Presentation on theme: "Welcome to Malaga WeBex Common Rail Fuel System"— Presentation transcript:
1Welcome to Malaga WeBex Common Rail Fuel System CATERPILLARCommon Rail Fuel System
2The fuel system consist of the fuel transfer pump, high pressure pump, high pressure rail, which includes the pressure relief valve and rail pressure sensor, injectors and fuel filters.
3The common rail fuel system, is a two stage fuel distribution system. Gear driven fuel pump maintain constant fuel supply pressure. This pressure is supplied to the common rail then to all injectors.Pressure Generation and actual injection process have been decoupled from each other in the Common Rail accumulator system. The injection is generated independent of engine speed and and injected fuel quantity, and is stored, ready for each injection event, in the rail.The start of injection and the injected fuel quantity are calculated by the ECM via inputs, and implemented at each injector through triggered solenoid valve.The high pressure fuel pump is not serviceable. Fuel Rail relief valve is set to 190 MPa, when the relief valve opens will generate Event code E396, in case the valves opens 3 times, the the valve, the rail and all high pressure pipes must be replaced.
4Orifice Here we can see the Low pressure and high pressure generation. The Low pressure system works with a pressure of about 500 kPa,High pressure is between 70 to 140 Mpa. High pressure will withstands spikes pressure of up to 190 Mpa, but it will open at 160 Mpa steady pressure.Primary Fuel Filter 20 microns, Secondary 2 microns, there are some applications will need a 3rd filter, also 2 microns.Two orifices to control low system minimum working pressure.Maximum system pressure is controlled by a valve on the fuel transfer pump.
5Electronic Control Module (ECM) ECM Controls:Fuel PressureSpeed GoverningAir/Fuel RatioStart/Stop SequenceEngine Protection Devices/ DiagnosticsECM A4E2 recognizes the engine condition using the inputs from its various sensors. The ECM determines the injection strategy, timing, quantity and pressure based on engine control maps, by comparing the engine conditions and the required engine speed.Input sensor information comes from:Coolant Temperature SensorEngine Speed and timing Sensor.Throttle position SensorBoost pressure sensor.
6Fuel Pump Function Do it Again! Pump Raises Pressure ECM tells Injector to FireRail Pressure DropsECM Detects Pressure DropSensed by Fuel Rail Pressure SensorECM tells Pump Solenoid to Increase VolumeAlso tells Pump Solenoid to Spill fuel once pressure is reachedDo it Again!The common rail fuel system is a closed loop controlling action. It is exactly as on HEUI engines.ECM driver send a 70 volts pulse to activate the injector Solenoid. Upon or depending of emissions compliances, the system is capable of multi shot.Pilot, Main and Post injection.
7Fuel in from Secondary Filter Fuel Leak off to Tank Oil lubricationFuel in from Secondary FilterFuel Leak off to TankTo Fuel HPManifoldTo Secondary FilterPump SpeedPosition SensorHere is a view of the HIGH PRESSURE PUMP.High pressure Pump must be Phased timed to the engine, also the Pump must be locked while installing it.In case the secondary sensor fails, it can be interchanged with the primary Engine speed timing sensor. In case the secondary EST Sensor fails, the engine will not run.For a 6 liter engines, the HIGH PRESSURE PUMP requires about 11 kW.From Primary FilterLocks the Pump
8Transfer Pump Driven by High Pressure Pump Draws Fuel through Primary FilterOutput Pressure300 to 600 kPaTransfer Pump Primed by Priming PumpHand or ElectricPump Ratio is of 1.35 x Engine Speed. It is a serviceable item.
9High Pressure Fuel System Do’s & Don’tsDo Check for leaksDo Not Loosen HP Connection with Engine RunningDo Replace HP Pipes After they are LoosenedDo Replace ALL Hp Pipes if new manifold is InstalledDo Not Force Pipes to FitDo Cap Manifold and Injector Connections Immediately when HP Pipe is removedFuel ManifoldInjector LinesHigh PRVRail Pressure Sensor
10High Pressure Relief Valve Fuel Pressure Relief ValveHigh Pressure Relief ValveProtects System from Over-PressureOpens at Constant Pressure of 160 MPa (23,000 PSI)Withstands Spikes to 190 Mpa (27,500 PSI)Returns fuel to Tank
11Excess Fuel Returned to Transfer Pump Fuel Return from HeadExcess Fuel Returned to Transfer PumpNot High PressureFuel Return from Head LIneLeak off test.Actual pressure just above fuel transfer pressure.If more than ml on 3 test, all of the injectors must be changed.Perform 3 test and find average. Disconnect cables at injectors. There is a back pressure on the line, back pressure is fuel transfer pressure, the idea de have a back pressure is to protect the injectors from the hammering effect of fuel on fuel off
12Injector Function Injector De-energizes Valve Closes Unused fuel flows back to Transfer Pump via passage in the Head
13Fuel Injector Do’s and Don’ts Do Write down the Injector Serial Number and Confirmation Code before you install the InjectorDo use Cat ET to Program ECM with proper Injector Trim FileDo Look for the Trim File CD in the Injector BoxInjector TRIMService/Injector TRIM/Flash.May need to type the confirmation code.
14Injector Adaptive TRIM Fuel System Optimization RoutineRuns every hundred hours or soAudible changes when engine is runningNO performance or Power ChangesEverything’s OKSimilar to HD ACERT engines
15Here is a picture of a C9 ACERT Technology. Lets look at the new engine components. As you can see by the different color schemes there are several several groups of components that the mechanic will need to identify before being able to work on this engine. This lesson will deal with component identification in the classroom and in the lab.
