Balance shaft: Difference between revisions
m Task 18 (cosmetic): eval 5 templates: del empty params (4×); hyphenate params (2×); |
Rescuing 1 sources and tagging 0 as dead.) #IABot (v2.0.9.5 |
||
| (19 intermediate revisions by 15 users not shown) | |||
| Line 1: | Line 1: | ||
{{Short description|Weights used to balance otherwise unbalanced engine movement}} |
|||
[[Image:Balanceshaft.jpg|thumb|right|Balance shaft in [[Ford Taunus V4 engine]].]]<!--Please note - Taunus is not a typo: the Taunus is a Ford for the Europe market, not to be confused with the Taurus, a U.S. domestic brand--> |
[[Image:Balanceshaft.jpg|thumb|right|Balance shaft in [[Ford Taunus V4 engine]].]]<!--Please note - Taunus is not a typo: the Taunus is a Ford for the Europe market, not to be confused with the Taurus, a U.S. domestic brand--> |
||
'''Balance shafts''' are used in [[piston engine]]s to reduce [[vibration]] by cancelling out unbalanced dynamic forces. The balance shafts have eccentric weights and rotate in opposite direction to each other, which generates a net vertical force. |
'''Balance shafts''' are used in [[piston engine]]s to reduce [[vibration]] by cancelling out unbalanced dynamic forces. The counter balance shafts have [[eccentric (mechanism)|eccentric]] weights and rotate in opposite direction to each other, which generates a net vertical force. |
||
The balance shaft was invented and patented by British engineer [[Frederick W. Lanchester]] in 1907.<ref name="The Royal Society 1948 p. 761">{{cite journal | title=Frederick William Lanchester, 1868-1946 | journal=Obituary Notices of Fellows of the Royal Society | url=https://royalsocietypublishing.org/doi/pdf/10.1098/rsbm.1948.0010 | publisher=The Royal Society | volume=5 | issue=16 | year=1948 | issn=1479-571X | doi=10.1098/rsbm.1948.0010 | page=761| doi-access=free }}</ref><ref name="Google Patents 1912">{{cite web | author=Frederick William Lanchester | |
|||
The balance shaft was invented and patented by British engineer [[Frederick W. Lanchester]] in 1904. It is most commonly used in inline-four and V6 engines used in automobiles and motorcycles. |
|||
title=US1163832A - Balancing means for reciprocating engines. | website=Google Patents | date=1912-10-31 | url=https://patents.google.com/patent/US1163832A/en | access-date=2021-04-03}}</ref> It is most commonly used in [[inline-four]] and [[V6 engines]] used in automobiles and motorcycles. |
|||
==Overview== |
==Overview== |
||
[[File:Lanchester patent harmonic balancer (Modern Motors, I) 031.jpg|thumb|Lanchester's vertical force balancer. The eccentric masses are labelled "C" and "D".]] |
[[File:Lanchester patent harmonic balancer (Modern Motors, I) 031.jpg|thumb|Lanchester's vertical force balancer. The eccentric masses are labelled "C" and "D".]] |
||
| ⚫ | The operating principle of a balance shaft system is that two shafts carrying identical eccentric weights rotate in opposite directions at twice the engine speed. The phasing of the shafts is such that the [[centrifugal forces]] produced by the weights cancel the vertical second-order forces (at twice the engine [[RPM]]) produced by the engine.<ref>{{cite web |title=Engine Balance and the Balance Shafts |url=https://zzperformance.com/blogs/import1/engine-balance-and-the-balance-shafts |website=www.zzperformance.com |access-date=20 August 2019 |language=en}}</ref> The horizontal forces produced by the balance shafts are equal and opposite, and so cancel each other. |
||
| ⚫ | The balance shafts do not reduce the vibrations experienced by the [[crankshaft]].<ref>{{cite web |title=Weighing the Benefits of Engine Balancing |url=http://www.babcox.com/editorial/ar/eb10330.htm |website=www.babcox.com |url-status=dead |archive-url=https://web.archive.org/web/20090224032857/http://www.babcox.com/editorial/ar/eb10330.htm |archive-date=24 February 2009 |access-date=12 December 2004 }}</ref> |
||
| ⚫ | The operating principle of a balance shaft system is that two shafts carrying identical |
||
| ⚫ | The balance shafts do not reduce the vibrations experienced by the [[crankshaft]]. |
||
==Applications== |
==Applications== |
||
=== Two-cylinder engines === |
=== Two-cylinder engines === |
||
Numerous motorcycle engines— particularly [[ |
Numerous motorcycle engines— particularly [[parallel-twin engine]]s— have employed balance shaft systems, for example the [[Yamaha TRX850]] and [[Yamaha TDM850]] engines have a 270° crankshaft with a balance shaft. An alternative approach, as used by the [[BMW GS parallel-twin]], is to use a 'dummy' connecting rod which moves a hinged counterweight. |
||
=== Four-cylinder engines === |
=== Four-cylinder engines === |
||
