GB2264160A - Pneumatic conveyor valve - Google Patents

Abstract

A pneumatic conveyor switching valve, particularly for use in a flour mill, comprises a housing 10 with an inlet 17 connected to an inlet tube 18, and an axially aligned outlet 19 with an outlet tube 21. The housing also provides a second outlet 20 with an outlet tube 22 diverging from the alignment of the tubes 18, 21 and intersecting the same at 16 t9 the plane of inlet 17. The housing contains a rotatable body 12, which has two bores 23, 24 which can be alternately aligned with the inlet 17 to connect it either to the aligned outlet 19, or the divergent outlet 20, respectively. An arcuate slot 25 and a nozzle 26, with fluid pressure connections comprise a fluid pressure motor for effecting change-over between the bores thereby connecting either outlet 19 or 20 to the inlet 17. <IMAGE>

Description

IMPROVED PNEUMATIC CONVEYOR VALVE This invention relates to an improved flow switching valve for switching a flow of particulate or powdered materials such as grain or flour within a system of conveyor tubes, for example within a flour mill. The valve is also applicable in the handling of other particulate materials which are transported through tubiny using a current of air.

A major difficulty with handling grain or similar materials is the abrasion of tubing at corners or other places where the direction of flow changes. Prior two-way switching valves have incorporated a flap which is movable to block one or other of the outlets. Such an arrangement has the disadvantage that abrasion causes wear of the edges of the flap, resulting in turbulence with consequent loss of velocity, which can in turn lead to blockages.

In order to overcome the disadvantages of flap-valve diverter valves, it has been proposed, in GB-A 2,190,726 to provide a pneumatic conveyor valve comprising a housing for location at a bifurcation of a conveyor tube, with a single inlet tube, and alternative outlet tubes, one of which is substantially aligned with the inlet tube, and the other set at an angle thereto. The housing having a single passage therethrough which can be selectively aligned to provide a connection between the inlet tube and either of the outlet tubes, by rotating through a quarter circle about an axis which bisects the angle from the inlet tube subtended by the outlet tubes.

In practise, despite the presence of seals, there is a "dead";space within the housing outside of the passage through the housing on which dust can collect. Furthermore, even in the "straight-through" position of the valve housing, there is not a completely smooth bore, but instead a slight kink at the location of the inlet side of the valve caused by the need to provide a planar surface for rotation of the inlet end of the valve, normal to the axes of rotation of the valve housing Consequently, turbulence with associated airflow velocity loss, and material deposition can occur even in the straight-through condition of the valve An object of the invention is to provide an improved pneumatic conveyor valve, which is completely sealed, incorporates no "dead" space in the valve wherein dust can be deposited, and provides a completely unobstructed flow passage in at least one setting of the valve According to the invention, an improved pneumatic conveyor valve comprises a housing having ports therein for connection to a first inlet or outlet tube and at least two second outlet or inlet tubes, a body located in said housing, and rotatable about an axis parallel to said first tube, said body having a plurality of rectilinear bores therethrough, one of each said second port, each separately alignable with the first port to connect the first port to a respective second port on rotation of said body.

Preferably one such bore, when rotated into position to connect the first port and its respective second port is configured, together with the first tube and the respective second tube, to provide a rectilinearly aligned passage, through said body, which is substantially free from any obstruction or C\QV(t\O% of alignment which might cause turbulence.

The first tube and port are preferably an inlet tube or port, and the second tubes and ports are preferably outlet tubes and ports. However, the valve can be applied in a reversed connection for feeding alternative sources to a common destination, as well as switching material from a single source to alternative destinations.

