The first designs of DC motors. Part 2

The first electric motors of Jacobi

The second stage of the development of electric motors (1834 - 1860 gg.) Is characterized by the predominance of structures with rotational movement of the apparent pole armature. The torque on the shaft of such engines was usually dramatically pulsating. The most characteristic and essential work on the construction of electric motors of this kind belong to B. S. Jacobi.

General view of the Jacobi electric motor (construction of 1834)

Studying the designs of the electric motors of their predecessors, in which the armature was moved back and forth or swinging, Jacobi responded about one of them that "such a device will be no more than an amusing toy for enriching physical cabinets" and that "it can not be used in Scale with some economic benefit "- so he focused his attention on building a more powerful electric motor with a rotational movement of the anchor.

In 1834, Jacobi constructed and described an electric motor that operated on the principle of attraction and repulsion between electromagnets. This engine had two groups of U-shaped electromagnets, of which one group (four U-shaped electromagnets) was located on a stationary frame, and another similar group - on a rotating disk. As a current source, a battery of galvanic cells was used to power the electromagnets . A switch was used to alternately change the polarity of the movable electromagnets.

The switch was an extremely important and deeply thought out part of the Jacobi electric motor device. Structurally, it consisted of four metal rings mounted on the shaft and isolated from it; Each ring had four cutouts that corresponded to one eighth of the circumference. The notches were filled with insulating tabs; Each ring was offset by 45 ° relative to the previous one. On the circumference of the ring slid the lever, which was a kind of brush; The second end of the lever was immersed in an appropriate vessel with mercury, to which the conductors from the battery were brought (mercury-containing vessels were the most common contact devices at that time).

Thus, with each revolution of the ring, the electric circuit was broken four times, the conductors reinforced on the shaft of the machine moved away from the rings to the electromagnets of the rotating disk. The windings of all electromagnets in the fixed frame were connected in series and flowed around the battery in one direction.

The windings of the electromagnets of the rotating disk were also connected in series, but the direction of the current in them with the switch was changed 8 times in one revolution of the shaft. Consequently, the polarity of these electromagnets also changed 8 times in one revolution of the shaft and these electromagnets were alternately attracted and repelled by the electromagnets of the stationary frame.

The first electric motor, built by Jacobi, could lift a weight of 10-12 pounds (i.e., about 4-5 kg) to a height of 1 foot (about 30 cm) per second, which was about 15 watts. The desire to increase the power of the electric motor led BS Yakobi to create a design of a twin-type electric motor.

Double Jacobi electric motor

This electric motor had 24 fixed П-shaped electromagnets and 12 movable rod electromagnets, but operated on the same principle as its first electric motor. Progressive in this version of the Jacobi engine was that, with a similar motor design, the bearings were unloaded from the axial forces that arose in the first electric motor when the axes of the movable and immovable electromagnets were aligned.

The design change, however, did not give a significant increase in power and did not allow the electric motor to be used in practice. It was necessary to look for a new constructive solution, which was discovered in a few years by B. S. Jacobi.

Jacobi built his first electric motor in May 1834, and in November of the same year he presented a report on this device to the Paris Academy of Sciences. The message was read at a meeting of the Paris Academy in December 1834 and immediately thereafter published. Thus, the news of Jacobi's invention quickly spread to all countries.

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