VOLVO'S Drive-E Engines
- Cylinder head
- Chill cast cylinder head and die cast camshaft bearing housing, both made of a light metal alloy.
- Cylinder block
- Manufactured in die cast aluminum alloy.
- Has an open water mantle where coolant flows freely around the upper section of the cylinders.
- The cylinder liners are made of cast iron and cast in the piece.
- Intermediate section
- Made of die cast aluminum alloy.
- The crankshaft's bearing caps are made of cast iron and are cast in the piece.
- Oil sump
- Made of die cast aluminum alloy.
The surfaces between the different parts are sealed with a silicone based sealing compound, so-called RTV-silicone (Room Temperature Vulcanizing silicone), except between the block and cylinder head where a four layer metal gasket is used.
Cylinder block
- Cylinder block
- Base plate
- Cast iron liner
- Aluminum coating
- Cast steel liner reinforcements
Overview
Volvo's new Drive-E engines share many common engine parts, such as crankshafts, oil pump, sump, alternator and AC-compressor. Other parts are similar, such as the engine block and the balance module of the motors.
Engine weight
Both Volvo's diesel and petrol engines have high-pressure cast connecting rods. The engine's base plate has cast steel linings and cast iron reinforcements. Diesel and petrol engine blocks are identical, except for the higher height of the block and the heavier cast steel liner for the diesel engine. The casting method, combined with unique design, gives a strong construction with light weight. Only two engine block variants are needed, with the main bearing diameter as the only difference. The transition to the new Drive-E engines has given a weight saving of 30-50 kg.
Engine friction
To minimize bearing sizes, the crankshaft is made of forged steel. The base plate's alignment to the engine block has been improved with new patented position wedges. This has led to improved straightness and roundness of the main bearings. The piston diameter is minimized by use of a fixed bushing. The different petrol engine variants have similar pistons, only the machining of the piston top is different for different compression ratios. Petrol engines with lower power have a shorter piston. The petrol engine variants use the same piston rings and all diesel engine variants use the same piston rings. The piston pins on all petrol and diesel variants are coated with diamond-like carbon (DLC). An improved piston and cylinder bore coating as well as roller bearing camshafts mean that the Drive-E engines have low internal friction.
Cylinder head and valve system
The design of the cylinder heads is based on Volvo's five and six cylinder engines. The main changes are related to friction reduction, increased specific output and the creation of common interfaces for petrol and diesel engines. The petrol engine's cylinder head must be able to withstand a very high thermal load and is therefore made of a heat resistant aluminum alloy. The transverse cooling concept, shared with the diesel engine, provides excellent and consistent cooling.
Petrol
The petrol engines have a system of VVT solenoids (Variable Valve Timing) with service free DLC-coated mechanical tappets. The camshaft front bearing is a roller bearing to reduce friction. The camshafts are made of cast iron which is the best material for use in combination with sliding contact with the DLC coated tappet.
Diesel
The diesel engine has been heat-treated to improve the strength and temperature limit of the material, and thereby withstand a cylinder pressure of 190 bar and high power output. The diesel engines have steel camshafts for reduced weight and increased material hardness.
Cylinder head
The cylinder heads on the petrol engines from the VEA family are divided into two with a jointly machined cam carrier cover and integrated cap for the camshaft bearing. The front bearing positions for the camshafts are not slide bearing but have roller bearings for minimum integrated depth and friction. For further information, see heading "valve system".
Cylinder head screws
The cylinder head is attached to the block by ten M11 screws. In order to get enough clamping pressure despite small diameter screw heads, the screws are located through the left threaded sleeves in the cylinder head. The sleeves distribute the force through their threads out into a large area in the cylinder head. The same technology is used in the B6324S and B6304T engines. The sleeves have an internal Torx that is used when tightening.
Cylinder block/intermediate section
The cylinder block's lining has, after a modified honing process, a finer surface finish on the cylinder bores. The finer surface reduces friction between piston rings and cylinder bores, which, in addition to contributing to an overall reduction in internal friction, also reduces the running-in period.
Intermediate section
For improved strength and stability and to ensure roundness when the block/intermediate section's main bearing seats are machined, the five cast iron main bearing caps are cast in the piece. RTV silicone is used as sealing agent between the cylinder block and intermediate section.
Matching
Each main bearing cap has a lug that protrudes from the top surface of the intermediate section. Before the block and intermediate section are jointly machined, the sections are screwed together, which creates a groove in the block at each bearing cap. The grooves create a unique pattern for the block that ensures good attachment between the components. The block and intermediate section are then even easier to take apart.
Crank system
The crank system for the VEA engines is largely the same, whether in a petrol or a diesel engine. The same crankshaft is used for all variants, while pistons and connecting rods differ slightly. The package of the two counter-rotating balancer shafts under the crankshaft is identical in all variants, as is the drive of the oil pump at the front of the crankshaft.
Pistons
The piston is cast in a light metal alloy consisting mostly of aluminum and silicon. The top ring groove is protected by a cast iron ring carrier to withstand the high pressure that the piston is subjected to. There are outlets on top for intake and exhaust valves. The piston is weight-optimized with weight recess above the piston pin and trapezoidal surface against the connecting rod. Even the piston pin has been optimized for weight. Making it extra short not only minimizes the weight of the pin, but also contributes to reduced piston weight. To control piston temperature, there is controllable piston cooling that is controlled by oil pressure. The amount of cooling to be activated is controlled by a model that is calibrated for optimal fuel consumption and low emissions.
