Balance shaft in Ford Taunus V4 engine.

In piston engine engineering, a balance shaft is an eccentric weighted shaft which offsets the vibrations engine designs that are not inherently balanced (for example, most four-cylinder engines). Image File history File linksMetadata Balanceshaft. ... Image File history File linksMetadata Balanceshaft. ... 1. ... Components of a typical, four stroke cycle, DOHC piston engine. ... In mechanical engineering, an eccentric (mechanism) is a wheel that rotates on an axle that is displaced from the focus of the circle described by the wheel; in other words, a mechanical motion that can operate either as a cam or a crank, depending upon what is connected to the... See Oscillator (disambiguation) for particular types of oscillation and oscillators. ...

Four cylinder applications

Balance shafts are most common in inline four cylinder engines which, due to the asymmetry of their design, have an inherent second order vibration (vibrating at twice the engine RPM) which, contrary to popular belief, cannot be eliminated no matter how well the internal components are balanced. This vibration is generated because the movement of the connecting rods in an inline engine is not symmetrical throughout the crankshaft rotation; thus during a given period of crankshaft rotation, the descending pistons and ascending pistons are not always completely opposed in their acceleration, giving rise to a net vertical inertial force twice in each revolution whose intensity increases quadratically with RPM, no matter how closely the components are matched for weight. See the 0 degree cylinder angle, 180 degree crankshaft angle animated example here for a very clear depiction of this sometimes hard to visualize vibration (as well as the mathematical equation which describes it). rpm or RPM may mean: revolutions per minute RPM Package Manager (originally called Red Hat Package Manager) RPM (movie) RPM (band), a Brazilian rock band RPM (magazine), a former Canadian music industry magazine In firearms, Rounds Per Minute: how many shots an automatic weapon can fire in one minute On... piston + connecting rod In a reciprocating piston engine, the connecting rod or con rod connects the piston to the crank or crankshaft. ... An inline engine is an internal-combustion engine with cylinders aligned in one or several rows. ... Crankshaft, pistons, and flywheel Continental engine marine crankshafts, 1942 For the comic strip about an old, curmudgeonly bus driver, see Crankshaft (comic strip). ... piston + connecting rod Components of a typical, four stroke cycle, DOHC piston engine. ... The principle of inertia is one of the fundamental laws of classical physics which are used to describe the motion of matter and how it is affected by applied forces. ...

The problem increases with larger engine displacement, since the only ways to achieve larger displacement are with a longer piston stroke, increasing the difference in acceleration, or by a larger bore, increasing the mass of the pistons; either way, the magnitude of the inertial vibration increases. For many years, two litres was viewed as the 'unofficial' displacement limit for a production inline four-cylinder engine with acceptable NVH characteristics. The development of the General Motors 2.3 litre Quad 4 engine in 1987, described as "rough as a cob" by one automotive reviewer, and its subsequent development into the much more positively received 2.4 L version with balance shafts confirms the wisdom of this assessment. Displacement, One complete cycle of a four cylinder, four stroke engine. ... A stroke is a single action of certain engines. ... Bore may refer to: A wave in a river caused by an incoming tide - see tidal bore The diameter of a pipe or tube, or the caliber of a gun The diameter of a cylinder and piston in a piston engine (See also: Stroke) A person who is boring The... Unsolved problems in physics: What causes anything to have mass? Mass is a property of a physical object that quantifies the amount of matter and energy it is equivalent to. ... // Real numbers The magnitude of a real number is usually called the absolute value or modulus. ... This page is a candidate to be moved to Wiktionary. ... General Motors Corporation (NYSE: GM), also known as GM, is an American automobile maker with worldwide operations and brands including Buick, Cadillac, Chevrolet, GMC, Holden, Hummer, Opel, Pontiac, Saturn, Saab and Vauxhall. ... The litre or liter (see spelling differences) is a unit of volume. ... The Quad 4 (called Twin Cam after 1995) was a DOHC straight-4 automobile engine produced by General Motors Oldsmobile division in the 1990s. ... 1987 (MCMLXXXVII) was a common year starting on Thursday of the Gregorian calendar. ...

The basic concept behind balance shafts has existed for nearly a century and is no longer patentable. Two balance shafts rotate in opposite directions at twice engine speed. Equally sized eccentric weights on these shafts are sized and phased so that the inertial reaction to their counter-rotation cancels out in the horizontal plane, but adds in the vertical plane, giving a net force equal to but 180 degrees out of phase with the undesired second-order vibration of the basic engine, thereby canceling it. (Some motorcycle enthusiasts believe that Honda's original application of this technology to their V-twin motorcycle engine overly damped out the vibration, giving an excessively 'dead' feel, so that they later reduced the size of the balance shafts in order to furnish the rider with some feedback as to engine speed). A patent is a set of exclusive rights granted by a state to a person for a fixed period of time in exchange for the regulated, public disclosure of certain details of a device, method, process or composition of matter (substance) (known as an invention) which is new, inventive, and... This article is about vectors. ... A motorcycle is a two-wheeled vehicle powered by an engine. ... Honda 90° V-twin A V-twin is a two cylinder internal combustion engine where the cylinders are arranged in a V configuration. ...

