SUNWARD MEDIUM EXCAVATOR Hydraulic System [PDF]

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SUNWARD Medium Excavator Hydraulic System



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Table of Contents



目 录



1 3



Hydraulic System Overview



2



Main Pump Control Principle



3



MCV Control Principle



Content 4 3



Hydraulic Actuators of Excavator



Hydraulic System Overview



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Power Train Engine



Implements



Hydraulic System Main Pump



MCV



Cylinders



Slew Mechanism Slew Motor



Undercarriage Diesel Tank



Hydraulic Tank



PCV



Travel Motor



Hydraulic System Overview



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Features of Sunward hydraulic system ：Sunward medium excavator utilized a hydraulic system with dual-pump, double-circuit, of which power can be regulated by negative flow for less energy loss caused by relief, and regulated under constant power by crossed mutual work pressure, as well as power transition by pressure induced by proportional solenoid valve .



Dual Pump :The Sunward excavator employs dual-tandem-pump to deliver oil to all hydraulic implements,each pump has its own duties,generally,the front pump deliver oil to left travel motor,swing motor and arm cylinder,while the rear pump deliver oil to right travel motor,boom cylinder and bucket cylinder .



Double-circuit :Just like a cow hoof, the main control valve (MCV) is composed of two parralelled sections, each section has its own duty, the front pump supply oil through the left section to hydraulic actuators and the rear pump supply oil through the right section to hydraulic actuators, and each oil circuit of the two sections are relatively separate.



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Medium Excavator Hydraulic System Overview



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Front Pump



Regulator



Rear Pump



Regulator



Pilot Pump



Pilot Pump



Pressuer Sensor



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Features: Front Pump Regulator



Rear Pump Regulator



● Front and rear pump deliver pressurized oil to each actuator ● Pilot pump provides pressure oil to pilot control circuit to shift spools. ● The regulator is used to realize the automatic regulating of displacement of the pumps ● Proportional solenoid valve is



used to remotely set power of Front Pump



Middle Body



Rear Pump



Pilot Pump



the main pump.



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1: Front pump



2: Rear pump 3:Pilot Pump 4: Psv Coil 5: regulator A1: Front pump outlet port A2: Rear Pump outlet port B1: main pump suction port Dr: drainage port



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Pi1: Front pump negative flow inlet Pi2: Rear pump negative flow inlet Psv: Proportional Solenoid Valve



A1: Front Pump testing port A2: Rear Pump testing port a3: pilot pump pressure testing port A3: Pilot pump outlet port B3: pilot pump inlet port DR3: pilot pump drainage



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Pump displacement variation control Pump displacement are mainly governed by 4 factors:,autologous circuit pressure, opposite pump circuit pressure,negative flow and the proportional solenoid valve.



Autologous Circuit Pressure Oppsite Pump Pressure Psv Negative Flow



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Negative Flow Control ： We set a bypass throttle valve at downstream of oil return line in each section of main valve ,so that we can get a pressure signal from each of the two circuits.This pressure signal



can feedback to the regulator of the main pump,and it will control the swashplate inclination and displacement of the main pump,so that it can regulate the speed of the work equipment. Usually,the bigger angle you push the joystick to ,the higher pilot pressure will be ,and the



bigger angle swash plate will incline to,and the more oil will be diacharged by the pump within unit time,and vice versa.



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Negative Flow Control ： Servo Spool & Sleeves



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Crossed Mutual Regulation： Each of the two pumps has its own regulator ,and the regulator can be regulated by the pressure of both pumps circuit, that’s to say the pressure of each pump circuit can regulate the swashplate inclination and displacement of both pumps.



Constant power control: once the work mode and gear of the throttle dial is selected,the engine power output will be constant. if the load of one of the pumps is lighter



than the other one ,the other pump can automatically absorb the surplus power from this pump,so that the power output by engine can be utilized to its utmost.



