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Caterpillar and Navistar H.E.U.I. Chapter 27

Caterpillar and Navistar H.E.U.I. Chapter 27. DSL 131. OBJECTIVES. Describe the H.E.U.I. system layout and the primary components. Outline the role of the four primary H.E.U.I. subsystems. Describe the operating principles of an injection pressure regulator (IPR ).

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Caterpillar and Navistar H.E.U.I. Chapter 27

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  1. Caterpillar and Navistar H.E.U.I.Chapter 27 DSL 131

  2. OBJECTIVES • Describe the H.E.U.I. system layout and the primary components. • Outline the role of the four primary H.E.U.I. subsystems. • Describe the operating principles of an injection pressure regulator (IPR). • Describe the operating principles and subcomponents of Caterpillar-manufactured H.E.U.I. injector units. • Outline the operating principles of 2004 Siemens-manufactured H.E.U.I. injector units. • Define the role played by the ECM input circuit and the factors that govern ECM processing logic.

  3. OBJECTIVES (Cont.) • Describe how the ECM switches output devices control engine fueling and manage combustion. • Describe the role of the consolidated engine controller. • Perform basic electronic troubleshooting on an H.E.U.I. system. • Outline the procedure required to perform proprietary data reprogramming of an ECM. • Perform customer data programming using an EST.

  4. INTRODUCTION • When it was introduced in 1994, Hydraulically-actuated Electronic Unit Injector (H.E.U.I.) technology represented a new direction for the Caterpillar Engine Division because, for the first time, it launched the business of supplying fuel system engineering and components to competitor engine original equipment manufacturers (OEMs). • It was developed as a joint venture with International. • Introduced on a light duty 7.3L International engine that was marketed in Ford trucks 1994. • Catarpillar used this system from 2004 to 2007 then changed to common rail tech for small and medium-bore highway engines. • Still in use by International Navistar.

  5. ADVANTAGES AND LIMITATIONS OF H.E.U.I. • The HEUI fuel system was the first to offer significant control over injection rate and duration. • It could do this because its injectors were actuated, not by cam profile, but hydraulically using oil pressure.

  6. Component Locations on an International Trucks I-6 H.E.U.I. Fuel System

  7. Cutaway View of an International TrucksI-6 Engine with H.E.U.I. System

  8. Side and Overhead Views of a Caterpillar 3126 Engine with H.E.U.I.

  9. Highway Engines Currently Using HEUI • Navistar MaxxForce DT (7.6L), 300 max BHP. • Navistar MaxxForce 9 (9.3L), 330 max BHP • Navistar MaxxForce 10 (9.3L), 350 max BHP

  10. PRINCIPLES OF OPERATION • A disadvantage of a cam-actuated fuel injection system is that the fueling window available to the ECM is defined by the hard parameters of the injector train cam profile. • The H.E.U.I. system has no such limitation because it uses engine lube oil as a hydraulic medium to actuate the fuel delivery pulse. • Advantages: • Significant control over injection rate. • Precise control of injection pressure regardless of engine speed. • Disadvantages: • Not as precise as CR (common rail) systems.

  11. HEUI Subsystems • HEUI management can be loosely divided into four subsystems. • Fuel Supply System • Injection actuation circuit. • HEUI assembly. • Electronic management and switching.

  12. FUEL SUPPLY SYSTEM • The fuel supply system consists of the following components: • Fuel tank • Fuel strainer • Fuel filter • Fuel transfer pump and hand primer • Fuel supply gallery (feeds H.E.U.I.) • Charge pressure regulator • Fuel is moved through fuel supply system by either a plunger pump or an external gear pump. • Fuel charging pressure is between 40 and 60 PSI. • Normally includes a hand priming pump

  13. INJECTION ACTUATION SYSTEM • The H.E.U.I. system uses hydraulically-actuated, electronically-controlled injector assemblies to deliver fuel to the engine’s cylinders. • Then engine’s oil pump supplies oil to the HEUI high pressure oil pump which in-turn supplies oil to the HEUI injectors at up to 4000 psi.

  14. INJECTION ACTUATION SYSTEM (Cont.) • The injection actuation circuit consists of the following components: • Main engine lube circuit • H.E.U.I. oil reservoir • High-pressure (stepper) pump • Swash plate type pump • Injection pressure regulator (ECM output) • Oil manifold (feeds H.E.U.I. control cartridges) • Actuation oil pressure sensor

  15. Operation of the International Trucks IPR Valve • Pressure is controlled by the IPR valve which receives its instructions from the ECU. • Operates at a frequency of 400 hz • Manages pressures from a low of 485 psi to a high of 4000 psi. • Pressure is controlled by dumping excess oil back into the engine lube system.

  16. H.E.U.I. INJECTOR • The HEUI injector is an integral pumping, metering, and atomizing unit controlled by ECM drivers. • The unit is best understood if you think of it as being an EUI that is actuated hydraulically rather than by cam profile.

  17. H.E.U.I. INJECTOR (Cont.) • Amplifier or Intensifier Piston • Uses hydraulic oil pressure to power a piston using up to 4000 psi oil pressure to produce 28000 psi fuel pressure. • HEUI Effective Stroke • Begins when the piston covers the spill port and ends when the solenoid cuts off oil pressure to the amplifier piston. • Collapse Phase • Oil used to power the amplifier piston is rapidly dumped into the engine rocker chamber. • HUI Oil and Fuel Manifold

  18. H.E.U.I. SUBCOMPONENTS • Solenoid • Electrically switched by ECM. • 115vdc • Poppet Valve • Controls flow of oil to intensifier piston. • Intensifier or Amplifier Piston • Raises fuel pressure from around 60 psi up to 28000psi. • Plunger and Barrel • Injector Nozzle • VOC (valve closed orifice type).

