Torque vectoring is a technology employed in automobile
differentials that has the ability to vary the
torque
In physics and mechanics, torque is the rotational equivalent of linear force. It is also referred to as the moment of force (also abbreviated to moment). It represents the capability of a force to produce change in the rotational motion of th ...
to each half-shaft with an
electronic
Electronic may refer to:
*Electronics, the science of how to control electric energy in semiconductor
* ''Electronics'' (magazine), a defunct American trade journal
*Electronic storage, the storage of data using an electronic device
*Electronic co ...
system; or in rail vehicles which achieve the same using individually motored wheels. This method of power transfer has recently become popular in
all-wheel drive
An all-wheel drive vehicle (AWD vehicle) is one with a powertrain capable of providing power to all its wheels, whether full-time or on-demand.
The most common forms of all-wheel drive are:
;1x1 : All unicycles Reflecting one axle with one w ...
vehicles. Some newer
front-wheel drive
Front-wheel drive (FWD) is a form of engine and transmission layout used in motor vehicles, where the engine drives the front wheels only. Most modern front-wheel drive vehicles feature a transverse engine, rather than the conventional longit ...
vehicles also have a basic torque vectoring differential. As technology in the automotive industry improves, more vehicles are equipped with torque vectoring differentials. This allows for the wheels to grip the road for better launch and handling.
History
![1997-2001 Honda Prelude VTi-R ATTS coupe (2011-11-17) 01](https://upload.wikimedia.org/wikipedia/commons/8/8e/1997-2001_Honda_Prelude_VTi-R_ATTS_coupe_%282011-11-17%29_01.jpg)
In 1996, Honda released the
fifth-generation Prelude with the flagship
Active Torque Transfer System
A differential is a gear train with three drive shafts that has the property that the rotational speed of one shaft is the average of the speeds of the others, or a fixed multiple of that average.
Functional description
The following descri ...
(ATTS) torque-vectoring differential driving the front wheels; it was known in different markets as the Type S (Japan), VTi-S (Europe), and Type SH (North America).
[ At about the same time, Mitsubishi equipped its Lancer Evolution IV GSR with a similar ]Active Yaw Control
Active may refer to:
Music
* ''Active'' (album), a 1992 album by Casiopea
* Active Records, a record label
Ships
* ''Active'' (ship), several commercial ships by that name
* HMS ''Active'', the name of various ships of the British Royal ...
(AYC) system in 1996. In essence, ATTS is a small automatic transmission coupled to the differential, with an electronic control unit actuating clutches to vary the torque output between each driven wheel. ATTS effectively counteracted the natural tendency of the front-engine, front-wheel-drive
In automotive design, a front-engine, front-wheel-drive (FWD) layout, or FF layout, places both the internal combustion engine and driven roadwheels at the front of the vehicle.
Usage implications
Historically, this designation was used reg ...
Prelude to understeer
Understeer and oversteer are vehicle dynamics terms used to describe the sensitivity of a vehicle to steering. Oversteer is what occurs when a car turns (steers) by more than the amount commanded by the driver. Conversely, understeer is what occu ...
. Honda developed the system into their Super Handling all-wheel-drive
An all-wheel drive vehicle (AWD vehicle) is one with a powertrain capable of providing power to all its wheels, whether full-time or on-demand.
The most common forms of all-wheel drive are:
;1x1 : All unicycles Reflecting one axle with one w ...
(SH-AWD) system by 2004, which improved handling by increasing torque to the outside wheels.
The phrase "Torque Vectoring" was first used by Ricardo in 2006 in relation to their driveline technologies. The torque vectoring idea builds on the basic principles of a standard differential. A torque vectoring differential performs basic differential tasks while also transmitting torque independently between wheels. This torque transferring ability improves handling and traction in almost any situation. Torque vectoring differentials were originally used in racing. Mitsubishi
The is a group of autonomous Japanese multinational companies in a variety of industries.
Founded by Yatarō Iwasaki in 1870, the Mitsubishi Group historically descended from the Mitsubishi zaibatsu, a unified company which existed from 1870 ...
rally cars were some of the earliest to use the technology. The technology has slowly developed and is now being implemented in a small variety of production vehicles. The most common use of torque vectoring in automobiles today is in all-wheel drive vehicles.
Functional description
The idea and implementation of torque vectoring are both complex. The main goal of torque vectoring is to independently vary torque to each wheel. Differentials generally consist of only mechanical components. A torque vectoring differential requires an electronic monitoring system in addition to standard mechanical components. This electronic system tells the differential when and how to vary the torque. Due to the number of wheels that receive power, a front or rear wheel drive differential is less complex than an all-wheel drive differential.
The impact of torque distribution is the generation of yaw moment arising from longitudinal forces and changes to the lateral resistance generated by each tire. Applying more longitudinal force reduces the lateral resistance that can be generated. The specific driving condition dictates what the trade-off should be to either damp or excite yaw acceleration.
The function is independent of technology and could be achieved by driveline devices for a conventional powertrain, or with electrical torque sources.
Then comes the practical element of integration with brake stability functions for both fun and safety.
Front/rear wheel drive
Torque vectoring differentials on front or rear wheel drive vehicles are less complex, yet share many of the same benefits as all-wheel drive differentials. The differential only varies torque between two wheels. The electronic monitoring system only monitors two wheels, making it less complex. A front-wheel drive differential must take into account several factors. It must monitor rotational and steering angle of the wheels. As these factors vary during driving, different forces are exerted on the wheels. The differential monitors these forces, and adjusts torque accordingly. Many front-wheel drive differentials can increase or decrease torque transmitted to a certain wheel. This ability improves a vehicle's capability to maintain traction in poor weather conditions. When one wheel begins to slip, the differential can reduce the torque to that wheel, effectively braking the wheel. The differential also increases torque to the opposite wheel, helping balance the power output and keep the vehicle stable. A rear-wheel drive torque vectoring differential works similarly to a front-wheel drive differential.
