Commutator motor - is an electric motor, wherein rotor movement is accompanied by a constant internal commutating windings.
The main part is considered to be a collector. The photo shows the item hard to confuse. The collector is easily visible through any gap. This copper color drum consisting of a plurality of separated from each other by grooves slats. collector structure is complex, each coil should be included in two directions to increase the power. I did not do one of Jacobi, and the result is mediocre.
The winding of the armature (moving engine parts) consists of a plurality of coils forming the pole. The design is symmetrical to minimize the backlash, beats, reduce vibrations. This increases the lifetime of the product.
The collector, fixed on the shaft becomes distributor electrical energy to mechanical switch. Today, the alternative variant recognized valve engines with electronic control. Due to the peculiar structure of the collector greatly sparks: at break brushes and lamellae surfaces formed quickly fading arc. This causes noise. By the level of extraneous sound collector engines excel at times other devices.
Brushes eventually wear out. They consist of a washer-contact threaded connection; thick, distinctive look of stranded copper wire and the graphite body. On these grounds recognizable commutator motor, if the rear part of the cover is closed, as shown in the photo. No need to look graphite body, enough to see where there is a cable. Design holders differs, but brush can be easily removed and replaced with a new one. clamping spring serves to ensure reliable contact. It is present in all designs, graphite body during operation grinds.
It is easy to illustrate in the grinder (angular-grinder). To access have special cover, allowing to replace the brush without opening the housing. The high performance is provided. Often the amount of work for cutting and stripping of metals on the grinder goes great in the heat of operation to disassemble the cabinet will not be the best solution. If there are caps, shown in the photo, is enough to remove them and replace the part. A threaded connection is absent here, a brush is pressed directly to the collector cover.
Slotted screwdriver is necessary to turn the plug and pull the old brush. Pad easily thrown out, pushed by a spring. If it is impossible to get an identical brush, graphite body is allowed to erode. Contact form does not matter, the desired shape is soldered washer, playground, etc., if necessary.
It follows that the commutator motor is highly maintainable. The ratio of down to the structure of DC wrong policy. Efficacy alternating current (torque, efficiency) below. The reason - the rotational speed does not always coincide with the mains frequency. It is difficult to predict the result of the vector addition of fields, all poles.
From the history
The first powerful electric motors that can pull the train composition, based on the forward motion of the armature is attracted and pushed by an electromagnet. This motors Clark and Page that appeared in the 40s of XIX century. Rotary actuators with collectors, invented earlier, was not found due to the popularity of low power. The latter type concerned engines:
Start of construction of collector engines laid Wollaston, Faraday, Ampere, Barlow and Ritchie. All of the following - a repeat of their ideas to a certain extent. At the time of 1850 by many engineers (Joel, Scoresby, and so on.) Calculated that the electrical energy costs up to 25 times more expensive than a pair. Therefore, the designers have rested in the need to create a generator that and reached in a short time (the reversibility of generators and motors predicted Lenz in 1833).
Collector engines came first. All came from Michael Faraday showed that when continuously fed to wire an electric current, manages to make wire rotated around the magnet. The experience of the work done in 1821, as reported to the Royal Academy. Subject - Faraday said that the idea failed. The scientist continued experiments and by November was successful. Parallel experiences do other physicists who heard the report, and too successful.
Michael Faraday today considered the father of collector engines. Following a similar machine assembled Barlow.
Most wheel Barlow reminds gear disk saws, hanging low over the table. Its lower edge immersed in a container with mercury in the end of which hang over the wire with the current. This liquid contact, and used by Michael Faraday in 1821. With the ends of the lower edge of the disc is the two poles of a horseshoe permanent magnet: north and south. tension line drive directed at an angle, the rotation begins. The wire is shorted through the disk and a frame to voltage (volts column).
From this it is clear that the principle of the wheel Barlow similar to that used by Michael Faraday. Last stop their research. Mentor Faraday many radevshy Michael acceptance of the Royal Society of England, considered the idea of plagiarism from the ward installation Wollaston does not work for some reason. Instead of mercury may pour colored water (see. rice), and limits the speed of rotation of the wheel -. indicator light. By as much as 10 years history of the commutator motor stopped.
