Wheel hub motor

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Raleigh SC30 converted to an electric bicycle with an aftermarket electric conversion hub motor kit Electricbike1raleigh.JPG
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 motor that is incorporated into the hub of the wheel. Wheel-hub motors are commonly found on electric bicycles. Electric hub motors were well-received in early electric cars, but have not been commercially successful in modern production cars [1] [2] because they negatively affect vehicle handling due to higher dynamic wheel load [3] and their placement makes them prone to damage. [2]

Contents

Bicycles

Patents for electric bicycles with hub motors were granted as early as 1895. [4] Bicycle hub motors are simple, durable, and affordable compared to other designs, but less suitable for high speeds. [5] Hub motors rose in popularity over other designs in the late 2000s and 2010s. [6]

Automotive

History

1900 Lohner-Porsche "Chaise" battery electric vehicle with two front-wheel hub motors TMW 1428 Lohner-Porsche-Elektromobil.jpg
1900 Lohner-Porsche "Chaise" battery electric vehicle with two front-wheel hub motors
1900 Lohner-Porsche "Mixte" racecar with four wheel-hub motors Lohner Porsche.jpg
1900 Lohner–Porsche "Mixte" racecar with four wheel-hub motors

Several electric, combustion, and steam powered in-wheel motor designs were patented in the 1880s and 1890s. [8] Among those who were awarded patents: Wellington Adams of St. Louis in 1884; [9] Edward Parkhurst of Woburn in 1890; [10] Albert Parcelle later in 1890; [11] Charles Theryc in 1896, who cites no transmission losses thanks to an absence of classic transmission rods from engines to wheels; [12] C F Goddard in 1896 who cites a piston hub motor for horseless carriages powered by expanding gas of some kind; [13] 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. [14]

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. [15] 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. [16] [7]

Design

Hub motors may be implemented with direct-drive or planetary gears. [17] They rotate the wheel either through an axial, inrunner, or outrunner rotor design, with either brushed or brushless commutator design. [18]

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. Honda FCX rear in-wheel motor Honda Collection Hall.jpg
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. [3] [19] High-voltage in-wheel motors must be robust against damage to their high-voltage cables and components. [2]

Unsprung weight

One disadvantage of a wheel hub motor is that the weight of the motor is not supported by the suspension's shock absorbers, 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 wheel load. [3] Protean Electric and 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. [20]

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 coreless design or Litz wire coil windings. These weight-saving designs may have a negative effect on motor durability. [19]

Near-wheel motors

2011 Mercedes-Benz SLS AMG E-Cell prototype with four near-wheel motors which share the advantages of in-wheel motors while avoiding issues of unsprung weight and wear Geneva Motor Show 2011 - Mercedes SLS AMG E-Cell (5559795194).jpg
2011 Mercedes-Benz SLS AMG E-Cell prototype with four near-wheel motors 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, [22] they avoid the risks associated with out-of-chassis high-voltage components, [2] and they simplify vehicle design and assembly. [23]

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 heavy rare earth elements. [24] The 100 kW 3-in-1 wheel-end drive unit has become commercially available in the REE Automotive vehicle product line. [23]

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 25 kW (34 hp) motors. [25]

Other concept cars presented at auto shows include: Chevrolet Sequel, 2005; [26] Mitsubishi MIEV, 2005; [27] Hi-Pa Drive Mini QED, 2006; [28] Honda FCX concept, 2005; [29] Citroën C-Métisse, 2006; [30] Protean Electric Ford F-150, 2008; [31] Heuliez WILL using the Michelin Active Wheel suspension, 2008; [32] Peugeot BB1, 2009; [33] Hiriko Fold, shown in 2012, a folding urban car with a maximum speed of 50 km/h (31 mph) [34] [35] with a motor, steering actuators, suspension, and brake integrated into each wheel, controlled with a drive-by-wire system; [36] FlatFormer, a concept 6x6 autonomous truck chassis, shown in 2019; [37] various vehicles by Indigo Technologies since 2019; [2] and an Aptera Motors prototype in 2022. [38]

