GB2252180A - Liquid level control float valve - Google Patents

Abstract

A float valve consisting of a modified washing machine-type liquid control pilot-operated diaphragm valve is constructed, whereby the control plunger, normally operated electromagnetically, is moved instead mechanically by the vertical movement of an indirectly-linked float 16. A positive toggle action is achieved by float buoyancy suddenly overcoming resistance offered by a stressed flexed sheet 18 of suitable material. The float linkage thereby becomes de-linked mechanically from the plunger after valve closure. An alternative method of achieving this cistern overfill at valve closure using magnetic attraction is also described. <IMAGE>

Description

iIQUILv CONTROL FTOAT VALVE This invention reiates to Float Vaives / Liquid Level Control Valves.

Float valves are weli known. various designs beina employed in domestic water cisterns. lavatory cisterns. etc.

Almost universally these operate when the pressure aenerated by a float in rising liquid causes two surfaces. (rubber or plastic/rubber or metal). to come together. producing a liquid proof seal. The force required to achieve this over a range of liquid pressures is considerable. as a result such devices typically have a long arm between the valve body and the float which acts as a lever. increasing the force generated by float movement.

Disadvantages of this set-up include: a) The length of the arm requires cisterns to be of a minimum width. (Approximately 80 cms). with resultant design constraints.

b) In the case of lavatory cisterns containing various designs of central syphoning mechanisms it may not be possible to fit all types of lever-assisted float valve.

(the lever and syphoning mechanism competing for the same space within the cistern).

c) All these valves. by nature of their design. close slowly, particularly during the final part of the cycle.

often accompanied by an annoying dripping or hissing noise.

Because of these disadvantages various alternative valves have been proposed which use a modification of the liquid control valve used in domestic washing machines. eletric showers. etc. The washing machine valve relies on electromagnetically induced movement of a steel plunger to open or close a diaphragm port. pressure differentials between different compartments thereby induced lifting or lowering the diaphragm over an outlet port thereby altering flow of liquid through the valve. In the alternative valves.

instead of using electro-magnetic induction to move the plunger this is achieved by direct mechanical linkage of the plunger. via a pin. to an external float. moving in reponse to changing levels of liquid in the cistern in which it is suspended.

Invent ions of this type have been patented in the past however none are without certain difficulties. Patent 861 970. (London patent office. 1957), describes a mechanically linked float and valve apparatus for which provision is not made to disconnect the float from the control pin after valve closure. bobbing of the float at this point causing a vacillating on/off operation of the valve, exaggerated by lack of provision of a mechanism to raise the float above the level at which the valve first turns off. This design also involves various lateral stresses on both float and operating pins increasing the likelihood or lamming and mechanical failure. Patent 974376. (London patent office.

1962). also does not allow for seperation and over-lift between the operative pin and float mechanism. in addition the substantial nature of the operative post will require a very heavy float to open the valve against high water pressure. and there are probiems regarding lateral stresses and surface tension acting on the moving components which would render the valve unreliable. 1JS patents 1 501 157 and 4 258 746 suffer from the above difficulties. in addition to which the seal of the control port area of the valve is not assisted by liquid pressure applied to the valve. and therefore a substantial float will be required to cause valve closure.Patent application 2 162 339A .(London patent office 1984), likewise has no means by which a positive on/off can be reliably obtained since movement of liquid within the cistern will open and close the control port intermittently until significant after-fill is obtained. In addition the weight of a large fluid filled float is supported by an insubstantial Fin when the valve first opens. lateral movement is inevitable. with resultant damage and unreliability. US patent 4 562 859. (1985).

suffers from the majority of the difficuities out-lined above. ie. no after-lift. direct linkage of float and operative pin, lateral stresses, and surface tension developing between the float and it's guides. It is also doubtful the weight of the float is sufficiently large practically, to overcome high liquid supply pressures.

According to the present invention a liquid level control float valve is provided being a modified version of a standard electric washing machine type liquid control valve incorporating a control pin attached to the operative plunger. The control pin is moved vertically by indirect mechanical linkage to a float thereby opening and closing the valve. The float and linkages move vertically in guides attached to the valve body. and this movement is in response to changes in the level of liquid contained in the cistern in which the valve is fitted.

A further essential modification not anticipated in the aforementioned patented valves allows the mechanical linkage between the float and control pin to be broken once the valve has closed, and re-established on valve opening. This is achieved by up-lift of the float being resisted near the end of the filling cycle by a stressed sheet of suitable material, (eg. a slightly bent plastic sheet). which changes from a stressed downward convex profile to a stressed upward convex profile at the point of valve closure. This shift in convexity allows the plastic sheet to seperate from the pin attached to the plunger when the valve closes. and thereby seperates the pin and float.

An alternative method of achieving this "over-lift" or the float is also proposed. Here final float movement is resisted by suitably placed magnets such that there is an attraction between the float linkaae and the valve body which is suddenly overcome at the point of valve closure.

With both proposals the end resuit is that at the completion of the filling cycle the float and linkage has bobbed clear of the control pin.

In the present invention the valve body is mounted above the liquid level it controls so there can be no back syphoning of liquid into the liquid supply and also surface tension effects restricting float movement are reduced as the float support linkages and their guides are above the liquid and designed to have minimal contacting area.

Movement of all linkages, pins and plungers is vertical so no destructive lateral forces are developed and space is economized.

A specific embodiment of the invention will now be described by way of an example with reference to the accompanying drawings in which: Figure 1 shows a cross section through an open valve viewed from the side. (float not attached).

Figure 2 shows the same view with the valve in the closed position.

Figure 3 shows a front view of the complete valve and float in the closed position.

Figure 4 shows the same view with the valve in the open position.

