Volvo Engine Diesel 5 (VED5) Gen 2

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Introduction

The Volvo Engine Diesel 5 (VED5) Gen 2 engine – hereafter, VED5 Gen 2 – was a 2400 cc five-cylinder turbo diesel engine that commenced production at Volvo’s Skövde engine plant in 2005. Like the VED5 Gen 1 engine, the VED5 Gen 2 engine had:

• A five-cylinder, open-deck block made from die-cast aluminium;
• Cast iron integral cylinder liners;
• Aluminium alloy cylinder head;
• A single cam belt-drive system for the camshafts and injection pump;
• Four valves per cylinder actuated by roller finger followers;
• A Bosch second-generation common-rail injection system which provided maximum injection pressure of 1600 bar. For the Gen 2 engine, however, a higher injection pressure was used in general during the entire loading and engine speed range;
• Electronically-controlled, cooled Exhaust Gas Recirculation (EGR); and,
• An oxidising catalytic converter.

Changes for VED5 Gen 2 engine

Compared to the VED5 Gen 1 engine, changes for the Gen 2 engine included:

• While cylinder bores were unchanged at 81.0 mm, stroke was reduced from 93.2 mm to 93.15 mm such that total capacity decreased from 2401 cc to 2400 cc;
• Revised intake and exhaust ports that had greater volumes and more gentle air bends for more efficient gas-flow;
• A bigger compressor wheel for the VNT turbocharger and an electric servo motor to adjust the cambered vanes. Furthermore, the turbocharger was water-cooled (previously oil cooled);
• An electronically controlled multi-throttle system in the inlet ports for variable regulation of the swirl level;
• Coolant-heated crankcase ventilation (the PTC element was discontinued);
• A revised fuel rail;
• Seven-hole injectors which could pilot and post injections;
• A lower compression ratio of 17.3:1 (18.0:1 for theVED5 Gen 1);
• A more efficient EGR system (described below);
• Electronically regulated glow plugs for easier starting in cold weather;
• Bosch EDC16 engine management system which had greater processing power and used additional sensors for more accurate control of the engine’s functions, including electronic throttle control);
• A larger catalytic converter that was mounted closer to the engine for faster warm-up;
  A diesel particulate filter (DPF); and,
• Depending on market, 30,000 kilometre or 12 month service intervals (previously 20,000 kilometres for the VED5 Gen 1).

The D5244T4/T5/T6/T7 engines were identical expect for their performance which was determined by the software in the ECM. Upon its release, the VED5 Gen 2 engine complied with Euro IV emissions standards.
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Turbocharger

For the D5244T4/T5/T6/T7 VED5 Gen 2 engines, the compressor wheel for the new turbocharger had a diameter of 56 mm (compared to 52 mm for the precedingD5244T/T2 VED5 Gen 1 engines). According to Volvo, the increased diameter enabled the turbocharger to be used more efficiently over a wider range of speed. Furthermore, charge pressure was electronically controlled and the position of the guide rails was regulated by a Rotor Electric Actuator (REA). Controlled by the ECM, the REA was an electric direct current motor that provided faster and more precise control compared with the previous vacuum controlled system.

Other changes for the turbocharger in the VED5 Gen 2 engines, included:

• Cambered variable vanes for more efficient gas flow; and,
• The turbo centre housing was water-cooled. Although unusual for diesel engines, water cooling enabled continued cooling of the turbocharger after the engine had been turned off.

Multi-throttle system

The inlet ports of the VED5 Gen 2 engines featured a multi-throttle system that was controlled by a direct current motor for ‘infinitely variable regulation’ of the swirl level. Located in the cylinder head’s tangential ducts, the variable throttles (or ‘swirl throttles’) regulated air distribution between the tangential and swirl ducts to the cylinders. By closing the throttles, a higher proportion of air through the swirl ducts increased swirl and improved mixture formation. The throttles were closed at idle and opened steplessly up to an engine speed of approximately 3000 rpm. At engine speeds above 3000 rpm, the throttles were open.

