Caterpillar Electronic Engine卡特彼勒电控柴油机卡特彼勒电控柴油机1发动机控制模块(ECM)各种传感器(Sensors)喷油器监视系统主要构成部件主要构成部件21. 电控柴油机的大脑电控柴油机的大脑发动机控制模块（发动机控制模块（ECM）全权的发动机电子控制记录发动机故障改进的发动机故障诊断方式发动机的监视和保护更多的程序定制功能3基于两个32位微处理器体系的ECM监视发动机运行参数，由此提供精确的燃油计量和喷射正时控制。出色的燃油消耗、性能、耐久性、可靠性。燃油进口燃油进口燃油进口燃油进口燃油出口燃油出口燃油出口燃油出口E.C.M. J2E.C.M. J24040针针针针接口接口接口接口E.C.M. J1E.C.M. J14040针针针针接口接口接口接口5E Electronic电子电子C Control控制控制MModule模块模块 A Advanced高级高级D Diesel柴油柴油E Engine发动机发动机MManagement管理系统管理系统燃油冷却管道燃油冷却管道40 针接口针接口橡胶隔离橡胶隔离加强的铝合金密封盒体加强的铝合金密封盒体7ECM的主要功能的主要功能Powers componentsControls the engine Monitors sensor input8电子电子调速器调速器发动机发动机逻辑控制逻辑控制空燃比图空燃比图扭矩图扭矩图关机关机油门油门 速度速度正时齿轮正时齿轮理想转速理想转速rpm扭矩扭矩校正校正空燃比校正空燃比校正实际转速实际转速rpm到到各各喷喷油油器器的的信信号号燃油喷射控制燃油喷射控制信号转换信号转换传感器传感器大气压力、大气压力、进气歧管压力进气歧管压力机油、燃油压力机油、燃油压力排气温度、冷却水温排气温度、冷却水温命令转速命令转速rpm9正时正时发动机转速发动机转速供油量供油量中冷器温度中冷器温度30-25-20-15-10- 5-25-20-15-10-52000-1750-1500-1250-1000- 750-120-100-80-60-40-2010传感器的输入信息可以控制发动机的运行并显示给操作者。压力传感器温度传感器位置传感器速度传感器2. ECM的输入的输入 传感器传感器11This sensor provides engine speed and crankshaft position information to the ECM.Heavy hex-shaped aluminum body for durabilityStraight thread o-ring mount for a leak-free engineDeutsch connector for trouble-free operationSpeed Timing Sensor12In critical applications, backup sensor insures engine up-timeECM switches to backup without interruption in engine operationDual Speed Timing Sensors13Speed Timing Sensor (Active Sensor)The active sensor incorporates a powered circuit in the sensor.This sensor has three wires. The first wire supplies 13.2 volts from the ECM to power the sensor board. This supply voltage is precisely controlled to 0.5 volts.The second wire is a ground wire from the ECM that supplies a zero volt reference.The third wire is the signal voltage to the ECM.14Sensor reads special tooth pattern on camshaft gearSensor sends a signal to the ECM as each tooth passesUnique pattern of teeth indicate engine position to the ECMSpeed Timing Sensor Mounting15Simple, effective designAll applications utilize dual sensors for reliabilitySpeed Timing Sensor (Passive Sensor)The passive sensor does not incorporate active electronic circuitry. This sensor is used on the 3126B engine. The sensor has a permanent magnet and a coil of wire inside. A change in the magnetic field induces a voltage into the sensor. The ECM reads the increases and decreases in voltage from the sensor as a signal.16Temperature sensors continuously monitor system temperatures and send information to ECMHeavy brass body for trouble-free serviceLarge hex on body for easy installation and removalStraight thread o-ring mount for a leak-free engineTemperature Sensors Oil, Coolant, Fuel17Provides critical information to the ECM for fuel rate adjustmentsCarbon fiber body prevents higher engine temperatures from affecting temperature readings of intake airStraight thread o-ring mount for a leak-free engineTemperature Sensor Air Intake18Temperature Sensor CircuitsThe coolant temperature sensor measures the temperature of the coolant and sends a DC signal to the ECM. The ECM uses this information to determine injection timing, adjust the fuel rate calculation, and protect the engine from overheating.The oil temperature sensor measures the temperature of the engine lubricating oil and sends a DC signal to the ECM. The ECM uses this information to protect the engine from damage from lack of lubrication. The fuel temperature sensor measures the temperature of the engine fuel, and sends a DC signal to the ECM. The ECM uses this information to adjust the fuel rate calculation and for fuel temperature power correction.19Temperature Sensor ComponentsThe temperature sensors measure changes in temperature and send a variable DC voltage back to the ECM. The sensors have three wires. The first wire sends a supply voltage from the ECM, providing power for sensor operation. This supply voltage is precisely controlled to 0.5 volts. The second wire is a ground wire from the ECM that supplies a zero volt reference. The third wire is the signal voltage to the ECM. This signal voltage reflects changes in the temperature of the system it is monitoring. The operating range of the voltage is slightly greater than zero volts to slightly less than 5 volts. A typical operating voltage is 0.5 to 4.5 volts. The ECM also determines if the signal wire is shorted or open by monitoring the signal voltage. If the signal voltage is the same as supply voltage, the ECM knows the sensor or sensor circuit is open. If the signal voltage is zero, the ECM knows the sensor or sensor circuit is shorted. If the ECM senses the circuit is open or shorted, it will indicate a fault for that circuit to assist in trouble-shooting. The key