Figure 5 shows a side on view of the complete valve and float in the closed position, and, Figure (5 shows the same view with the valve in the open position.

The basic valve as shown in figures 1 and 2 represents a modification of the liquid control valves used in washing machines. eletric showers etc. In this design however, vertical movement of plunger 10 is made possible by vertical movement of pin 12.

1 represents the inlet area of the valve. 2 the outlet area.

and 3 the pressure control area. 4 represents liquid entry into the valve from supply, and arrow 5 liquid exit from the valve. 6 represents one component of the operative diaphragm being circular and rigid with a small single peripheral aperture 8 in addition to a central aperture 9 against which plunger 10 seals. and through which pin 12 passes. 7 represents the other component of the operative diaphragm being of flexible plastic or rubber with a central hole. In addition there are a number of small perforations arranged in a circular manner at approximately two thirds of the radius from the centre of the diaphragm on it's upper surface, (as viewed in figures 1 and 2).These perforations communicate with a circular channel running on the underside of the diaphragm. ias viewed in figures l and 2) and in turn this channel communicates with the aperture 8 in the diaphragm member 6. This arrangement of holes within the two components of the diaphragm allows liquid to pass from inlet area 1 to the pressure control area 3. The seal between the diaphragm's central hole 9 and the plunger 10 is open in figure 1. sealed in figure 2. A small spring 11 assists this seal when the valve is closed. The seal 13 between the valve body and the rubber diaphragm results from upward movement of the diaphragm. following closure of aperture 9. It can be seen that in this situation the pressure control area 3 is isolated from the outlet area 2.

and the valve is closed.

Figure 3 shows the valve. seen from the front. with float attached. in the closed position. Figure 4 shows the same.

but with the valve in the open position. 14 represents the float support linkage. 15 the guides for the support linkages, 16 the fluid filled float. and 17 the actuating arms of the float assembly. Through vertical movement of these actuating arms. following vertical movement of the float, a flexible sheet 18 is made to adopt an upward.

(valve closed), or downward. (valve open). convexity. In figure 3 the convexity points vertically upwards and consequently does not impinge on pin 12. ie. the valve is closed. In figure 4 the float has fallen on cistern emptying. The actuating arms 17 have also fallen. and these have caused the sheet 18 to adopt a downwards convexity.

This in turn has pushed the pin 12 downwards. opening the valve. 19 represents a bung on the upper surafce of the float allowing variable quantities of liquid to be put in the float, thereby altering it's weight. determining cistern fill height, and allowing the valve to work over a variable range of inlet pressures. (ie. heavier float for higher inlet liquid pressures).

Figures 5 and 6 similarly show the valve in the open and closed position respectively. as viewed from the side. In figure 5 the sheet 18 has adopted an upward convexity and is therefore not impinging on the pin 12, (unseen), and the valve is closed. Similarly in figure 6 downward movement of the float has caused the actuating arms 17 to deform the sheet 18 into a downward convexity, thereby depressing the pin 12, (unseen). and opening the valve, It should be noted that the actuating arms 17 could bridge the linkage arms entirely and the lower arm could therefore be the part that contacts the pin 12. The main purpose of the deformable sheet 18 is to provide resistance to the upward movement of the float and then suddenly reiease ensuring the arms 17 and sheet 18 are clear of and above the pin 12 at valve closure. ie. the level of fluid in the cistern is slightly above the level at which the valve would otherwise have closed if the sheet 18 were not fitted.

The sheet 18 therefore constitutes an 'overfill device'.

Claims (7)

1. i. A liquid level control float valve consisting of a modified version of a standard washing machine liquid control valve is manufactured incorporating a control pin attached to an operative plunger. The control pin is moved vertically by indirect mechanical linkage to a float.

   movement of the operative plunger follows movement of the control pin, and thereby opens or closes the valve. The float and linkages move vertically in guides attached to the valve body, this movement being in response to changes in the level of liquid contained in the cistern in which the valve is fitted.

   An essential feature of the design allows this mechanical linkage between the pin and float to be broken once the valve has closed. and re-established on valve opening. This is achieved by up-lift of the float being resisted near the end of the filling cycle by a stressed sheet of suitable material. (eg. a slightly bent plastic sheet). which changes from a stressed downward convex profile to a stressed upward convex profile at the point of valve closure. This sudden shift in convexity allows the plastic sheet and float linkage to seperate from the pin attached to the plunger when the valve closes, such that the float linkage bobs clear of the pin. preventing movement of water in the cistern from interfering with valve closure, ensuring a positive on/off operation,
2. 2.A liquid level control float valve as claimed in Claim 1 incorpoating an alternative method of achieving "over-lift" of the float whereby final float movement is resisted by suitably placed magnets such that there is an attraction between the float linkage and the valve body which is suddenly overcome at the point of valve closure. The overall effect is slight cistern over-fill. and a resultant positive on/off valve operation.
3. 3. A liquid level control float valve as claimed in Claim 1 and claim 2 where the valve body is mounted above the level of liquid in the cistern in which the valve is fitted.
4. 4. A liquid level control float valve as claimed in Claim 3 in which the float guides are attached to the valve body and above the level of liquid in the cistern in which the valve is fitted. thereby eleviating surface tension problems on float movement.
5. 5 . A liquid level control float valve as claimed in Claim 4 where final upward movement of the float on cistern filling is resisted until a stressed sheet of material is forced to adopt an opposite convexity. allowing slight cistern overfill. and positive on/off valve operation.
6. 0. A liquid level control float valve as claimed in claim 4 in which movement of all components occurs vertically preventing destructive lateral stresses.
7. 7. A liquid level control float valve substantially as described herein with reference to Figures 1 to 6.