  19. STAGES OF INJECTION • Pre-Injection • Pilot Injection • Small amount of fuel to start combustion. • Delay • Allow flame front to begin • Main Injection • Into existing flame front for complete combustion. • End of Injection

  20. TECH TIP • The importance of the engine oil type and condition in an H.E.U.I.-fueled engine cannot be overemphasized. • Because engine oil is the H.E.U.I. actuation media, it should meet OEM temperature and operating condition specifications. • Contaminated, high mileage, and degraded engine oil can cause H.E.U.I. injector malfunctions.

  21. Siemens H.E.U.I. • Only used by Navistar during the 2004 model year. • Requires only 48vdc. • Uses a spool valve which is moved from one electro magnet to another. • Somewhat sleeker design.

  22. Stop for now.

  23. ECM Switching of Spool Valvein a Siemens H.E.U.I.

  24. H.E.U.I. ELECTRONIC MANAGEMENT AND SWITCHING • H.E.U.I. systems are full authority electronic management systems with comprehensive monitoring, vehicle management, and self-diagnostic capabilities.

  25. ECM FUNCTIONS • Reference voltage regulator • Input conditioning • Microcomputer • Outputs

  26. ECM Processing Cycle

  27. IDM Operation

  28. IDM: Relationship Between an H.E.U.I., Capacitors, a Coil, and Switching

  29. Injector Driver Module Operation: Output Driver Operation

  30. IDM and ECM Communications Signals and Relationship with CMP Input

  31. Caterpillar H.E.U.I. Schematic

  32. HEUI DIAGNOSTICS • Diagnostic Software • Injector Cutout Test • Injection Actuation Pressure Test • Fuel Rate Test • Navistar Self-Test

  33. TECH TIP • Whenever making a warranty claim for a defective H.E.U.I., a printout of the injector cutout test profile may be required to ensure that the warranty claim is processed.

  34. ET Graphical User Interface During a Cylinder Cutout Test

  35. International Trucks Self-Test Button Location and Troubleshooting with a DMM and Breakout Box

  36. International Trucks I-6 H.E.U.I.Circuit Schematics

  37. SUMMARY • The H.E.U.I. engine management system was the first to use electronically-controlled, hydraulically-actuated injection pump units. • Until the introduction of H.E.U.I. technology, pumping fuel to diesel injection pressure values was always achieved mechanically. • Effective injection pumping stroke in H.E.U.I. units is not confined by the hard limits of cam geometry as in other full authority electronic management systems. • Fuel charging pressure to the H.E.U.I’s is at values between 30 psi (2 bar) and 60 psi (4 bar).

  38. SUMMARY (Cont.) • Engine-lubricating oil is used as the hydraulic actuating medium for the H.E.U.I’s. The pressure is boosted to values of up to 4,000 psi (276 bar) by a swash plate–type hydraulic pump. • Actual H.E.U.I.-actuating oil pressure values are precisely controlled by the ECM, which switches the IPR to achieve oil pressure values of between 485 psi (33 bar) and 4,000 psi (276 bar). • The IPR is a spool valve positionally-controlled by a pulse width modulated ECM signal. • The actuating oil pressure value defines the descent (actuation) velocity of the HEUI pumping plunger. This determines the pumping pressure and therefore the injection rate and the emitted atomized droplet sizing.

  39. SUMMARY (Cont.) • The H.E.U.I. solenoid controls a poppet valve that, when energized, admits high-pressure oil so that it acts on the amplifier piston. • In Caterpillar manufactured H.E.U.I., when the control solenoid is energized, actuation oil is admitted to the H.E.U.I. to create a pumping stroke. When the control solenoid is de-energized, the high-pressure oil is spilled to the rocker housing. • In the more recent Siemens H.E.U.I., a transverse spool actuated by a pair of coils controls the entry of oil to the HEUI internal circuit. • H.E.U.I’s use multi-orifii, hydraulic injector nozzles of the VCO type.

  40. SUMMARY (Cont.) • H.E.U.I. NOP values are typically 5,000 psi (345 bar) with peak system values rising to between 18,000 and 28,000 psi (1,241 and 1,931 bar). • The H.E.U.I. ECM uses an IDM to switch the H.E.U.I. control solenoids. • Some Navistar ECMs use three-module architecture consisting of an ECM, an IDM, and a personality module. • Most later versions adopted a consolidated engine controller (CEC) in which the three modules were incorporated into a single housing.

  41. SUMMARY (Cont.) • Caterpillar has always used an integral ECM, incorporating all of the processing, memory, and switching functions required by its H.E.U.I. system. • The IDM used to drive Caterpillar manufactured H.E.U.I’s steps the actuation voltage to 115 V-DC using induction coils. • The IDM used to drive Siemens manufactured H.E.U.I’s used in Navistar applications after 2004 steps the actuation voltage to 48 V-DC using induction coils. • Caterpillar’s Electronic Technician (ET) and Navistar’s Master Diagnostics (MD) or ServiceMaxx (SM) software are used to diagnose and program HEUI engines. • ET and MD/SM are used in conjunction with each OEM’s online service information system (SIS).

  42. Any Questions ? • Thank You !

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