Internal Design of Office Chair Armrests

The internal design of office chair armrests varies significantly depending on their type and function, primarily divided into adjustable and fixed types, with core structures and functional implementations as follows:

Internal Design of Adjustable Armrests

Adjustable armrests achieve dynamic adjustments in height, angle, or position through mechanical or pneumatic structures, featuring relatively complex internal designs. Common types include:

1. Height Adjustment Mechanisms

   • Push-button Ratchet Type: Internally, a spring drives a ratchet to engage with the teeth on the armrest post. Pressing the button disengages the ratchet, allowing the armrest to slide up or down; releasing the button resets the ratchet to lock the height. This structure is cost-effective, but adjustment precision is limited by the spacing of the teeth.
   • Knob Tightening Type: Relies on the cooperation between a threaded rod and a nut. Rotating the knob moves the nut along the threaded rod, fixing the armrest height through friction. Its advantage is smooth adjustment, but the threads may wear out over time, leading to looseness.
   • Infinite Pneumatic Drive Type: Commonly used in high-end office chairs, integrating a pneumatic cylinder internally to achieve infinite height adjustment through air pressure differences. When the user presses the lift button, the piston inside the pneumatic cylinder moves, changing the internal pressure and causing the armrest to rise or fall; releasing the button balances the air pressure to lock the position. This structure provides smooth adjustment but requires regular inspection of the pneumatic cylinder's seal.

2. Multi-dimensional Adjustment Mechanisms

   • Forward and Backward Sliding: The armrest is equipped with a slide rail and a locking block internally. When the user pushes the armrest, the locking block moves within the slide rail and is fixed by a spring or screw upon reaching the target position.
   • Inward and Outward Swinging: The armrest is connected to the chair body via a pivot shaft, with a damper or limit block installed internally to control the swing amplitude and provide resistance, preventing the armrest from swinging freely.
   • Angular Rotation: Some armrests support 360° rotation, utilizing a rotary bearing and a定位销 (positioning pin) internally. When the user rotates the armrest, the positioning pin switches between grooves at different angles to achieve angle locking.

Internal Design of Fixed Armrests

Fixed armrests have a simple structure, typically consisting only of a support frame and connectors internally:

• Support Frame: Made of metal (such as steel tubes) or high-strength plastic, providing the basic load-bearing capacity of the armrest.
• Connectors: The armrest is fixed to the side panels of the chair body with screws or rivets, with some designs incorporating rubber pads to reduce vibration and noise.

Summary: Adjustable armrests achieve functional diversity through precise mechanical or pneumatic structures, suitable for users who need flexible adjustment of their sitting posture; fixed armrests meet basic needs with low cost and high stability. The choice should be based on the usage scenario and budget.