16Cat Common Rail Fuel System C175 Meets emissionsLower fuel consumptionBetter transient responseAdvantagesHigh Pressure RailHigh PressurePumpPrimary Fuel Filter/Water SeparatorCooler--The Cat Common Rail Fuel System consists of the following components: The Primary Fuel Filter/Water Separator, The Secondary Fuel Filters, the High Pressure Pump, the High Pressure Lines and Rails, and the optional Fuel Cooler.--The flow of fuel is as follows—The fuel begins in the tank--filters to the 10 micron primary fuel filter/water separator--flows to the fuel transfer pump which initially pressurizes the fuel to a nominal pressure of 650 +/- 100 KPa (95 psi)--the fuel then goes to the 2 micron secondary fuel filters (the number of secondary filters will vary depending on application and engine size)--then to the high pressure pump that pressurizes the fuel to 180 MPa (1800 Bar or 26,000 psi)--the 180 MPa (26,000 psi) fuel then goes to the high pressure rails--and finally to the injectors.--The drainage from the injectors will return to tank.--The fuel cooler is optional and depends on application.--The electric priming pump is standard and activated during start-up by the ECM.--The Cat Common Rail Fuel System has both low pressure components and high pressure components.--We will discuss the Low Pressure components first.--check on if a water sensor is an option or standardSecondary Fuel FiltersFuel TankElectric PrimingPump
17Cat Common Rail Fuel System Low Pressure Fuel SystemFTPElectric PrimingFiltration--This is an introduction to the Low Pressure System and the components include: the Fuel Transfer Pump, the Electric Priming Pump, and Filtration.--The Transfer Pump sends the fuel to the High Pressure Pump and is driven directly off of the High Pressure Pump.--The Transfer Pump pressurizes the fuel to 650 Kpa or 95 psi.--The Electric Priming Pump (click) pulls fuel from the tank and pushes it through to the 10 micron primary filter or filters and purges the air out the system.--The (click) Filters are located right here.-- Extra Note The Electric Priming Pump is also used when filling new, dry fuel filters and is activated during starting by the ECM.
18Cat Common Rail Fuel System HP PumpDouble Wall LinesDouble Wall RailsFlow LimiterInjector--The High Pressure Fuel System consists of the High Pressure Pump, The Double Wall Lines and Rails, the Flow Limiter, and the Injectors.--The high pressure pump is lubricated by engine oil and this provides an extended pump life compared to pumps lubricated by fuel.--The Double Wall Lines (click) and Double Wall Rails (click) are an integral part of the fuel delivery.--The Flow Limiter is a protection device for an individual cylinder that limits maximum fuel flow (in the case of a component failure).--Return lines have a nominal regulated back pressure of 550 Kpa (or 80 psi).
19Cat Common Rail Fuel System - HP Rail Low PressureInjector returnPressure Sensor--This is another look at the High Pressure and Low Pressure Fuel Systems components together.--There is a total of 1 Pressure Sensor(located in left hand rail as shown) for machine and electric power applications.--In Marine applications there is a total of 2 Pressure sensors(one per fuel rail); as a redundant system in case of sensor failure at sea.--The Pressure Sensor or Sensors are Regulated by a 500 KPa check valve.Double WallLines From HP PumpTo RailDouble WallCrossover Line
20High Pressure Fuel System Hardware PRVPRV OutletHP OutletOil Supply--This is an image of the exterior of the High Pressure Pump.--You will notice some familiar features such as the Oil Supply, The Fuel Pump that is auxiliary gear driven, the Flow Control Valve that sends the precise amount of fuel the injectors demand, and the Fuel Transfer Pump Drive.--PRV or Pressure Relief Valve will bleed pressure from the High Pressure Pump if the pressure goes above 2050 Mpa or 250 bar.--HP Outlet or High Pressure Outlet is the exit port for the High Pressure Fuel being supplied from the pump to the rest of the Cat Common Rail System.--Fuel Temperature is monitored at the Temperature Port and inputs go directly to the ECM.CamshaftFTV DriveOil ReturnFlow Control Valve
21Flow Limiter Flow Limiter Protection Device Against Cylinder Over FuelingPiston Moves With Every InjectionTrips at Set Point To Prevent Continuous Injection and Remains Shut--This image shows you a cross section of the flow limiter in relation to the position of the Fuel Lines and Fuel Rails--FLOW LIMITER prevents over fueling by retracting the Flow Limiter PISTON TO SEATED POSITION ON EVERY INJECTION EVENT AT THAT CYLINDER, EVEN ON VERY SMALL INJECTIONS including PILOT injection and POST injection.--THE SET POINT OF THE FLOW LIMITER IS VOLUME BASED, SO THAT WHEN A SPECIFIC QUANTITY OF CONTINUOUS FUEL FLOW PASSES THE PISTON, THE PISTON WILL TRAVEL TO DISPLACE THAT VOLUME.--ONCE THE PISTON REACHES ITS HARD STOP, THE FLOW OF FUEL TO THAT CYLINDER IS CUT OFF, AND THE PISTON WILL NOT RESET UNLESS THE ENGINE IS SHUT DOWN AND FUEL PRESSURE IS BLED DOWN.--The TARGET FOR FLOW LIMITER SHUT OFF HAS BEEN APPROXIMATELY 1500 TO 1700 Cubic Millimeters OF FUEL IN ONE INJECTION EVENT.--FLOW LIMITER WILL TRIP CLOSED ALSO IF THERE IS AN EXCESSIVE LEAK DOWNSTREAM OF THE FLOW LIMITER (for example LEAK AT HIGH PRESSURE SEALING JOINTS, ETC.).SpringPiston