Solutions for Critical Raw Materials Under Extreme Conditions (CRM-EXTREME) METAL FIBER BRUSHES FOR SLIP RING AND INNOVATIVE APPLICATION Antonio-José Sala (Spain) Training School "The challenge of CRMs in extreme condition: advanced multidisciplinary view", SOFIA, 6-8 February 2018 COST is supported by the EU Framework Programme Horizon 2020 1
Lecture overview. : Reviewing basics o Abstract of the project o Description of the project o Description of drawings o Formules o Conditions for it work o Art state backgrounds Example and practical application 2
Lecture overview. : Abstract o Although graphite and metal-graphite brushes have for nearly 100 years dominated the field of electrical brushes, for many applications there now exists a superior form of sliding electrical conduction. 3
Lecture overview.: Abstract o High performance fiber brushes wherein typically the fibers are made of metal for which reason they are called metal fiber brushes o Prime candidates for this new technology include sliding electrical systems which require high current densities, high sliding speeds, low electrical noise, high efficiency (low brush losses), compact size, or long brush lifetimes 4
Lecture overview.: Abstract o In particular, low voltage electric motors and generators can be made smaller, more powerful and longer lasting owing to the increased current capacity, higher efficiency and longer wear life. 5
Lecture overview.: Abstract o This has a direct bearing on electric vehicular and ship drive systems as well as low voltage electrical power generators. Other applications which require high currents, such as high-force linear actuators, electromagnetic brakes, and armatures, are similarly well suited. 6
Lecture overview.: Abstract Percentages in metal alloys o As an interface, metal fiber structures and material can provide a low loss connection at greatly reduced forces, thereby providing high-efficiency, low force electrical contact. 7
Lecture overview.: Abstract o This is particularly important for high-current, low voltage switching, such as encountered in variable voltage battery storage systems which are charged at high voltages. 8
Lecture overview.: Abstract o Based on simple laws of physics, the capability of fiber brushes to efficiently transfer electrical current across interfaces which are in relative motion or at rest, is paralleled by their capability to similarly transfer heat. 9
Lecture overview.: Abstract o As an application we will see an description for an slip ring to transmit electric current from the car frame to the interior of a tire to refrigerate or heat it and thus optimize its performance. 10
Lecture overview.: Abstract o Therefore the brushes can also be used as heat transducers for cooling or heating purposes. The outstanding features of metal fiber brushes and some suggested applications are listed as follows: 11
Metal Fiber Brushes: Features o High Current Capacity: Because metal fiber brushes can operate at very low losses, and consequently at low heat evolution rates, they can conduct higher current with lower losses than graphite based brushes: Continuous current densities of over 310 A/cm 2 (2000 A/in 2 ) have been demonstrated and this does not by any means represent an upper limit. 12
Metal Fiber Brushes: Features o Low Electrical Noise: This can have dramatic benefits for signalcritical equipment on one mainly front. 13
Metal Fiber Brushes: Features o Long Wear Life Metal fiber brushes can achieve not only low dimensionless wear rates, measured in wear length of brush shortening per length of sliding path, but they can also be constructed with very long, and in some cases nearly unlimited, permissible wear lengths. 14
Metal Fiber Brushes: Features o High Sliding Speeds Many applications such as high speed motors and generators require electrical brushes which can operate at high sliding speeds. o Metal fiber brushes have been successfully operated at speeds in excess of 70 m/s and their theoretical limit certainly lies considerably higher than that. 15
Metal Fiber Brushes: Features o Compact Size Electronic systems which need close proximity to a moving power or signal coupling, or spacecritical sliding contacts could be further miniaturized by the use of this new generation of metal fiber brushes because these brushes can be made in sizes down to fractions of millimeters in thickness or diameter. 16
Metal Fiber Brushes: Features o Low Heat Dissipation Because they operate at low loads and have very low resistance, metal fiber brushes dissipate much less heat than typical brushes in high-current or high-sliding-speed applications. 17
Metal Fiber Brushes: Features o Clean Operating Unlike graphite-based brushes, metal fiber brushes do not generate fine carbon dust, which can cause problems not only with appearance and clean-up but also with longterm fouling and shorting. Metal fiber brush wear debris is heavy enough to be easily trapped or filtered making it therefore much easier to keep the system clean. 18
