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An applicator by which small, discrete, uniform quantities of molten thermoplastic adhesive can be dispensed in rapid succession comprises a body having a heated inlet chamber, which hot melt enters under low pressure, and a pump chamber. A plunger in the pump chamber is reciprocated by a pneumatic

An applicator by which small, discrete, uniform quantities of molten thermoplastic adhesive can be dispensed in rapid succession comprises a body having a heated inlet chamber, which hot melt enters under low pressure, and a pump chamber. A plunger in the pump chamber is reciprocated by a pneumatic motor. A charging stroke of the plunger draws hot melt out of the inlet chamber, across a check valve and into the pump chamber. The discharging stroke expels the hot melt across an outlet check valve and through an outlet orifice coaxial with the pump chamber.

대표청구항 ▼

A dispenser having a discharge orifice and by which molten thermoplastic fluid can be delivered from a source thereof to a zone of use in successive small, discrete, uniform quantities, said dispenser comprising: A. body means; B. means at an external surface of the body means providing the discharg

A dispenser having a discharge orifice and by which molten thermoplastic fluid can be delivered from a source thereof to a zone of use in successive small, discrete, uniform quantities, said dispenser comprising: A. body means; B. means at an external surface of the body means providing the discharge orifice of the dispenser; C. said body means having 1. a bore therein providing a pump cylinder with a mouth at one end thereof through which fluid enters and leaves the cylinder, 2. a cavity providing an inlet compartment having an entrance through which fluid enters from a source thereof and an exit through which fluid can leave the inlet compartment, 3. first passage means therein to communicate the exit of the inlet compartment with the mouth of the pump cylinder, and 4. second passage means to communicate the mouth of the pump cylinder with the discharge orifice, said first passage means comprising a. an inlet valve chamber communicated with the exit of the inlet compartment through the port of an inlet valve seat, b. a ball in said inlet valve chamber movable to and from engagement with said inlet valve seat, and c. an elongated leaf spring having an anchored end portion and a free end portion the latter of which projects into the inlet valve chamber and engages the ball therein to yieldingly hold the same on the inlet valve seat, said second passage means comprising a. an outlet valve chamber in open communication with the discharge orifice and communicated with the inlet valve chamber through the port of an outlet valve seat, b. a ball in said outlet valve chamber, and c. an elongated leaf spring having an anchored end portion and a free end portion the latter of which projects into the outlet valve chamber and engages the ball therein to yieldingly hold the same on the outlet valve seat, each of said leaf springs being flatwise normal to its associated valve seat so that the inlet and outlet valve chambers can have small volume and still accommodate flexing of the free end portions of the leaf springs therein; D. a plunger reciprocable in the pump cylinder to draw fluid into the mouth of the cylinder during the charging stroke of the plunger and to expel fluid from the cylinder mouth during its discharging stroke, the orientation of said first and and second passage means and their respective valve seats being such that during the charging stroke of the plunger the ball in the outlet valve chamber is drawn tightly against its seat and the ball in the inlet valve chamber is drawn off its seat, enabling fluid to pass from the exit of the inlet compartment into the mouth of the pump cylinder, while during the discharge stroke of the plunger the disposition of the balls with respect to their respective seats is reversed, enabling fluid to be forced from the pump cylinder and out of the discharge orifice; and E. means for reciprocating the plunger.