Viscous material dispensing machine having programmed positioning

A machine for accurately and selectively depositing a viscous material at predetermined locations on a surface, comprising:

• first means including a nozzle and a closed reservoir for containing said viscous material under predetermined pressure;
• second means including a controllable valve assembly and a fluid conduit in series between said nozzle and said reservoir, said valve assembly being responsive to a flow control signal for correspondingly controlling emmission of said viscous material;
• third means including a servomechanism for positioning said nozzle with respect to said surface in response to position control signals;
• fourth means including a programmable controller for generating and applying said position control signals to said servomechanism in a sequence corresponding to a predetermined program extant in said controller;
• fifth means within said second means comprising a valve assembly housing, an axially operative poppet valve within said housing and connected to said fluid conduit at its input side, an axially operative solenoid for opening said valve in response to said flow control signals and a chamber within said housing between the output side of said poppet valve and said solenoid, said nozzle being connected to said chamber, said poppet valve having a stem projecting axially at its output side and said solenoid having a core pin projecting axially toward said poppet stem and contacting and axially translating said stem to open said poppet valve when said solenoid is energized by said flow control signal;
• sixth means comprising a resilient diaphragm at the end of said chamber adjacent said solenoid forming at least a portion of the wall of said chamber, said resilient wall deflecting to decrease the volume of said chamber in response to operation of said solenoid;
• and first spring means arranged to restore said resilient wall to its position prior to energizing of said solenoid when said solenoid is de-energized thereby to increase the volume of said chamber to produce a draw-back effect at said nozzle.