Principle of Pneumatic Office Chair

The principle of a pneumatic office chair is to utilize the force of compressed gas to achieve height adjustment. Its core component is a pneumatic rod (gas spring), which drives piston movement through changes in gas pressure to complete the lifting and lowering functions.

Structure of the Pneumatic Rod and the Role of Gas

The pneumatic rod consists of a cylinder, a piston, and sealed gas (usually nitrogen or an inert gas). After the gas inside the cylinder is compressed, a high-pressure environment is formed. The piston moves up and down in the cylinder through the pressure difference of the gas. The cylinder end is fixed to the seat, the piston rod end is connected to the base housing, and there is a small valve at the top of the cylinder that can be controlled by a height adjustment lever. When the valve is closed, the gas inside the cylinder is in a sealed state, and the pressure is stable. When the valve is opened, the gas flow causes a pressure change, thereby driving the piston movement.

Two Mechanisms for Height Adjustment

1. Seat Lowering Mechanism
   When a user needs to lower the seat height, the valve is opened to allow some of the gas inside the cylinder to flow out, reducing the pressure inside the cylinder. At this time, the external atmospheric pressure pushes the piston upward, and the seat lowers accordingly. The pressure difference is the key to driving the piston movement: the lower the pressure inside the cylinder, the greater the upward movement of the piston, and the more obvious the lowering of the seat height.

2. Seat Raising Mechanism
   Raising the seat requires a two-step operation:

   • When the user is not fully seated: Pull up the height adjustment lever, the valve opens, and external gas enters the inner cylinder from the outer cylinder, increasing the pressure inside the inner cylinder, pushing the piston outward, and raising the seat.
   • After the user is seated: If further fine-tuning of the height is required, the pressure distribution inside the cylinder can be changed by briefly leaving the seat or adjusting the sitting posture, and then the operation of the adjustment lever can be used to achieve raising. This process relies on the rapid flow of gas and the re-balancing of pressure.

Source of Support Force and Stability

The pressurized nitrogen or inert gas filled in the cylinder can generate a continuous thrust, usually capable of supporting a weight of up to 110 kilograms. The gas is sealed inside the cylinder to prevent leakage and a consequent decrease in support force. The design of a purely mechanical structure (without electronic components) gives the pneumatic rod high reliability and a long service life, allowing it to maintain stable performance even after long-term use.

Considerations for Safety Design

The safety of the pneumatic rod is ensured through multiple mechanisms:

• Gas selection: Nitrogen or inert gases have stable chemical properties, are non-flammable and non-explosive, reducing usage risks.
• Pressure limitation: The cylinder is designed with a maximum pressure threshold to prevent structural damage caused by excessive compression.
• Valve control: The linkage design between the height adjustment lever and the valve ensures precise operation, avoiding accidents caused by sudden lifting or lowering.