Concept cars that were announced without publicly presenting a physical model include: Siemens VDO eCorner concept, 2006; [39] and ZAP-X, 2007. [40]

Production vehicles

Production vehicles with in-wheel motors include:

Planned production vehicles include:

See also

Related Research Articles

<span class="mw-page-title-main">Ferdinand Porsche</span> Bohemian-German automotive engineer and inventor (1875–1951)

Ferdinand Porsche was an Austrian-Bohemian-German automotive engineer and founder of the Porsche AG. He is best known for creating the first gasoline–electric hybrid vehicle (Lohner–Porsche), the Volkswagen Beetle, the Auto Union racing cars, the Mercedes-Benz SS/SSK, and several other important developments and Porsche automobiles.

<span class="mw-page-title-main">Axle</span> Central shaft for a rotating wheel or gear

An axle or axletree is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, bearings or bushings are provided at the mounting points where the axle is supported. In the latter case, a bearing or bushing sits inside a central hole in the wheel to allow the wheel or gear to rotate around the axle. Sometimes, especially on bicycles, the latter type of axle is referred to as a spindle.

<span class="mw-page-title-main">MacPherson strut</span> Type of automotive suspension design

The MacPherson strut is a type of automotive suspension system that uses the top of a telescopic damper as the upper steering pivot. It is widely used in the front suspension of modern vehicles. The name comes from American automotive engineer Earle S. MacPherson, who invented and developed the design.

<span class="mw-page-title-main">Steering</span> The control of the direction of motion of vehicles and other objects

Steering is the control of the direction of motion or the components that enable its control. Steering is achieved through various arrangements, among them ailerons for airplanes, rudders for boats, tilting rotors for helicopters, and many more.

<span class="mw-page-title-main">Torsion bar suspension</span> Vehicle suspension that uses a torsion bar

A torsion bar suspension, also known as a torsion spring suspension, is any vehicle suspension that uses a torsion bar as its main weight-bearing spring. One end of a long metal bar is attached firmly to the vehicle chassis; the opposite end terminates in a lever, the torsion key, mounted perpendicular to the bar, that is attached to a suspension arm, a spindle, or the axle. Vertical motion of the wheel causes the bar to twist around its axis and is resisted by the bar's torsion resistance. The effective spring rate of the bar is determined by its length, cross section, shape, material, and manufacturing process.

<span class="mw-page-title-main">Car suspension</span> Suspension system for a vehicle

Suspension is the system of tires, tire air, springs, shock absorbers and linkages that connects a vehicle to its wheels and allows relative motion between the two. Suspension systems must support both road holding/handling and ride quality, which are at odds with each other. The tuning of suspensions involves finding the right compromise. It is important for the suspension to keep the road wheel in contact with the road surface as much as possible, because all the road or ground forces acting on the vehicle do so through the contact patches of the tires. The suspension also protects the vehicle itself and any cargo or luggage from damage and wear. The design of front and rear suspension of a car may be different.

<span class="mw-page-title-main">Four-wheel drive</span> Type of drivetrain with four driven wheels

A four-wheel drive, also called 4×4 or 4WD, is a two-axled vehicle drivetrain capable of providing torque to all of its wheels simultaneously. It may be full-time or on-demand, and is typically linked via a transfer case providing an additional output drive shaft and, in many instances, additional gear ranges.

<span class="mw-page-title-main">Independent suspension</span> Vehicle suspension in which each wheel is suspended independently

Independent suspension is any automobile suspension system that allows each wheel on the same axle to move vertically independently of the others. This is contrasted with a beam axle or deDion axle system in which the wheels are linked. "Independent" refers to the motion or path of movement of the wheels or suspension. It is common for the left and right sides of the suspension to be connected with anti-roll bars or other such mechanisms. The anti-roll bar ties the left and right suspension spring rates together but does not tie their motion together.