temperature sensors on the engine are the coolant temperature sensor and the intake manifold air temperature sensor.20Pressure sensors continuously monitor system pressure and send information to ECMHeavy metal body for trouble-free serviceStraight thread o-ring mount for a leak-free enginePressure Sensors Oil and Air21Pressure Sensors Oil and AirEngine system pressures are critical to performance, economy, engine life, and the environment. Oil pressure is the most critical system pressure. The oil pressure sensor is located in the main oil galley and sends a continuous stream of analog data to the ECM. The correct turbocharger boost pressure is essential to engine performance. Boost pressure is measured at the outlet of the turbocharger and in the intake manifold. The ECM monitors boost and ambient pressures and then delivers the correct amount of fuel at the exact time required to achieve optimum power and fuel economy with minimal emissions. 22Active electronic circuitry for a strong, dependable signalPressure Sensor Components23Pressure Sensor ComponentsPressure sensors measure changes in pressure and send a variable DC voltage back to the ECM. Pressure sensors have three wires. The first wire sends a supply voltage from the ECM, providing power for sensor operation. This supply voltage is precisely controlled to 0.5 volts. The second wire is a ground wire from the ECM that supplies a zero volt reference. The third wire is the signal voltage to the ECM. This signal voltage reflects changes in the pressure of the system it is monitoring. The operating range of the voltage is slightly greater than zero volts to slightly less than 5 volts. A typical operating voltage is 0.5 to 4.5 volts. The ECM also determines if the signal wire is shorted or open by monitoring the signal voltage. If the signal voltage is the same as supply voltage, the ECM knows the sensor or sensor circuit is open. If the signal voltage is zero, the ECM knows the sensor or sensor circuit is shorted. If the ECM senses the circuit is open or shorted, it will indicate a fault for that circuit to assist in trouble-shooting. The key pressure sensors on the engine are the engine oil pressure sensor, the injection actuation pressure sensor, the boost pressure sensor, and the atmospheric pressure sensor.24Pressure sensors provide continuous information to ECMPressure information is used by the ECM to adjust the fuel rate and protect the enginePressure Sensor Circuit25Pressure Sensor CircuitThe boost pressure sensor measures pressure in the intake manifold and sends a DC signal to the ECM. The ECM uses this information to prevent overfueling, which eliminates black smoke.The atmospheric pressure sensor sends a DC signal to the ECM. The ECM utilizes this information to determine the altitude at which the engine is operating. The ECM then adjusts fuel delivery and timing to compensate for altitude and maintain engine performance and emissions. This sensor is not used on some lower hp rated engines.The oil pressure sensor sends a DC signal to the ECM. The ECM utilizes this information to determine the engine oil pressure. The ECM uses this information to protect the engine. The ECM will warn the operator of low pressure and then, if configured, will shut down the engine.26Continuously monitors coolant level and sends information to the ECMHeavy metal body for durabilityStraight thread o-ring mount for leak-free engineCoolant Level Sensor27Coolant Level SensorThe coolant level sensor is mounted below the full level mark in the radiator top expansion tank. It monitors the existence of the coolant in the tank and sends a signal to the ECM indicating that coolant is present at that level. If the coolant falls below the level of the sensor, a signal indicating a low coolant level is sent to the ECM. The coolant level sensor is usually installed by the OEM.28Active electronic circuitry for strong, accurate signalCoolant Level Sensor Circuit29Coolant Level Sensor CircuitOn engines installed in over-the-road vehicles, the coolant level sensor is an OEM installed component. This is the only optional sensor on over-the-road engines. This sensor detects the presence or absence of coolant. The sensor has four circuit wires. The signal wires reverse the voltages with the absence of coolant. The first wire is the +5 VDC supply. The second wire is the coolant level normal signal wire. When the coolant level is normal, this wire (coolant level normal) sends a +5 VDC signal to the ECM. The third wire is the return. The fourth wire is the coolant level low signal wire. When the coolant level drops below the tip of the sensor, this wire sends a 0 