{{Short description|Electric motor in the middle of a wheel}} {{Use dmy dates|date=April 2021}} [[File:Electricbike1raleigh.JPG|thumb|Raleigh SC30 converted to an [[electric bicycle]] with an aftermarket electric conversion hub motor kit]]
A '''wheel hub motor''', '''hub motor''', or '''in-wheel motor''' is a [[brushless DC electric motor]] that is incorporated into the [[Wheel#Hub|hub]] of the wheel. Wheel-hub motors are commonly found on [[electric bicycle]]s. Electric hub motors were well received in early [[electric car]]s, but have not been commercially successful in modern production cars<ref>{{cite news |title=Wheel Motors to Drive Dutch Buses |url=https://www.technologyreview.com/2009/03/23/31935/wheel-motors-to-drive-dutch-buses/ |date=23 March 2009 |website=[[Technology Review]]}}</ref><ref name="highvoltage">{{cite news |url=https://www.economist.com/science-and-technology/2019/07/11/a-new-type-of-engine-for-electric-cars|title=A new type of engine for electric cars|date=2019-07-11|newspaper=The Economist|access-date=2019-08-31|issn=0013-0613}}</ref> because they negatively affect vehicle handling due to higher dynamic [[rolling resistance|wheel load]]<ref name="AVEC10" /> and their placement makes them prone to damage.<ref name="highvoltage" />
==Bicycles== {{Main|Electric bicycle}} Patents for electric bicycles with hub motors were granted as early as 1895.<ref>({{US Patent|552271}}</ref> Bicycle hub motors are simple, durable, and affordable compared to other designs, but less suitable for high speeds.<ref>{{cite web |url=https://www.nationalgeographic.com/environment/article/electric-bike-sustainable-transportation |title=Are electric bikes the future of green transportation? |first=Elaina |last=Zachos |date=June 16, 2023 |website=National Geographic}}</ref> Hub motors rose in popularity over other designs in the late 2000s and 2010s.<ref>{{cite web |url=https://www.cyclist.co.uk/in-depth/introduction-to-electric-bikes-everything-you-need-to-know |title=Introduction to electric bikes: Everything you need to know |date=April 18, 2017 |website=Cyclist |location=UK}}</ref>
==Automotive== ===History=== [[File:TMW 1428 Lohner-Porsche-Elektromobil.jpg| thumb |1900 Lohner-Porsche "Chaise" [[battery electric vehicle]] with two front-wheel hub motors<ref name="Frankenberg1961" />]] [[File:Lohner Porsche.jpg|thumb |1900 [[Lohner–Porsche]] "Mixte" racecar with four wheel-hub motors<ref name="Frankenberg1961" />]]
Several electric, combustion, and steam powered in-wheel motor designs were patented in the 1880s and 1890s.<ref>{{cite web |url=https://www.hemmings.com/stories/2014/02/12/ferdinand-porsche-joseph-ledwinka-and-the-invention-of-the-electric-hub-motor |title= Ferdinand Porsche, Joseph Ledwinka, and the invention of the electric hub motor |first=Daniel |last=Strohl |date=February 12, 2014 | website=Hemmings}}</ref> Among those who were awarded patents: Wellington Adams of St. Louis in 1884;<ref name="Adams1884">{{US Patent|300,827}}</ref> Edward Parkhurst of Woburn in 1890;<ref name="Parkhurst1890">{{US Patent|422,149}}</ref> Albert Parcelle later in 1890;<ref name="Parcelle">{{US Patent|433,180}}</ref> Charles Theryc in 1896, who cites no transmission losses thanks to an absence of classic transmission rods from engines to wheels;<ref>{{US Patent|572,036}}</ref> C F Goddard in 1896 who cites a piston hub motor for horseless carriages powered by expanding gas of some kind;<ref>{{US Patent|574,200}}</ref> and W C Smith in 1897 who cites an explosive gas expansion motor inside a wheel hub that utilized cams on a track in the hub to transmit power to the wheel.<ref>{{US Patent|593,248}}</ref>