The actual implementation of the concept, however, is concrete enough to be patented. The basic problem presented by the concept is adequately supporting and lubricating a part rotating at twice engine speed, at the higher RPMs where the second order vibration becomes unacceptable. Mitsubishi Motors pioneered the design in the modern era with its "Silent Shaft" Astron engines in 1975, with balance shafts located low on the side of the engine block, driven by chains from the oil pump, and subsequently licensed the patent to Porsche, then to other manufacturers. Since then, other manufacturers have adapted the same basic layout to their needs. Lubrication occurs when opposing surfaces are completely separated by a lubricant film. ... Mitsubishi Motors Corporation ) is the fourth largest auto-manufacturer in Japan, and in 2006 was ranked 782nd on Forbes list of the 2000 largest public companies. ... The Mitsubishi Astron is series of straight-4 internal combustion engines, along with Orion, Sirius, and Saturn. ... 1975 (MCMLXXV) was a common year starting on Wednesday. ... Pumpjack pumping an oil well near Sarnia, Ontario Ignacy Łukasiewicz - inventor of the refining of kerosene from crude oil. ... An electrically-driven waterworks pump near the Hengsteysee, Germany. ... Dr. Ing. ...

Saab has further refined the balance shaft principle to overcome second harmonic sideways vibrations (due to the same basic asymmetry in engine design, but much smaller in magnitude) by locating the balance shafts with lateral symmetry but at different heights above the crankshaft, thereby introducing a torque which counteracts the sideways vibrations at double engine RPM, resulting in an exceptionally smooth four cylinder engine. Saab Automobile AB is a subsidiary of General Motors. ...

There is some debate as to how much power the twin balance shafts cost the engine. The basic figure given is usually around 15 horsepower (11 kW), but this seems excessive for pure friction losses. It is likely that this is a miscalculation derived from the common use of an inertial dynamometer, which calculates power from angular acceleration rather than actual measurement of steady state torque. The 15 hp (11 kW), then, includes both the actual frictional loss as well as the increase in angular inertia of the rapidly rotating shafts, which would not be a factor at steady speed. Nevertheless, many owners modify their engines by removing the balance shafts, both to reclaim some of this power, but also to reduce complexity and potential areas of breakage for high performance and racing use. As mentioned above, it is commonly believed that the smoothness provided by the balance shafts can be attained after their removal by careful balancing of the reciprocating components of the engine, but that stems from a basic misunderstanding of their operation. The horsepower (hp) is the name of several non-metric units of power. ... It has been suggested that Coefficient of friction be merged into this article or section. ... The principle of inertia is one of the fundamental laws of classical physics which are used to describe the motion of matter and how it is affected by applied forces. ... A dynamometer, or dyno for short, is a device used to measure RPM and torque from which power produced by an engine or other rotating device can be calculated. ... Angular acceleration is the rate of change of angular velocity over time. ... In physics, torque can be thought of informally as rotational force. The SI units for Torque are newton meters although centinewton meters (cN·m), foot-pounds force (ft·lbf), inch pounds (lbf·in) and inch ounces (ozf·in) are also frequently used expressions of torque. ...

Six cylinder applications

Another balance shaft design is found in many V6 engines. While an optimally designed V6 engine would have a 60 degree angle between the two banks of cylinders, many current V6 engines are derived from older V8 engines, which have a 90 degree angle between the two banks of cylinders. While this provides for an evenly spaced firing order in an 8 cylinder engine, in a six cylinder engine this results in a loping rhythm, where during each rotation of the crankshaft three cylinders fire at 90 degree intervals, followed by a gap of 90 degrees with no power pulse. This can be eliminated by using a more complex, and expensive, crankshaft which alters the relationship between the cylinders in the two banks to give an effective 60 degree difference, but recently many manufacturers have found it more economical to adapt the balance shaft concept, using a single shaft with counterweights spaced so as to provide a vibration which cancels out the shake inherent in the 90 degree V6. The Ford Essex V6 engine V6 and V-6 redirect here. ... The Liberty V8 aircraft engine clearly shows the configuration A V8 engine is a V engine with eight cylinders. ... The firing order is the sequence of sparking of the spark plugs in a reciprocating engine, or the sequence of fuel injection in each cylinder in a Diesel engine. ...

