First, story from the wire that likes a twisting the rope
Now image that there is a common operation condition, namely one part is rotating and another part is actionless for radar antenna in the square, the blade facing the wind and CT scanner in the hospital.
So, the question is that owing to the rotating part needs the power and to transmit the signal, where is the wire? If the wire directly connects from the fixed end to the rotating end, the wire will be like a twisting the rope and even to be snapped.
An engineer will easily solve the above-mentioned problem, namely building a "transfer station" in the joint of the rotating area for the purpose of transmitting the current and the signal. And, that "transfer station" remains the Slip Ring. We can say that the slip ring acts as a component for continuous transmission the power and the signal between the "fixed parts" and the "rotating parts".
Second, the main bodies of the slip ring: the rotator and the stator
Whatever its different shapes of the slip ring, its structures includes two parts.
The rotator (the rotating end): connecting the rotating structure of the equipment. Its core part is a set of conductive rings, namely a set of metallic circular ring on the shaft which each and every ring remains a unique channel for the current and for the signal.
The stator (the fixed end): the static structure for connecting the equipment. Its core part is a set of brushes which is connecting flexible contact point of the conductive ring for the purpose of linking its external circuit with its rotating ring.
The relationship between the rotator and the stator is its sliding contact. When the rotator rotates, the brush is always connecting on the surface of the conductive ring for the purpose of transmitting the current, which reflects the operation principle of the slip ring-sliding electrical contact.
It just likes the food hatch in the revolving restaurant, namely the food (the current) is passed to the rotating dinner table from the kitchen without a welded table but with a relative sliding interface.
Third, the inner components of the slip ring
The traditional slip ring usually includes the followings:
The conductive ring-the "traffic lane"
The conductive ring remains the traffic lane for transmitting the current and the signal with excellent electrical conductivity and anti-wearable metallic materials, such copper alloy, silver alloy. For higher-requirement signal, the slip ring will be covered with gold to reduce its contact resistance and to ensure a stable transmission. And, multiphase slip ring is designed with multiple conductive rings with parallel arrangement with each-and-every-
conductive-ring function of transmitting its independent signal.
The brush-the tentacle connecting the surface of the ring
The brush presents the hardworking component of the slip ring. It should be remaining a reliable electric contact with its high-speed rotating with excellent anti-wearable performance. There are two common kinds in the following.
The Carbon Brush (the graphite series): lower cost to suit for a large current. Its defection remains that the carbon powder will be generated with a long period of operation and with a regular clean.
Precious metal alloy bristle: excellent electrical conductivity, anti-wearable performance and lower contact resistance. It is the mainstream choice for the precious slip ring. Many precision slip rings will be designed with "II-style" brush wire for the purpose of dual contact with the conductive ring groove, ensuring continuous touching in the process of the operation.
Insulation structure-avoid the barrier for visiting relatives
Multiple conductive rings should be strictly insulated each other, otherwise the short-circuiting of wire connections will be generated. The inner structure of the slip ring will be designed with high-performance insulated materials, such as special engineering plastic and Teflon as well. Therefore, the design level of its insulated structure will directly decide how many channels in the slip ring and what is the maximum voltage that can be tolerated.
Bearing and the cover-the framework for measuring the precision
Only the stable working of the conductive ring, the contact of the brush will be suitable and the signal will be excellent. Therefore, the inner slip ring is usually equipped with precious bearing to support the rotator for the purpose of the concentricity. And, the cover selected with the metal or the engineering plastics will be packaging its inner components for the purpose of fixing, protecting and shielding as well. Many slip rings are also equipped with seal ring and dust cover for the purpose of protecting its inner contact surface against the dust and oil mist.
Outlet and auxiliary structure
There are two outlets for the stator and the rotator for the purpose of linking external circuit for the slip ring. But, how to synchronize the contacting and the rotating? The conductive ring will be responsible for "transmitting while rotating", and the brush will be responsible for "close touching", and the insulated material will be responsible for "separating" and the bearing and the cover will be responsible for "the stability", transmitting the current and the signal smoothly.
When you see the radar antenna or the wind blade next time, you can image that there is a set of precious rings and the brushes in the invisible axis with their silently continuous operating.
