A solenoid is a control device that uses electromagnetism to convert electrical energy into mechanical energy. Its components consist of a coil, an iron casing, and a movable plunger. The coil must carry the current and generate turns of amperes, an iron casing must provide a magnetic circuit while the movable plunger must act as a working element. When applying a solenoid, it is extremely important to consider the effects of heat, since for a constant voltage application; an increase in coil temperature reduces work output.
When current flows through the coil conductor, it produces a magnetic field. The magnetic flux produced by the coil results in the establishment of north and south poles in both the core and the plunger. The plunger is attracted along the lines of force to a position in the center of the coil. The de-energized position of the plunger is partially out of the coil due to spring action. When voltage is applied, the current through the coil produces a magnetic field. This magnetic field draws the plunger into the coil, creating a mechanical movement.
The solenoids themselves are energized by some other control device, such as a switch or relay. One of the main advantages of using solenoids is that a mechanical movement can be achieved at a considerable distance from the control device. The solenoid may have large contacts for high current control. Therefore, the solenoid also provides a means to control high current with a low current switch.
Custom solenoids provide the best match for the mechanical load requirement, reducing excessive power dissipation. Premature drive failure is reduced due to reduction resulting from excessive shock. Wiring and connectors can exit the solenoid at the chosen location, and various kinds of insulating materials are available.
The basic plug and plunger configurations are flat, stepped, and 60 and 90 degree conical. Other configurations can be designed to fit unique force/stroke specifications. A variety of coatings are available, including electroplating, anodizing or painting depending on requirements.
In physics, the term solenoid refers to a long, thin loop of wire, often wrapped around a metallic core, that produces a magnetic field when an electric current is passed through it. In engineering, the term solenoid refers to a variety of transducer devices that convert energy into linear motion.
The term is also often used to refer to a solenoid valve, which is an integrated device containing an electromechanical solenoid that acts like a pneumatic or hydraulic valve, or a linear solenoid, which is an electromechanical solenoid. A linear solenoid can provide up to 30 pounds of force with a drive less than 2-1/4 inches long.
Common applications of linear solenoids:
• Brakes
• copiers
• Door locks
• Pumps
• Interpose
• money changer
• Film processors
• Disk drive crashes
• Electronic typewriters
• Vending machines