# US 10,501,256 B2 · Plunger for dispenser, dispenser, and method for dispensing liquid material > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,501,256 B2 - Document ID: US10501256B2 - Status: Granted - Kind: B2 - Application number: 15/702,908 - Filed: 2017-09-13 - Published: 2018-01-11 - Granted: 2019-12-10 - Earliest claimed: 2012-10-01 - Assignees: Musashi Engineering, Inc. - Applicants: Musashi Engineering, Inc. - Inventors: Kazumasa Ikushima - Web page: https://patentgrep.com/patent/US10501256B2 ## CPC - B65D 83/76: for dispensing fluent contents by means of a piston - B05C 5/02: {the liquid or other fluent material being discharged through an outlet orifice by pressure, e.g.} from an outlet device in contact or almost in contact, with the work - B05C 17/00576: {characterised by the construction of a piston as pressure exerting means, or of the co-operating container} - B05C 17/00579: {comprising means for allowing entrapped air to escape to the atmosphere} - B05C 17/015: with pneumatically {or hydraulically} actuated piston or the like {(B05C17/00543 takes precedence)} - B65D: CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES - B05C: APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL (spraying apparatus, atomising apparatus, nozzles B05B; plant for applying liquids or other fluent materials to objects by electrostatic spraying B05B5/08) ## Abstract The present invention provides a plunger (20) for a dispenser, the plunger including a large diameter body portion (23) provided with ring-shaped contact surfaces (24, 25) that contact an inner wall surface of a syringe, a rear opening (26) formed in a backside of the large diameter body portion (23), and a small diameter body portion (22) provided with a front opening (28), wherein the front opening (28) is formed in a size allowing a liquid material to be directly pressed by pressurized air, and allowing at least the plunger (20) to move following a fall in water head position, which is caused with discharge and consumption of the liquid material. With those features, the liquid material can be prevented from adhering to the inner wall surface of the syringe, and the liquid material in the syringe can be prevented from flowing backwards. ## Claims ### Claim 1 A plunger for a dispenser of a liquid material, to be slidably fitted in a syringe that is filled with the liquid material and to be driven by pressurized air, comprising: a large diameter body portion provided with a ring-shaped contact surface that contacts an inner wall surface of the syringe, a rear opening formed in a backside of the large diameter body portion, through the rear opening the plunger is to be driven by pressurized air, and a small diameter body portion extending forward from the large diameter body portion, having a front end portion to contact the liquid material, and having a diameter smaller than the large diameter body portion, the small diameter body portion provided with a front opening disposed at the front end portion of the small diameter body portion and configured to have the liquid material and the pressurized air contact each other, wherein the front opening of the plunger has a larger opening area than a discharge port of the syringe, and wherein the plunger is made of an elastic resin material. ### Claim 2 (depends on 1) The plunger for the dispenser according to claim 1, wherein the front opening is formed in a size allowing the liquid material, which remains in a discharge port of the syringe when the plunger is present at a most advanced position, to be discharged by the pressurized air. ### Claim 3 (depends on 1) The plunger for the dispenser according to claim 1, wherein the front opening has an opening area of 5 mm2 or more. ### Claim 4 (depends on 1) The plunger for the dispenser according to claim 1, wherein the front opening has an opening area of 10 mm2 or more. ### Claim 5 (depends on 1) The plunger for the dispenser according to claim 1, wherein the front opening is made up of a plurality of openings that are divided by one or more bridging members. ### Claim 6 (depends on 1) The plunger for the dispenser according to claim 1, wherein the plunger further includes a pressurization passage that is communicating with the front opening, and that functions as a buffer passage acting to avoid a response delay of the liquid material when the pressurized air is not supplied. ### Claim 7 (depends on 6) The plunger for the dispenser according to claim 6, wherein the plunger includes a tubular raised portion having the pressurization passage therein. ### Claim 8 (depends on 1) The plunger for the dispenser according to claim 1, wherein the small diameter body portion includes a tapered portion. ### Claim 9 (depends on 1) The plunger for the dispenser according to claim 1, wherein a lateral surface of the large diameter body portion is constituted by an upper contact surface, a lower contact surface, and an intermediate region positioned between the upper contact surface and the lower contact surface, and when the pressurized air is supplied to the rear opening, the large diameter body portion is expanded such that a part or a whole of the intermediate region contacts the inner wall surface of the syringe. ### Claim 10 (depends on 1) The plunger for the dispenser according to claim 1, wherein a ratio of an opening area of the front opening to the pressure receiving area is 1:80 to 1:0.5. ### Claim 11 (depends on 1) The plunger for the dispenser according to claim 1, wherein a ratio of an opening area of the front opening to the pressure receiving area is 1:40 to 1:0.5. ### Claim 12 (depends on 1) A dispenser comprising: the plunger for the dispenser according to claim 1; a syringe having a discharge port; and a controller that supplies pressurized air to the syringe. ### Claim 13 (depends on 12) A method for discharging a liquid material by employing the dispenser according to claim 12. ### Claim 14 (depends on 2) A method for discharging a liquid material by employing a dispenser comprising the plunger for the dispenser according to claim 2, a syringe having a discharge port, and a controller that supplies pressurized air to the syringe, wherein the liquid material remaining in the discharge port after the plunger has reached the most advanced position is discharged by the pressurized air. ### Claim 15 (depends on 13) The method for discharging the liquid material according to claim 13, wherein the liquid material is a liquid material having high viscosity. ### Claim 16 (depends on 14) The method for discharging the liquid material according to claim 14, wherein the liquid material is a liquid material having high viscosity.