VDC signal to the ECM.30Same sensor used for many applications making OEM installation and service easyActive electronic circuitry for strong, accurate signalThrottle Position Sensor31Active electronic circuitry for strong, accurate signalPWM signal provides reliable signals to ECMPosition Sensor PWM Signal32Position Sensor PWM SignalThe throttle position sensor monitors the position of the throttle (pedal or lever) and converts that position into a PWM signal which it sends to the ECM. The position sensor has three wires. The first wire provides voltage from the ECM to provide power for operation. This supply voltage is precisely controlled to 8 0.5 volts. The second wire is a ground wire from the ECM that supplies a zero volts reference voltage. The third wire is the signal voltage to the ECM.33Position Sensor PWM SignalThe position sensor generates a PWM signal which is a square wave. A square wave signal is either full voltage or no voltage on or off. The percent of time the signal is on versus the time off is called the duty cycle. Duty cycle at low idle pedal position is 10% to 22%. Duty cycle at high idle pedal position is 75% to 90%. The pedal position sensor transmits the signal to the ECM at a constant frequency. This type of sensor provides a very accurate signal to the ECM with a smooth transition between acceleration and deceleration. The ECM determines if the sensor is faulty by monitoring the duty cycle. If the duty cycle is greater than 90% or less than 10%, the ECM will log an active fault.34Position sensors provide continuous information to ECM to maintain accurate throttle positionThrottle Position Sensor Circuit35Throttle Position Sensor CircuitThe acceleration pedal circuit determines desired engine speed by sensing the position of the accelerator pedal and sending a PWM signal back to the ECM. The ECM then compares desired engine speed to actual engine speed and determines the quantity of fuel delivered by the injectors. The operator selects a desired engine speed with the accelerator pedal. The position of the pedal is converted into a PWM signal and sent to the ECM. The duty cycle of the signal is translated into a desired engine speed by the ECM. The ECM then compares desired and actual speed and determines if the injectors should deliver more or less fuel to the cylinders. If actual engine speed is lower than desired, the ECM will increase current to the injectors to increase the delivery of fuel. If actual engine speed is higher, the ECM does the opposite.36Output devices on the 3406E, C-10, C-12, and 3196 are the injectorsIn addition to the injectors, the 3126B, 3408E, and 3412E have an injection actuation pressure valveECM Output Devices37EUI injectors have been in service since the mid-eightiesHeavy forged injector body handles high injection pressureLarge solenoid and precision valve provides excellent reliabilityCaterpillar Electronic Unit Injector EUI38High injection pressure at low rpm for excellent load starting and lugging capabilitiesHEUI is simple and requires no adjustments for serviceability and reliabilityHeavy forged body handles high injection pressureCaterpillar Hydraulic Electronic Unit Injector HEUI39The IAPCV controls the HEUI oil pressureThe valve is an integral part of the HEUI hydraulic pump and is externally mounted for easy serviceLarge externally mounted electrical solenoid for efficiency and serviceabilityInjection Actuation Pressure Control Valve (IAPCV)40A Caterpillar designed system with only one moving part for simplicityInjection Actuation Pressure Control Valve (IAPCV)41Injection Actuation Pressure Control Valve (IAPCV)A significant performance benefit of the HEUI system is that it can produce any desired injection pressure at any engine speed or operating condition. This is accomplished by controlling the injection oil actuation pressure that powers the injectors. The HEUI oil pump pressurizes engine lubricating oil to power the HEUI injectors. The IAPCV is located in the pump and controls the oil pressure by venting some of the oil flow back to the oil pan. The IAPCV is an electrically activated relief valve, which operates by receiving a variable current from the ECM. A low current will produce low oil pressure and a high current produces high oil pressure.42The valve receives current from the ECM to control the hydraulic pressure in the HEUI systemInjection Actuation Pressure Circuit43Injection Actuation Pressure CircuitThe injection actuation pressure circuit controls the operation of the IAPCV. The ECM determines desired engine speed based on input from the throttle pedal and other engine sensors. The ECM then uses software maps programmed into the personality module to determine the required actuation pressure to produce the desired engine speed. The ECM then calculates the required control current to send to the IAPCV to produce the desired actuation pressure. The IAPCV responds to the control current and regulates actuation pressure. The ECM continually monitors actuation pressure and adjusts the control current to regulate the actuation oil pressure. 