CLSS Hydraulic Pump Section 2.2 [PDF]

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CLSS - Hydraulic Pumps Section 2.2



Section 2.2



CLSS



Hydraulic Pump HPV95+95 VARIABLE DISPLACEMENT PISTON PUMP 112 CC PER PUMP MAX DISPLACEMENT Controlled by 2 LS valves and 2 PC valves With an LS EPC and PC EPC mounted on the side of the pump body



Section 2.2



CLSS



Hydraulic Pump.



Rear Pump



Front Pump



Text



The two pumps can work independently or together as one. Section 2.2



CLSS



Hydraulic Pump.



Front Seal



Input shaft (front) Input Shaft (front)



Shaft Coupling



Section 2.2



CLSS



Input shaft (rear)



Hydraulic Pump. Rod. (Connection between servo & swash plate)



Rocker Cam



Section 2.2



Servo-piston



Input Shaft (front)



CLSS



Hydraulic Pump.



Valve Plate



Shoes



Section 2.2



Input Shaft (front)



Piston



Cylinder Block



CLSS



Hydraulic Pump. Control of Discharge Amount. Servo piston moves in a reciprocal movement, according to the signal pressure from the LS or PC valves. This movement is transmitted through the rod to the rocker cam to increase or decrease swash plate angle.



Section 2.2



CLSS



Hydraulic Pump. Operation of Pump. Cylinder block is splined onto input shaft and all rotate together. When the rocker cam is in the minimum swash plate angle. The volume in the inlet and outlet chamber are the same, discharging a small flow of oil.



Minimum Discharge



The rocker cam is moved into the maximum position, volume in the inlet chamber become larger than the outlet. Causing a greater flow of oil. Maximum Discharge



Section 2.2



The swash plate angle on this pump never becomes 0 CLSS



LS Valve.



LS Valve: Detects the load and controls the pump discharge amount. The pump discharge or flow is proportional to differential pressure.



Section 2.2



CLSS



LS Valve.



Differential Pressure. PLS = PP – PLS. PP Main pump Pressure. PLS Control valve outlet Pressure



Spool



Main Pump Pressure Section 2.2



CLSS



Control Valve Outlet Pressure



LS Valve Control of Pump Discharge. When Differential Pressure



PLS = 0 to 22 pump discharge increases. PLS = 22 to 30 pump discharge is reduced. PLS PP



Section 2.2



CLSS



PLS



LS Valve LS Valve Ports. The LS valve is a three way selector valve. Depending on the differential pressure this will determine the position of the LS spool. LS EPC Solenoid Signal



PC control Valve Input Port



LS Pressure.



(PSIG)



(PPL)



(PLS)



Pump Pressure (PP)



LS Control Pressure



Pump Pressure.



To Servo Piston Large end.



(PP)



(PLP) Section 2.2



CLSS



LS Valve. Increase Pump Discharge. When the operator uses the work equipment LS pressure is introduced to the LS valve. Pump pressure is always acting on the LS valve. With LS pressure (PLS) introduce into the LS valve and with the assistance of the spring and spool area surface is able to over come the pump pressure (PP) pushing the LS spool to the Left, increasing pump discharge. PP



-



PLS



=



PLS



180



-



170



=



10 Kg/cm2



(Less than 22 Kg/cm2 pump will increase discharge) PLS = 170 Kg/cm2



PP = 180 Kg/cm2



Section 2.2



CLSS



LS Valve. Decrease Pump Discharge. When the operator reduces the speed of work equipment or stops working LS pressure is reduced to the LS valve. Pump pressure is always acting on the LS valve. With LS pressure (PLS) reduced Pump Pressure is able to overcome LS valve, spring tension and spool area surface. This will push the LS spool to the Right, decreasing pump discharge. PP



-



PLS



=



PLS



180



-



150



=



30 Kg/cm2



(Greater than 22 Kg/cm2 pump will decrease discharge) PLS 150 Kg/cm2



PP = 180 Kg/cm2



Section 2.2



CLSS



LS Valve. LS Valve Balanced. If the work load is maintained at the same flow and load the pump discharge or flow will equalize to the load. When this occurs the pump in neither increasing of decreasing its discharge. This is the benefit of having CLSS, it will only deliver the oil flow that’s required. LS pressure, spring tension is equal to Pump Pressure, the LS spool in neither stroking or de-stroking the pump. PP



-



PLS



=



PLS



180



-



158



=



22 Kg/cm2



PLS 158 Kg/cm2



PP = 180 Kg/cm2



Section 2.2



CLSS



LS Valve Control Levers in Neutral. When the levers are in the neutral position There is no LS pressure (PLS) delivered to the LS Valve. Pump Pressure (PP) is able to push the LS spool to the left. This will introduce PP into the Large end to servo-piston, because of the difference in servo piston surface area the swash plate is moved to minimum position.