New original idea by Professor William Ritchie. He invented the first motor with a rotating shaft, although Russian literature gives prerogative Jacobi. In the journal Philosophical Transactions of the March 20, 1833 under number 123 published an article, which stated several designs. The author says that the first device appeared collected more 9 months ago (June 1832). According to the recommendations should make a round pedestal made of wood with clapboard on the outer perimeter with poured to mercury. Trench in diameter divided into two equal parts sloping wall of the timber.
In the center of the stand mounted thin axis on which revolves a long bar of the electromagnet. Pole from its feed two wires dipped in mercury. At the time of passage of improvised barriers contacts pole change occurs. Now, if the above was disabled installation to hang a horseshoe-shaped permanent magnet, and the power supply to close, the rotor starts to rotate!
Installing Ritchie is considered the world's first commutator motors. However, the mercury dispenser is standing on the stator, now it has become part of the rotor. Meaning: special design allows you to change the polarity of the electromagnet, which is considered the main idea of the design of any of the commutator motor. Using the idea of Ampère, Ritchie orientated machine frame so that the boundary of the groove section, filled with mercury, coincided with the geographical meridian, and the rotor began to spin in the field of the Earth!
He invented the professor and other interesting things, some of which is related to the topic under consideration. At that time (1834) Dr. Edmundson from Baltimore built the similarity of the mill with a DPDT contact. There is already a dual collector of frogs standing on the terminals of the rotor axis, and only one dial-formed horseshoe magnet stator. And disabling including nutrition, spinning the shaft causes the motor to work - to attract one end of the central cross. The last two devices form the basis for the design of this class of products.
The first practical electric collector
So, now it is clear that Jacobi did not invent the commutator motor. But he was able to adapt and improve borrowed ideas and a year to gather a great engine, which was already a collector of the 4 sections on each of the 4 current collector. Borrowing ideas can be recognized by the fact that the walls between the contact pads are formed on the model.
The main merit of the engineer - was able to knock out the king of 8000 rubles for the development of the invention, promising to surprise the Neva electric boats on the Thames and the envy of the Tiber. Jacobi engines differ large number of poles. The first option consisted of four electromagnets on the stator and the rotor of a similar amount. For switching the axis were four rings on each - 4 conductive sector separated sections of wood. There was repeated the described structures.
The idea is not original. Four magnet rotor and stator alternately switched on and off by switching the supply contacts. Two rings were designed to control the moving part and two - fixed. The poles were divided into two pairs included in rotation. The design of the rotor and the stator is identical in this respect. To ensure correct time switching-pullers ring pairs are offset from each other by 45 degrees: while operating the first, second idle.
Video running engine posted on YouTube youtube.com/watch? v = kIPyyGyBZ60, screens and colorful, thanks to the Institute of Electrical Engineering ETI, division of the Karlsruhe Institute of Technology KIT (eti.kit.edu) in general, and in particular Martin Doppelbaueru. Construction is considered the most powerful engine of the collector before the arrival of the 40-ies of the XIX century
It documented that September 13, 1838 the first electric boat 28 feet long was held for 7 hrs Hiking Distance 7.5 km and back of Neve with an average speed of 2.5 km / h. Engine 300 W fed from the 320 pairs of copper and zinc plates weighing a total of 200 kg, placed on both sides of the vessel. It is not known for sure if there are any happy with 14 passengers and was there among them Lenz, but the mass dissemination of this type of transport is not received, for obvious reasons: too much consumption zinc.
Things began to change after 1859, in which Gaston Plante invented the lead-acid batteries to make up for a charge. Jacobi spent several years working on his own invention, but the only answer to the effort has been to increase the ship's speed in half (1839). The next year Sibrandus Strating from Groningen launched the electric boat, engaged and electric vehicles.
As a result, the first electric fleet appeared on the Thames. This happened half a century later (1882). The flotilla began with the first vessel is 7.6 meters long, called a rant Electricity. Bringing on board new batteries and advanced collector engines, it was able to develop a speed of 13 km / h and keep the rate for 6 hours. By 1888 the Thames walked a small fleet of ships (6 pieces), charged from power plants scattered along the banks of the river. None of the creatures did not survive, but modern museum boasts a 16-meter Mary Gordon in August 1900 release.
