Patent GB-861798-A (GB)
Title: Dispensing device
IPC: B65D35/40
Filed: 1958-11-10
Abstract: 861,798. Gas meters. AU-YONG, A. B. Oct. 29, 1959 [Nov. 10, 1958 ; April 15, 1959 ; June 27, 1959], No. 36030/59. Class 54. [Also in Group XVIII] A device for dispensing a predetermined volume of paste, liquids or gases comprises means for separating the desired volume from a main supply, means for displacing the severed volume to a dispensing orifice, and means for ejecting such volume through the orifice, all the said means being actuated successively by pressure created in the main supply. The device shown in Fig. 1 is mounted on a collapsible tube 15 containing paste and comprises two valve members in the form of pistons 4, 5 carried by pivoted levers 6, 7 mounted in a recess 17 and urged apart by a torsion spring 12. In the unoperated position shown in Fig. 1, a measuring chamber 13 is defined between the ends of the pistons. When pressure is applied to the tube 15 by squeezing it, paste is forced via the inlet 10 between the piston 5 and housing into the chamber 13 and the pressure then acts upon the rear end of both pistons to move them until the inlet 10 is closed by the piston 5 ; continued pressure on the rear end of the piston 5 results first in the chamber 13 being aligned with a discharge orifice 11, with the piston 4 abutting the end wall of the recess, as shown in Fig. 4, and then in the piston 5 ejecting the measured quantity of paste. A blade 18 secured to the lever 7 defines one wall of the chamber 13 and serves as a shield to prevent paste entering the recess 17. The volume of the measuring chamber 13 may be rendered adjustable by providing means for varying the angular spacing of the levers 6, 7. In the modification shown in Fig. 8, the inlet 10 is replaced by two small inlets 21, 22 of which the rear inlet 22 is blocked by the piston 4 in the unoperated position shown. Filling of the dosage chamber is then accomplished via the front inlet 21, pressure via the rear inlet 22 upon the piston 5 serves to move both pistons in unison until the leading piston 4 is arrested, and pressure acting via both the inlets upon the piston 5 ejects the measured volume; in this arrangement, a leaf spring 23 repleaces the torsion spring 12. Fig. 15 shows the measuring chamber 13 defined between two axiallymovable pistons 4, 5 which are urged to the unoperated position shown by a spring 27. A rearward extension 29 on the piston 4 has an abutment 30 to engage a flange 31 on the piston 5 in order to prevent more than a predetermined separation between the pistons, and the discharge orifice is provided between the rear of the piston 4 and housing. In the embodiment shown in Fig. 19, the two pistons 4, 5 are connected by a rod 34 on which the piston 5 can slide as allowed by a stop 35, and a compression spring 38 acts against an abutment 37  on a shaft 36 secured to the piston 5. As shown in Fig. 24, the piston 4 is fixed on an upwardly-biased rod 40 passing through the piston 5 and a tubular extension 39 thereof, a fixed collar 44 on the rod limiting the movement of the piston 4 in its upper unoperated position ; in operation, the initial pressure first forces the piston 4 forwardly away from the piston 5 until an adjustable collar 41 abuts the rear face of the latter, whereupon the two pistons move in unison. Various modifications include the provision of safety means for preventing inadvertent operation of the device (e.g. a plug cap on the orifice which must be moved before the piston 4 can be moved), the location of the biasing means outside the housing, the formation of the orifice as a very small hole, the use for the container 15, instead of a collapsible tube, of an aerosol container or a container fitted with a piston operable manually, pneumatically or hydraulically, and the fitting of the device upon the container by a screwing or twisting action. In addition, either or both faces of the pistons may be serrated or of concave form, and, in order to deal with air trapped in the measuring chamber, a cavity may be provided in the piston 4 in communication with the chamber via a port in its trailing end face. Trapped air may be largely eliminated by arranging for the two pistons to move in contact while being returned to inoperative position by reason of the adhesiveness of the paste being dispersed, or the use of springs &c.