Section 2.2



CLSS



LS Valve Reduce Flow When the control lever reduces its stroke the pump pressure increases and the LS pressure drops. PP pressure pushing LS spool to the left. Introducing PP to large end of servo piston. The pump will reduce its flow until the LS valve is balanced. The LS EPC solenoid supplies a varying pressure depending on machine condition to assist in reducing the pump flow



Section 2.2



CLSS



LS Valve Increase Flow. When the machine is in use, the LS pressure (PLS) is introduced to the LS Valve. Able to overcome Pump Pressure (PP). Pushing the LS spool to the Right. This will close off the PP and open the port back to tank. Draining the Large end to servo-piston allowing the swash plate is moved to maximum position.



Section 2.2



CLSS



LS Valve Servo Piston Balanced. When the machine is working at a even load the pump pressure (PP) will equal LS pressure (PLS) and spring (4). At this point the pump is delivering the correct flow required. The LS spool is neither introducing PP to the large end of the servo or draining it off. At this point the pressure applied to both ends of servo piston is 3:5. Section 2.2



CLSS



PC Valve PC Valve The PC Valve will maintain equal horse power control so that the horse power absorption by the pump does not exceed the engine horsepower. If the load during operation increases and pump discharge rises, the PC valve will reduce the pump discharge.



Section 2.2



CLSS



PC Valve PC Valve Ports. The PC valve is a three way hydraulic valve situated inside the Servo piston. The valve is regulated by pump controller via an EPC solenoid in order to reach optimum matching between the load (pressure P) and the flow (Q). PC Control Pressure.



Second Pump Pressure



Pump Pressure



(PPL)



PP2



PP1



PC Mode Select Pilot Pressure



Pump Pressure.



Drain Port.



(PM)



(PP1)



(PT)



Section 2.2



CLSS



PC Valve No load condition When the servo piston is at maximum flow the spring pressure from springs 4 &6 is low. The spool 3 is forced to the right by spring pressure. PP1 or PP2 pressure is not high enough to over come the spring tension. This allows the connection C from the LS valve to go to tank , through the centre of spool 3 . The PC EPC output which is controlled by the controller varying the pressure acting on spool 3. Will change the pump torque output.



Section 2.2



CLSS



PC Valve High Pressure The pump pressures has increased enough push the PC spool against the springs to close off port C (Return to tank) and introduce Pump pressure. This pressure returns to the large end of the servo piston via the LS valve. As the servo piston is being pushed back to reduce the pumps flow, at the same time the springs are being compressing Eventually the spring tension will equal the pump pressure allowing the optimum flow at that particular pressure.



Section 2.2



CLSS



Pump Discharge: Pressure and Flow Engine horse-power unable to maintain pump out put. PC Valve



LS Valve in control



Section 2.2



Springs



CLSS



LS & PC EPC Solenoids PC Prolix Switch ON If there is a failure in the pump controller, the Prolix Switch can be switch on to switch to the resistor side, by pass the controller. When this is done the current becomes constant so the force pushing the PC valve is constant. There is no pump sensing.



Section 2.2



CLSS



LS & PC EPC Solenoids PC EPC



LS EPC



EPC Valves When the solenoid receives a signal from the controller it generates the EPC out-put pressure in proportion to the electrical signal. The higher the signal an increased pressure is applied to the LS and PC valves, this will back the pump off earlier. Section 2.2



CLSS



LS & PC EPC Solenoids



Operation: No Signal. When there is no signal current flowing from the controller the coil is deenergized. The spool is pushed across to the left by spring (3). Allowing the signal oil to drain back to tank.



Section 2.2



CLSS



LS & PC EPS Solenoids Operation: Signal from Controller When a signal current flows to the coil, energizes the coil and propulsion force is generated which pushes the plunger (4). Moving the spool to the right against the spring. Opening the oil supply (PEPC) to flow to the LS or PC valve. As the pressure raises in PSIG plus spring force this will push spool (3) to close and maintain a set pressure going to the LS & PC valves.



Section 2.2



CLSS



LS & PC EPS Solenoids Selecting Work Mode. The operator can set the work mode on the monitor panel to suit the working conditions. According to the type of work the machine can work using the proper engine torque and pump absorption. The modes available are:



Section 2.2



CLSS



A



Active.



E



Economy.



B



Breaker.



L



Loading



CLSS Hydraulic Pumps



End of Hydraulic Pumps CLSS



Section 2.2



CLSS