Glow plugs

For the VED5 Gen 2 engines, the glow plugs had a lower inner resistance for faster heating and engine starting. While the glow plugs were designed for a continuous voltage of 4.4 volts, rapid heating was achieved by supplying an ‘overvoltage’ of 12 volts and a temperature of approximately 1000 degrees Celsius would be reached after a second. After the glow plugs had been supplied with 12 volt power for a few seconds, the voltage was reduced to 9 volts for a few more seconds, and then reduced to 4.4 volts.

Injection

The VED5 Gen 2 engines had seven-hole injections that could inject fuel into the cylinders in three stages:

1. Primary injection; and,
2. Post injection.

Both the pilot and post injection stages were new developments for the VED5 Gen 2 engine.

During certain conditions, two pilot injections would be used at low ambient temperatures (lower than 4 degrees Celsius) and at high altitudes (over 1000 metres above sea level) and at engine speeds up to 2800 rpm. However, only one pilot injection would be used from 2800-3400 rpm, with no pilot injection at engine speeds above 3400 rpm. The purpose of the pilot injections was to provide stable combustion with low noise.

Post injection could occur in one or two stages –

• A post injection would take place at half loads and engine speeds between 1500-2500 rpm to combust carbon during after-burning in the cylinder;
• Two re-injections would occur during cDPF regeneration. The first re-injection would increase the temperature before the catalytic converter and the second would heat the exhaust gases when they passed through the catalytic converter to initiate the regeneration process.

Exhaust Gas Recirculation (EGR)

For the VED5 Gen 2 engines, the control motor for the EGR valve was located on the engine’s cold side, i.e. in direct connection to the intake manifold, for higher EGR flow. As such, coolant flowed in the opposite direction to the exhaust gases (previously in the same direction) for more efficient cooling and the design of the pipes through which the exhaust gases passed was modified to a ’round with spiral’ shape for improved cooling capacity. Furthermore,

• The VED5 Gen 2 engines introduced a new EGR cooler;
• The valve regulating the EGR flow only had one valve disc; and,
• The position of the valve was controlled by a direct current motor (previously solenoid) for improved flow/regulation.

According to Volvo, the EGR cooling system reduced exhaust gas temperatures by up to 200 degrees Celsius.

Some variants of the VED5 Gen 2 engines had a by-pass throttle located at the EGR cooler outlet for exhaust gases. During the engine’s warm-up phase, the throttle was open and the majority of the exhaust gases were directed to the intake manifold without being cooled to raise the combustion temperature and reduce emissions. At normal operating temperature, however, the throttle would close so that all exhaust gases passed through the cooler.

Diesel particulate filter

The VED5 Gen 2 engines were fitted with a maintenance-free coated Diesel Particulate Filter (cDPF). The cDPF worked partly as a particle filter and partly as an oxidation catalytic converter so that particle emissions, HC and CO were reduced. The particle filter was made of porous silicon carbide coated with a washcoat (surface enlarger). The washcoat, in turn, was coated with a layer of precious metal. The precious metal worked as a catalyst and oxidised CO and HC to CO2 and water. A new filter would trap approximately 70 per cent of PM and a ‘slightly’ used one would trap more than 95 per cent of particles.

Re-generation of the cDPF – which burned the soot away – took approximately 20 minutes and occurred automatically at 500 to 1000 km intervals depending on driving conditions.

D5244T8 and D5244T13: Volvo C30, S40, V50 and C70

The D5244T8 and D5244T13 engines in the Volvo C30, S40, V50 and C70 produced peak power of 132 kW and peak torque of 350 Nm and 400 Nm, respectively). Since these vehicles were based on Volvo’s P1 platform and had a smaller engine compartment, the following changes were made:

• A smaller radiator;
• A revised air intake system;
• A smaller charge air cooler; and,
• A revised exhaust system.