In a preferred embodiment, the inlet port and one of the outlet ports are axially aligned, and the valve housing also has a second outlet port with an axis which is inclined to the axis of the inlet port, and intersects the inlet port axis at the mouth of the inlet port. The body is rotatable about an axis which is parallel to the axis of alignment of the inlet and first outlet portS, through an angle of 1200 (one third of a complete rotation).The body is preferably a solid member in the form of a cylinder or solid of rotation having shallow conical end faces, and has a bore parallel with the axis of rotation of the body which is alignable with the inlet port and first outlet port along said axis of alignment of said ports, and a second rectilinear bore therethrough, the inlet of which is offset by 1200 with respect to the axis of rotation of the body, and can be aligned with said inlet port and said second outlet port upon rotation of the body through said angle of 120no The rotation of the body may be both powered and delimited by a pneumatic or hydraulic motor arrangement embodied in the valve.This may take the form of a slot, over 1200 of arc, formed on the surface of the body and sealingly engaging with the inner surface of the housing, and a feed nozzle with connections to a source of air or hydraulic fluid under pressure to apply the pressure to move the slot in one sense or the other, the feed nozzle acting at the same time as a stop fixed to the housing which limits relative angular rotation of the body within the housing to the arcuate extent of the slot The ports are preferably provided with tubular spigots for connection to other respective inlet or outlet tubes A preferred embodiment of pneumatic convyeor valve according to the invention will now be described, by way of example, with reference to the accompanying drawings, wherein:: Fig. 1 is a cross-sectional view of the conveyor valve according to the invention, set to permit flow or air-borne particulate matter to a preferred destination; Fig. 2 is a crpss-sectional view, similar to Fig.

1, but wherein the valve is set to permit flow of the air-borne particulate matter into a secondary branch tube; Fig. 3 is an exploded view of the valve according to the invention; Fig. 4 is a view of one end of the valve, from the direction of arrow IV in Fig. 3, with some internal features shown by dotted lines, and a cross-section of a pneumatic connection into a motor cavity or slot in the valve; and Fig. 5 is a cross-sectional view, at right-angles to the axis of the valve, on line V to V of Fig. 2.

A pneumatic conveyor valve according to the invention is shown in the drawings, and comprises a two-part housing, consisting of an inlet-end part 10 and an outlet-end part 11, connected at flanges 10a, lla by screws or other fasteners. (The terms "inlet" and "outlet" are used in the following description to denote connection of the valve into a distribution tube system for conveying airborne particulate or powdered material so as to divert materials from a single source to alternative destinations. It will be understood however that the valve could be connected in reverse , to connect a single destination to alternative sources).

The housing 10, 11 contains a body 12, which is in the form of a cylinder with conical end faces 13,14 with a relatively low conical elevation, and the body 12 is journalled in the housing for rotation on bearing pins 15, 16.

The inlet end part 10 of the housing is provided with a single inlet port 17, having a tubular spigot 18 for connection to an inlet conveyor tube This is displaced to one side of the rotation axis of the body 12, defined by the bearing pins 15, 16 and the axis of the spigot 18 is parallel to the said rotation axis.

The outlet end part 11 of the housing is provided with two outlet ports 19 and 20, each with an associated tubular spigot 21, 22 respectively, for connection to respective outlet conveyor tubes. Outlet port 19 and its associated spigot 21 are aligned precisely with the inlet port 17 and spigot 18 in the other part of the housing. The second outlet port 20, and its associated spigot 22 are axially aligned to intersect the axis of the alignment just described in the plane of the inlet port 17 as it enters the housing.

The body 12 constitutes a valve member which is rotatable through a restricted arc of 1200. It is provided with alternative bores 23 and 24. The inlets of the bores 23 and 24 are angularly spaced by 1200 with respect to the rotation axis of the body 12, so that they can be alternatively aligned with the inlet port ]7 at respective extremes of the displacement range of the body 12. When passage 23 is aligned with inlet port 17, it is also aligned with outlet port 19, completing a rectilinear flow path through the valve due to the alignment of the ports already mentioned above. (This position is shown in Fig. 1). In the alternative position of the body 12, passage 24 is aligned with the outlet port 20, forming a passage which intersects the inlet at the plane of the housing 10.This serves to divert flow from the main passage to a secondary outlet conduit connected to the spigot 22. This position is shown in Fig. 2.

The valve change over is operated by use of a pneumatic or hydraulic motor embodied in the valve.

