| 摘要 |
A simple and economical drive mechanism for caulk dispensing devices that gives a dripstop release feature to improve control over the bead of caulk. The drive mechanism is shown in the context of an open frame housing (which may be a single piece of molded plastic) having a downwardly extending handle. A plunger shaft is slidably supported in the housing for dispensing caulking composition, and a trigger is pivoted to the housing and retractable against the handle. The trigger includes an upper portion extending above the plunger shaft. A first gripping member encircles the plunger shaft forwardly of the trigger and protrudes downward for engagement with the trigger when the trigger is retracted. A first compression spring rearwardly biases the first gripping member, the first compression spring being formed with a forward constricted end having increasingly tighter helical coils to frictionally grip the plunger shaft. Upon retraction of the trigger, the first grip drives the plunger shaft to overcome the friction of the constricted end of the first compression spring and the plunger shaft slides on through. Upon release the first gripping member and compression spring are able to retreat a bit until blocked by the frame. At that point the constricted end of the spring grips the plunger shaft and prevents further retraction, thereby cutting off the flow of caulk. This provides a dripless release feature by relieving pressure in the cartridge upon initial release of the trigger.
|