44The tough vinyl coated nylon webbing over the harness resists abrasions and creates a secure harnessWiring Harness45A Caterpillar standard color and identification for each wireWires are Color Coded and Numbered46Connector covers provide extra protection for critical applicationsHarness Connector Covers Marine and Industrial47Heavy-duty AMP and Deutsch connectorsConnectors have large pins and sockets for reliabilityDurable Harness Connectors48Provide operator/driver with immediate informationAn operator convenience as well as an engine protection featureWarning Lamps49Warning LampsThe check engine lamp is often referred to as the diagnostic lamp. The check engine lamp is used to indicate the presence of an active diagnostic code and alert the driver that the idle shutdown timer has started. It is also used to flash diagnostic codes. The warning lamp is an optional feature. It operates in conjunction with the engine monitoring system. The lamp will turn on when the customer parameter for engine monitoring is set to warning, derate, or shutdown. The maintenance indicator lamp is used to inform the operator that a maintenance interval (PM1, PM2, or Coolant Flush/Fill) is due.50ECM activates a valve to shutoff intake air to stop engineQuick and positive stopping of engine in emergencyEmergency Stop Control51ECM controls quantity and time of ether injection according to temperature and engine rpmSystem provides safe use of ether and is a great operator convenienceEther Injection Station52Ether Injection StationThe ether injection system is optional on industrial and marine engines. The ECM uses temperature information from the engine coolant temperature sensor and engine speed information to determine if ether is needed and the amount to inject. If the temperature is between -40C and 10C (-40F and 50F) and the engine is cranking over 30 rpm, ether can be injected. The injection time is determined by temperature and will be between 15 and 130 seconds.53ECM VariablesSystem configuration parameters set at the factoryCustomer programmable parameters modified by the customer to fine-tune the engine54ECM Monitors Engine and ItselfECM continually monitors all engine systems and its own circuitryIssues active codes to warn the operator of an immediate problemKeeps track of old problems with a logged code function55ECM Monitors Engine and ItselfIn addition to monitoring all of the engine systems, the ECM continually monitors itself. When a problem is detected, the ECM generates an active fault code and turns on the diagnostic/check engine lamp. Each code has a unique number and is stored in memory. Codes that are no longer active are called logged codes. A logged code indicates that a problem has occurred, but is not presently active.56Lifetime Totals Stored by the ECMLifetime totals provide a complete operating history of the engine57Trip Data Stored in the ECMECM stores trip data for operator and management use58Fleet HistogramsEasy-to-understand graphical information59Cold ModeAutomatically limits power at start up until the engine reaches operating temperature60Fuel Temperature Power CompensationECM adjusts power output to compensate for inconsistencies caused by fuel temperature variations61Fuel Temperature Power CompensationThe fuel temperature sensor continually monitors the temperature of the engine fuel. The ECM uses this information to adjust the fuel rate calculation (fuel injection rate) and for fuel temperature power correction. The ECM performs a fuel temperature power correction when the fuel temperature exceeds 30C (86F) to maintain a consistent power level. Maximum power correction is achieved at 70C (158F). Fuel temperatures exceeding 80C (176F) for 30 seconds cause a diagnostic code to be logged.62Engine Monitoring SystemEMS is a programmable monitoring system designed to operate with Caterpillar engines63Engine Monitoring SystemThe ECM provides access to enormous amounts of real-time data. The Caterpillar EMS is an excellent and convenient method for viewing this engine data. With EMS, you can view important engine, transmission, and related system parameters. EMS provides excellent visibility in all lighting situations. It is programmed to display