and the energy transfer device is a carbon brush signals, between the fixed portion and the rotating portion of the motor, a generator or other rotating machinery used, become one of the important part. Brush as a sliding contact, it is widely used in many electrical devices. Main products are made electrically graphite, graphite fat dip, metals (copper, silver) graphite.
1. Brush features
brushes are kind of like a pencil eraser rub strip as topped with wire leads. Volume sizes. Brush generally made of pure carbon plus coagulant, typically the outer shape is a block type, the card holder on the metal, which has a spring pressed it on the shaft, such as the oil drilling is completed, it is necessary to detect, it is necessary from the wellbore put the instrument down, is through the carbon brushes signal from the rotating part (outsourcing wire cable drum) to the ground of the instrument.
2. Brush Brush
moving the brush member is slidably in contact with the electrically conductive member to form a connection. The brush is a slip ring or commutator, as the slidable contact body import and export current. Its conductivity, thermal conductivity and good lubricating properties, and having a certain mechanical strength and commutation spark instinct. Almost all the DC motor and the motor commutator brushes are used, it is an important part of the machine. .
3 brushes action
(1) in the motor commutator, the brush also plays the role of commutation, the current direction may be varied;
(2) Ground carbon brushes may be output current, a large electrostatic charge through the carbon brush shaft into the earth;
(3) on the external current (field current) applied by the brushes rotating rotor (input current) brushless motor;
(4) the large axis (ground) lead to a protection apparatus for measuring rotor and rotor ground fault protection is positive or negative voltage to ground by a brush and the commutator change the composition of the ring, the carbon brush is a kind of brush.
4. The manufacturing materials and processes
(1) natural graphite
such as natural graphite is the main raw material of the carbon brush using pitch or resin binder, after the baking or sintering of 1000 made. Such motors have good lubricating properties and the current collecting performance. Most small and medium sized DC motor for smooth operation and high-speed turbine generator collector ring.
(2) electrochemical graphite
The main component is carbon black, graphite, coke, and other carbonaceous material powder, the high temperature treatment of 2500, so that the artificial into microcrystalline graphite. Such commutation brushes and having excellent self-lubricating properties, are widely used in various types of AC and DC motors not only long life and low wear of the commutator.
(3) metal-graphite-based
The main material of the carbon brush is such electroless copper and graphite. The use is sometimes necessary to use silver powder (with a precision instruments, very expensive) other metals, aluminum, lead powder, these brushes which have sub-containing binder and the binder-free. Such friction characteristics of graphite brushes have both highly conductive metal, therefore, suitable for high-load and low voltage commutation demanding the motor (such as automotive starter motor, etc.). Peripheral speed not exceeding 30 m / sec.