In the modern aerospace industry, aviation electromagnets serve as the core actuators in electromagnetic control systems and are widely used in landing gear retraction and extension, door locking, fuel valve control, and various servo mechanisms. Due to the extremely harsh operating environments faced by aircraft (such as severe vibration, drastic temperature fluctuations, low air pressure, and stringent weight reduction requirements), the design and manufacturing processes of aviation solenoid coils differ fundamentally from those of ordinary industrial solenoids.This article will provide an in-depth analysis of the core characteristics of aviation solenoid coils and focus on their key manufacturing process—the close-winding method.

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I. Core Characteristics of Aviation Electromagnet Coils

The design of aviation electromagnet coils pursues “high reliability, high power density, and long service life,” with their primary characteristics manifested in the following dimensions:

1. Extremely High Power Density and Weight Reduction Requirements

Aerospace vehicles are extremely sensitive to weight. To generate sufficient electromagnetic thrust within limited volume and weight constraints, aviation solenoid coils must maximize the space factor—the ratio of the cross-sectional area of the copper conductors to the total cross-sectional area of the coil. This necessitates minimizing internal voids within the coil.

2. Excellent High-Temperature Resistance and Thermal Dissipation Performance

Aviation electromagnets generate intense Joule heating during continuous operation or frequent actuation, and the low-pressure environment at high altitudes causes a sharp decline in the air’s convective cooling capacity. Consequently, aviation coils typically use high-temperature enameled wires rated H-class (180°C) or even C-class (220°C and above), such as polyimide-coated enameled wire. The coil assembly must also possess excellent thermal conductivity to prevent internal heat buildup that could cause the insulation to burn out.

3. Resistance to Severe Mechanical Stress (Vibration and Shock)

Aircraft generate high-frequency vibrations and immense shock accelerations during takeoff, landing, and flight. If the internal wire arrangement within the coil is loose, the superposition of alternating electromagnetic forces and mechanical vibrations can cause the wires to rub against each other, damaging the enamel coating and ultimately leading to inter-turn short circuits. Therefore, aviation coils must possess extremely high mechanical integrity.

4. Adaptability to Harsh Environments (Moisture, Mildew, and Salt Fog Resistance)

Aviation electromagnets often operate in environments with high humidity, salt fog, and condensation caused by temperature fluctuations between high and low altitudes. The coil’s insulation structure must be perfectly sealed, typically requiring vacuum pressure impregnation (VPI) or a full potting process.