All-wheel drive
Most torque vectoring differentials are on all-wheel drive vehicles. A basic torque vectoring differential varies torque between the front and rear wheels. This means that, under normal driving conditions, the front wheels receive a set percentage of the engine torque, and the rear wheels receive the rest. If needed, the differential can transfer more torque between the front and rear wheels to improve vehicle performance.
For example, a vehicle might have a standard torque distribution of 90% to the front wheels and 10% to the rear. When necessary, the differential changes the distribution to 50/50. This new distribution spreads the torque more evenly between all four wheels. Having more even torque distribution increases the vehicle's traction.
There are more advanced torque vectoring differentials as well. These differentials build on basic torque transfer between front and rear wheels. They add the capability to transfer torque between individual wheels. This provides an even more effective method of improving handling characteristics. The differential monitors each wheel independently, and distributes available torque to match current conditions.
Electric vehicles
In electric vehicle
An electric vehicle (EV) is a vehicle that uses one or more electric motors for propulsion. It can be powered by a collector system, with electricity from extravehicular sources, or it can be powered autonomously by a battery (sometimes cha ...
s all-wheel drive is typically implemented with two independent electric motor
An electric motor is an Electric machine, electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a Electromagneti ...
s, one for each axle. In this case the torque vectoring between the front and rear axles is just a matter of electronically controlling the power distribution between the two motors, which can be done on a millisecond scale. In the case of EVs with three or four motors, even more precise torque vectoring can be applied electronically, with millisecond-specific ''per wheel'' torque control in the quad-motor case,[ and two wheels of ''per wheel'' control plus one of ''per axle'' control in the tri-motor case.
Torque vectoring can be even more effective if it is actuated through two electric motor drives located on the same axle, as this configuration can be used for shaping the vehicle understeer characteristic and improving the transient response of the vehicle, The ]Tesla Cybertruck
The Tesla Cybertruck is an upcoming battery electric light-duty truck announced by Tesla, Inc. in 2019. Three models have been announced, with EPA range estimates of and an estimated time of 2.9–6.5 seconds, depending on the model.
The ...
(scheduled for 2022) tri-motor model has one axle with two motors, while the Rivian R1T
The Rivian R1T is an mid-size electric light duty luxury pickup truck produced by the American company Rivian.
The first production R1T rolled off the assembly line in Illinois and was delivered to a customer in September 2021.
The official ...
(in production in 2021) has two motors on each axle, front and rear.
A special transmission unit was used in the experimental 2014 car MUTE of the Technical University of Munich
The Technical University of Munich (TUM or TU Munich; german: Technische Universität München) is a public research university in Munich, Germany. It specializes in engineering, technology, medicine, and applied and natural sciences.
Establis ...
, where the bigger motor is providing the driving power and the smaller for the torque vectoring functionality. The detailed control system of the torque vectoring is described in the doctoral thesis of Dr.-Ing. Michael Graf.[Graf M.]
'Methode zur Erstellung und Absicherung einer modellbasierten Sollvorgabe für Fahrdynamikregelsysteme'
Technical University of Munich, 2014.
In case of electric vehicles with four electric motor drives, the same total wheel torque and yaw moment can be generated through a near infinite number of wheel torque distributions. Energy efficiency can be used as a criterion for allocating torque across the wheels. This approach is used in the Rivian
Rivian Automotive, Inc. is an American electric vehicle manufacturer and automotive technology company founded in 2009. Rivian is building an electric sport utility vehicle (SUV) and pickup truck on a "skateboard" platform that can support fut ...
R1T
The Rivian R1T is an mid-size electric light duty luxury pickup truck produced by the American company Rivian.
The first production R1T rolled off the assembly line in Illinois and was delivered to a customer in September 2021.
The official ...
light-duty truck introduced in 2021.[
]
Rail vehicles
Research is taking place into using torque vectoring to actively steer railway wheelsets on the track. Claimed benefits include a drastic reduction of wear on both track and wheel and the opportunity to simplify or even eliminate the mechanically complex, heavy and bulky bogie
A bogie ( ) (in some senses called a truck in North American English) is a chassis or framework that carries a wheelset, attached to a vehicle—a modular subassembly of wheels and axles. Bogies take various forms in various modes of transp ...
.
Stored Energy Technology Limited has built and successfully demonstrated their torque vectoring Actiwheel system which employs a wheel hub motor
The wheel hub motor (also called wheel motor, wheel hub drive, hub motor or in-wheel motor) is an electric motor that is incorporated into the hub of a wheel and drives it directly.
History
* First wheel motor concept: Wellington Adams of ...
of their own design.[Actiwheel, a revolutionary traction technology](_blank)
SET Limited
German Aerospace Centre unveiled a full scale mockup of torque vectoring running gear intended for their Next Generation Train
Next may refer to:
Arts and entertainment Film
* ''Next'' (1990 film), an animated short about William Shakespeare
* ''Next'' (2007 film), a sci-fi film starring Nicolas Cage
* '' Next: A Primer on Urban Painting'', a 2005 documentary film
Lit ...
at Innotrans 2022.A high-tech running gear for the train of the future
DLR Portal
See also
* Differential
* Differential steering
Differential steering is the means of steering a land vehicle by applying more drive torque to one side of the vehicle than the other. Differential steering is the primary means of steering tracked vehicles, such as tanks and bulldozers, is als ...
References
Automotive transmission technologies
Automotive steering technologies
Advanced driver assistance systems
Mitsubishi Motors technologies
Train axles