U.S. customary units or metric units.64Ten icon warning lampsThe LCD displays different engine and transmission parametersMain Unit65Four analog gauges with red danger zonesUnit has an alarm outputMonitors selected systemsQuad-Gauge Unit66Large analog gaugeDigital LCD for other dataTachometer Unit67Allows the customer to fine-tune engine performance to a specific applicationCustomer Specified Programmable Parameters68Customer Specified Programmable ParametersCaterpillar specified programmable parameters allow the engine owner/customer to select features, operating parameters, and power ratings (within specified families) to precisely match the vehicle to the application. These features can provide operator conveniences, enhance fuel efficiency, and even influence how a vehicle is driven. These features are accessed through the Caterpillar service tools (ECAP and ET). 69Engine monitoring system can be programmed to provide several different levels of protectionEngine Monitoring System70Engine Monitoring SystemEach engine subsystem is monitored by one or more sensors, which provide continuous information to the ECM about operating conditions. The ECM utilizes this information to control engine operation and alert the operator to a potential problem. This monitoring system can be programmed to provide four different levels of protection:OEMs can program the monitoring system to better match existing vehicle systems.OFF - no monitoringWarning - alerts driver to take action to avoid engine damageWarning/Derate - alerts driver and derates engineWarning/Derate/Shutdown - automatically shuts the engine down if one of the monitored conditions exceeds a predetermined setting71Two modes provide standard and enhanced operation for operator conveniencePTO Mode72Allows the PTO ramp speed to be precisely matched to a critical applicationPTO Ramp Rate73Allows the torque to be matched to a specific PTO function or applicationPrevents excess torque from potentially damaging a sensitive applicationTorque Limit74Low Engine IdleAllows idle speed to be set between 600 and 750 to match vehicle requirements75Allows the high idle to be matched to a specific applicationProvides a safe upper rpm limitHigh Engine Idle76Allows a programmed intermediate rpm for a unique PTO or engine applicationIntermediate Engine Speed77Provides a maximum rpm when the engine is under loadTop Engine Limit (TEL)78Allows other vital systems to be monitored by the ECMAuxiliary Pressure and Temperature79ECM calculates maintenance intervals and informs the operator of necessary maintenanceMaintenance Indicator ModeWhen this function is activated, the ECM tracks and records data related to unit maintenance. When the unit reaches a maintenance interval (PM1, PM2, or Coolant Flush/Fill), the ECM will turn on the maintenance lamp. 80814 Basic Functions of EUI InjectorsPressurize supply fuel injection pressureAtomize the high pressure fuel by pumping it through orifices in the injector tipDeliver the correct quantity of atomized fuel into the combustion chamberDisperse the atomized fuel evenly throughout the combustion chamber82Injector Components83EUI vs. Earlier InjectorsThe EUI injector is mechanically actuated much like earlier Caterpillar unit injectors. The major difference is in the injector control system. The EUI is electronically controlled by the engine ECM.84SolenoidThe solenoid and poppet valve are an integral unit and mount on the side of the injector body. The solenoid assembly contains the solenoid coil, armature, and poppet valve. The armature and poppet valve are attached and function as a unit. The solenoid is an electromagnet which creates a very strong magnetic field that attracts the armature. As the armature moves toward the solenoid, the valve seats and shuts off the flow of fuel to start the injection process.85Poppet ValveOpen PositionWhen the solenoid is not energized, the valve is in the open position. This is the normal position for the valve.Closed PositionWhen the solenoid is energized, the armature lifts the poppet and seats it to stop the flow of fuel through the valve.86Injector BodyThe injector body contains the barrel and plunger, fuel drillings, and the mount for the solenoid. The plunger and barrel together act as a pump, much like a medical syringe. Both the plunger and barrel are precision components with very small working clearances. These tight clearances are required to produce injection pressures above 20,000 psi.87Nozzle Assembly Components88Nozzle AssemblyThe nozzle assembly is similar to other Caterpillar unit injectors. Fuel at injection pressure flows from the plunger cavity through a passage to the