GB2268791A - Dispensing valve - Google Patents

Abstract

A dispensing valve (1) has a body (2) having a dispensing chamber (3) with an inlet (4) and an outlet (5). The outlet (5) is closed by a first, full flow, valve (7) which also includes a fine flow outlet (8) normally closed by a second, fine flow, valve (9). The dispensing valve (1) is arranged to operate in three selectively operable nodes; full flow with the first valve (7) open, fine flow with the first valve (7) closed and the second valve (9) open, and pulsed fine flow where the first valve (7) is closed and the second valve (9) is selectively opened and closed. In the preferred arrangement continued opening of the second valve (9) is operative to open the first valve (7) such that the full flow mode includes both the first (7) and second valves (9) open. The valve (9) is carried by a rod (10) which is moved by a piston and cylinder actuator (12, 13). A further piston (19) provides an adjustable stop for the rod (10). The valve is used for dispensing paint, dyes, petrol, etc. <IMAGE>

Description

DISPENSING VALVE This invention relates to a dispensing valve.

In the gravimetric mixing and blending of two or more fluid components, it is necessary to have dispensing valves which are controllable to extremely fine limits over a wide range of flow rates. A typical fluid blending system will have 12-20 ingredients, each to be precisely dispensed in order to maintain conformance to recipe/formulation and guarantee repeatability.

An object of the present invention is to provide an improved dispensing valve.

According to the present invention, a dispensing valve for fluid material comprises first and second valve means providing, respectively, full and fine flow for the fluid material being dispensed, the second valve means being operable when the first valve means is closed to provide a fine flow of fluid material.

Preferably, the opening of the first valve means is effected by movement of the second valve means, providing modes of opening comprising the second valve means alone or the first and second valve means together.

In the preferred arrangement the second valve means may be selectively opened and closed when the first valve means is closed providing a third mode of operation with extreme accuracy of control over flow of the fluid material. Suitably the selective movement of the second valve means is microprocessor controlled for accurate repeatability.

In a preferred arrangement a dispensing valve comprises a body having a dispensing chamber, an inlet to the chamber, an outlet from the chamber, first valve means closing the outlet, and a fine flow outlet in the first valve means closed by second valve means, the dispensing valve being arranged to operate in three selectively operable modes; full flow with the first valve means open, fine flow with the first valve means closed and the second valve means open, and pulsed fine flow where the first valve means is closed and the second valve means is selectively opened and closed.

Preferably, continued opening of the second valve means is operative to open the first valve means such that the full flow mode includes both the first and second valve means open.

The invention will now be described by way of example with reference to the accompanying drawing which is a side view, partially sectioned, of a preferred embodiment of the invention.

In the drawing a dispensing valve (1) comprises a body (2) having a valve chamber (3) with a top or side inlet (4) and an outlet (5).

The outlet (5) is normally closed by the head (6) of a full flow valve assembly (7). The head (6) includes a central fine aperture (8) normally closed by a fine flow valve (9) as well as replaceable seating seals for the head (6) and the valve (9).

The fine flow valve (9) comprises an elongate valve rod (10) with a collar (11) adjacent one end and a first piston (12) mounted towards the other end. The first piston (12) is disposed within a first cylinder (13) with pneumatic flow paths (14) and (15) to respective chambers (16) and (17) to either side of the first piston (12). A second cylinder (18) is located behind the first cylinder (13) and pneumatic fluid is supplied behind a second piston (19) through flow path (20). The second piston (19) carries a stop rod (21) which is adjustable by means of adjustment head (22).

The full flow valve assembly (7) includes a main body (23) connected to the head (6) by means of a cylindrical barrel (24) having flats milled through its wall to provide two radial openings for passage of fluid material to the fine flow aperture (8). The main body (23) surrounds the valve rod (10) and has an annular shoulder (25) aligned with the collar (11). The full flow valve assembly (7) is biassed into its closed position by spring (26).

In use, the dispenser (1) is normally disposed in an upright position with the outlet (5) facing downwardly and the fluid component to be dispensed is introduced to the valve chamber (3) either through side inlet (4) or top inlet (4), the inlet not used being closed as shown.

Air is then supplied to the chamber (16) of the first cylinder (13). This forces the first piston (12) upwardly carrying the valve rod (10) which in turn opens fine flow valve (9). This has the effect of dumping any residual fluid pressure in the main valve chamber (3). The continued movement of the first piston (12) causes collar (11) to make contact with the shoulder (25) of full flow valve assembly (7). Further movement of piston (13) opens the full flow valve assembly (7) by moving the head (6) off its seating in the outlet (5) compressing spring (26). Valve (1) is now in full flow mode.

