V engine
A V-engine (formerly also known as " fork motor ") is a construction of a reciprocating engine with several cylinders. These are divided into two cylinder banks, each other in a certain angle ( " Bank angle "). After the line engine is the most common motor design.
Description
In classic V-engine - mounting "stand" the two cylinder banks to the banking angle inclined towards each other on the underlying crankshaft. For aircraft engines, the reverse installation is spread is preferred in which the cylinder banks are arranged " suspended", which facilitates the accessibility of cylinder heads (valve control) and spark plugs. Especially in older descriptions, this is often referred to as " A- Motor", although this type of installation is not an own engine design.
The bank angle has a strong influence on the size of the ground forces, however, is limited by side available installation space, which is why usually a 45 ° angle comes into play. If the room is available, it often is 90 °. Practically a minimum bank angle is required in order to take advantage of the V- arrangement can. In order to keep the bank angle small, the cylinder feet can be arranged offset outwards; the cylinder axes then intersect at the crankshaft. Bank angle Previously shown start at about 10 ° in the Lancia Appia and Rohr 8 The so-called VR engines that are V engines with a very small bank angle (<15 ° ), the two banks usually have a common cylinder head.
Of the bank angle may be up to 180 °. Then we speak of a 180 ° V engine.
In a V - engine, the connecting rods of two opposing cylinders are coupled to the crank pin of a crankshaft throw next to each other, resulting in a slight displacement of the cylinder result (cylinder displacement ). Exactly opposite cylinders require the use of ( cheap ) Anlenkpleueln, but due to their kinematics have a different stroke and thus an unequal compression ratio of the two cylinder banks result. The cylinders are exactly opposite AND their compaction are to be the same, elaborate and therefore costly Gabelpleuel are required.
Chance and V - engines were built with an odd number of cylinders (NS Honda 400R ) in motorcycles as V3 and V5 (Honda RC211V ). VW used in the Golf IV V5 with a designated VR - five-cylinder engine.
In car engines always uniform ignition intervals between the cylinders will be sought for the sake of smoothness. These amount for four-stroke engines - specified as a crank angle - 720 ° divided by the number of cylinders, as in two crankshaft revolutions, each cylinder fires once. With a V8, the firing interval so is 90 °, with a V6 120 °. If the bank angle is not a multiple of the ignition interval, one needs different crank pins. These can sit right next to each other when they are not too strong acid ( PRV engine from 1985), are associated with an intermediate flange ( Ford V4), sometimes for each cylinder its own crank throw is executed ( Lancia Aurelia ) what the overall length of the motor increases.
The most common bank angle is 90 ° for many V6, almost all V8 and V10 engines some. For technical reasons, it is advantageous if a V8 engine with an angle of 90 ° as the basis of a series of V engines with different numbers of cylinders is used (eg, V6, V8 and V10 ), since all engines largely manufactured on the same production lines can be and realizing cost advantages as a result of common parts. Examples include the V6, V8 and V10 FSI engines from Audi and V6 and V8 engines from Mercedes -Benz. Some V6 and almost all have V12 60 °. V6 with 120 °, which would only need three crank pins, there is little, because the motor is then very wide.
In large engines and motors for special applications (eg, racing ) are also often other considerations for the choice of bank angle decisive, such as the accessibility for maintenance, the space requirement or the height of the center of gravity.
180 ° V-type engine
In addition to the VR engine and the V-engine with 180 ° angle of bank is a special case. In the V- engine typically storage of two connecting rods to a common crank pin being referred to as " 180-degree V-type engine ". By contrast, if the connecting rods of opposing cylinders mounted on its own crank throws, which are offset by 180 ° to each other, it is a boxer engine. Because of the better mass balance of the boxer engine 180 ° V engines are rarely built, mostly as a high-revving race engines with many cylinders.
In twelve cylinders conventional design, the crank throws are arranged similar to a straight-six. Therefore, there is independent of the cylinder bank angle, a complete settlement of all inertial forces and moments of first and second order, since the engine can be considered as a double R6. For uniform ignition intervals of the bank angle must be a multiple of 60 °. (60 ° are common in cars, 180 not running at racing and sports cars. 120 ° be because two cylinders then would be lit at the same time ). Examples of sports car with 180 ° V12 are the Mercedes -Benz C291, the Ferrari Testarossa or Porsche 917
Structurally interesting to compare 180 ° V against Boxer in the two- stroke engine: The Boxer engine has the better mass balance, but a lower degree of uniformity, since at each revolution even two cylinders simultaneously ignite (360 ° firing interval ). As a 180 ° V engine the mass balance is not optimal, but the ignitions are more evenly distributed (180 ° firing interval ). 180 ° V engines are not suitable for crankcase scavenged and therefore need separate pump to the cylinder flush.
Designations
V-engines are usually described by the term the number of cylinders, preceded by a "V " for the design of the motor and an attached figure for the number of cylinders. "V12 " thus indicates a twelve-cylinder V-engine. A number followed by the letter V on the other hand refers to motors with more than two valves per cylinder and not the number of cylinders. The abbreviation 12V can mean, for example: Four-cylinder engine with two intake and one exhaust valve per cylinder or three-cylinder engine with four valves per cylinder ( four-valve ). A 20V motor can be a four-cylinder engine with three intake and two exhaust valves per cylinder; possible is also a four-valve five-cylinder engine. For the now widely used four-valve four -cylinder engines, the abbreviation is used 16V.