nozzle tip. Fuel flow out of the tip is stopped by the nozzle check, which covers the orifices in the end of the tip. The tip is held in the closed position by the force of the nozzle spring.89Valve Opening PressureWhen injection pressure increases to approximately 5,500 psi, hydraulic force acting on the nozzle check overcomes the spring force and lifts the check off its seat. The pressure at which the check opens is called Valve Opening Pressure (VOP).90Valve Closing PressureThe check remains open and fuel is injected into the combustion chamber until injection pressure drops below 5,500 psi. When pressure drops, the check closes and injection is stopped. The pressure at which the check closes is called Valve Closing Pressure (VCP).914 Stages of EUI InjectionPre-injectionInjectionEnd of InjectionFuel fill92Pre-InjectionWith no pressure applied to the plunger from the camshaft, the injector return spring keeps the plunger retracted. Fuel flows at approximately 60 psi from the transfer pump through the injector to keep it filled with fuel and cooled.93Start of InjectionAs the camshaft lobe contacts the roller follower, the plunger will start its downward travel. Since the solenoid valve has not been activated yet, the fuel in the barrel will flow through the solenoid valve and out of the fill/spill port.94InjectionWhen the ECM determines that the injector should fire, it sends a current to the injector solenoid to close the poppet valve. This blocks the flow of fuel out of the injector and traps the fuel within the injector. Pressure elevates quickly as the plunger continues its downward travel. When the fuel reaches valve opening pressure, approximately 5,500 psi, the nozzle check valve lifts off its seat and injection begins.95InjectionAs the camshaft continues to rotate, the plunger will continue its downward travel. Fuel will now be injected into the combustion chamber. The spray holes in the nozzle are very small and will resist the flow of fuel into the combustion chamber. The fuel pressure will continue to rise to near 20,000 psi as injection continues. The high fuel pressure, along with the small size and angle of the holes in the nozzle will control the atomization of the fuel into the combustion chamber. Fuel will continue to be injected until the solenoid is de-activated.96End of InjectionThe end of the injection cycle begins when the ECM shuts off the current to the injector solenoid. As the magnetic field of the solenoid collapses, the poppet valve un-seats. This allows the high pressure fuel in the barrel to escape to the fill/spill port. When the injection pressure drops below Valve Closing Pressure, the nozzle check closes, ending injection.97Fuel FillSince the plunger is activated by the camshaft, it will continue to the bottom of its stroke in the barrel. Fuel in the barrel will be forced out the fill/spill port as it was before injection started. At the bottom of its stroke, the plunger return spring will force the plunger up in the barrel. The fuel pressure from the transfer pump will fill the barrel. The injector is now ready for the next cycle.98994 Basic Functions of HEUI InjectorsPressurize supply fuel from 65 psi to 5,400 - 23,500 psiAtomize the high pressure fuel by pumping it through orifices in the injector tipDeliver the correct quantity of atomized fuel into the combustion chamberDisperse the atomized fuel evenly throughout the combustion chamber100Injector Components101SolenoidThe top 1/3 of the injector contains the solenoid, armature, and poppet. The armature is attached to the poppet valve. The solenoid is an electromagnet which creates a very strong magnetic field that attracts the armature. As the armature moves toward the solenoid, it lifts the poppet valve off its lower seat to start the injection process. 102Poppet Valve Closed PositionIn the closed position, the poppet is held on its lower seat by a spring. The closed lower seat prevents high pressure actuation oil from entering the injector. 103Poppet Valve Open PositionWhen the solenoid is energized, the poppet is lifted off its seat. This allows high pressure actuation oil to enter the injector and act on the top of the intensifier piston. The upper seat of the poppet valve closes, blocking the vent and preventing actuation oil from leaking out of the injector. 104Intensifier Piston and PlungerThe center of the injector contains the intensifier piston, plunger, barrel, and plunger return spring. The intensifier piston is about 6 times larger in surface area than the plunger. This difference provides a multiplication force which allows 3,500 psi of actuation oil to produce 23,500 psi of fuel injection pressure. 