| 摘要 |
A pump mechanism 10 for a spray dispenser, comprising a piston assembly 64 movable with respect to a housing 14 between charged and initial positions. The piston assembly comprises liquid and gas seals, being movable boundaries of respective chambers whose volume is determined by the position of the seal relative to the housing. When the piston assembly moves toward the charged position (figure 2), the volume of the liquid chamber increases to draw liquid into the liquid chamber and the changing volume of the gas chamber 94 changes the pressure of gas in that chamber from its pressure when the piston assembly was in the initial position (figure 1). This biases the piston assembly to return from the charged position toward the initial position, that return movement of the piston assembly pressurising the liquid in the liquid chamber 90 for dispensing. |
