Patent ID: 9044771
Filing Date: 2015-06-02
Classification: B05B

Abstract:
1. A pump to be vertically suspended and mounted in a container body for discharging liquid contained in the container body, comprising: a cylinder including: the actuator member includes: the depression head comprises: the annular piston has a lower end forming a discharge valve in cooperation with a discharge valve seat protruding from the outer circumference of the stem and is configured to be pressed against the valve seat to close the discharge valve at a lowermost displacement position and displaced off the discharge valve seat to open the discharge valve at an uppermost displacement position, the annular piston has an H-shaped cross section formed by joining an outer peripheral tubular portion and an inner peripheral tubular portion with a joining portion, the outer peripheral tubular portion being fitted at upper and lower edges thereof to an inner periphery of the cylinder for a leak tight sliding contact with the cylinder and the inner peripheral tubular portion being fitted at an upper edge thereof to an inner periphery of a sealing tubular portion for a leak tight sliding contact with the sealing tubular portion, the sealing tubular portion being suspended around the outer circumference of the stem to form a double tube structure, and the discharge valve is formed by an lower edge of the inner peripheral tubular portion in cooperation with the discharge valve seat, and the annular piston is relatively displaced upward and downward with respect to the stem from a position where the lower edge of the inner peripheral tubular portion is pressed against the discharge valve seat to a position where an upper end surface of a connecting part is abutted against a lower end surface of the sealing tubular portion, and a stroke width from the position where the lower edge of the inner peripheral tubular portion of the annular piston is pressed against the discharge valve seat to the uppermost displacement position is selected so that back suction is caused due to a negative pressure state in the stem occurring until the discharge valve seat is closed by the annular piston during upward displacement of the stem.