motors

In Wheel Motor

2011-10-05T18:14:00.000-07:00

In Wheel Motor

TM4
The Advanced Technology Trasportation Institute explains that an in-wheel motor assembly consists of:

Highly efficient electric motor
Motor-Wheel Slave Controller (MWSC) including power and control electronics
Brake
Wheel bearings
Steerable front suspension interface
Heat sink embedded in the stator.

The configuration of the 3-phase synchronous motor consists of a central stator which supports the windings and the inverter, surrounded by an external rotor which supports the permanent magnets. The motor assembly is liquid-cooled to sustain high continuous power demands.
Currently, one of the more interesting designs for an electric drivetrain, the motor-wheel assembly is an elegant integration of an electric motor and other components into a package that fits inside a regular-size tire. Mounting the wheel directly on the rotor provides for direct transmission of torque, enhanced freewheeling, regenerative braking, and more economical inclusion of vehicle control, e.g., braking, traction, and stability systems.
Note: Nissan has an even more economical approach: two motors doing the job of four, nevertheless, this design relies upon a more traditional four wheel drive arrangement.
These in-wheel motors are becoming the norm in personal mobility and robots. Mitsubishi has set a precedent by offering cars with in-wheel motors; it remains to be seen whether the majority of carmakers will adopt this design.
There are advantages and disadvantages to providing propulsion in the wheel and removing a tremendous amount of mechanical devices from a main engine compartment. Some of the advantages include:

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Friction clutch

2011-10-05T18:06:00.000-07:00

friction clutch

(Engineering / Mechanical Engineering) a mechanical clutch in which the drive is transmitted by the friction between surfaces, lined with cork, asbestos, or other fibrous materials, attached to the driving and driven shafts

Collins English Dictionary – Complete and Unabridged © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003

ThesaurusLegend: Synonyms Related Words Antonyms

Noun

friction clutch - a clutch in which one part turns the other by the friction between them

clutch - a coupling that connects or disconnects driving and driven parts of a driving mechanism; "this year's model has an improved clutch"

cone clutch, cone friction clutch - a friction clutch in which the frictional surfaces are cone-shaped

disk clutch - a friction clutch in which the frictional surfaces are disks

slip clutch, slip friction clutch - a friction clutch that will slip when the torque is too great

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Bremtec Premium

2011-10-05T18:00:00.000-07:00

Bremtec Premium

Premium Bremtec Brake Pads

Bremtec brake pads are manufactured to the highest original equipment standard, developed and engineered to offer the optimum balance of performance and durability.
Manufactured using only quality components, sourcing the highest grade raw material and bonding agents like Hexion and Cardolite (a high end friction particle sometimes called friction dust) used as a stabilizing agent in brake products.
These particles have a resilient nature which cushions the engaging property of the brake pad. A key feature is that the friction component decomposes on the surface of the brake pad at various elevated temperatures. This ensures that the brake pad is protected from brake fade even in extreme temperatures, ensuring consistent pedal feel and braking.

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Diesel Fuel Injection

2011-10-05T17:52:00.001-07:00

Diesel Fuel Injection

One big difference between a diesel engine and a gas engine is in the injection process. Most car engines use port injection or a carburetor. A port injection system injects fuel just prior to the intake stroke (outside the cylinder). A carburetor mixes air and fuel long before the air enters the cylinder. In a car engine, therefore, all of the fuel is loaded into the cylinder during the intake stroke and then compressed. The compression of the fuel/air mixture limits the compression ratio of the engine -- if it compresses the air too much, the fuel/air mixture spontaneously ignites and causes knocking. Because it causes excessive heat, knocking can damage the engine.
Diesel engines use direct fuel injection -- the diesel fuel is injected directly into the cylinder.
The injector on a diesel engine is its most complex component and has been the subject of a great deal of experimentation -- in any particular engine, it may be located in a variety of places. The injector has to be able to withstand the temperature and pressure inside the cylinder and still deliver the fuel in a fine mist. Getting the mist circulated in the cylinder so that it is evenly distributed is also a problem, so some diesel engines employ special induction valves, pre-combustion chambers or other devices to swirl the air in the combustion chamber or otherwise improve the ignition and combustion process.
Some diesel engines contain a glow plug. When a diesel engine is cold, the compression process may not raise the air to a high enough temperature to ignite the fuel. The glow plug is an electrically heated wire (think of the hot wires you see in a toaster) that heats the combustion chambers and raises the air temperature when the engine is cold so that the engine can start. According to Cley Brotherton, a Journeyman heavy equipment technician:

All functions in a modern engine are controlled by the ECM communicating with an elaborate set of sensors measuring everything from R.P.M. to engine coolant and oil temperatures and even engine position (i.e. T.D.C.). Glow plugs are rarely used today on larger engines. The ECM senses ambient air temperature and retards the timing of the engine in cold weather so the injector sprays the fuel at a later time. The air in the cylinder is compressed more, creating more heat, which aids in starting.

Smaller engines and engines that do not have such advanced computer control use glow plugs to solve the cold-starting problem.
Of course, mechanics aren't the only difference between diesel engines and gasoline engines. There's also the issue of the fuel itself.

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Diesel Fuel

2011-10-05T17:48:00.000-07:00

Diesel Fuel

Petroleum fuel, or crude oil, is naturally found in the Earth. When crude oil is refined at refineries, it can be separated into several different kinds of fuels, including gasoline, jet fuel, kerosene and, of course, diesel.
If you have ever compared diesel fuel and gasoline, you know that they are different. They certainly smell different. Diesel fuel is heavier and oilier. Diesel fuel evaporates much more slowly than gasoline -- its boiling point is actually higher than the boiling point of water. You will often hear diesel fuel referred to as "diesel oil" because it is so oily.
Diesel fuel evaporates more slowly because it is heavier. It contains more carbon atoms in longer chains than gasoline does (gasoline is typically C9H20, while diesel fuel is typically C14H30). It takes less refining to create diesel fuel, which is why it used to be cheaper than gasoline. Since 2004, however, demand for diesel has risen for several reasons, including increased industrialization and construction in China and the U.S. [source: Energy Information Administration].
Diesel fuel has a higher energy density than gasoline. On average, 1 gallon (3.8 L) of diesel fuel contains approximately 155x10⁶ joules (147,000 BTU), while 1 gallon of gasoline contains 132x10⁶ joules (125,000 BTU). This, combined with the improved efficiency of diesel engines, explains why diesel engines get better mileage than equivalent gasoline engines.
Diesel fuel is used to power a wide variety of vehicles and operations. It of course fuels the diesel trucks you see lumbering down the highway, but it also helps move boats, school buses, city buses, trains, cranes, farming equipment and various emergency response vehicles and power generators. Think about how important diesel is to the economy -- without its high efficiency, both the construction industry and farming businesses would suffer immensely from investments in fuels with low power and efficiency. About 94 percent of freight -- whether it's shipped in trucks, trains or boats -- relys on diesel.
In terms of the environment, diesel has some pros and cons. The pros -- diesel emits very small amounts of carbon monoxide, hydrocarbons and carbon dioxide, emissions that lead to global warming. The cons -- high amounts of nitrogen compounds and particulate matter (soot) are released from burning diesel fuel, which lead to acid rain, smog and poor health conditions. On the next page we'll look at some recent improvements made in these areas.

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Electric motor

2011-10-05T13:30:00.000-07:00

An electric motor converts electrical energy into mechanical energy.
Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force. The reverse process, producing electrical energy from mechanical energy, is done by generators such as an alternator or a dynamo; some electric motors can also be used as generators, for example, a traction motor on a vehicle may perform both tasks. Electric motors and generators are commonly referred to as electric machines.
Electric motors are found in applications as diverse as industrial fans, blowers and pumps, machine tools, household appliances, power tools, and disk drives. They may be powered by direct current, e.g., a battery powered portable device or motor vehicle, or by alternating current from a central electrical distribution grid or inverter. The smallest motors may be found in electric wristwatches. Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses. The very largest electric motors are used for propulsion of ships, pipeline compressors, and water pumps with ratings in the millions of watts. Electric motors may be classified by the source of electric power, by their internal construction, by their application, or by the type of motion they give.
The physical principle of production of mechanical force by the interactions of an electric current and a magnetic field was known as early as 1821. Electric motors of increasing efficiency were constructed throughout the 19th century, but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks.
Some devices convert electricity into motion but do not generate usable mechanical power as a primary objective and so are not generally referred to as electric motors. For example, magnetic solenoids and loudspeakers are usually described as actuators and transducers,^[1] respectively, instead of motors. Some electric motors are used to produce torque or force.^[2]

