The structural principle of carbon brushes for power tools mainly involves the use of carbon brushes in motors or generators, as a sliding contact, carbon brushes are mainly used in products made of graphite, grease-impregnated graphite, and metal (containing copper and silver) graphiteA carbon brush is a device that transmits energy or signals between the fixed and rotating parts of an electric motor or generator or other rotating machineryIt is generally made of pure carbon with coagulant, and has the appearance of a square, which is stuck on a metal bracket with a spring inside that presses it against the hingeWhen the motor rotates, the carbon brush transmits electrical energy to the coil through the commutator, and it is called a carbon brush because its main component is carbonIt is susceptible to wear and tear and should be regularly maintained and replaced, and carbon deposits should be cleaned up
In the brushed motor, the working principle of the carbon brush is to arrange the two power input ends of each group of coils in turn into a ring, separated from each other by insulating materials, to form a thing like a cylinder, which is connected with the motor shaftThe power supply is made of two small pillars (carbon brushes) made of carbon elements, and under the action of spring pressure, two points on the toroidal cylinder of the coil power input are pressed from two specific fixed positions to energize a group of coilsAs the motor rotates, different coils or different poles of the same coil are energized at different times, so that the N-S pole of the coil generating the magnetic field and the N-S pole of the nearest permanent magnet stator have a suitable angle differenceThe carbon electrode slides on the coil terminal, like a brush brushing on the surface of an object, hence the name carbon "brush". Sliding against each other will cause friction, causing wear and tear, and carbon brushes need to be replaced regularlyThe on-off alternation between the carbon brush and the coil terminal will cause electric sparks, electromagnetic interference, and affect electronic equipment
The brush is fixed in the brush grip, the brush grip is fixed on the casing or end cover, and some are fixed on the special hitch in the casingThere are many forms of brush grips, which can be roughly divided into three types: tubular type, built-in type and coil spring typeAmong them, the brush grip of the tubular structure is round tubular on the outside, pressed by plastic, lined with metal conduit, which is very convenient to use and maintain, and most complete motors use this brush gripThe structure of the built-in brush grip is similar to that of the tubular brush grip, but the exterior is rectangular, and some have convex circles on the top and sides, which is easy to be embedded in the grooves and round holes in the casingThe brush grip structure of the coil spring structure is relatively simple, and the fixed frame of the two brushes and the connected coil spring frame are fixed on a plastic plate, and the plastic plate is fixed on the hitch of the casingThe fixing holes on the plastic plate are generally long holes, so the plastic plate can be moved to change the position of the brushes