Prerequisites for further development
Today collector traction engines put on locomotives and vacuum cleaners in drills and washing machines. C 1844 actively used alternators Woolrich together with the rectifying switches. This measure have tried to reduce the price of the produced energy. Before the experiments were conducted with a constant current generated by copper and zinc circles, and collector motors are calculated for these conditions.
The first generator was created in 1832 by Hippolyte Pixie. As the first high-powered engines, was created with the progressive course of the anchor. The next year, Lenz reported the reversibility of generators, which led to a conclusion about the possibility of creating a collector varieties of devices. What has directly led to the use of wind energy, water, gas, steam and so on. to create electricity. Although up to 90s generator partner remained rectifier switch.
It is believed that the first pressing Werner Siemens invented the brush. He is engaged in designing powerful dynamo (1866). Researchers in this area play an important role Anoshu Ányos Jedlik. His name is called first among DC motors inventors (see. Video youtube.com/watch? v = QFz70sdPf-8). The inventor says that his own car assembled in 1827. The fact is not documented among patents, journals, periodicals. You have to think that a rotating design is really going to the experiments of Michael Faraday with electromagnetic induction.
Ányos Jedlik design resembles like two drops of water the product Ritchie described above. Comparing favorably to the lack of mercury. the battery terminal is a copper disc diametrically divided in half. the stator field created by coil thick copper wire anchor has two series-connected windings, a current collector, on the trailing surface of the disc. Twice per revolution polarity of the stator poles changes, which ensures the viability of the design.
It turns out Ányos Jedlik appropriate to consider the inventor of the first device with automatic switching poles in the world. The collector is located on the frame, therefore, considered stator. Mention Jacobi, the first to show the world how to make the current collector on the basis of which future generations could make the pinch brush. Ányos Jedlik and Jacobi made two things, right on further fate of collector engines:
- Jacobi attracted to the work of Lenz, the latter was quick to realize the reversibility of generators and engines of almost any type. What in 1833 he wrote a report, and five years later, already involved in the construction of a dynamo.
- Ányos Jedlik in 1856, 6 years before the creation of the first industrial generators Siemens and Wheatstone already built a theory on the subject. If you would have listened to his opinion, the progress would be accelerated.
It seems incredible, but Ányos Jedlik not patented his invention and are not made public, because I thought: the information has long been known. It will be recalled that with the beginning of the technological revolution, scientific society in Europe was split, and the United States began to pull the blanket over himself. Industrialists were quick to see that at the expense of science easy to make, the idea did not receive publicity.
I guessed first apply an AC voltage to generate a rotating magnetic field Tesla. The scientist, as opposed to Edison completely abandoned collectors and worked exclusively on synchronous and asynchronous motors. This is dictated by personal dislike of the two designers. It is noted that the commutator motor can be operated by the AC - to the detriment of the efficiency - making a versatile device (so-collector engines often called).
Pros and Cons
Any device type inherent advantages and disadvantages. If you take the collector engines, they are appreciated for the simplicity of controlling the speed, high torque accuracy in the work. The disadvantages are considered to be a lot of weight, tolerance to shock and vibration, the need for frequent maintenance. Commutator motors occupy at home leading role. If we calculate the ratio of the two types of houses:
- the washing machine is powered by a collector motor.
- refrigerator compressor generally asynchronous (do not take industrial variants).
- vacuum cleaner motor is always a collector, which gives the device the power and ease of control.
- Any electric hand tool with a few exceptions contains commutator motor.
- Hoods are usually provided with a noisy collector engines, is the most effective way to achieve high power, despite the noise. Weak dome sometimes work on induction motors.
- Fans of the requirements to noise include induction motor.
- Food processors, mixers, meat grinders and blenders equipped with a commutator motor. Difference products is the frequent use of thyristor speed control circuit using the feedback circuit estimates the amount of arcing at schotkah. This is an obvious example of a parasitic effect for good.
How to distinguish the device of the internal arrangement of devices mentioned above. A collector external features are arcing and increased noise. The set times are graphite brushes.