Dispensing Apparatus
A hand-held multi-dose dispensing apparatus ( 10 ) comprising a metering chamber ( 20 ) having an axis ( 21 ), an end portion ( 22 ) at one axial end of the chamber ( 20 ) and a side body portion ( 23 ) extending from the axial end portion ( 22 ), a piston arrangement ( 30 ) movable with a piston stroke along the axis of the metering chamber ( 20 ) with a seal portion ( 34 ) of the piston arrangement ( 30 ) being slidably engageable with an inside surface of a side portion ( 23 ) of the metering chamber, an inlet ( 27 ) for fluid to enter the metering chamber ( 20 ), and an outlet ( 31, 32 ) for fluid to be dispensed from the metering chamber ( 20 ), wherein the inlet ( 27 ) is provided on the side body portion ( 23 ) of the metering chamber and, in use, during a first portion of the piston stroke, the inlet ( 27 ) is in fluid communication with the metering chamber ( 20 ) and during a second portion of the piston stroke, the seal portion ( 34 ) of the piston arrangement ( 30 ) blocks the inlet ( 27 ) preventing fluid from passing from the inlet ( 27 ) into the metering chamber ( 20 ). This dispensing apparatus ( 10 ) reduces variations in the shot weight dispensed, by the metering of the fluid commencing at the point at which the piston enters the second portion of its stroke blocking off the inlet.
1 . A hand-held multi-dose dispensing apparatus comprising
a metering chamber having an axis, and end portion at one axial end of the chamber and a side body portion extending from the axial end portion,
a piston arrangement movable with a piston stroke along the axis of the metering chamber with a seal portion of the piston arrangement being slidably engageable with an inside surface of a side portion of the metering chamber,
an inlet for fluid to enter the metering chamber, and
an outlet for fluid to be dispensed from the metering chamber,
wherein the inlet is provided on the side body portion of the metering chamber and, in use, during a first portion of the piston stroke, the inlet is in fluid communication with the metering chamber and during a second portion of the piston stroke, the seal portion of the piston arrangement blocks the inlet preventing fluid from passing from the inlet into or out of the metering chamber.
2 . An apparatus according to claim 1 , wherein a resilient means is provided between the piston arrangement and the end portion of the chamber.
3 . An apparatus according to claim 2 , wherein the resilient means is a spring.
4 . An apparatus according to claim 1 , wherein the inlet is connectable to a reservoir of fluid to be dispensed.
5 . An apparatus according to claim 4 , wherein the reservoir of fluid is a container attachable to the dispensing apparatus.
6 . An apparatus according to claim 1 , wherein the piston arrangement comprises a first portion and a piston seal, the piston seal being arranged to slidably engage and seal against the inside surface of the metering chamber and to be movable relative to the first portion of the piston arrangement, such that during a second portion of the piston stroke when the pressure in the metering chamber exceeds a particular level, the first portion and the piston seal move relative to each other to open an outlet for fluid to be dispensed.
7 . An apparatus according to claim 1 , wherein during a second portion of the piston stroke with the piston arrangement moving away from the end portion of the metering chamber and with the seal portion of the piston arrangement blocking the inlet, the pressure within the metering chamber reduces until the first portion of the piston stroke is reached in which the inlet is in fluid communication with the metering chamber and the reduced pressure within the metering chamber draws fluid into the metering chamber ready for the next actuation.
8 . (canceled)