Cartridge for viscous-material dispenser

A cartridge for a viscous-material dispenser configured to discharge a viscous material, comprising:

• a cylinder having a first end and a second end;
• a plunger axially slidably fitted within the cylinder and dividing the cylinder into an anterior chamber between the first end of the cylinder and the plunger and a posterior chamber between the second end of the cylinder and the plunger, the anterior chamber serving as a filling chamber into which the viscous material is fillable from outside the cylinder;
• and
• a seal between an inner circumferential surface of the cylinder and an outer circumferential surface of the plunger,
• wherein the seal comprises:
• a plurality of solid spacers in an annular gap between the outer circumferential surface of the plunger and the inner circumferential surface of the cylinder, the plurality of solid spacers defining a radial distance between the outer circumferential surface of the plunger and the inner circumferential surface of the cylinder;
• a plurality of axially-continuous clearances between the plunger and the cylinder formed such that the axially-continuous clearances are circumferentially spaced apart from each other by the plurality of spacers, each axially-continuous clearance extending in a direction having an axial directional component and fluidically connecting the anterior chamber and the posterior chamber;
• and
• a body of the viscous material extending from the filling chamber into the plurality of axially-continuous clearances such that the plurality of filled axially-continuous clearances and the plurality of spacers together form the seal,
• wherein the plurality of solid spacers is integrally formed with the cylinder and protrude radially inwardly from the inner circumferential surface of the cylinder.

A cartridge for a viscous-material dispenser configured to discharge a viscous material, comprising:

• a cylinder having a first end and a second end;
• a plunger axially slidably fitted within the cylinder and dividing the cylinder into an anterior chamber between the first end of the cylinder and the plunger and a posterior chamber between the second end of the cylinder and the plunger, the anterior chamber serving as a filling chamber into which the viscous material is fillable from outside the cylinder;
• and
• a seal between an inner circumferential surface of the cylinder and an outer circumferential surface of the plunger,
• wherein the seal comprises:
• a plurality of solid spacers in an annular gap between the outer circumferential surface of the plunger and the inner circumferential surface of the cylinder, the plurality of solid spacers defining a radial distance between the outer circumferential surface of the plunger and the inner circumferential surface of the cylinder;
• a plurality of axially-continuous clearances between the plunger and the cylinder formed such that the axially-continuous clearances are circumferentially spaced apart from each other by the plurality of spacers, each axially-continuous clearance extending in a direction having an axial directional component and fluidically connecting the anterior chamber and the posterior chamber;
• and
• a body of the viscous material extending from the filling chamber into the plurality of axially-continuous clearances such that the plurality of filled axially-continuous clearances and the plurality of spacers together form the seal,
• wherein the plurality of solid spacers are not integrally formed with the plunger and are not integrally formed with the cylinder and are disposed between the outer circumferential surface of the plunger and the inner circumferential surface of the cylinder.