105BarrelThe barrel is the mating cylinder in which the plunger moves. The plunger and barrel together act as a pump, much like a medical syringe. Both the plunger and barrel are precision components with very small working clearances. These tight clearances are required to produce injection pressures above 20,000 psi. The barrel also contains the PRIME spill port. 106PRIME Spill PortThe PRIME spill port is a small precision hole in the barrel. This port momentarily vents fuel injection pressure during the downward stroke of the plunger. The operation of the PRIME feature is fully explained in the Pilot Injection operation description. 107Nozzle Assembly Components108Nozzle AssemblyThe nozzle assembly is similar to other Caterpillar unit injectors. Fuel at injection pressure flows from the plunger cavity through a passage to the nozzle tip. Fuel flow out of the tip is stopped by the nozzle check, which covers the orifices in the end of the tip. The tip is held in the closed position by the force of the nozzle spring.109When injection pressure increases to approximately 4,500 psi, hydraulic force acting on nozzle check overcomes the spring force and lifts the check off its seat. The pressure at which the check opens is called Valve Opening Pressure (VOP).Valve Opening Pressure (VOP)110The check remains open and fuel is injected into the combustion chamber until injection pressure drops below 4,000 psi. When pressure drops, the check closes and injection is stopped. The pressure at which the check closes is called Valve Closing Pressure (VCP). Valve Closing Pressure (VCP)1115 Stages of HEUI InjectionPre-injectionPilot InjectionDelayMain InjectionEnd of Injection112Pre-injectionAll internal components are in their spring loaded, non-actuated position. The solenoid is not energized and the poppet valve is blocking high pressure actuation oil from entering the injector. The plunger and intensifier piston are at the top of their bore and the plunger cavity is full of fuel. Fuel pressure in the plunger cavity is the same as fuel supply pressure; approximately 65 psi. 113Pre-injection Metering (PRIME)The HEUI fuel system has a unique feature called PRIME, which is an acronym for Pre-Injection Metering. PRIME breaks the single large injection charge into two separate injections: Pilot Injection and Main Injection. 114Initial Pilot InjectionThe plungers downward movement produces the initial pilot injection of fuel into the combustion chamber. During the downward movement of the plunger, grooves in the plunger will align with the spill port in the barrel. High pressure fuel in the barrel will vent through the spill port interrupting fuel injection, and causing a short delay in the injection process.115Injection DelayDuring pilot injection a small quantity of fuel is injected into the combustion chamber. The brief delay allows time for this fuel to ignite and start burning. After the delay, the main injection is delivered into the flame front established by the pilot injection. The main injection immediately ignites and burns smoothly and completely. This efficient combustion significantly reduces exhaust emissions and lowers overall engine noise by up to 50%, resulting in noticeably quieter engine operation.116Main InjectionAs the plunger continues its downward stroke, fuel will be injected until the solenoid is de-energized.117End of InjectionThe end of the injection cycle begins when the ECM shuts off the current to the injector solenoid. As the magnetic field of the solenoid collapses, the poppet valve moves down and seats. This shuts off flow of high pressure oil to the intensifier piston and opens the vent. As high pressure oil over the intensifier piston vents, injection pressure will drop. When the injection pressure drops below Valve Closing Pressure, the nozzle check closes, ending injection.118Industrial and Marine Electronics Schematic119Industrial and Marine Electronics SchematicThe ECM has two harness connectors - one for the engine harness, and one for the vehicle harness. The engine harness connector links the ECM to all the engine sensors and actuators, including the injectors. The vehicle harness connector links the ECM to the engine control section of the main vehicle electrical system. This includes the throttle position sensor, vehicle speed sensor, transmission and brake relays, cruise control, and vehicle PTO control switches. This wiring may seem complicated, but is quite simple. It is made up of many small circuits.120Industrial and Marine Electronics Schematic121Industrial and Marine Electronics Schematic122Industrial and Marine Electronics Schematic123谢谢！谢谢！124