An electric wheel hub motor car was raced by [[Ferdinand Porsche]] in 1897 in [[Vienna]], Austria. He developed his first cars as electric cars with electric wheel hub motors that ran on batteries.<ref>{{cite web |url=https://www.biography.com/business-leaders/ferdinand-porsche |title=Ferdinand Porsche |date=April 5, 2021 |website=Biography.com}}</ref> A racecar by [[Lohner–Porsche]] fitted with four wheel-hub motors debuted at the [[World Exhibition]] in Paris in 1900. Alongside it a commercial model was introduced, the Lohner–Porsche Chaise, with two front wheel-hub motors. It was well-received, and several models based on its design were produced by Lohner and other manufacturers until the 1920s.<ref name="WorldGuide1987">{{cite encyclopedia |url=https://archive.org/details/worldguidetoauto0000unse_p7u4/page/294/mode/2up?q=%22Lohner+Porsche%22 |page=294 |encyclopedia=The World Guide to Automobile Manufacturers |title=Lohner |year=1987 |publisher=[[Infobase|Facts on File Publications]]}}</ref><ref name="Frankenberg1961">{{cite book |title=Porsche – the Man and His Cars |page=58 |first=Richard |last=von Frankenberg |year=1961 |publisher=Robert Bentley}}</ref>
===Design=== Hub motors may be implemented with [[direct-drive mechanism|direct-drive]] or [[Epicyclic gearing|planetary gears]].<ref>{{cite web |url=https://www.ebikeschool.com/geared-hub-motors-vs-gearless-hub-motors/ |title=Geared Hub Motors Vs Gearless Hub Motors |website=EbikeSchool.com |access-date=2023-06-24}}</ref> They rotate the wheel either through an [[axial flux motor|axial]], [[inrunner]], or [[outrunner]] rotor design, with either brushed or [[brushless motor|brushless]] commutator design.<ref>{{cite web |url=https://www.machinedesign.com/motors-drives/article/21833665/designing-inhub-brushless-motors |title=Designing In-Hub Brushless Motors |date=July 22, 2014 |first=Lowell |last=Christensen |website=Machine Design}}</ref>
[[File:Honda FCX rear in-wheel motor Honda Collection Hall.jpg|thumb|Honda FCX Concept 2005 in-wheel motor with high-voltage wires in orange. Running high voltage outside the chassis can be avoided by using near-wheel motors, which have similar advantages to in-wheel motors.]]
Hub motors are attractive from a design standpoint because of their flexibility. They can be used for front-, rear-, or [[individual-wheel drive]]. They are compact and hence allow for more room for passengers, cargo, or other vehicle components. They allow for better weight distribution compared to a single motor, and they eliminate the need for many of the drive components in traditional vehicles like transmissions, differentials, and axles, which reduces wear and mechanical losses.<ref name="AVEC10" /><ref name="Mraz2010" /> High-voltage in-wheel motors must be robust against damage to their high-voltage cables and components.<ref name="highvoltage" />
===Unsprung weight=== One disadvantage of a wheel hub motor is that the weight of the motor is not supported by the suspension's [[shock absorber]]s, adding to the vehicle's [[unsprung weight]] which adversely affects handling and ride quality. Despite this reduction in ride quality with electric hub motors, it is still better than the ride quality of equivalent combustion engine vehicles, but vehicle handling is still negatively affected due to higher dynamic [[rolling resistance|wheel load]].<ref name="AVEC10">{{cite conference |last1=Vos |first1=R. |last2=Besselink |first2=I. J. M. |last3=Nijmeijer |first3=H. |title=Influence of in-wheel motors on the ride comfort of electric vehicles |conference =Proceedings of the 10th International Symposium on Advanced Vehicle Control (AVEC10) |date=22–26 August 2010 |location=Loughborough, United Kingdom |pages=835–840}}</ref> [[Protean Electric]] and [[Lotus Cars|Lotus]] found that most negative effects of added unsprung mass could be eliminated by adding suspension damping, and that the ability to utilize accurate torque vectoring actually improved car's handling so much that the net effect of the whole arrangement was positive.