Production implementations

Valve timing gears on a Ford Taunus V4 engine — the small gear is on the crankshaft, the larger gear is on the camshaft. Since the camshaft gear is twice the circumference of the crankshaft gear, it runs at half the crankshaft RPM. See gear ratio. The small gear left is on the balance shaft.

Other manufacturers producing engines with one or two balance shafts include(d): Image File history File links Front view of distribution gear in a Ford Taunus V4 engine. ... Image File history File links Front view of distribution gear in a Ford Taunus V4 engine. ... A poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. ... Spur gears found on a piece of farm equipment. ... 1. ... Crankshaft, pistons, and flywheel Continental engine marine crankshafts, 1942 For the comic strip about an old, curmudgeonly bus driver, see Crankshaft (comic strip). ... Double overhead cams control the opening and closing of a cylinders valves The camshaft is an apparatus used in piston engines to operate poppet valves. ... Gears on a piece of farm equipment, gear ratio 1:1. ...

• Alfa Romeo 2.0L four-cylinder, as fitted to the Alfa Romeo 156
• BMW 1200GS motorcycle
• Chrysler 2.4 L and 2.5 L Neon engine
• Ford Modular engine V10
• Ford Taunus V4 engine
• General Motors Corporation Quad 4 and Ecotec
• GM Atlas engine four- and five-cylinder engines (two balance shafts)
• GM Vortec engine V-6 (single balance shaft)
• Honda 2.2 L four cylinder engine
• Mazda's 2.3L MZR engine (two balance shafts)
• Mitsubishi 'Astron' engine
• Nissan 2.5L (QR25DE) four-cylinder engine
• Porsche 2.5L and 3.0L
• Saab H engine
• Volvo B234F, B204GT and B204FT (four cylinder, two balance shafts, 16V-head, used in 700 and 900 series)

as well as numerous motorcycle engines, particularly vertical twins, and even some small single cylinder engines. Alfa Romeo is an Italian automobile manufacturing company, founded as Darracq Italiana by Cavaliere Ugo Stella, an aristocrat from Milan in partnership with the French automobile firm of Alexandre Darracq. ... The Alfa Romeo 156, manufactured by Alfa Romeo, was introduced in 1997 as replacement for the 155. ... This article or section does not cite its references or sources. ... The Chrysler Corporation was a United States-based automobile manufacturer that existed independently from 1925–1998. ... The Chrysler Neon engine is a small straight-4 piston engine designed originally for the Dodge Neon compact car. ... The Modular engine, or mod motor, is Ford Motor Companys modern overhead camshaft (OHC) V8 and V10 engine family. ... A V10 engine is a V engine with 10 cylinders in two banks of five. ... 1. ... General Motors Corporation (NYSE: GM), also known as GM, is an American automobile maker with worldwide operations and brands including Buick, Cadillac, Chevrolet, GMC, Holden, Hummer, Opel, Pontiac, Saturn, Saab and Vauxhall. ... The Quad 4 (called Twin Cam after 1995) was a DOHC straight-4 automobile engine produced by General Motors Oldsmobile division in the 1990s. ... Ecotec is the name of a straight-4 piston engine made by General Motors since 2000. ... Atlas is a name for a family of modern inline piston engines for trucks from General Motors. ... Vortec is a trademarked name for a line of piston engines for General Motors trucks. ... Honda - Wikipedia, the free encyclopedia /**/ @import /skins-1. ... Mazda Motor Corporation ) (TYO: 7261 ) is a Japanese automobile maker based in Hiroshima, Japan. ... Turbocharged MZR engine in a 2006 Mazdaspeed 6 The MZR is Mazdas latest Straight-4 engine. ... Mitsubishi Motors Corporation ) is the fourth largest auto-manufacturer in Japan, and in 2006 was ranked 782nd on Forbes list of the 2000 largest public companies. ... The Mitsubishi Astron is series of straight-4 internal combustion engines, along with Orion, Sirius, and Saturn. ... Dr. Ing. ... Saab Automobile AB is a subsidiary of General Motors. ... Saab H engine (B201) in a 1987 Saab 90 The Saab H engine is a redesign of the Saab B engine. ... AB Volvo (or Aktiebolaget Volvo) is a world-leading Swedish manufacturer of commercial vehicles, buses and construction equipment, drive systems for marine and industrial applications, aerospace components and services. ...

See also

• Engine balance.

Engine balance is the design, construction and tuning of an engine to run smoothly. ...

External links

• Engine balancing
• Animated representations of the vibrations characteristic of various two cylinder engine and crankshaft configurations.