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Autologous Circuit Pressure Regulating: as the red line in the next diagram shows. the discharged oil by the front pump flows through the checkvalve and enters into small



end of servo piston,and the same stream of flow will reach to left side of compensator spool, as pressure increases, once it's strong enough to get over spring force of the servo spool,the servo spool will move right, and let the pressurized oilfrom pump in itself enter into big end of the servo piston, and push the servo piston to the right slowly, and the swashplate of the pump will be driven



clockwisely, and pump displacement will decrease, once the pressure from pump in itself start to drop, the spring force will push the servo spool to the left gradually, oil in the big chamber of servo piston will return to tank, and the pressure in small chamber will push



servo piston to the left, and inclination of swashplate will increase. if the force generated by the pressure is equal to compensator spring force, the servo spool will stay at neutral position, and pump displacement will not change.



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Opposite pump pressure control : as the pink line shows in the picture below.



The autologous pump pressure and opposite pump pressure work together, and form a constant power control.



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The Kawasaki K3V Series Hydraulic Pump equipped



Constant Power Control Strategy



with a synchronized constant power type regulator, its displacement is regulated according to the total load of front pump and rear pump, so during the



power regulating process, the engine can avoid from overload, and no need to care about load of either single pump. and it's also because of this regulator is a synchronized constant power type,it will keep the swashplate inclination of both pump always the same



when the two pumps work at the same time. . this constant power control strategy will let the implements work fast with light load, and slow with heavy load, and take full advantage of power output by engine, but will not overload.



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Constant Power Control Strategy When the engine speed is constant, the power of the hydraulic pump is also constant. as output pressure P1 of autologous pump or output pressure P2 of the opposite



pump increases, the pump regulator will automatically reduce the inclination of the swash plate, that is, the displacement of the pump is reduced, so that the power of the hydraulic pump can maintained at a constant range. When the work load of the excavator is small, the machine can work with high flow to ensure a fast work speed without exceeding power output by engine, When the power of the hydraulic pump tends to exceed output power of the engine, the displacement of the piston pump must decrease.. The regulating principle just as shown in the firgure on the left.



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Constant Power Control Strategy Constant power control is performed by the compensating spool. there are two ring steps on the compensator spool, and pressure from both front pump and rear pump will apply on these two steps respectively, As the load on the two pumps increases, When the sum of pressures (P l + P2) acted on the compensation spool reaches the setted value of the power spring, it will overcome the spring force to shift the servo spool to the right and let it work in its left position.The pressure oil CD connected to the servo valve enters the big end of the servo piston, due to the cross-section area difference of the two ends, the pressurized oil will push the servo piston moves to the right,



and the swashplate will be pulled to rotate clockwise synchronously by servo piston , and then the pump displacement will reduce, and keep power of pump constant. thereby preventing the engine from being overloaded.



1. Compensator Spool; 2. Power Spring, 3. Spring Retainer 4. Servo spool 5. Feedback lever, 6.Servo Piston, 7.Negative Control Spring, 8. Negative Control Plunger



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Constant Power Control Strategy At the same time when the displacement is reduced, the servo piston simultaneously drives the feedback lever to rotate counterclockwise. The feedback lever drives the servo spool to move to the left to close the servo valve. The oil inlet passage of the servo piston large chamber is then closed. and the whole displacement regulating process finished..



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● The pump regulator is a type of hydraulic servo mechanism. On the K3V main pump regulator, two springs are used to form two straight line ,and these two straight lines form an approximate constant power curve on the pressure-flow diagram. ● By adjusting the pre-compression of the spring to change the pump pressure starting point, the absorbed power of pump can be adjusted therefore. The pump outlet pressure is directly proportional to the spring force, and the spring force is inversely proportional to



the pump displacement. Shifting pressure p0 = spring precompression force ÷ oil pressure acting area



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Constant Power Control Strategy



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Constant Power Control Strategy The purpose of constant power control strategy is to adequately absorb power output from engine, and keep engine speed constant, so it can be called constant torque control strategy as well.