<ref>{{cite journal |last1=Whitehead |first1=Andrew |last2=Hilton |first2=Chris |title=In-Wheel Motors Roll Again |journal=IEEE Spectrum |issue=July 2018 |page=27 |quote=The Lotus engineers were able to eliminate much of the effect of the added unsprung mass by using slightly more suspension damping. What's more, they found that when that unsprung mass came from actual motors attached to the wheels, the ability to power each side of the car independently improved the car's handling substantially. We've now carried out similar studies on other vehicles. And in all cases, we've found that once the dampers are retuned and we add individual wheel control, the net effect on the vehicle's handling is for the better. So unsprung mass really isn't a showstopper after all.}}</ref>
Without being supported by the suspension's shock absorbers, in-wheel motors are themselves less shielded both from shocks and debris, reducing their durability. Some designs reduce unsprung weight by reducing the weight of the motor, for example by using a [[Electric motor#Ironless or coreless rotor motor|coreless design]] or [[Litz wire]] coil windings. These weight-saving designs may have a negative effect on motor durability.<ref name="Mraz2010">{{cite web |url=https://www.machinedesign.com/markets/automotive/article/21831614/hub-motors-for-allelectric-vehicles-still-have-some-technological-challenges-to-overcome |title=Hub Motors for All-Electric Vehicles Still Have Some Technological Challenges to Overcome |date=August 10, 2010 |first=Stephen J. |last=Mraz |website=Machine Design}}</ref>
===Near-wheel motors=== [[File:Geneva Motor Show 2011 - Mercedes SLS AMG E-Cell (5559795194).jpg|thumb|[[Mercedes-Benz SLS AMG#SLS AMG E-CELL prototype (2011)|2011 Mercedes-Benz SLS AMG E-Cell prototype]] with four near-wheel motors<ref>{{cite news |url=https://www.autoblog.com/2011/01/10/mercedes-benz-sls-amg-e-cell-detroit-2011/ |title= Detroit 2011: Mercedes-Benz SLS AMG E-Cell is the color of electric hotness |date=January 10, 2011 |website=Autoblog}}</ref> which share the advantages of in-wheel motors while avoiding issues of unsprung weight and wear]]
Similar to ''in''-wheel motors, electric vehicles can be designed with ''near''-wheel motors, sometimes called wheel-end motors. This design shares the same advantages as in-wheel motors while avoiding unsprung weight and wear issues, as the motors are near the wheels but inside the chassis, supported by the suspension. Near-wheel motors are less compact than in-wheel motors, but as of 2022 they are more reliable and more cost-effective,<ref>{{cite journal |title=Route Towards Road Freight Electrification in India: Examining Battery Electric Truck Powertrain and Energy Consumption |first1=Sreedhar |last1=Madichetty |first2=Avram John |last2=Neroth |first3=Sukumar |last3=Mishra |first4=B. Chitti |last4=Babu |journal=Chinese Journal of Electrical Engineering |volume=8 |issue=3 |date=September 2022 |pages=57–75 |doi=10.23919/CJEE.2022.000026|s2cid=252841869 |doi-access=free }}</ref> they avoid the risks associated with out-of-chassis high-voltage components,<ref name="highvoltage" /> and they simplify vehicle design and assembly.<ref name="detroitnews2023" />
