US 3715058 A
A dosing device having a pin which is movable through a liquid chamber and comprises a recess which passes into the liquid and is filled after the forward stroke of the pin. The recess is emptied outside the chamber after a return stroke. Capable of cooperating with this pin is a spring-loaded member which is in the form of the recess and is capable of displacing a quantity of gas which may be in said recess after which the recess is filled with liquid.
Description (OCR text may contain errors)
Ftfb. 6, 1973 United States Patent [191 Clymans References Cited UNITED STATES PATENTS DOSING APPARATUS Inventor: Augustien Maria Clymans, Emmas- 9/1968 Stoll et a1.
I Primary ExaminerRobert B. Reeves  Flled: March 1971 Assistant ExaminerJames M. Slattery [21 1 Attorney-Frank R. Trifari App], No.: 120,664
[ ABSTRACT A dosing device having a pin which is movable  Foreign Application Priority Data April 4, 1970 through a chambsr and Comprises a recess which passes into the liquid and is filled after the for- }g? 'i 222/422 132 2 ward stroke of the pin. The recess is emptied outside n the chamber after a return stroke Capable of  held of cooperating with this pin is a spring-loaded member which is in the form of the recess and is capable of dis- 73/422 GC placing a quantity of gas which may be in said recess Y after which the recess is filled with liquid.
9 Claims, 1 Drawing, Figure PATENTEDFEB 6 I973 INVENTOR. AUGUSTIEN M. CLYMANS AGENT DOSING APPARATUS The invention relates to a dosing apparatus intended for dosing a liquid material. The apparatus has a storage container for the material, which is sealed in a liquid-tight manner on at least one side. A cylindrical pin is arranged for axial movement through the pin. The pin has a recess on its side which is located in the storage container when the pin is fully lifted and is located outside the storage container when the pin is fully depressed.
Such a dosing apparatus is known, but it has a disadvantage in that when dosing takes place in a space containing air and/or gas, air and/or gas can be returned to the container. This is undesirable, however, since the resulting dosing becomes non-uniform, because the recess is already filled, at least partly with air or gas, which remains in said recess so that the liquid material cannot fill the recess or cannot fill it completely.
The invention avoids this drawback by providing a member in the storage container secured to said container in a resilient manner. The member has approximately the same shape as the recess and enters the recess when the pin is fully lifted. As a result of this the recess is completely emptied and air and/or gas, if any, is removed prior to the recess being filled again so that the dosing becomes as uniform as possible and it is ensured that the complete space is filled.
According to an embodiment of the invention the recess is in the form of a part ofa cylinder envelope.
According to an another embodiment of the invention, in order to facilitate the flowing-out of the liquid, the recess is in the form ofa drop.
Another further embodiment of the invention in which the material to be closed is an amalgam, communications are provided to supply and/or remove a protective inert gas, preferably argon, both to and from, the storage container and to and from an outlet pipe for the dosed amalgam connected to said container. As a result of this both the amalgam to be dosed and the closed quantity do not experience undesirable variations under the influence of the atmosphere.
In order to ensure that the recess is emptied as completely as possible when the pin is depressed, a device may be provided by which the pin receives an impact during its downward movement and after the recess has left the container.
According to an embodiment of the invention, said impact device preferably is formed of a spring which is tensioned by the downward movement of the pin and is suddenly relaxed during the further downward movement.
According to another further embodiment of the invention the container comprises a heating device which preferably consists of an electric heating coil wound around the container.
According to an embodiment of the invention, the inert protective gas to be supplied may also be preheated.
In order that the invention may be readily carried into effect, it will now be described in greater detail, by way of example, with reference to the accompanying drawing, the sole FIGURE of which is a longitudinal cross-sectional view of a dosing apparatus according to the invention.
Reference numeral 1 in the figure denotes a cylindrical container manufactured from chromium nickel steel and comprising a flange 2 to which a cover 3 likewise manufactured from chromium nickel steel is secured in a gas-tight manner. This cover has an inlet 4 through which argon under a slight positive pressure of a few cms of water is conducted to the inside of the container 1 and an inlet 5 having a larger diameter than the inlet 4 and through which a liquid warm amalgam, for example consisting of mercury-sodium, is poured in the container 1 and the argon flows out of the container.