Automobile handling and vehicle handling are descriptions of the way a wheeled vehicle responds and reacts to the inputs of a driver, as well as how it moves along a track or road. It is commonly judged by how a vehicle performs particularly during cornering, acceleration, and braking as well as on the vehicle's directional stability when moving in steady state condition.

A swing axle is a simple type of independent suspension, almost always for the rear axles, designed and patented by Edmund Rumpler in 1903. This was a revolutionary invention in automotive suspension, allowing driven (powered) wheels to follow uneven road surfaces independently, thus enabling the vehicle's wheels to maintain better road contact and holding; plus each wheel's reduced unsprung weight means their movements have less impact on the vehicle as a whole. The first automotive application was the Rumpler Tropfenwagen, later followed by the Mercedes 130H/150H/170H, the Standard Superior, the Volkswagen Beetle and its derivatives, the Chevrolet Corvair, and the roll-over prone M151 jeep amongst others.

<span class="mw-page-title-main">De Dion suspension</span>

A de Dion axle is a form of non-independent automobile suspension. It is a considerable improvement over the swing axle, Hotchkiss drive, or live axle. Because it plays no part in transmitting power to the drive wheels, it is sometimes called a "dead axle".

<span class="mw-page-title-main">Inboard brake</span>

An inboard brake is an automobile technology wherein the disc brakes are mounted on the chassis of the vehicle, rather than directly on the wheel hubs. Its main advantages are twofold: a reduction in the unsprung weight of the wheel hubs, as this no longer includes the brake discs and calipers; and braking torque is applied directly to the chassis, rather than being transferred to it through the suspension arms.

A Corvette leaf spring is a type of independent suspension that utilizes a fiber-reinforced plastic (FRP) mono-leaf spring instead of more conventional coil springs. It is named after the Chevrolet Corvette, the American sports car for which it was originally developed and first utilized. A notable characteristic of this suspension configuration is the mounting of the mono-leaf spring such that it can serve as both ride spring and anti-roll spring. In contrast to many applications of leaf springs in automotive suspension designs, this type does not use the spring as a locating link. While this suspension type is most notably associated with several generations of the Chevrolet Corvette the design has been used in other production General Motors cars, as well as vehicles from Volvo Cars and Mercedes-Benz Sprinter van. Fiat produced cars with a similar configuration, using a multi-leaf steel spring in place of the FRP mono-leaf spring.

Hybrid vehicle drivetrains transmit power to the driving wheels for hybrid vehicles. A hybrid vehicle has multiple forms of motive power.

The following outline is provided as an overview of and topical guide to automobiles:

<span class="mw-page-title-main">Lohner–Porsche</span> Motor vehicle

Lohner–Porsche is a term encompassing several electric vehicles designed by Ferdinand Porsche and manufactured at Lohner-Werke in the early 1900s. They include the first hybrid electric vehicle and the first commercial hub motor car. The hybrid "Mixed" or "Mixte" racecars are powered by a gasoline engine which drives four electric motors, one in each wheel hub. The battery-powered "Touring" or "Chaise" commercial cars utilize only two front-wheel hub motors.

<span class="mw-page-title-main">Bombardier Transportation Austria</span>

Bombardier Transportation Austria GmbH is an Austrian subsidiary company of Bombardier Transportation located in Vienna, Austria.

Protean Electric is an automotive technology company specializing in in-wheel motor technology. The company has developed an in-wheel, electric-drive system for hybrid, plug-in hybrid, and battery electric vehicles. Their technology creates a permanent magnet e-machine with relatively high torque and power density with the power electronics and controls packaged within the motor itself. Their in-wheel motor product is intended to be produced in low volume by Protean Electric and licensed in high volume to global automotive and Tier 1 automotive supply companies. Protean Electric is a privately held company with approximately 114 employees. Protean Electric has operations in the United States, United Kingdom, and China.

