Metal Bellows SCR Pump for Precise Urea Dosing

The patent uses a metal bellows as a flexible element to replace conventional pump components. The metal bellows expands and contracts axially during pumping operation, providing both the pumping action and structural integrity. This flexible shell approach enables the pump to achieve robustness and long service life while maintaining a relatively simple overall structure, directly resolving the contradiction between reliability and device complexity.

The patent replaces complex mechanical dosing mechanisms with a metal bellows-based pumping mechanism. The bellows' axial expansion and contraction provide precise volume displacement, enabling accurate dosing through purely mechanical means without requiring additional complex dosing control systems. This substitution achieves precise dosage while keeping the pump design relatively simple.

The metal bellows in the patent serves multiple functions simultaneously: it acts as the pumping element, the structural component, the sealing element, and the dosing mechanism. By making the bellows multi-functional, the patent achieves high reliability and long service life without proportionally increasing device complexity, as the same component performs multiple critical roles in the pump system.

The patent introduces a fluid medium (urea solution) as an intermediary between the metal bellows and the hollow piston. The bellows expands and contracts in the fluid medium, transferring pumping action without direct mechanical contact between the bellows and piston surfaces. This intermediary approach maintains pumping efficiency through fluid pressure transmission while eliminating wear on the bellows, thereby extending service life.