To minimize wear and friction:
- The piston skirt is coated with a graphite polymer, which helps to withstand extreme loads, as well as prevent piston noise during cold starts
- the piston pin slide surfaces are coated with DLC
- the cylinder liner surface is refined by means of an optimized honing process at the assembly plant
- the piston rings' tangential forces have been reduced
- the piston rings are coated with a low friction coating
To withstand increased load and reduced friction without compromising on oil consumption, a new ring package has been developed.
- The upper compression ring is 1.2 mm high, nitrated stainless steel ring. The ring is coated with PVD* technology, which both reduces friction and gives good wear properties.
- The lower compression ring is 1.2 mm high, cast in grey iron with phosphated surface.
- The oil control ring is 1.5 mm high, cast iron two-piece ring with conical shaped mating surfaces against the liner. As on the upper compression ring, the surface is PVD coated*.
*PVD (Physical Vapor Deposition) is a type of surface treatment that is created by ionizing an evenly rotating metal surface while introducing a reactive gas. The process takes place under very low vacuum and in temperatures of 400-600 °C. This forms a thin, strongly adherent coating.
Connecting rods
Connecting rods are forged in I-profile with trapezoidal small ends. They are produced in five different weight classes with regard to the connecting rod's weight at the big end. The big end has a cracked bearing cap, which provides a stable joint in that the bearing cap and connecting rod are secured in the actual fracture surface. The bearing halves are of different materials. The top is of stronger material to withstand high loads. The connecting rod length is 147 mm. Piston pin diameter is 21 mm. Weight (including screws) is 537 g.
Crankshaft
The crankshaft is made of forged steel and has induction hardened bearing surfaces. The crankshaft has five bearings with a main bearing diameter of 60 mm. The upper bearing half on main bearing 4 also acts as a thrust bearing or 180° bearing. The thrust washer is larger than usual to maintain the bearing surface with only one thrust washer. A gear is shrunk onto the crankshaft between cylinders 3 and 4. The gear drives the balancer shafts. In front of the main bearing is a gear that drives the oil pump. The crankshaft has a vibration damper positioned in the front pulley. Crankshaft weight is 15.2 kg, excluding gears.
Balancer shaft
The function of the balancer shafts is to smooth out the engine's oscillations. The balancer shafts are driven by a gear on the crankshaft. The two counter-rotating balancer shafts are located in their own housing in the oil sump. Drive to the balancer shafts is via the crankshaft to one balancer shaft, which in turn drives the second balancer shaft. One of the balancer shafts' gears is two-piece. The "narrow" half (Scissor gear) is spring tensioned in the opposite direction to the "wide" half. It provides silent backlash elimination. This technology is already found in the gear on the B63x4x engine. To ensure correct backlash, the balancer shaft housing is shimmed to the engine block at the assembly plant.
Vibration damper crankshaft
Volvo's new Drive-E engines have a new type of crankshaft pulley. As before, the pulley has an integrated vibration damper. It has been combined with a releaser. The device's vibration damper and releaser have two tasks that are described below.
Vibration damper
The task of the vibration damper is to offset the crankshaft's oscillations, using a rubber-suspended mass. The construction consists of two metal parts with a determined mass, which is bonded in an intermediate section of rubber of which the inner part is rigidly mounted against the crankshaft. The damping effect is determined by the rubber shim's hardness and the rotating mass.
- Mass
- Rubber
- Hub
- Transport rivets
Variants
- B4204T9, T10 (4.4 kg)
- Other variants (4.0 kg)
Volvo's Drive-E engines have two variants of vibration damper that differ regarding weight and appearance. The difference can be seen by looking at the width of the outer end.
Releaser
- Pulley.
- Housing
- Springs
- Armature
A four stroke engine has two ignition pulses per crankshaft revolution. These give rise to a frequency that is forwarded through the crankshaft to the crankshaft's outer pulley. The releaser is used as a filter, with the function of isolating the inertia of the auxiliaries from the from engine's pulsations. Reduced irregularity in the pulley rotation extends the service life of the component parts such as drive belt, tensioner, etc. In addition, the spring force of the tensioner is reduced, which contributes to reduced fuel consumption.
Function
Inside the releaser, a spring assembly takes up the forces of the combustion pulsations. Through indentations in the housing as well as the central flange, the outer part is allowed to flex approx. 25° back and forth with the help of the spring assembly. Including the distance the springs are compressed, the two main parts can rotate approximately 65° to each other.
Attachment
The vibration damper is attached to the crankshaft by a center screw (m12) as well as four M8 screws.
Diamond washers
- Corresponding surface
- Diamond
- Washer
- Attachment layer
There are diamond washers between the crankshaft and the different parts whose task is to ensure that the correct friction is achieved in the joint. The diamond washers are thin steel washers with a coating of small industrial diamonds. The diamonds give an extremely high friction level between the surfaces. The coating wears during removal and tightening. It is therefore important to replace the washers with new ones when reinstalling this joints.