[[Image:FordtaunusV4front.jpg|thumb|right|Valve timing gears on a [[Ford Taunus V4 engine]]. The balance shaft runs off the small gear on the left (the large gear is for the [[camshaft]], causing it to rotate at half the speed of the crankshaft).]] |
[[Image:FordtaunusV4front.jpg|thumb|right|Valve timing gears on a [[Ford Taunus V4 engine]]. The balance shaft runs off the small gear on the left (the large gear is for the [[camshaft]], causing it to rotate at half the speed of the crankshaft).]] |
||
Balance shafts are often used in [[inline-four engine]]s, to reduce the [[ |
Balance shafts are often used in [[inline-four engine]]s, to reduce the [[engine balance#Secondary vibration|second-order vibration]] (a vertical force oscillating at twice the engine [[revolutions per minute|RPM]]) that is inherent in the design of a typical inline-four engine. This vibration is generated because the movement of the [[connecting rod]]s in an even-firing inline-four engine is not symmetrical throughout the crankshaft rotation; thus during a given period of crankshaft rotation, the descending and ascending pistons are not always completely opposed in their acceleration, giving rise to a net vertical force twice in each revolution (which increases [[quadratic growth|quadratically]] with RPM).<ref >[http://www.dinamoto.it/dinamoto/8_on-line_papers/twin%20motors/twin.html "Shaking forces of twin engines"] {{Webarchive|url=https://web.archive.org/web/20100715064543/http://dinamoto.it/DINAMOTO/8_on-line_papers/twin%20motors/twin.html |date=2010-07-15 }}, Vittore Cossalter, Dinamoto.it</ref> |
||
The amount of vibration also increases with engine displacement, resulting in balance shafts often being used in inline-four engines with displacements of {{convert|2.2|L|cuin|0|abbr=on}} or more. Both an increased [[stroke (engine)|stroke]] or [[bore (engine)|bore]] cause an increased secondary vibration; a larger stroke increases the difference in acceleration and a larger bore increases the mass of the pistons. |
The amount of vibration also increases with engine displacement, resulting in balance shafts often being used in inline-four engines with displacements of {{convert|2.2|L|cuin|0|abbr=on}} or more. Both an increased [[stroke (engine)|stroke]] or [[bore (engine)|bore]] cause an increased secondary vibration; a larger stroke increases the difference in acceleration and a larger bore increases the mass of the pistons. |
||
| Line 26: | Line 27: | ||
In a [[flat-four engine]], the forces are cancelled out by the pistons moving in opposite directions. Therefore balance shafts are not needed in flat-four engines. |
In a [[flat-four engine]], the forces are cancelled out by the pistons moving in opposite directions. Therefore balance shafts are not needed in flat-four engines. |
||
=== Five-cylinder engines === |
=== Five-cylinder engines === |
||
Balance |
Balance shafts are also used in [[straight-five engine]]s such as GM [[General Motors Atlas engine#LLR (Vortec 3700)|Vortec 3700]]. |
||
=== Six-cylinder engines === |
=== Six-cylinder engines === |
||
In a [[straight-six engine]] and [[flat-six engine]], the rocking forces are naturally balanced out, therefore balance shafts are not required. |
In a [[straight-six engine]] and [[flat-six engine]], the rocking forces are naturally balanced out, therefore balance shafts are not required. |
||
V6 engines are inherently unbalanced, regardless of the V-angle. Any inline engine with an odd number of cylinders has a [[engine balance#Primary balance|primary imbalance]], which causes an end-to-end rocking motion. As each cylinder bank in a V6 has three cylinders, each cylinder bank experiences this motion.<ref>{{cite web |title=The Physics of: Engine Cylinder-Bank Angles |url=https://www.caranddriver.com/features/a15126436/the-physics-of-engine-cylinder-bank-angles-feature/ |website=www.caranddriver.com |access-date=22 August 2019 |date=14 January 2011}}</ref> Balance shaft(s) are used on various V6 engines to reduce this rocking motion. |
|||
=== Eight-cylinder engines === |
|||
Examples are the [[Mercedes-Benz OM629]] and [[Volvo B8444S engine|Volvo B8444S]] engine.<ref>{{cite web|author= |url=http://www.australiancar.reviews/Volvo_B8444S_Engine.php |title=Volvo B8444S/Yamaha 4.4 V8 Engine |work=australiancar.reviews |date= |access-date=2022-12-29}}</ref> |
|||
==See also== |
==See also== |
||
| Line 41: | Line 44: | ||
==References== |
==References== |
||
{{reflist |
{{reflist}} |
||
{{Automotive engine}} |
{{Automotive engine}} |
||
Latest revision as of 10:05, 23 September 2023
Balance shafts are used in piston engines to reduce vibration by cancelling out unbalanced dynamic forces. The counter balance shafts have eccentric weights and rotate in opposite direction to each other, which generates a net vertical force.