Priciple：



P = T·n／9550 T= p x v / ( 2 xπ) P: engine power output n: Engine speed T: Engine output torque



p: Pump pressure V:Pump displacement



P=p x V (p and V are inversely related) T=Constant



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The Regulator adjust pump



displacement according to external feedbacks in real-time, and realized the following functions: ●Flow Control （Negative Flow Control ）



●Power Control： 1.Constant Power Control （Crossed mutual control） 2.Powershift Control



Power Control



Flow Control



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• ● It’s forbidden to adjusting all these screws



Power Adjusting



• ● loosen(anti-clockwise) • Min. displacement screw, pump displacement Negative oil adjusting



will decrease • ● loosen(outer direction) Max. Min. displacement adjusting screw Pilot relief pressure adjusting



Max. displacement adjusting screw



Displacement bolt, pump displacement increased • ● loosen(outer direction) the other adjusting



bolts, the concerned parameters decreased



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Pilot Pump



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SERVO PISTON



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Compensator Spool



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SERVO SPOOL



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● Function: Used to set the absorbed power of pump in real time ● The input current of Psv is inversely correlated with outlet oil pressure, and positive correlated with absorbed power (that is, the larger the current value is, the lower outlet pressure and the greater absorbed power will be.) ● Poor toleration with impurities. ● When wire connector disconnected, the pf pressure is: 3.66MPa



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SWING MOTOR-KPM M5X180CHB



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SWING MOTOR-KPM M5X180CHB



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SWING MOTOR-KPM M5X180CHB



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SWING MOTOR-KPM M5X180CHB



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SWING MOTOR-KPM M5X180CHB



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SWING MOTOR-KPM M5X180CHB



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SWING RELIEF VALE



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REBOUND DAMPING VALVE



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REBOUND DAMPING VALVE



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REBOUND DAMPING VALVE



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REBOUND DAMPING VALVE



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SWING CHECK VALVE



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BRAKE TIME DELAY VALVE



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BRAKE VALVE



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TRAVEL MOTOR-KYB MAG-170VP



PA DR



PB



PS



COUNTER BALANCE VALVE



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COUNTER BALANCE VALVE



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COUNTER BALANCE VALVE SPOOL



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COUNTER BALANCE VALVE



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RELIEF VALVE



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RELIEF VALVE



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DOUBLE SPEED VALVE



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DOUBLE SPEED SPOOL



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BREAK CYLINDER



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BREAK CYLINDER



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BREAK PLATE



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DOUBLE SPEED PIN-AGAINST SWASH PLATE



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PISTON/SWASH PLATE



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Travel Motor Working



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AUTO-REDUCED SPEED OF DOWN SLOPE



AUTO-REDUCED SPEED OF DOWN SLOPE



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Speed control: Anti-overrun (especial down slope)



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Function: High-Low Speed



Low Speed



High Speed



Automatic change back single speed(especial while climbing)



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HYDRAULIC MAIN CONTROL VALVE



Arm regeneration disable valve Negative Flow Vale Bypass cut-off valve



Arm Flow Limit Valve



Arm rodless chamber relief valve



Negative flow valve



Arm Rod Chamber Relief Valve



Bucket flow limit valve



Arm 2 Boom Holding Valve



Boom 1



Bk Rod Chmb Relief Valve



Bucket Boom rod chamber relief valve Swing flow limit valve



Arm 1 Boom rodless chmb relief valve



Boom 2



swing



Strt Tr Pilot Control Valve



RH travel



Strt Tr Valve Bucket Rodless Chmb relief valve



Arm holding valve



Optiona l LH Travel



Main Relief valve



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arm(1)



arm(2)



boom(2)



boom(1)



swing



bucket



hammer



Right travel



Left travel



straight



P70



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4



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Oil flow-Neutral position



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Oil flow-boom up



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P1,p2 conflux



Oil flow-boom down



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Return oil regeneration



Oil flow-arm curl



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P1,p2 conflux regeneration



Oil flow-arm in(p1,p2 increased)



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P1,p2 conflux Non-regeneration



Oil flow-bucket curl



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regeneration



Oil flow-swing



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p1



Oil flow-singe travel



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P1/ p2



Oil flow-boom up & swing



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P1 priority to boom P2 totally to boom



Oil flow-arm curl & bucket curl



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P1 priority to arm P2 totally to arm



Oil flow-boom up & arm curl



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P1 priority to boom P2 to boom and arm



ARM Curl CONFLUX AND REGENERATION



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BOOM UP CONFLUX



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STRAIGHT VALVE



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HOLDING VALVE



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Holding VALVE



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Front view



Rear view



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Left view



Right view



Diagram-main spool



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Front view-spool



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spool



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relief valve



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Secondary relief valve



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Secondary relief valve



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● Relief pressure when cylinders overload ● Cylinder Anti-cavitation ● Pilot operated cartridge valve



Adjusting is generally prohibited.



