Delphi E3 Diesel Electronic Unit Injector

Transcription

1 Delphi E3 Diesel Electronic Unit Injector The Delphi E3 Diesel Electronic Unit Injector (EUI), was introduced for the 2002 EGR equipped diesel engines onhighway heavy duty applications. A version of this injector is available for cam-in block engines however the most common configuration uses the engine's overhead camshaft. What is unique about the Delphi's E3 EUI is its dual control valve, 4-wire design which enables highspeed, ultra high pressure operation (as much as 2,500 bars or ~37,000psi) with rate shaped injection capabilities. This means the injector enables pilot, post and split injections as well as ramped injection profiles. Benefits High speed dual valve operation for accurate control of injection events High pressure injection for optimized combustion and reduced aftertreatment Lightweight, compact design for enhanced efficiency (15lbs/6cylinder engine) Multiple injection capability with programmable shot-to-shot injection control Programmable variable nozzle opening and closing pressure On board diagnostic and dynamic trimming capability One million Km durability 40% fewer parts than previous unit injector (E1 7 E2) Target emissions: Euro IV, V, and VI; US 07 and US 10 and beyond. Applications The Delphi E3 Diesel Electronic Unit Injector is suitable for nine to 16 liter heavy duty diesel engines used for on- and off-highway applications. Detroit Diesel S60, Mercedes MBE 4000, Volvo D11,13, 7 16, Mack MP-7, Caterpillar etc.. It helps meet 2007 and 2110 emission standards Specifications Plunger diameter range Stroke range Engine cylinder capacity Peak pressure Weight Drive voltage 9 mm to 11 mm Up to 18 mm 1.5 L to 2.6 L 2,500 bar 1.1 kg 50 V

2 Features The Delphi E3 Diesel Electronic Unit Injector has two independent, fast response precision actuators that can change the injection pressure level (up to 2500 bar) and adjust fuel delivery timing and duration on a per shot basis. Older EUI systems integrate a pump with each injector, traditionally mounting the spill valve and control solenoid on the side of the injector body. This provides a highly effective unit with excellent responsiveness, but the offset forging required makes it both bulky and complicated to manufacture. With the E3, launched in June 2000, Delphi the problems of cumbersome large injectors by developing new technologies that allow the spill valve and control solenoid to be integrated within the injector body, concentric with the pump and nozzle mechanisms. This provides a very compact unit that, compared with the previous generation EUI, is no larger than the conventional injector body alone and uses 40 percent fewer components. The shorter, more direct fuel path of the E1 allows more accurate fuel metering, improved injector responsiveness and a peak injection pressure of 2,400 bar, up substantially compared with older injectors with no increase in power consumption. Elimination of the offset forging considerably increases opportunities for improved cylinder head and valve train layouts and reduces the weight of each unit from 2.2kg to 1.1kg -- resulting in a considerable saving on six- and eight-cylinder engines. Older Forged injector body E1 & E2

3 Delphi E-3 in a 07 CAT and Mack MP-7 Spill Valve Solenoid Needle Valve Solenoid Delphi's E3 injector builds on this technology platform by introducing an additional valve in the injector body, just before the nozzle. This piezoelectric type valve is variously called a Direct Operated Control Valve DOC or needle control valve NCV. This valve is controlled by the engine management system and enables programmable injection timing and pressure events. It also allows the engine management unit to change the pressure at which the nozzle opens to provide variable injection rates, up to a maximum of 1,400 bar over 20,305psi for each injection event. This means the fuel system allows rising rates (increasing the fuel delivery rate through the injection event) and multiple events offering the opportunity to introduce pilot, close-coupled pilot, main split and late post events in addition to the main injection event. Operation Overview The E3 injector is designed as an inline concept. This injector features two solenoids. The fuel metering unit or module is positioned under the plunger, so the overall envelope of the E3 similar to previous injectors. The E3 has an inwardly opening of solenoid valve which controls beginning of injection and end of injection. The solenoid valve closing point defines the beginning of injection (BOI) and the solenoid valve opening point defines the end of injection (EOI). Pressure is generated by the downward movement of the plunger in combination with the closed solenoid valve. Fuel quantity is metered by the length of time the solenoid valve remains closed.

4 1. Spring Chamber 11. Header 21. Guide 2. Nozzle Spring 12. Header Retaining Clip 22. Armature 3. Capnut 13. Plunger Return Spring 23. Shims 4. Piston Pin 14. Spring Carrier 24. Stator 5. Seal 15. Socket Retaining Circlip 25. Spring 6. Piston Guide 16. Thrust Pad 26. Armature 7. Lower Insulating Sleeve 17. Plunger 27. Pin 8. Pin SVG 18. Snap Ring 28. Guide 9. Seal 19. Clip Support Washer 29. Nozzle Assembly 10. Seal Backing Plate 20. Seal