Cylinder arrangement
The arrangement is seen in a front longitudinally mounted V6 engine from the front of the vehicle from (DIN 73 021 ):
Power output 3 6 2 5 1 4 The arrangement is seen in a front longitudinally mounted V8 engine from the front of the vehicle from (DIN 73 021 ):
Power output 4 8 3 7 2 6 1 5 The following numbering (ISO 1204, ISO 1205 and DIN 6265 ) For a V8 engine for general use:
Power output 8 4 7 3 6 2 5 1 The arrangement is seen in a front longitudinally mounted V10 engine from the front of the vehicle from (DIN 73 021 ):
Power output 5 10 4 9 3 8 2 7 1 6 application
V-engines are widely used, especially at higher number of cylinders and space is limited. Engines having 8 or more cylinders are almost exclusively V-engines.
In cars with V-engines come mainly V6, V8 or V12 engines. V4 and V2 motors are uncommon, although earlier, V4 ( eg, various Ford models ) but some V2 engines (mainly micro- Mobile such as Morgan Three Wheeler ) were used. The first series- V4 engines were from 1922 Lancia Lambda and the first V6 engines from 1950 Lancia Aurelia in. Similarly, in V8 - engine Lancia took the 1928 -built Dilambda a leading position. In some car models such as the Lamborghini Gallardo or VW Touareg V10 TDI V10 engines are used - even more frequently in motorsport. The BMW M5 E60/E61 series also had a V10.
Motorcycles use the V-type engine as V2 and V4 rarer than ( such as the Yamaha V -Max, Honda VFR 750 R, Ducati Desmosedici ). The V-type engine also became famous in the American muscle cars (eg Ford Mustang, Pontiac GTO) and the motorcycles from Ducati, Moto Guzzi, Harley -Davidson and formerly also Indian. The irregular firing order of V engines, motorcycles contributes significantly to their characteristic running noise. The special design of the V2 engine of historical Iver Johnson motorcycle allows a uniform firing order, thereby generating the exhaust sound of a parallel - twin engine.
In commercial vehicles (trucks, buses ), the proportion of V-engines is bigger, even V10 engines are mainly V6 and V8 engines, occasionally installed. In marine and locomotive engines V8, V12, V16, V18 and V20 engines are used, the V18 version is the rarest variant. In tanks V12 diesel engines have long been common and are there still partly (Leopard 2, T -90). Also in aircraft V-engines have been used in which the banks of cylinders are arranged in "suspended ", the crankshaft is at the top.
V4 engine of a Saporoshez SAS 965A
V6 engine Lancia Flaminia Coupé a
Air-cooled Tatra 87 V8 engine
Sliced Daimler -Benz DB 601, a V12 engine with overhead cylinders.
Ford " Flathead ", the first mass-produced V -8 engine
12 - cylinder V- engine in an inland waterway
Harley -Davidson Evolution 88 cubic inches V-2 engine
Pros and Cons
One of the main advantages of the V engine is its short length and halved the number of crank throws - if this is the normal case (see above) - in comparison to the series motor. The compact design also some material and thus saves weight. A V12 with a six- cranked crankshaft is only slightly longer than an engine with six cylinders. A V- engine is for more and more elaborate than a series motor with the same number of cylinders, as some parts have to be duplicated (cylinder head, camshaft) and the crankcase has a more complex shape. However, there are except the V8 engine as the newer Chevrolet Corvette models, which has a single, centrally positioned camshaft. In addition, a V engine in the car almost always requires two exhaust lines, for that must also be present according to place.
Disadvantages are the poorer compensation of inertial forces (V4 ) and moments of inertia (V4 and V6) in V4 and V6 engines. V6 engines are often used in cars instead of R6- series engines because they are shorter and not as high build. Disadvantages are vibrations and rougher sound at high engine speeds through free mass moments. The non- symmetrical along the crankshaft occur free mass moments on first and second order. A counter-rotating balance shaft can eliminate the free mass moment of first order. The second-order residual -free mass moment is relatively small. Since a balance would have an excessive expense, this will be waived.
In four-stroke V8 engines can be the inertial forces and moments of first and second order fully offset with a cylinder angle of 90 °, as well - regardless of the cylinder angle - the V12 and the V16 very rare. The almost complete mass balance results in a very smooth running.
The original V8 design has with a cylinder angle of 90 °, a crankshaft with four cranks are offset by 180 ° in a plane ( hence the name flat -plane design). This design is simple and inexpensive to manufacture. It requires less counter weights, causing the engine to rev up easily and on. In this design, however, there are free inertial forces of the second order and thus more vibration. All V8 engines until 1925 were flat -plane engines. Today, the design is used, for example, even in racing and continuously from Ferrari.
In the cross -plane construction of V8, the first and final throw of the crankshaft in a plane and the two middle cranks lie in a plane perpendicular thereto. In viewing direction of the longitudinal axis of the cranks form a cross. cross -plane crankshaft is considerably more difficult to design and to manufacture. However, they offer the advantage that the free mass forces first and second order and the free mass moment of the second order to compensate themselves. It occurs on a free mass moment of first order, which can be compensated by a counterweight couple to the crankshaft. Due to the complete balance of the inertial forces and moments results in a very smooth engine operation. The design was introduced in 1915, but took until 1923 Cadillac and 1924 Peerless the first production engines of this design on the market. It has the disadvantage that the ignition - and therefore also the input and exhaust strokes - not take place alternately in the left and right bank of cylinders, but irregular. This is unfavorable for a good cylinder filling and a uniform distribution of the mixture and the combustion air to all cylinders, which can be mastered by appropriate design of the intake manifold though. Also, this creates the acoustically distinctive exhaust noise ( " V8 babbling "). At high engine performance, such as in racing, the construction requires very elaborate exhaust systems.