydraulic Pump. $peration o- Pump. Cylinder (loc1 i* *plined onto input *,a-t and all rotate toet,er.
!inimum i*c,are
,en t,e roc1er cam i* in t,e minimum *0a*, plate anle. #,e )olume in t,e inlet and outlet c,am(er are t,e *ame7 di*c,arin a *mall -lo0 o- oil. #,e roc1er cam i* mo)ed into t,e maimum po*ition7 )olume in t,e inlet c,am(er (ecome larer t,an t,e out let. Cau*in a reater -lo0 ooil.
!aimum i*c,are
#,e *0a*, plate anle on t,i* pump ne)er (ecome* 8
LS Valve.
LS Valve: Detects the load and controls the pump discharge amount. The pump discharge or flow is proportional to differential pressure.
LS Valve.
Differential Pressure . PLS = PP PLS. PP !ain pump Pressure. PLS Control valve outlet Pressure
Spool
!ain Pump Pressure
Control Valve "utlet Pressure
LS Valve Control of Pump Discharge. #hen Differential Pressure
PLS = $ to 22 pump discharge increases. PLS = 22 to %$ pump discharge is reduced. PLS PP
PLS
LS Valve LS Valve Ports. The LS valve is a three wa& selector valve. Depending on the differential pressure this will determine the position of the LS spool. LS )PC Solenoid Signal
PC control Valve *nput Port
LS Pressure.
'PS*+(
'PPL(
'PLS(
Pump Pressure 'PP(
LS Control Pressure
Pump Pressure.
To Servo Piston Large end.
'PP(
'PLP(
LS Valve. *ncrease Pump Discharge. #hen the operator uses the wor, e-uipment LS pressure is introduced to the LS valve. Pump pressure is alwa&s acting on the LS valve. #ith LS pressure 'PLS( introduce into the LS valve and with the assistance of the spring and spool area surface is ale to over come the pump pressure 'PP( pushing the LS spool to the Left/ increasing pump discharge. PP
0
PLS
=
PLS
1$
0
13$
=
1$ 4g5cm2
'Less than 22 4g5cm2 pump will increase discharge( PLS = 13$ 4g5cm2
PP = 1$ 4g5cm2
LS Valve. Decrease Pump Discharge. #hen the operator reduces the speed of wor, e-uipment or stops wor,ing LS pressure is reduced to the LS valve. Pump pressure is alwa&s acting on the LS valve. #ith LS pressure 'PLS( reduced Pump Pressure is ale to overcome LS valve/ spring tension and spool area surface. This will push the LS spool to the 6ight/ decreasing pump discharge. PP
0
PLS
=
PLS
1$
0
17$
=
%$ 4g5cm2
'+reater than 22 4g5cm2 pump will decrease discharge( PLS 17$ 4g5cm2
PP = 1$ 4g5cm2
LS Valve. LS Valve 8alanced. *f the wor, load is maintained at the same flow and load the pump discharge or flow will e-uali9e to the load. #hen this occurs the pump in neither increasing of decreasing its discharge. This is the enefit of having CLSS/ it will onl& deliver the oil flow thats re-uired. LS pressure/ spring tension is e-ual to Pump Pressure/ the LS spool in neither stro,ing or de0stro,ing the pump. PP
0
PLS
=
PLS
1$
0
17
=
22 4g5cm2
PLS 17 4g5cm2
PP = 1$ 4g5cm2
LS Valve Control Levers in ;eutral. #hen the levers are in the neutral position There is no LS pressure 'PLS( delivered to the LS Valve. Pump Pressure 'PP( is ale to push the LS spool to the left. This will introduce PP into the Large end to servo0piston/ ecause of the difference in servo piston surface area the swash plate is moved to minimum position.
LS Valve Reduce Flow When the control lever reduces its stroke the pump pressure increases and the LS pressure and drops. PP pressure pushing LS spool to the left. ntroducing PP to large end of servo piston. !he pump will reduce its flow until the LS valve is "alanced. !he LS #PC solenoid supplies supplies a var$ing var$ing pressure depending on machine condition to assist in reducing the pump flow
LS Valve ncrease Flow. When the machine is in use% the LS pressure &PLS' is introduced to the LS Valve. ("le to overcome Pump Pressure &PP'. Pushing the LS spool to the Right. !his will close off the PP and open the port "ack to tank. )raining the Large end to servo*piston allowing the swash plate is moved to ma+imum position.
