Hollow valve element with embedded spring

The invention relates to a hollow valve element with an embedded spring, belongs to the technical field of fluid flow control valves and aims at the problem that fluid flow cannot be controlled accurately under different applied pressures through existing U-shaped valve elements. The hollow valve element comprises a hollow valve element body and the spring. The hollow valve element is a cylinder with a step. The upper portion of the cylinder is thicker than the lower portion of the cylinder. A concave cambered face is formed in the outer surface of the lower end, close to the step, of the cylinder. A step trough is formed in the middle of the upper end of the cylinder. A through hole is formed in the concave cambered face of the lower end of the cylinder in the radial direction. The step trough is connected with the through hole. The spring is embedded in the step trough of the hollow valve element. The effects that the fluid flow is stable and controllable and oil is output smoothly under the action of diffe