The VR engine is combined in a particularly compact variant of a multi-cylinder engine that features a V-engine and a series motor. Here, the cylinders are in a cylinder block with a slight V -position. Which makes it possible to reduce the distance from the crank pin in-line engine without two cylinder blocks and cylinder heads are required.
The V- engine with a narrow cylinder angle was developed by the Italian company Lancia & C., which is why the design was called " Lancia " principle. This was based on a patent of Lancia & C. from July 1, 1915, which makes it possible to crank engine displacement across the connecting rod in the V motor as the perfect mass balance of the respective V- engine ( V12: 60 degree V8: 90 degrees) to meet but, at the same time allows a lower actual cylinder angle.
This has been realized for the first time in two Lancia - V12 aero engines with 50 degree cylinder angle and 350 or 600 hp. This was followed by two engines for automobiles: A V8 with 45 degrees and 30 degrees with a V12 that Vincenzo Lancia in September 1918 for a patent.
In 1919, Lancia chassis including a V12 engine with 13 ° 6 ' cylinder angle without a body at the exhibitions in Paris and London. The bore was 80 mm and stroke of 130 mm. The engine produced from 7837 cc at 2200 rpm 150 hp. However, the car did not go into mass production.
1930 series motorcycle Matchless Silver Hawk was presented with a VR4 engine to the public. In the same year the car Rohr AG started construction of VR engines with eight cylinders, 2.5 liters and 10 ° cylinder angle for the Rohr 8 Lancia produced over the decades, more compact VR engines for longitudinal installation ( for example, 1937 Lancia Aprilia and 1963 Lancia Fulvia ) and remained this engine concept faithfully until 1976.
Volkswagen grabbed the early 1990s to the concept and built a six-cylinder engine, and later a five-cylinder engine with compact exterior dimensions for vehicles with a transverse engine. This Volkswagen VR engines are exclusively Langhuber to save additional mounting space. In the VW development, the cylinder axes intersect in contrast to Lancia development is not in center of the crankshaft, but below ( " of set crank drive ").
Launched in 2005, Bugatti Veyron 16.4 has a 1001 -hp V- engine with two banks of cylinders V- ( 15 degrees cylinder angle and 90-degree V- angle).
Under the type designation Horex VR6 a motorcycle with particularly compact finished buildings VR -6 cylinder engine on the market since the end of 2012/early 2013. The development of the engine Volkswagen was involved as part of a consulting agreement.
Reasons for the development of the VR concept
The VR concept allows to combine the brevity of the V engine, the small width of the line engine. The first VR - flight engine from Lancia could be built four inches narrower by reducing the cylinder angle of 10 degrees. Just so he could meet the Baumaßanforderungen which were due to the aerodynamics of the aircraft of Caproni.
Also in motor vehicle resulting from the small dimensions advantages. The V4 of the car model Lancia Lambda had a total length of only 58 centimeters, including flywheel, despite up to 2.5 liters. This engine, clutch and gearbox were completely housed in the engine compartment. There was no transmission tunnel needed, which would have affected the interior space. With front-wheel drive models with engine in direction of travel of the front axle, as the Lancia Fulvia, the VR engine enables a more neutral handling. The weight of the motor is removed by the short length less distance from the center of the vehicle.
For cars with front-wheel drive, the engine is now installed transversely in the rule. Because beside the engine still needs to find space in the engine compartment and the transmission is flanged extension of the motor, the width of the motor is limited, so that four-cylinder engines dominate the market in this arrangement.
Higher numbers of cylinders can be realized when the engine is not built as a series motor, but as a V engine. Here, however, a conflict in aims through several claims:
- A minimum distance between the cylinders is required so that the channels of water cooling and oil paths be given a place.
- The cylinder walls must have a certain minimum thickness, otherwise it may overheat the wall between the individual cylinders.
- The angle of the V engine must not be too large, otherwise it will adversely affect the crash safety. A too broad engine bridges the plastic deformation zones and penetrates possibly a frontal impact into the passenger compartment.
- For quiet running (compensation of inertial forces and moments of higher order ) certain cylinder angle are preferred: the six- cylinder after the line engine of the V- engine with 60 degree cylinder angle is particularly favorable when eight-cylinder design with 90 degree cylinder angle.
- The V- engine brings increased construction costs and higher cost, because in addition to the more expensive engine block, two cylinder banks with their own heads and valve trains are required.
- With a wide cylinder bank angle engines can be realized, which are much longer than in-line engines with half the number of cylinders.
The concept of the VR engine is a compromise between the two types dar. The VR design shows an additional geometrical problem, because the cylinder would penetrate in the lower part in a classic V-type with a cylinder bank angle of 15 degrees. Lancia solved the problem by relatively long connecting rods.
In a simple tilting of the cylinder banks, as is customary in the V- arrangement, the cylinder center axes of the crankshaft and the center axis would intersect - as in -line engine. " Entangled " cylinder banks, however, are offset parallel to the outside, thus avoiding even with short connecting rods and small cylinder bank angles penetration of the cylinder, its cylinder center axes intersect below the crankshaft axis. Thus low heights are reached, which also enable use in the motorcycle. The disadvantage, however, is the greater inclination of the connecting rod, so that the pistons are pushed higher radial forces unilaterally against their careers. The movement characteristics of the crank mechanism - the assignment of rotary motion and reciprocating motion - is asymmetrical to the upper dead center.
In VR engines can with a small cylinder bank angle - as in -line engine - a common cylinder head can be used for both cylinder banks. The V shaped arrangement of cylinders, however, the joint between the cylinder head and is no longer perpendicular to the cylinder axis. The resulting disadvantage are of unequal length intake and exhaust paths between the two cylinder banks, as a rule, a cylinder head side of fresh gases come from all cylinders and all flue gases are led away to the other side of the cylinder head. In addition, this type of cylinder head manufacturing complex in the casting technology as well as in mechanical processing, especially for four-valve engines.
Another common feature of a six-cylinder VR engine with a six- cylinder in-line engine, for example, his seven -bearing crankshaft with six bends.