LS Valve Servo Piston ,alanced. When the machine is working at a even load the pump pressure &PP' will e-ual LS pressure &PLS' and spring &'. (t this point the pump is delivering the correct flow re-uired. !he LS spool is neither introducing PP to the large end of the servo or draining it off. (t this point the pressure applied to "oth ends of servo piston is /01.
PC Valve PC Valve !he PC Valve will maintain e-ual horse power control so that the horse power a"sorption "$ the pump does not e+ceed the engine horsepower. f the load during operation increases and pump discharge rises% the PC valve will reduce the pump discharge.
PC Valve PC Valve Ports. !he PC valve is a three wa$ h$draulic valve situated inside the Servo piston. !he valve is regulated "$ pump controller via an #PC solenoid in order to reach optimum matching "etween the load &pressure P' and the flow &'. PC Control Pressure.
Second Pump Pressure
Pump Pressure
&PPL'
PP2
PP3
PC 4ode Select Pilot Pressure
Pump Pressure.
)rain Port.
&P4'
&PP3'
&P!'
PC Valve 5o load condition When the servo piston is at ma+imum flow the spring ma+imum pressure from springs 67 pressure is low. !he spool / is forced to the right "$ "$ spring spring pressure. PP3 or PP2 pressure is not high enough to over come the spring tension. !his allows the connection C from the LS valve to go to tank % through the centre of spool / . !he PC #PC output which is controlled "$ the controller controlled var$ing var$ing the the pressure acting on spool /. Will change the pump tor-ue output.
PC Valve 8igh Pressure !he pump pressures has increased enough push the PC spool against the springs to close off port C &Return to tank' and introduce Pump pressure. !his pressure returns to the large end of the servo piston via the LS valve. (s the servo piston is "eing pushed "ack to reduce the pumps flow% at the same time the springs are "eing compressing #ventuall$ the spring spring tension will e-ual the pump pressure allowing the optimum flow at that particular pressure.
Pump )ischarge0 Pressure and Flow #ngine horse*power una"le to maintain pump out put. PC Valve
LS Valve in control
Springs
LS & PC EPC Solenoids PC Prolix Switch ON If there is a failure in the pump controller, the Prolix Switch can e switch on to switch to the resistor side, ! pass the controller. "hen this is done the current ecomes constant so the force pushin# the PC $al$e is constant. %here is no pump sensin#.
LS & PC EPC Solenoids PC EPC
LS EPC
EPC al$es "hen the solenoid recei$es a si#nal from the controller it #enerates the EPC out'put pressure in proportion to the electrical si#nal. %he hi#her the si#nal an increased pressure is applied to the LS and PC $al$es, this will ac( the pump off earlier.
LS & PC EPC Solenoids
Operation) No Si#nal. "hen there is no si#nal current flowin# from the controller the coil is de' ener#i*ed. %he spool is pushed across to the left ! sprin# +-. llowin# the si#nal oil to drain ac( to tan(.
LS & PC EPS Solenoids Operation) Si#nal from Controller "hen a si#nal current flows to the coil, ener#i*es the coil and propulsion force is #enerated which pushes the plun#er +/-. 0o$in# the spool to the ri#ht a#ainst the sprin#. Openin# the oil suppl! +PEPC- to flow to the LS or PC $al$e. s the pressure raises in PSI1 plus sprin# force this will push spool +to close and maintain a set pressure #oin# to the LS & PC $al$es.
LS & PC EPS Solenoids Selectin# "or( 0ode. %he operator can set the wor( mode on the monitor panel to suit the wor(in# conditions. ccordin# to the t!pe of wor( the machine can wor( usin# the proper en#ine torue and pump asorption. %he modes a$ailale are)
cti$e.
E
Econom!.
3
3rea(er.
L
Loadin#