Secondary relief valve



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Secondary Relief Valve（Relief）



Closed



溢流状态



先导开启状态



Main relief valve



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• ●boost function • 31.4Map(normal) • 34.3Mpa(boost） • It’s forbidden to adjust this valve.



Main relief valve



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1



2



3



4



Main relief valve



Closed status



Pilot for boost coming



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Relief status



Power Boosting



Secondary relief valve



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Oil flow limited relief valve(rear view)



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1. Arm flow limit valve 2. Swing flow limit valve 3. Bucket flow limit valve



1



2



3



Oil flow restrict valve (Left/right view)



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Swing Flow Restrict valve



Flow Restrict valve



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Flow restrict valve



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Diagram-Holding valve



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Holding valve-front view Arm(piston side)



Boom(nonpiston side)



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Holding valve



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Anti-drift valve



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Straight travel valve



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Straight travel valve-pilot



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Straight valve-pilot



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diagram-relief valve



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Diagram-check valve



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SPOOLS



R（1）ARM 1、 R（2）BOOM 2、 R（3）SWING、 R（4）HAMMER、 R（5）LEFT TRAVEL。



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L（1）ARM 2、 L（2）BOOM 1 L（3）BUCKET、 L（4）RIGHT TRAVEL、 L（5）STRAIGHT。



SAFETY VALVE-IN CASE HOSE BROKEN



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SAFETY VALVE-IN CASE HOSE BROKEN



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PILOT OIL BLOCK



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1：ACCULATOR 2：PILOT SOLENOID 3：STAND BY SOLENOID 4：BOOST SOLENOID 5：TWO SPEED SOLENOID FP:PILOT OIL INPUT FT:TO TANK F1:BOOST OIL OUT F2:TWO SPEED OUT F3:JOYSTICK OUT



PILOT OIL BLOCK



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TESTING&PERFORMANCE-SWE230B



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1 PILOT RELIEF VALVE）



1



2



a1



3 4 a2 a3



MAIN RELIEF VALVE）



TESTING&PERFORMANCE-SWE230B



1



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2



1



SECONDARY RELIEF VALVE）



1



2 TREAD MOTOR RELIEF VALVE



SWING MOTOR RELIEF VALVE



2



CYLINDER SPEED TEST



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AV/3 TIMES



OPERATION



STANDARD



BOOM CYLINDER



RAISE



3.5±0.3 (S)



LOWER



3.5±0.3 (S)



ROLL-IN



3.4±0.3 (S)



ROLL -OUT



3.2±0.3 (S)



ROLL-IN



3.4±0.3 (S)



ROLL -OUT



3.1±0.3 (S)



ARM CYLINDER



BUCKET CYLINDER



TESTING&PERFORMANCE



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AV/3 TIMES



WITHOUT LOAD



RATED LOAD



BOOM CYLINDER



Less than 5 mm



Less than 20 mm



ARM CYLINDER



Less than 15 mm



Less than 20 mm



BUCKET CYLINDER



Less than 10 mm



Less than 20 mm



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SWING SPEED AV/3 TIMES



THREE ROTATIONS



STANDARD



SWING SPEED



LEFT



11.5±1 (S)



RIGHT



11.5±1 (S)



TESTING & PERFORMANCE



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Standard Travel of coasting



Less than 900 mm



TESTING&PERFORMANCE



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Standard Coasting amount



Less than 900 mm



TESTING&PERFORMANCE



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20 Meter distance



Standard(S)



LOW speed



23.2±2(S)



TWO-Speed



15.5±1 (S)



TESTING&PERFORMANCE



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