History and development

Faraday's electromagnetic experiment, 1821^[3]

The conversion of electrical energy into mechanical energy by electromagnetic means was demonstrated by the British scientist Michael Faraday in 1821. A free-hanging wire was dipped into a pool of mercury, on which a permanent magnet was placed. When a current was passed through the wire, the wire rotated around the magnet, showing that the current gave rise to a close circular magnetic field around the wire.^[4] This motor is often demonstrated in school physics classes, but brine (salt water) is sometimes used in place of the toxic mercury. This is the simplest form of a class of devices called homopolar motors. A later refinement is the Barlow's wheel. These were demonstration devices only, unsuited to practical applications due to their primitive construction.^{[citation needed]}

historic motor still works perfectly today.^[5])

In 1827, Hungarian physicist Ányos Jedlik started experimenting with devices he called "electromagnetic self-rotors". Although they were used only for instructional purposes, in 1828 Jedlik demonstrated the first device to contain the three main components of practical direct current motors: the stator, rotor and commutator. The device employed no permanent magnets, as the magnetic fields of both the stationary and revolving components were produced solely by the currents flowing through their windings.^[6]^[7]^[8]^[9]^[10]^[11]

[edit] The first electric motors

The first commutator-type direct current electric motor capable of turning machinery was invented by the British scientist William Sturgeon in 1832.^[12] Following Sturgeon's work, a commutator-type direct-current electric motor made with the intention of commercial use was built by Americans Emily and Thomas Davenport and patented in 1837. Their motors ran at up to 600 revolutions per minute, and powered machine tools and a printing press.^[13] Due to the high cost of the zinc electrodes required by primary battery power, the motors were commercially unsuccessful and the Davenports went bankrupt. Several inventors followed Sturgeon in the development of DC motors but all encountered the same cost issues with primary battery power. No electricity distribution had been developed at the time. Like Sturgeon's motor, there was no practical commercial market for these motors.^{[citation needed]}
In 1855 Jedlik built a device using similar principles to those used in his electromagnetic self-rotors that was capable of useful work.^[6]^[8] He built a model electric motor-propelled vehicle that same year.^[14]
The modern DC motor was invented by accident in 1873, when Zénobe Gramme connected the dynamo he had invented to a second similar unit, driving it as a motor. The Gramme machine was the first electric motor that was successful in the industry.^{[citation needed]}
In 1886 Frank Julian Sprague invented the first practical DC motor, a non-sparking motor capable of constant speed under variable loads. Other Sprague electric inventions about this time greatly improved grid electric distribution (prior work done while employed by Thomas Edison), allowed power from electric motors to be returned to the electric grid, provided for electric distribution to trolleys via overhead wires and the trolley pole, and provided controls systems for electric operations. This allowed Sprague to use electric motors to invent the first electric trolley system in 1887–88 in Richmond VA, the electric elevator and control system in 1892, and the electric subway with independently powered centrally controlled cars, which was first installed in 1892 in Chicago by the South Side Elevated Railway where it became popularly known as the "L". Sprague's motor and related inventions led to an explosion of interest and use in electric motors for industry, while almost simultaneously another great inventor was developing its primary competitor, which would become much more widespread.
In 1888 Nikola Tesla invented the first practicable AC motor and with it the polyphase power transmission system. Tesla continued his work on the AC motor in the years to follow at the Westinghouse company.
The development of electric motors of acceptable efficiency was delayed for several decades by failure to recognize the extreme importance of a relatively small air gap between rotor and stator. Efficient designs have a comparatively small air gap.^[15]
The St. Louis motor, long used in classrooms to illustrate motor principles, is extremely inefficient for the same reason, as well as appearing nothing like a modern motor. Photo of a traditional form of the St. Louis motor: [4]
Application of electric motors revolutionized industry. Industrial processes were no longer limited by power transmission using line shafts, belts, compressed air or hydraulic pressure. Instead every machine could be equipped with its own electric motor, providing easy control at the point of use, and improving power transmission efficiency. Electric motors applied in agriculture eliminated human and animal muscle power from such tasks as handling grain or pumping water. Household uses of electric motors reduced heavy labor in the home and made higher standards of convenience, comfort and safety possible. Today, electric motors consume more than half of all electric energy produced.^[16]^[17]

