| 摘要 |
<p>An applicator head for the metered release of flowing media, particularly hot-melt glues, cold glue paste, lubricants, paints, or similar substances, comprises a housing within which there is disposed a pivoting rocker having two oppositely disposed rocker arms which are operatively associated with two valve mechanisms. Two stacks of piezoelectric elements are disposed upon opposite sides of a rocker axis such that when a particular one of the stacks of piezoelectric elements is energized or activated, the rocker is pivoted about the rocker axis whereby one of the valves is opened while the other valve is simultaneously closed. In accordance with one embodiment of the invention, one of the valves is an applicator or dispensing valve and the other one of the valves is a closing or recirculation valve operatively connected to a recirculation system. In accordance with a second embodiment of the invention, both valves are applicator or dispensing valves. In either case, the provision of the two valves and the simultaneous opening of one valve and the closing of the other valve permits the pressure levels within the system, and at the applicator or dispensing valves, to be rendered substantially constant or uniform whereby in view of the elimination of pressure variations within the system and at the applicator or dispensing valves, the amount and formation of the media, such as, for example, the hot-melt glue, discharged or deposited upon a substrate is rendered substantially uniform.</p> |
