A brushed DC motor is a compact electrical device designed to convert electrical energy into mechanical motion. It is widely used in toy cars, power tools, small fans, and various compact appliances.
Let’s start with the external components. The motor is encased in a metal housing, commonly referred to as the stator. Inside the stator, you will typically find either two permanent magnets or a single ring magnet. These magnets form the north and south poles of the magnetic field.
One end of the motor features a protruding shaft, also known as the output shaft, which can be coupled with additional components such as worm gears, gearboxes, fan blades, pulleys, or transmission systems.
The opposite end of the motor houses the end cap, which may be made of plastic or metal. Mounted on this cap are two terminal pins. When a power supply is connected to these terminals, the internal rotor generates a magnetic field, converting electrical energy into mechanical energy—causing the shaft to rotate.
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Once the motor casing is disassembled, the internal components become visible:
At the core is a steel shaft, which transmits rotational energy out of the motor to drive a load.
Fixed to the shaft is the rotor, composed of multiple laminated silicon steel sheets stacked together. To ensure electrical insulation and smooth rotation, the rotor surface is usually coated or insulated with plastic.
Within the rotor’s slots are tightly wound copper wire coils. When electric current flows through these coils, they produce a dynamic electromagnetic field. By controlling the polarity and timing of the field, a rotational electromagnetic force is generated, driving the motor.
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The ends of the coils are connected to a component called the commutator, which is typically made of three segmented copper contacts, each electrically isolated from one another and from the central shaft. The commutator is mounted directly on the shaft and rotates with it. Each coil winding is connected to one of the commutator segments.
On the end cap, you’ll find the brushes, which maintain continuous electrical contact with the commutator. Brushes are typically made of precious metals or carbon, depending on the required lifespan and performance conditions. Engineers select the appropriate brush material based on application needs.
As the commutator rotates between the two brushes, it mechanically switches the direction of current flow through the windings. This switching is what allows the motor to maintain unidirectional rotation.
Here’s how the current flows:
It enters through one terminal pin,
Passes through the top brush,
Flows into one commutator segment,
Enters the rotor coil,
Exits via the opposite commutator segment and bottom brush,
And finally leaves through the second terminal pin.
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In summary, a miniature brushed DC motor mainly consists of the following four components:
Stator:
Contains permanent magnets (such as Neodymium Iron Boron or Ferrite) or electromagnetic coils, creating a static magnetic field. The stator is fixed to the outer motor casing, which also supports the entire motor structure.
Rotor:
Composed of stacked silicon steel laminations and armature windings. The windings are powered through the commutator and brushes to produce a rotating magnetic field. The rotor is coupled to the motor shaft for power output.
Commutator:
A segmented copper ring that rotates with the rotor. It reverses the current direction through the coils at the right time, enabling continuous rotation.
Brushes:
Spring-loaded conductive contacts (metal or carbon) that press against the commutator, supplying current to the rotating windings.
Together, these components form a compact yet powerful system capable of converting direct electrical current into rotational mechanical energy.
In our next article, we will explore various DC motor models and their application scenarios.
If you need a customized miniature motor solution tailored to your specific product requirements, please feel free to contact us or visit our website:
Jailyne (Ms.)
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Email: sell02@hcsmotors.com
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