[[American Axle]] has developed 100 kW and 150 kW wheel-end motors through a project funded by the [[United States Department of Energy]] for the commercialization of clean-energy low-cost wheel-end motors. Costs were lowered by integrating the motor, inverter, and gear reduction into a single unit, and by avoiding [[Rare-earth element#Light versus heavy classification|heavy rare earth]] elements.<ref>{{citation |url=https://www.energy.gov/eere/vehicles/articles/low-cost-high-performance-hre-free-3-1-electric-drive-unit |contribution=Low Cost, High-Performance, HRE-Free 3-In-1 Electric Drive Unit |first=David |last=Crecelius |date=June 22, 2021 |title=2021 DOE Vehicle Technologies Office Annual Merit Review about Electrification |publisher=[[United States Department of Energy]]}}</ref> The 100 kW 3-in-1 wheel-end drive unit was planned for the [[REE Automotive]] vehicle product line.<ref name="detroitnews2023">{{cite news |url=https://www.detroitnews.com/story/business/autos/2023/01/26/american-axle-ev-plans-independence-innovation/69766807007/ |archive-url=https://web.archive.org/web/20230126052129/https://eu.detroitnews.com/story/business/autos/2023/01/26/american-axle-ev-plans-independence-innovation/69766807007/ |archive-date=January 26, 2023 |date=January 26, 2023 |title=American Axle plows ahead with independence, innovation |first=Breana |last=Noble |website=The Detroit News}}</ref> Production was planned for 2025 but it was halted after REE couldn't secure major automaker partners or large institutional buyers.<ref>{{citation |url=https://www.calcalistech.com/ctechnews/article/rkn0ugvbeg |title=From $3.1 billion to $25 million: REE Automotive on the brink |first=Tomer |last=Hadar |website=[[Calcalist]] |location=Israel |date=18 May 2025 |access-date=15 July 2025}}</ref>
===Concept cars=== An early modern [[concept car]] utilizing electric hub motors was the IZA, presented in at the [[IEEE]] conference in 1997, built with four {{cvt|25|kW|hp|0}} motors.<ref>{{cite thesis |url=https://www.diva-portal.org/smash/get/diva2:503940/FULLTEXT01.pdf |title=Wheel Corner Modules: Technology and Concept Analysis |first=Johan |last=Hag |publisher=[[KTH Royal Institute of Technology]] |year=2011 |page=8}}</ref>
Other concept cars presented at auto shows include: [[Chevrolet Sequel]], 2005;<ref name=RSC>{{cite journal |title=Sustainable transportation based on electric vehicle concepts: a brief overview |url=http://www.rsc.org/Publishing/Journals/EE/article.asp?doi=c001674h|last1=Eberle|first1=Ulrich|first2=Rittmar|last2=von Helmolt |publisher=[[Royal Society of Chemistry]]| journal=Energy & Environmental Science |date=2010-05-14| volume=3 | issue=6 | page=689 | doi=10.1039/C001674H | bibcode=2010EnEnS...3..689E | access-date=2010-06-08|url-access=subscription}}</ref> [[MIEV|Mitsubishi MIEV]], 2005;<ref>{{cite news |url=https://www.nbcnews.com/id/wbna7816102 |title=Mitsubishi unveils electric car for 2010 |website=NBC News |date=May 11, 2005}}</ref> [[Hi-Pa Drive]] Mini QED, 2006;<ref>{{cite news |url=https://www.wired.com/2006/10/lets-motor-motor-motor-motor/ |title=Let's Motor, Motor, Motor, Motor |first=Michael |last=Spinelli |date=October 1, 2006 |website=[[Wired.com]]}}</ref> [[Honda FCX]] concept, 2005;<ref>{{cite web |title=Honda Worldwide - Tokyo 2005 |url=http://world.honda.com/Tokyo2005/fcx/index02.html |archive-url=https://web.archive.org/web/20060501144651/http://world.honda.com/Tokyo2005/fcx/index02.html |archive-date=May 1, 2006 |access-date=September 22, 2023 |website=Honda.com}}</ref> [[Citroën C-Métisse]], 2006;<ref>{{cite news |url=https://www.motor1.com/news/227536/concept-we-forgot-citroen-c-metisse/ |title=2006 Citroën C-Métisse: Concept We Forgot |first=Adrian |last=Padeanu |date=January 17, 2018 |website=[[Motor1.com]]}}</ref> [[Protean Electric]] Ford F-150, 2008;<ref>{{cite news |url=http://news.pickuptrucks.com/2011/05/driven-protean-ford-f-150-all-electric-pickup-truck.html |title=Driven: Protean Ford F-150 All-Electric Pickup Truck |date=May 12, 2017 |first=Ben |last=Wojdyla |website=PickupTrucks.com}}</ref> [[Heuliez]] WILL using the Michelin [[Active Wheel]] suspension, 2008;<ref>{{cite news |url=https://www.autoblog.com/2008/10/09/paris-2008-heuliez-michelin-and-orange-wrap-a-revolution-in-a/ |title= Paris 2008: Heuliez, Michelin