The balance shaft was invented and patented by British engineer Frederick W. Lanchester in 1907.[1][2] It is most commonly used in inline-four and V6 engines used in automobiles and motorcycles.
Overview
[edit]_031.jpg)
The operating principle of a balance shaft system is that two shafts carrying identical eccentric weights rotate in opposite directions at twice the engine speed. The phasing of the shafts is such that the centrifugal forces produced by the weights cancel the vertical second-order forces (at twice the engine RPM) produced by the engine.[3] The horizontal forces produced by the balance shafts are equal and opposite, and so cancel each other.
The balance shafts do not reduce the vibrations experienced by the crankshaft.[4]
Applications
[edit]Two-cylinder engines
[edit]Numerous motorcycle engines— particularly parallel-twin engines— have employed balance shaft systems, for example the Yamaha TRX850 and Yamaha TDM850 engines have a 270° crankshaft with a balance shaft. An alternative approach, as used by the BMW GS parallel-twin, is to use a 'dummy' connecting rod which moves a hinged counterweight.
Four-cylinder engines
[edit]
Balance shafts are often used in inline-four engines, to reduce the second-order vibration (a vertical force oscillating at twice the engine RPM) that is inherent in the design of a typical inline-four engine. This vibration is generated because the movement of the connecting rods in an even-firing inline-four engine is not symmetrical throughout the crankshaft rotation; thus during a given period of crankshaft rotation, the descending and ascending pistons are not always completely opposed in their acceleration, giving rise to a net vertical force twice in each revolution (which increases quadratically with RPM).[5]
The amount of vibration also increases with engine displacement, resulting in balance shafts often being used in inline-four engines with displacements of 2.2 L (134 cu in) or more. Both an increased stroke or bore cause an increased secondary vibration; a larger stroke increases the difference in acceleration and a larger bore increases the mass of the pistons.
The Lanchester design of balance shaft systems was refined with the Mitsubishi Astron 80, an inline-four car engine introduced in 1975. This engine was the first to locate one balance shaft higher than the other, to counteract the second order rolling couple (i.e. about the crankshaft axis) due to the torque exerted by the inertia caused by increases and decreases in engine speed.[6][7]
In a flat-four engine, the forces are cancelled out by the pistons moving in opposite directions. Therefore balance shafts are not needed in flat-four engines.
Five-cylinder engines
[edit]Balance shafts are also used in straight-five engines such as GM Vortec 3700.
Six-cylinder engines
[edit]In a straight-six engine and flat-six engine, the rocking forces are naturally balanced out, therefore balance shafts are not required.
V6 engines are inherently unbalanced, regardless of the V-angle. Any inline engine with an odd number of cylinders has a primary imbalance, which causes an end-to-end rocking motion. As each cylinder bank in a V6 has three cylinders, each cylinder bank experiences this motion.[8] Balance shaft(s) are used on various V6 engines to reduce this rocking motion.
Eight-cylinder engines
[edit]Examples are the Mercedes-Benz OM629 and Volvo B8444S engine.[9]
See also
[edit]References
[edit]- ^ "Frederick William Lanchester, 1868-1946". Obituary Notices of Fellows of the Royal Society. 5 (16). The Royal Society: 761. 1948. doi:10.1098/rsbm.1948.0010. ISSN 1479-571X.
- ^ Frederick William Lanchester (1912-10-31). "US1163832A - Balancing means for reciprocating engines". Google Patents. Retrieved 2021-04-03.
- ^ "Engine Balance and the Balance Shafts". www.zzperformance.com. Retrieved 20 August 2019.
- ^ "Weighing the Benefits of Engine Balancing". www.babcox.com. Archived from the original on 24 February 2009. Retrieved 12 December 2004.
- ^ "Shaking forces of twin engines" Archived 2010-07-15 at the Wayback Machine, Vittore Cossalter, Dinamoto.it
- ^ Carney, Dan (2014-06-10). "Before they were carmakers". UK: BBC. Retrieved 2018-11-01.
- ^ Nadel, Brian (June 1989). "Balancing Act". Popular Science. p. 52.
- ^ "The Physics of: Engine Cylinder-Bank Angles". www.caranddriver.com. 14 January 2011. Retrieved 22 August 2019.
- ^ "Volvo B8444S/Yamaha 4.4 V8 Engine". australiancar.reviews. Retrieved 2022-12-29.