Application and structural optimization design of magnetic fluid sealing in valve plate pairs of plunger pumps

The flow distribution pair of the piston pump, the largest contact area among the three friction pairs in a plunger pump, significantly influences the pump's overall performance. Magnetic fluid sealing, a novel sealing method, offers advantages such as zero leakage, long lifespan, high reliability, and no pollution, making it widely applicable across various fields. This approach provides a new solution for the end-face sealing valve plate pairs in plunger pumps. To address the leakage issue of the flow distribution pair, we designed a magnetic fluid radial sealing structure for the end face of the flow distribution pair and optimized the key parameters of the sealing structure by numerical simulation. Based on the optimization results, we developed a corresponding magnetic fluid sealing device and tested its pressure resistance performance under both static and dynamic conditions. The experimental results indicate that the sealing performance is superior when sealing gases compared to liquids, especially under dynamic conditions. This is attributed to the instability of the sealing interface caused by centrifugal force, leading to seal failure. Under static conditions, the sealing performance primarily depends on the saturation magnetization of the magnetic fluid and is independent of other physical properties. In dynamic conditions, the pressure resistance decreases with increasing speed. While the viscosity of the magnetic fluid impacts the sealing performance, the saturation magnetization remains the critical factor determining the critical sealing capacity. These findings provide valuable insights for the design of end-face radial magnetic fluid sealing devices.