Dispensing device with abrupt ejection terminating means

Claim 1

A dispensing device, particularly for applying a bonding agent, comprising cylinder means having an elongated internal chamber; a piston rod member extending longitudinally through said chamber; a piston member surrounding and slidable along said piston rod member between a forward position and a retracted position with respect thereto, said piston member dividing said chamber into a first and a second compartment located respectively at opposite axial sides of said piston member; supply means communicating with said first compartment for supplying material to be dispensed thereinto; passage means communicating said first and said second compartments when said piston member is in said forward position thereof so as to permit passage of the material from said first into said second compartment and preventing communication betwen said compartments when said piston member is in said retracted position thereof; dispensing nozzle means; a valve chamber provided in said cylinder means intermediate said second compartment and said nozzle means; a first opening communicating said valve chamber with said second compartment and having a first sealing surface; a second opening communicating said valve chamber with said nozzle; a valve body accommodated in said valve chamber and having a side facing said first opening and provided with a first contact surface; biasing means normally urging said first contact surface into sealing contact with said first sealing surface and permitting yieldable displacement of said valve body away from said first opening when the pressure in said second compartment exceeds the pressure in said valve chamber, whereby the material being expelled from said second compartment is admitted into said valve chamber to be ejected therefrom through said nozzle means; and means for abruptly terminating the ejection of the material through said nozzle means and including a first abutment surface on one of said members, a second abutment surface provided on said side and extending into the path of movement of said first abutment surface, a second sealing surface surrounding said second opening, and a second contact surface on an additional side of said valve body facing said second opening and sealingly engaging said second sealing surface when said valve body is further displaced against the action of said biasing means upon abutment of said first abutment surface against said second abutment surface, whereby the ejection of the material through said nozzle means is terminated due to the sealing engagement between said second contact surface and said second sealing surface.