and Orange wrap a revolution in a plain package |first=Domenick |last=Yoney |date=October 9, 2008 |website=Autoblog}}</ref> [[Peugeot BB1]], 2009;<ref>{{cite web |url=http://www.greencarcongress.com/2009/09/hybrid4-bb1-20090915.html |title=Peugeot Shows Two HYbrid4 Concepts, New BB1 EV Concept at Frankfurt |date=15 September 2009 |website=Green Car Congress |access-date=31 May 2010}}</ref> [[Hiriko Fold]], shown in 2012, a folding [[urban car]] with a maximum speed of {{convert|50|km/h|abbr=on|0}}<ref name=WeirdUK>{{cite magazine|title=Hiriko electric city car folds up to save space|url=https://www.wired.co.uk/news/archive/2012-01/26/hiriko-city-car|magazine=Wired UK|access-date=1 February 2012|date=26 January 2012}}</ref><ref name=Hiriko>{{cite web|title=The Folding Electric Car|url=http://english.kompas.com/read/2012/01/30/13002021/The.Folding.Electric.Car|publisher=Kompas.com|first=Jimmy |last=Hitipeuw|date=30 January 2012|access-date=16 July 2012|url-status=dead|archive-url=https://web.archive.org/web/20120202112627/http://english.kompas.com/read/2012/01/30/13002021/The.Folding.Electric.Car|archive-date=2 February 2012}}</ref> with a motor, steering actuators, suspension, and brake integrated into each wheel, controlled with a [[drive-by-wire]] system;<ref>{{cite news|url=http://www.gizmag.com/hiriko-folding-electric-car/21506/|title=Hiriko - the fold-up electric two-seater set for 2013|first=James |last=Holloway|work=Gizmag|date=20 February 2012 |access-date=26 July 2012}}</ref> FlatFormer, a concept 6x6 autonomous truck chassis, shown in 2019;<ref name="Flatformer2019">{{cite news |title=REE Partnership With Hino Shows More On In-Wheel Motor Tech |url=https://insideevs.com/news/377977/ree-hino-in-wheel-motor/ |date=October 23, 2019 |first=Gustavo |last=Henrique Ruffo |website=InsideEVs}}</ref> various vehicles by Indigo Technologies since 2019;<ref name="highvoltage" /> [[Aptera (solar electric vehicle)|Aptera Motors prototype]] in 2022<ref>{{citation |url=https://newatlas.com/automotive/aptera-gamma-prototype-solar-electric-vehicle/ |title=Aptera Gamma prototype SEV makes public debut in San Diego |first=Paul |last=Ridden |date=September 12, 2022 |website=NewsAtlas}}</ref> though the 2024 Aptera prototypes did not feature in-wheel motors;<ref>{{cite web |last=Senbiba |first=Jennifer |date=July 25, 2024 |title=Aptera Ditches Hub Motors (For Now), Makes Real Progress Toward 2025 Production |url=https://cleantechnica.com/2024/07/25/aptera-ditches-hub-motors-for-now-makes-real-progress-toward-2025-production/|access-date=March 18, 2025 |website=[[CleanTechnica]]}}</ref> and [[Italdesign Giugiaro|Italdesign]] Quintessenza with Elaphe Sonic in-wheel motors in 2025.<ref>{{Cite news |last=Rivers |first=Stephen |date=January 10, 2025 |title=Italdesign's Quintessenza Is A Bonkers Pickup Coupe With More Horsepower Than An F1 Grid |url=https://www.carscoops.com/2025/01/italdesigns-quintessenza-is-like-a-subaru-brat-from-the-future-with-over-2000-hp/}}</ref>
Concept cars that were announced without publicly presenting a physical model include: [[Siemens]] [[VDO (company)|VDO]] eCorner concept, 2006;<ref>{{cite news |url=https://www.autoblog.com/2006/08/10/siemens-vdo-announces-ecorner-motor-in-hub-concept/ |title=Siemens VDO announces eCorner motor-in-hub concept |first=Eric |last=Bryant |date=August 10, 2006 |website=Autoblog}}</ref> and [[ZAP (motor company)#ZAP-X|ZAP-X]], 2007.<ref>{{cite news| url=https://www.nytimes.com/2007/09/23/automobiles/23AUTO.html | website=The New York Times | title=They're Electric, but Can They Be Fantastic? | first=Lawrence | last=Ulrich | date=23 September 2007}}</ref>
