During the compression stroke, it means that the car wheel moves close to the body and the pneumatic butterfly valve is compressed. At this time, the piston in the pneumatic butterfly valve moves downward. The volume of the lower chamber of the piston decreases, the oil pressure increases, and the oil flows through the flow valve to the chamber (upper chamber) above the piston. The upper chamber is partially occupied by the piston rod, so the increased volume of the upper chamber is smaller than the decreased volume of the lower chamber, and part of the oil then pushes open the compression valve and flows back to the storage cylinder. The saving of oil by these valves forms the damping force of the compressed movement of the suspension.
When the pneumatic butterfly valve stretches, the wheel is equivalent to being far away from the body, and the pneumatic butterfly valve is stretched. At this time, the piston of the pneumatic butterfly valve moves upward. When the oil pressure in the upper chamber of the piston rises, the flow valve is closed, and the oil in the upper chamber pushes open the stretching valve and flows into the lower chamber. Due to the existence of the piston rod, the oil flowing from the upper chamber is not enough to fill the increased volume of the lower chamber, which mainly causes the lower chamber to produce a vacuum degree. At this time, the oil in the oil reservoir pushes the compensation valve 7 open and flows into the lower chamber for supplement. Because of the throttling effect of these valves, the suspension will play a damping role during stretching movement.
Since the stiffness and preload of the stretching valve ball valve are designed to be greater than that of the compression valve, under the same pressure, the total channel load area of the stretching valve and the corresponding normal gap is less than the total channel cross section area of the compression valve and the corresponding normal gap. This makes the damping force generated by the stretching stroke of the pneumatic butterfly valve greater than the damping force generated by the compression stroke, meeting the requirements of rapid valve.