US 3579734 A
Description (OCR text may contain errors)
May 25, 1971 M. K. MEHTA FLOAT-OPERATED LEVEL CONTROL Filed May 27, 1968 United States Patent 3,579,734 FLOAT-OPERATED LEVEL CONTROL Maharaj K. Mehta, Cardiff, Wales, assignor to P. Lerner & Sons (Encapsulati0ns) Limited, Treforest, Glamorganshire, Wales Filed May 27, 1968, Ser. No. 732,201 Claims priority, application Great Britain, July 18, 1967, 32,919/ 67 Int. Cl. B29d 7/02 U.S. C]. 18-15 4 Claims ABSTRACT OF THE DISCLOSURE A spreader box for containing gelatine to be cast into ribbons or sheets on a casting drum including a floatoperated valve consisting of a hollow cylindrical rotary valve member and a cylindrical float parallel to the rotary axis of the valve member and connected thereto so that angular movement of the float about said axis is transmitted to the valve member. The valve member has an aperture in its side wall which cooperates with the end of a stationary flow passage to limit the flow of gelatine into the spreader box. The float is rotatable manually beyond a position above the rotary axis of the valve member to close the valve.
This invention relates to a float-operated level control for restoring the level of a liquid to a predetermined level. The invention is particularly suitable for use in a spreader box which contains gelatine for casting into ribbons or sheets on a casting drum.
Known ball-cocks have disadvantages when used With liquids of high viscosity, such as gelatine, due to high frictional and viscous forces, which tend to make the control of the liquid level inaccurate.
According to the invention there is provided a floatoperated valve for restoring a liquid level to a predetermined level, comprising a flow passage through which the liquid flows to alter the liquid level, a rotary member having an orifice for co-operating with the flow passage to pass the liquid which flows through the flow passage, a float connected to the rotary member for rotating the member to a position different from its normal position in accordance with the difference of the liquid level from the predetermined level, and the co-operation between the orifice and the flow passage being dependent upon the position of the float, whereby the rate at which liquid is passed through the orifice is controllable.
An embodiment of the invention will now be described, by way of example, with reference to the drawings, in which:
FIG. 1 is an elevation, partly in cross-section, of a spreader box employing a float-operated valve embodying the invention, and
FIG. 2 is a cross-sectional view taken along the line 2-2 of the spreader box shown in FIG. 1.
, The spreader box illustrated has two spaced parallel side walls 11 and 12, a front wall 13 in the form of an adjustable doctor blade, and a rear wall 14 sloping downwardly towards the front of the box. The rear wall 14 carries at its lower end a resilient bottom plate 15, which presses against a casting drum 16. The box has a floatoperated valve 20 mounted on the side wall 11 and connected to an inlet pipe 17, and an outlet '21 which is the slit between the bottom of the doctor blade 13 and the drum 16.
The spreader box is designed for supplying gelatine to the casting drum for casting ribbons or sheets of gelatine. As the drum 16 rotates in the direction of the arrow in =F-IG. 2, a sheet 22 of gelatine is formed on the surface of the drum 16. The thickness of the sheet depends on the 3,579,734 Patented May 25, 1971 speed of rotation of the drum 16 and the position of the doctor blade 13, which is adjustable by a captive screw 24.
The valve 20 is controlled by a cylindrical float 25, the side of which is attached to a rotatable bar 26 for rotation about the axis thereof, which is parallel to the longitudinal axis of the cylindrical float. The bar 26 is connected at one end to a length of hollow cylindrical tubing 30, and at the other end is supported by a bearing 33 mounted on the side wall 12. The tube 30 is closed at both ends and has two holes or orifices 31 and 32 in its side wall. The inlet hole 31 is arranged so that when the float 25 hangs down vertically (position A in FIG. 2) the inlet hole 31 fully co-operates with the end of the inlet pipe 17. The outlet hole 32 discharges directly into the spreader box.
FIG. 2 shows three positions of the float. Position A is adopted when the liquid level is low, and the valve 20 is fully open, as described above. As the box fills, the float 25 gradually rotates, causing the tube 30 to rotate also, and thereby reducing the rate of flow of gelatine into the box, until the gelatine has reached a predetermined level, at which point the float is in the steady position B and the rate at which gelatine enters the spreader box through the valve 20 equals the rate at which it leaves the box through the outlet 21. It is sometimes desired to empty the tank or close off the valve 20 for some other reason, and to do this the float has only to be rotated manually beyond the vertical to position C. The ease with which the valve 20 can be manually turned off completely makes it more convenient than a conventional ball-cock, as it may obviate the need for a tap or stop-cock.
The shape of the orifice 31 and the end of the inlet tube 17 can be altered so that any desired cut-off law can be employed, thus varying the permissible limits for the liquid level in normal operation.
The valve 20 illustrated is particularly useful for use with gelatine, since the cutting action of the tube 30 as it rotates is not affected by frictional and viscous forces as much as a conventional ball-cock would be. With less viscous fluids, it may be necessary to provide a seal to ensure that no fluid passes when the valve is closed.
1. In combination with a spreader box for containing a gelatinous liquid and having an orifice for cooperation with the surface of a casting drum to form a sheet or ribbons on the drum due to liquid discharged through said orifice, said box having a pair of spaced walls, a float-operated inlet valve means for controlling flow of liquid into said box, said valve means comprising a rotary valve member rotatably supported on one of said walls, an elongated substantially cylindrical float of substantially large diameter disposed within said box and positioned substantially parallel to the rotary axis of said valve member and connected to said valve member so that small vertical movement of said float about said axis causes comparatively large angular movement of said valve member, and bar means positioned on said rotary axis for fixedly connectin said float to said valve member, said bar means being disposed closely adjacent the periphery of said cylindrical float and having a first portion fixed to said valve member and to said float adjacent one end thereof, and said bar means including a second portion rotatably supported on said other wall and connected to said float adjacent the other end thereof.
2. The combination according to claim 1, wherein said bar means includes an elongated bar extending between said walls and disposed directly adjacent and attached to the external periphery of said float.
3. The combination according to claim 1, wherein said float is rotatable manually beyond a position vertically above said rotary axis to close said valve means.
r 3 4 4. The combination according to claim 1, wherein said 2,775,257 12/1956 Stirn et a1. 1815X valve member comprises a cylindrical tube lying on said 2,996,222 8/1961 Botkin 222-67 rotary axis and having an aperture in its sidewall for 3,357,052 12/ 1967 Vos 18 15 cooperation with the end of a stationary inlet flow passage 1 in dependence upon the position of said float. 5 J, SPENCER OVERHOLSER, Primary Ex in References Cited M. O. SUTTON, Assistant Examiner UNITED STATES PATENTS Us CL 1,650,806 11/1927 Slaten 22267 222-67 2,714,976 8/1955 Sucksdorif 22267X 10