Adhesive dispensing device having optimized reservoir and capacitive level sensor

摘要

An adhesive dispensing device includes a heater unit for melting adhesive, a fill system communicating with a receiving space for feeding the heater unit, and a reservoir for receiving melted adhesive from the heater unit. The dispensing device also includes a capacitive level sensor located along a sidewall of the receiving space such that the level of adhesive in the receiving space can be detected by sensing the difference in dielectric capacitance where the adhesive is located compared to where air acts as the dielectric. The size of the driven electrode produces a broader sensing window capable of generating multiple control signals corresponding to different fill levels of adhesive. The receiving space and reservoir are minimized in size so that adhesive is not held at elevated temperatures long enough to char or degrade.

主权项

1. A fluid level sensor for measuring a fill level of a hot melt adhesive within a receiving space that is at least partially defined by a sidewall and configured to receive adhesive to be melted, the fluid level sensor comprising:
a plate element having an electrically driven electrode and a ground electrode operatively connected for measuring a dielectric capacitance of air and adhesive acting as a dielectric between said driven and ground electrodes, said ground electrode adapted to be electrically connected to the sidewall such that the sidewall forms at least a portion of said ground electrode; and at least one fastener mount connected to said plate element and adapted to receive a fastener for coupling said plate element into adjacent relationship with the sidewall, such that the dielectric capacitance measured by said plate element varies with the fill level of the adhesive.