This takes the form of a slot or recess 25 formed in the body 12, and extending over 1200 of arc relative to the axis of body 12, as measured from centre to centre of the curved ends of the slot 25. A fixed position double nozzle 26 extends into the recess 25 through the housing, and acts both as a nozzle for introduction of pressurised working medium and as a stop which cooperates with the slot to limit rotary movement of the body 12 to the extent permitted by the arcuate length of the slot. The nozzle has alternative passages for working medium 27,28 with respective outlets directed one to each end of the slot. In the position shown in Fig. 4, so long as no pressure is applied, or is applied to the right-hand facing passage 28, the valve will not change over.

Change over is effected by directing pressure medium through the other left-hand facing passage 27, and of course vice versa when the valve is in the alternate position.

The ports of the valve, and the slot or recess 25 are sealed by packing rings.

Some means may be provided for "flagging" the valve in order to enable an operator to determine the setting of the valve at a glance. This may be effected both electrically at a centralised control board, and on the valve housing itself.

In alternative embodiments, there may be more than two outlet ports, and in such a case, a separate passage will be provided in the body for each outlet port. It may be possible to design a valve according to the invention to alternatively connect two or more input ports or two or more outlet ports. The geometry of the rotatable body may vary as required, for example it may be a flat-ended cylinder or spherical.

The valve may be suitable for use with any form of particulate material, from gravel through cereal grains to flour for example. The valve perhaps may be adaptable for conveyors using a gravity feed for transporting coarser materials in particular, instead of using air, and use with liquid transporting media may, with appropriate sealing arrangements, be possible. The valve may be operated by means other than a fluid-pressure operated motor, for example a rack and pinion, or worm arrangement.

Claims (10)

1. A pneumatic conveyor valve comprising a housing, having ports therein for connection to a first inlet or outlet tube and at least two second outlet or inlet tubes, a body located in said housing, and rotatable about an axis parallel to said first tube, said body having a plurality of rectilinear bores therethrough, one to each second port, each bore being separately alignable with the first port to connect the first port to a respective second port on rotation of said body.

2. A valve according to claim 1, wherein one of said bores is configured to provide a rectilinearly aligned passage through said body together with the first tube and the respective second tube, when rotated with a postion connecting the first port and the respective second port served by said one bore, said passage being substantially free from any obstruction or deviation of alignment.

3. A valve according to claim 1 or 2 wherein a sole inlet port and one of two or more outlet ports are axially aligned, the valve housing also having at least a second outlet port with an axis which is inclined to the axis of the inlet port and intersects the inlet port axis at the mouth of the inlet port, the body being rotatable about an axis which is parallel to the axis of alignment of the inlet and first outlet ports.

4. A valve according to claim 3 wherein the body is a solid member in the form of a cylinder or solid of rotation, having shallow conical end faces, and has a bore parallel with the axis of rotation of the body, said bore being alignable with the inlet port and first outlet port along said axis of alignment of said ports; and a second rectilinear bore being provided through said body, the inlet of said second bore being offset by an angle to the inlet of said first bore measured from the axis of said body, the body being rotatable through an equal angle within the housing to align the inlet port with either said port or said second bore.

5. A valve according to claim 4, wherein said angle is 1200.

6. A valve according to any preceding claim wherein the body is rotated by the operation of a fluid pressure operated motor, said motor being embodied in the valve structure.

7. A valve according to claim 6, wherein said motor comprises a slot, formed in the surface of the body, and extending over an arc equal in extent to said angle, and sealingly engaging with the inner surface of said housing, and a feed nozzle with connections to a source of fluid pressure, to apply such pressure to move the slot in one sense or the other, and acting at the same time, as a stop fixed to the housing which limits relative angular rotation of the body within the housing to the arcuate angular extent of the slot.

8. A pneumatic conveyor valve according to any one of claims 4 or 7, wherein said angle is 3600 divided by n+l where n is the number of said outlet ports.

9. A pneumatic conveyor valve according to claim 8 wherein n=2 and said angle is 1200.

10. A pneumatic conveyor valve susbtantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.