By closing the air supply to chamber (16) and applying air to chamber (17), the first piston (12) is moved down by spring (26) followed by closing of the fine flow valve (9). When the full flow valve (7) is in the open position, fine flow valve (9) is also open allowing purging of the fine flow valve nozzle aperture (8).

In order to move only fine flow valve (9) to the open position air is supplied to second cylinder (18) moving piston (19) to its bottom position. Air is then applied to-the chamber (16) of the first cylinder (13) which lifts fine flow valve (9) until the top (27) of valve rod (10) makes contact with the adjustable stop rod (21).

Cylinder (18) is of greater area than chamber (16) of cylinder (13) limiting the stroke of fine flow valve (9). Valve (1) is now in fine flow mode.

By cycling air alternatively on chambers (16) and (17) of cylinder (13) the fine flow valve (9) may be pulsed open and closed to very fine limits.

Alternatively, the fine flow valve (9) can be pulsed by air to chamber (16) against an optional alternative spring (28) shown in the drawing.

The dispensing valve (1) of the present invention has several advantages over existing valves: (a) it has three distinct modes of operation controlled by a minimum of two air lines: (i) fine flow valve open; (ii) fine flow and full flow valves open; and, (iii) fine flow valve pulsed open and closed.

Associated pneumatic/electrical equipment is therefore kept to a minimum, saving cost, and simplifying the system; (b) the dispensing valve can discharge in excess of 1Okg per minute in full flow mode and yet be accurate to 0.lgrm in fine flow mode when coupled to suitable weighing equipment; (c) the valve is self-purging, preventing accumulation of product within the valve and possible blockage. Purging will begin on opening of the fine flow valve and be completed on the full flow valve opening; (d) dumping fluid pressure on opening provides a soft start to the system preventing unnecessary wear and tear on pumps; (e) the valve can be configured side entry or top entry or side entry/top recirculating or top entry/top recirculating. Recirculation may be required, for example, to prevent settlement within the fluid component; (f) early detection of main fluid seals failure is possible by the provision of witness holes (30) in the side of the valve.

The valve of the present invention is suitable for: paints, inks, dyes, colourants, flavourings, essences, chemicals, oils, petroleum derivatives and like fluid components. Although operation is shown as pneumatic it may be hydraulic, if desired.

Claims (11)

ClAIMS

1. A dispensing valve for fluid material comprising first and second valve means providing, respectively, full and fine flow for the fluid material being dispensed, the second valve means being operable when the first valve means is closed to provide a fine flow of fluid material.

2. A dispensing valve according to claim 1 wherein the opening of the first valve means is effected by movement of the second valve means, providing modes of opening comprising the second valve means alone or the first and second valve means together.

3. A dispensing valve according to claim 1 or 2 wherein the second valve means may be selectively opened and closed when the first valve means is closed providing a third mode of operation.

4. A dispensing valve according to claim 3 wherein the selective movement of the second valve means is microprocessor controlled for accurate repeatability.

5. A dispensing valve comprising a body having a dispensing chamber, an inlet to the chamber, an outlet fran the chamber, first valve means closing the outlet, and a fine flow outlet in the first valve means closed by second valve means, the dispensing valve being arranged to operate in three selectively operable modes; full flow with the first valve means open, fine flow with the first valve means closed and the second valve means open, and pulsed fine flow where the first valve means is closed and the second valve means is selectively opened and closed.

6. A dispensing valve according to claim 5 wherein continued opening of the second valve means is operative to open the first valve means such that the full flow mode includes both the first and second valve means open.

7. A dispensing valve according to any one of the preceding claims comprising a body having a valve chamber with an outlet normally closed by a head forming said first valve means and the head including a central fine aperture normally closed by the second valve means.

8. A dispensing valve according to claim 7 wherein the first valve means includes a main body connected to the head by means of a cylindrical barrel having radial openings through its wall for passage of fluid material to the fine flow aperture.

9. A dispensing valve according to claim 8 wherein the second valve means comprises an elongate valve rod, a collar mounted on the valve rod adjacent one end, a first piston mounted on the valve rod towards the other end, a first pneumatic cylinder in which the first piston is disposed to define respective chambers in the cylinder to either side of the first piston, a second cylinder a second piston in the second cylinder, and an adjustable stop means carried by the second piston operable to limit the stroke of the valve rod.

10. A dispensing valve according to claim 9 wherein the main body of the first valve means surrounds the valve rod and has an annular shoulder aligned with the collar whereby retraction of the valve rod in the inoperative position of the second cylinder opens the first valve means by interengagement between the collar and the shoulder.

11. A dispensing valve substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.