Brushed DC motors

Main article: Brushed DC electric motor

DC motors have AC in a wound rotor also called an armature, with a split ring commutator, and either a wound or permanent magnet stator. The commutator and brushes are a long-life rotary switch. The rotor consists of one or more coils of wire wound around a laminated "soft" ferromagnetic core on a shaft; an electrical power source feeds the rotor windings through the commutator and its brushes, temporarily magnetizing the rotor core in a specific direction. The commutator switches power to the coils as the rotor turns, keeping the magnetic poles of the rotor from ever fully aligning with the magnetic poles of the stator field, so that the rotor never stops (like a compass needle does), but rather keeps rotating as long as power is applied.
Many of the limitations of the classic commutator DC motor are due to the need for brushes to press against the commutator. This creates friction. Sparks are created by the brushes making and breaking circuits through the rotor coils as the brushes cross the insulating gaps between commutator sections. Depending on the commutator design, this may include the brushes shorting together adjacent sections – and hence coil ends – momentarily while crossing the gaps. Furthermore, the inductance of the rotor coils causes the voltage across each to rise when its circuit is opened, increasing the sparking of the brushes. This sparking limits the maximum speed of the machine, as too-rapid sparking will overheat, erode, or even melt the commutator. The current density per unit area of the brushes, in combination with their resistivity, limits the output of the motor. The making and breaking of electric contact also generates electrical noise; sparking generates RFI. Brushes eventually wear out and require replacement, and the commutator itself is subject to wear and maintenance (on larger motors) or replacement (on small motors). The commutator assembly on a large motor is a costly element, requiring precision assembly of many parts. On small motors, the commutator is usually permanently integrated into the rotor, so replacing it usually requires replacing the whole rotor.
While most commutators are cylindrical, some are flat discs consisting of several segments (typically, at least three) mounted on an insulator.
Large brushes are desired for a larger brush contact area to maximize motor output, but small brushes are desired for low mass to maximize the speed at which the motor can run without the brushes excessively bouncing and sparking (comparable to the problem of "valve float" in internal combustion engines). (Small brushes are also desirable for lower cost.) Stiffer brush springs can also be used to make brushes of a given mass work at a higher speed, but at the cost of greater friction losses (lower efficiency) and accelerated brush and commutator wear. Therefore, DC motor brush design entails a trade-off between output power, speed, and efficiency/wear.

Notes on terminology

The first practical electric motors, used for street railways, were DC with commutators. Power was fed to the commutators (made of copper) by copper brushes, but the voltage difference between adjacent commutator bars, excellent conductivity of the copper brushes, and arcing created considerable damage after only a quite short period of operation. An electrical engineer realized that replacing the copper brushes with electrically resistive solid carbon blocks would provide much longer life. Although the term is no longer descriptive, the carbon blocks continue to be called "brushes" even to this day.

Sculptors who work with clay need support structures called armatures to keep larger works from sagging due to gravity. Magnetic laminations, in a rotor with windings, similarly support insulated-copper-wire coils. By analogy, wound rotors came to be called "armatures".^{[citation needed]}

Commutators, at least among some people who work with them daily, have become so familiar that some fail to realize that they are just a particular variety of rotary electrical switch. Considering how frequently connections make and break, they have very long lifetimes.

A: shunt
B: series
C: compound
f = field coil

There are five types of brushed DC motor:

DC shunt-wound motor
DC series-wound motor
DC compound motor (two configurations):
- Cumulative compound
- Differentially compounded
Permanent magnet DC motor (not shown)
Separately excited (not shown)

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