5 Fuel Flow 1. After entering the nut cavity, the fuel passes through a drilled passage into the module and plunger area. 2. The plunger operates up and down in the body bore of the injector. The motion of the injector rocker arm is transmitted to the plunger and follower that bears against the follower spring. 3. As the piston moves approximately two-thirds of the way up in the cylinder on the compression stroke, the injector cam lobe begins to lift causing the injector rocker arm to push down on the follower and the plunger. Just before injection begins, the MCM sends an electronic pulse which turns on the injector spill control valve solenoid. The energized solenoid creates a magnetic force which closes the spill control valve and traps fuel under the plunger and passages leading down to the needle valve. The fuel pressure increases as the plunger continues its downward stroke. 4. This fuel pressure acts on the top of needle valve. This prevents the needle valve from lifting from its seat and fuel pressure continues to build inside the injector. When the needle control valve is energized, fuel pressure is removed from the top of the needle valve. When fuel pressure is high enough to overcome the needle valve spring force holding the needle on its seat, the needle valve moves up, allowing the high pressure fuel to spray into the combustion chamber. The high pressure of the fuel passing through the small holes in the nozzle creates a finely atomized spray for combustion within the cylinder. 5. After the pulse width time has passed, the MCM turns off the current to the injector solenoids. The de-energized solenoid allows a spring to open the spill control valve, permitting the trapped fuel to spill down, dropping the pressure within the injector. When the pressure is low enough the needle valve closes and ends injection. Injector Response Time (IRT) The beginning of injection and metering of the fuel in relation to the crankshaft position are controlled by the MCM. Injection begins soon after the control valve is closed. The valve closing point known as the injector response time is returned to the MCM. This information is used to monitor and adjust injection timing, thus removing injector-toinjector variation influences on timing. The amount of fuel injected depends on the pulse width stored in the calibration which determines how long the control valve remains closed; the larger the pulse width the longer the valve is closed and the more fuel is injected. End of Injection When the injector rocker arm has completed its downward travel the injector follower spring returns it to the starting position. As the plunger moves up fuel enters the injector pumping cavity for another injection cycle. The constant circulation of fuel through the injector renews the fuel supply in the chamber and aids the cooling of the injector.

6 Operation Spill Valve Solenoid (SVS) The injector operates like a conventional EUI with a spill or poppet valve controlling the spill valve connected to a pumping chamber. When this valve (Spill valve solenoid SVS) is not energized or open, fuel cannot pressurize inside the pumping chamber and fuel moves back and forth from the low-pressure fuel gallery surrounding the injector. Energizing the normally open solenoid builds-up pressure in the pumping chamber. Needle Valve Solenoid (NVS) The needle or nozzle control valve (NCV) is also operated by a solenoid, usually a piezoelectric type material rather than a coil for faster more precise operation. When normally closed valve is not energized, it directs high pressure fuel from the plumping chamber to a chamber above the needle valve. Fuel pressure above the nozzle valve along with nozzle valve spring pressure hold the firmly valve onto it s seat. ECM control of this solenoid regulates the beginning and end of injection events, timing, and fuel pressurization. Programmable control of nozzle opening during pressurization of fuel (when the SCV is closed) allows for finer atomization of fuel with higher spray in pressures particularly at the end of injection events. This means NOP values can be as high as 20,000psi. Unlike older injectors which may open at 5,000-psi and close at 3,500- psi with a typical nozzle differential ratio, E3 nozzle can open high and stay high through out the injection event. Diagrams From Sean Bennett s 3 rd Ed Engines & Computerized Fuel Management Systems

7 Pressurization The SVC solenoid is energized and the pumping plunger is driven downwards by the camshaft. The NCV valve is closed and no energized. Fuel pressure hydraulically forces the needle valve against its seat. Injection Both solenoids are energized. Hydraulic pressure holding the nozzle valve on its seat is vented when the NCV solenoid opens. This allows the needle valve to lift. Injection pressurization, rate and timing are all electronically controlled. Calibration Codes When an injector does finally need replacing, Delphi's unique laser marking system ensures that it can be replaced individually, rather than replacing all six or eight injectors with matched units as is required with traditional EUI technology. This is achieved by individually testing each injector at the Delphi factory and laser etching its performance characteristics onto the terminal block. This data is then read into the engine management unit, providing accurate fuelling and timing characteristics for each injector. The same technique is used when the injector is initially installed in the engine at the factory, greatly increasing the accuracy of fuel metering and simplifying production logistics. On top of their injectors is a five letter code. This code is used by the ECM to calibrate flow through the injector. Once again, each injector is tested after it is manufactured and is measured against a nominal start of injection point, end of injection point and an idle quality factor. The first two letters of the alpha code refer to the response time comparing a nominal injector to the measured injectors start point. The second two letters in the alpha code refer to the end of the injector s response time. The tolerance band for the start and end of injection is ± 127mS ( seconds). The last letter in the alpha code is a measured variance in idle performance. The injector is given one of three idle letters: A, B or C to qualify idle performance.

8 The alpha codes used for both the start point and the end are not sequential, i.e. not AA through to ZZ. The codes have been picked at random to minimize the probability of intentionally over-fuelling the engine to enhance power output. The code does not indicate that one injector is better than another. The code simply provides the ECM with a mapping adjustment needed for that particular injector, enabling very precise fuelling and smooth idle performance. It is critical that the injector code is programmed into the ECM if an injector is replaced, or reinstalled in another cylinder to prevent rough running, and other performance complaints.