{{Gallery |width=200 | height=200 |align=center |File:PMLMini QED-wheel.jpg|Mini QED electric vehicle |File:MZKT open day 2019 p06.jpg|[[MAZ-7907]] truck. Each wheel has its own electric motor |File:Hiriko 1.jpg|[[Hiriko Fold]] with in-wheel motor, steering actuators, suspension, and braking, controlled by a drive-by-wire system }}
===Production vehicles=== Production vehicles with in-wheel motors include: * [[Lohner–Porsche]] Chaise, Mixte, and others. Several models based on this design were produced by Lohner and other manufacturers in the early 1900s.<ref name="WorldGuide1987" /><ref name="Frankenberg1961" /> * [[Lightyear 0]] with Elaphe in-wheel motors,<ref>{{Cite web |author=<!-- staff --> |date=2023 |title=Motor in the wheel for Lightyear's utmost performances |url=https://www.electricmotorengineering.com/motor-in-the-wheel-for-lightyears-utmost-performances/ |website=Electric Motor Engineering}}</ref> briefly produced in 2022 before its manufacturer filed for bankruptcy.<ref name=AutoExpress>{{cite news |title=Lightyear unveils long-range solar-electric car |url=https://www.autoexpress.co.uk/car-news/107239/lightyear-unveils-long-range-solar-electric-car |first=Luke |last=Wilkinson |work=Auto Express |location=UK |access-date=26 June 2019 |date=25 June 2019 |archive-date=29 November 2019 |archive-url=https://web.archive.org/web/20191129003759/https://www.autoexpress.co.uk/car-news/107239/lightyear-unveils-long-range-solar-electric-car |url-status=dead }}</ref><ref>{{cite news |title=Lightyear 0 Production On Hold As Company Focuses On Affordable Model |url=https://insideevs.com/news/632703/lightyear-0-production-on-hold/ |website=InsideEVs |language=en}}</ref> * [[Lordstown Endurance]] with Elaphe in-wheel motors,<ref>{{Cite web |last=Truett |first=Richard |date=September 12, 2023 |title=Wheel-hub motor maker Elaphe moving on from Lordstown |url=https://www.autonews.com/suppliers/elaphe-wheel-hub-motor-headed-new-vehicles/ |website=Autonews}}</ref> briefly produced in 2022 before its manufacturer filed for bankruptcy.<ref>{{cite news |url=https://www.caranddriver.com/news/a44359321/lordstown-files-for-bankruptcy-report/ |title=Lordstown Files for Bankruptcy, Endurance Pickup Assets up for Sale |first=Caleb |last=Miller |date=June 27, 2023 |website=[[Car and Driver]]}}</ref>
Planned production vehicles include:
* [[BMW Neue Klasse]], planned for production in 2026 with in-wheel motors developed by DeepDrive.<ref>{{citation |url=https://www.autoevolution.com/news/crazy-bmw-coupe-prototype-with-neue-klasse-dna-and-wheel-hub-motors-emerges-from-the-void-236549.html |title=Crazy BMW Coupe Prototype With Neue Klasse DNA and Wheel Hub Motors Emerges From the Void |date=July 5, 2024 |first=Cristian |last=Agatie |website=AutoEvolution}}</ref><ref>{{Cite web |last=Byrnes |first=Jones |date=August 25, 2024 |title=2026 BMW Neue Klasse Coupe: What We Know About Munich's EV Stunner |url=https://www.carscoops.com/2024/08/2026-bmw-neue-klasse-coupe-what-we-know-about-munichs-ev-stunner/ |website=Carscoops |access-date=18 March 2025}}</ref> * [[Renault 5 Turbo 3E]], planned for production in 2027 with two 200 kW rear in-wheel motors.<ref name="r5_turbo_3e_pr">{{Cite press release|url=https://media.renault.com/renault-5-turbo-3e-the-legend-returns-in-the-form-of-the-very-first-electric-mini-supercar/|title=Renault 5 Turbo 3E, the legend returns in the form of the very first electric "mini-supercar"|author=<!-- not stated --> |date=March 17, 2025|publisher=Renault |access-date=18 March 2025}}</ref>
==See also== * [[Active Wheel]] * [[Direct-drive mechanism]] * [[Hub-center steering]] * [[Individual wheel drive]] * [[Locking hubs]]
==References== {{Reflist}}
==External links== {{Commons category|In-wheel motors}} {{Electric vehicles}}{{DEFAULTSORT:Wheel Hub Motor}} [[Category:Wheel hub motors| ]] [[Category:Electric vehicles]] [[Category:Electric bicycles]] [[Category:Train wheels]] [[Category:Gearless electric drive]]