An electric heating coil with connections 7 is arranged around the container. On the lower side of the container 1, an outlet pipe 8 is connected in an air-tight and liquid-tight manner, said pipe consisting, for example, of quartz and comprising a branch pipe 9 through which preheated argon flows in the outlet pipe and leaves said pipe on the lower side. As a result of this the outlet of the dosed quantity of amalgam is like-wise supported and the rate of removal is increased. Inside the container 1 is the dosing pin 10 which is manufactured from tungsten and slides through the cover 3 and the bottom of the container 1 with the best possible fit. On the upper side of the pin 10, a button 11 is present; the pin furthermore comprises a recess 12 which, in the lowermost position of the pin, just engages in the outlet pipe 8 and in the upper position of the pin is in the container 1 and has the shape of a part of a cylinder envelope. A spring 13 is secured to the inside of the con tainer and a member 14 which has the same shape as the recess 12, is connected to the spring. When the pin 10 is lifted, said member 14 engages in the recess 12. As a result of the spring 13, said member can easily snap into and out of the recess 12 during the movement of the pin. A spring 16 is secured to the cover 3 by means of a screw 15.
Finally, a compressed-air cylinder 17 (shown diagrammatically) is present, a plunger 18 of which is connected to the knob 11 of the pin 10.
The entire dosing apparatus is intended for closing an amalgam of mercury-sodium, which amalgam should be introduced into a discharge tube in an accurately determined quantity.
When the container 1 is filled with amalgam, the pin 10 is moved downwards by means of the plunger 18. The protective gas argon ensures that the amalgam does not contact the atmosphere. As soon as the recess 12 which is filled with amalgam leaves the container, the quantity of amalgam present in the recess drops in the outlet pipe 8 and then in a discharge tube temporarily connected to the outlet pipe. When the pin 10 with the recess 12 is again moved upwards, a gas-bubble of argon mayremain in the recess as a result of which the correct quantitycf amalgam does not get into said recess; however, the member 14 then snaps into said recess 12 and ensures that all the gas is removed from the recess prior to said recess being filled with amalgam.
When the pin 10 is moved outwards the spring 16 is forced aside by A the knob 11; when the downward movement of the pin is continued and just when the recess 12 is free from the container 1, the spring is free from the knob 11 and springs back; as a result of this the whole pin 10 receivesan impact by which emptying of the recess 12 is promoted.
As explained, the embodiment of the invention described is intended for dosing a quantity of amalgam under the protection of an inert protective gas (argon) and gives excellent results in practice; the quantity of amalgam supplied varies within very narrow limits. Of course the apparatus may be used for many liquids whether or not using an inert protective gas and with or without heating of the container.
A preheated inert protective gas may also be used; particularly when said gas is supplied through inlet 9, the removal of the dosed quantity out of the recess is supported and the rate of removal in the pipe 8 is increased.
The recess 12 may also be in the form of a drop which is of advantage in the case of certain materials to be dosed.
What is claimed is:
1. A liquid dosing apparatus comprising a container for storing the liquid to be dosed, a liquid-tight seal on at least one side of said container, a cylindrical pin arranged for axial movement within said cylinder and through said liquid-tight seal, means connected to said pin at an end of the container remote from said liquidtight seal for causing said axial movement of said pin, means connected to said container for supplying the liquid to be dosed thereto, a recess situated on a side of said cylindrical pin for accommodating therein a predetermined quantity of liquid when said pin has been moved to its fully lifted position so that said recess will be located within the storage container and for delivering said predetermined quantity of liquid to an outlet pipe connected to said container when said cylindrical pin is in a fully depressed position so that said recess will have been moved outside said container and into said outlet pipe through said liquid-tight seal, a member having approximately the same shape as said recess carried within said storage container and resiliently secured to said container so that when said cylindrical pin is in its fully lifted position and located within said container said member will be engaged within said recess so as to displace any matter therefrom.
2. The liquid dosing apparatus according to claim 1 wherein said recess is formed as a part of a cylinder envelope.
3. The liquid dosing apparatus according to claim 1 wherein said recess is formed as a drop.
4. The liquid dosing apparatus according to claim 1 wherein said liquid to be dosed is amalgam and further comprising a first communication means connected to said storage container for supplying and removing a protective inert gas thereto and therefrom, and second communication means connected to said outlet pipe connected to said container for supplying and removing therefrom said protective inert gas.
5. The liquid dosing apparatus according to claim 4 wherein said protective inert gas is argon.
6. The liquid dosing apparatus according to claim 1 further comprising means connected to said storage container for causing an impact on said cylindrical pin during axial movement of said pin from said container into said outlet pipe and at a point after the recess has exited said container.
7. The liquid dosing apparatus according to claim 6 wherein said means for causing said impact comprises a spring tensioned by the downward movement of said cylindrical pin and sudden relaxation thereof upon further movement the pin.
8. The liquid dosing apparatus according to claim 1 further comprising an electric heating coil wound about said container for heating said container and electrical connection means connected to said heating coil for causing energization thereof.
9. The liquid dosing apparatus according to claim 4 wherein said inert protective gas supplied to said container and to said outlet pipe is a preheated inert gas.