Description the project: Slip Ring 19
Description the project: Theoretical review Simplified stable iron-carbon phase diagram othe carbon-rich solid phase that appears under equilibrium conditions in the iron-carbon system is graphite, and the diagram that represents the conditions in which this phase coexists with those that are rich in iron is known as the stable carbon iron diagram or iron diagram grafite 20
Description the project: Theoretical review Graphite unit cell Important feature ographite is an allotropic variety of carbon with stratified hexagonal structure, and with a density of 2.24 gr / cm3 21
Description the project: Theoretical review 22
Description: Formules and Theoretical review oas the coil rotates a voltage is induced by E= Blv ; where: B= flux density [T] E= induced voltage [V] l = active length of the conductor in the magnetic field [m] v = relative speed of the conductor [m/s] 23
Description the project: Theoretical review If the brushes could be switched from one slip ring to the other every time the polarity was about to change and we would obtain a voltage of a constant polarity across the load. Brush X would always be positive and brush Y negative o Value Induced voltage: Where: Eo = ZnΦ/60 Eo = voltage between] Φ= flux per pole [Wb] the brushes [V] Z = total number of conductors on the armature; n = speed of rotation [r/min 24
Theoretical review Magnetic field produced by the current flowing in the armature conductors: The flux in the neutral zone(flux density is zero) is no longer zero. The coils are short- circuited by the brushes 25
Description the project: Background Art State 26
Background Art State: Nikola Tesla o Nikola Tesla was a prolific inventor; perhaps not so much as his rival Thomas Edison, but certainly generous at the time of sharing his knowledgement. o It is better known that Tesla valued his inventions helping human being over any prize or recognizingly, even the economical. 27
Background state of art: Nikola Tesla o Many of his inventions were seeking to produce and transmit energy to the whole world in an unlimited way and without highly cost. o Many times he was deceived about his patents (as with the generation and electrical transmission, or the radio) and although he lived a full life, is less known that he died practically in poverty, in a sad worn unworthy of a such figure. 28
Background state of art: Nikola Tesla: Dynamo Dynamo electrical machine Fig. 1 Dynamo electrical machine Fig.2 29
Background state of art: Nikola Tesla:Dynamo Dynamo electric machine Dynamo electric machine 30
Background state of art: Nikola Tesla:Dynamo Dynamo electric machine Dynamo electric machine 31
Background state of art: Nikola Tesla: Dynamo electric machine or motor Dynamo electric machine or motor 32
Background state of art: Nikola Tesla Method of electrical power transmission Method of electrical power transmission 33
Background state of art: Nikola Tesla Electric railway system Electric railway system 34
Background state of art: Nikola Tesla o Tesla obtained about 300 patents of his inventions in the United States, some more fruitful and revolutionary than others. There, their remain the AC electric generator, the induction motor, the spark plug, the alternator, the remote control... 35
INNOVATION TO CLIMATE THE TIRES: SLIP RING TO ELECTRIFY A PELTIER CIRCUIT o The object of the present invention is to control the temperature inside a tire, it being possible for it to either heat or cool the interior surface, as well as the exterior surface by convection. 36
INNOVATION TO CLIMATE THE TIRES: SLIP RING TO ELECTRIFY A PELTIER CIRCUIT o The invention consists of a circuit of "peltier cells", which will be fixed to the interior of the rim, and a rotating device called "slip ring", located on the axis of the wheel and close to one of the valves of the tire in its part outside or inside, which will produce the necessary electrical power. This structure will consist of the following elements: 37
INNOVATION TO CLIMATE THE TIRES: SLIP RING TO ELECTRIFY A PELTIER CIRCUIT o "PELTIER CIRCUIT" That will be coupled to the axis of the rim, if a single circuit is sufficient, or by means of two symmetrical circuits to the width of the tire with electrical installation in parallel and therefore fed from the same power source cited. 38
INNOVATION TO CLIMATE THE TIRES: SLIP RING TO ELECTRIFY A PELTIER CIRCUIT o "SLIP RING The device that produces the electrical supply is characterized by being formed by a slip ring comprising a body called a rotor, and another one called stator, both fitted inside a cylindrical aluminum shell and formed by two rings to obtain the electric power supply current, and by two rings to obtain the control. 39
Application: Innovation Patent 40
Solutions for Critical Raw Materials Under Extreme Conditions (CRM-EXTREME) Contact of the Trainer: Antonio José Sala-Candela a.sala@coiim.es CRM-EXTREME crm-extreme@univpm.it www.crm-extreme.eu http://www.cost.eu/cost_actions/ca/ca15102 41