A modular vehicle is one in which substantial components of the vehicle are interchangeable. This modularity is intended to make repairs and maintenance easier, or to allow the vehicle to be reconfigured to suit different functions.

A centerlock wheel is a type of automobile wheel in which the wheel is fastened to the axle using a single, central nut, instead of the more common ring of 4 or 5 lug nuts or bolts.

References

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  2. 1 2 3 4 5 "A new type of engine for electric cars". The Economist. 11 July 2019. ISSN   0013-0613 . Retrieved 31 August 2019.
  3. 1 2 3 Vos, R.; Besselink, I. J. M.; Nijmeijer, H. (22–26 August 2010). Influence of in-wheel motors on the ride comfort of electric vehicles. Proceedings of the 10th International Symposium on Advanced Vehicle Control (AVEC10). Loughborough, United Kingdom. pp. 835–840.
  4. ↑ ( U.S. patent 552,271
  5. ↑ Zachos, Elaina (16 June 2023). "Are electric bikes the future of green transportation?". National Geographic.
  6. ↑ "Introduction to electric bikes: Everything you need to know". Cyclist.co.uk. 18 April 2017.
  7. 1 2 3 4 von Frankenberg, Richard (1961). Porsche – the Man and His Cars. Robert Bentley. p. 58.
  8. ↑ Strohl, Daniel (12 February 2014). "Ferdinand Porsche, Joseph Ledwinka, and the invention of the electric hub motor". Hemmings.
  9. ↑ U.S. patent 300,827
  10. ↑ U.S. patent 422,149
  11. ↑ U.S. patent 433,180
  12. ↑ U.S. patent 572,036
  13. ↑ U.S. patent 574,200
  14. ↑ U.S. patent 593,248
  15. ↑ "Ferdinand Porsche". Biography.com. 5 April 2021.
  16. 1 2 "Lohner". The World Guide to Automobile Manufacturers. Facts on File Publications. 1987. p. 294.
  17. ↑ "Geared Hub Motors Vs Gearless Hub Motors". EbikeSchool.com. Retrieved 24 June 2023.
  18. ↑ Christensen, Lowell (22 July 2014). "Designing In-Hub Brushless Motors". Machine Design.
  19. 1 2 Mraz, Stephen J. (10 August 2010). "Hub Motors for All-Electric Vehicles Still Have Some Technological Challenges to Overcome". Machine Design.
  20. ↑ Whitehead, Andrew; Hilton, Chris. "In-Wheel Motors Roll Again". IEEE Spectrum (July 2018): 27. 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.
  21. ↑ "Detroit 2011: Mercedes-Benz SLS AMG E-Cell is the color of electric hotness". AutoBlog. 10 January 2011.
  22. ↑ Madichetty, Sreedhar; Neroth, Avram John; Mishra, Sukumar; Babu, B. Chitti (September 2022). "Route Towards Road Freight Electrification in India: Examining Battery Electric Truck Powertrain and Energy Consumption". Chinese Journal of Electrical Engineering. 8 (3): 57–75. doi: 10.23919/CJEE.2022.000026 . S2CID   252841869.
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  28. ↑ Spinelli, Michael (1 October 2006). "Let's Motor, Motor, Motor, Motor". Wired.com .
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  37. ↑ Henrique Ruffo, Gustavo (23 October 2019). "REE Partnership With Hino Shows More On In-Wheel Motor Tech". InsideEVs.
  38. ↑ By Paul Ridden (12 September 2022), "Aptera Gamma prototype SEV makes public debut in San Diego", NewsAtlas
  39. ↑ Bryant, Eric (10 August 2006). "Siemens VDO announces eCorner motor-in-hub concept". AutoBlog.com.
  40. ↑ Ulrich, Lawrence (23 September 2007). "They're Electric, but Can They Be Fantastic?". The New York Times.
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  44. ↑ Cristian Agatie (5 July 2024), "Crazy BMW Coupe Prototype With Neue Klasse DNA and Wheel Hub Motors Emerges From the Void", AutoEvolution
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