GB2214901A

GB2214901A - Feeder for particulate material

Info

Publication number: GB2214901A
Application number: GB8803152A
Authority: GB
Inventors: Robert Henry Frederick Evans
Original assignee: LOHEAT Ltd
Current assignee: LOHEAT Ltd
Priority date: 1988-02-11
Filing date: 1988-02-11
Publication date: 1989-09-13
Anticipated expiration: 2008-02-11
Also published as: GB8803152D0; GB2214901B

Abstract

A feeder, operative to deliver material M, comprises an inclined duct 1 and a slide 3 formed with a control aperture 7 and which controls flow along the duct 1. The slide 3 moves upwardly towards a closed position through a slot or gap 22 at the upper side of the duct 1, of a width such as to provide a substantial clearance at each side of the slide 3. A void or free space 21, within which any particles of material picked up by the lower trailing edge of the slide aperture 7 as the slide moves to the closed position can fall back on to the mass of material within the duct 1, is provided above the slot or gap 22 at the upper side of the duct 1. Slide 3 may co-operate with a rigidly affixed second slide 4, the two being moved in synchronism by a vacuum piston, to constitute a volume batching device, delivering a volume V between the two slides at each successive operation. <IMAGE>

Description

"FEEDER" The invention relates to feeders, and in particular but not exclusively to metering feeders operative to deliver determined amounts of a particulate material. It is especially applicable to feeders for use in milking parlours to deliver feed to cows during milking according to the milk produced.

A feeder unit as used in a milking parlour most commonly comprises a screw feeder, the total rotation of the feed screw of which is determined by the amount of milk produced. Whilst such units have operated with success over a period of some years, recent changes in the animal feed used have resulted in a problem. The particle size of the feed has been reduced, thereby changing its angle of repose, and cows have learnt that by tapping the feeder outlet duct with the head a small flow of feed can be shaken through the unit past the feed screw.

In view of the foregoing there is renewed interest in feeders which employ inclined ducts with transverse slides acting as duct closure members and providing a positive cut-off action. Such a feeder commonly has a slide with an aperture controlling flow along the duct and there is the inherent problem that feed particles tend to be trapped between the trailing edge of the aperture, as it moves towards the closed position, and the wall of the duct at a slot through which the slide moves.

In order to overcome said inherent problem of known slide feeders, such a feeder according to the invention has an apertured slide which moves upwardly towards the closed position through a relatively wide slot or gap at the upper side of the duct, providing a substantial clearance at each side of the slide, a closed void being provided above said wide slot or gap within which any particles picked up by the lower trailing edge of the slide aperture can fall back on to the mass of material within the duct.

It will be appreciated that the substantial clearance at each side of the slide is chosen to be greater, and preferably considerably greater, than the maximum particle size of the material to be handled by the feeder.

Preferably the feeder is a metering feeder which supplies the material in discrete amounts determined by the volume of a section of an inclined duct between said slide and a further slide both movable transversely of the duct and operable in synchronized fashion so that when one is in the open position the other is in the closed position, and vice versa. The apertured slide of the invention is then disposed at the upstream end of said duct section, with the other slide disposed at the downstream end thereof.

Preferably the slides are directly linked and mounted for parallel movement and directly interconnected, conveniently being members of an integral slide structure s ..t with the two slides and an intermediate connecting member disposed in a generally U-shaped arrangement. An operating cylinder, such as a vacuum cylinder when for use in a milking parlour, may be connected. to the intermediate member. A return spring may also be connected to that member to urge the slide structure to a rest position in which the upstream apertured slide is preferably in the open position to allow filling of said duct section. The downstream slide may be arranged so that its free edge clears the controlled cross-section of the duct, when in the open position, to allow delivery of the material previously trapped in said duct section.

The invention will now be further described with reference to the accompanying drawings which illustrate, by way of example, a feeder in accordance with the invention.

In the drawings: Fig. 1 is a diagrammatic sectional side view of the feeder; Fig. 2 is a horizontal cross-sectional detail view; and Fig. 3 illustrates diagrammatically the operation of the feeder.

The feeder illustrated comprises a rectangular-section duct 1 which is inclined to the vertical at a suitable angle to ensure reliable gravity feeding of a particulate material M along the duct 1. This angle of inclination most suitably lies within the range of 450to 550 when the material M is an animal feed as fed to cows in a milking parlour. The duct 1 is supplied from above through the vertical outlet 2 of a feed hopper (not shown) which is topped up as necessary.

Two spaced vertical slides 3 and 4 disposed transversely of the duct act as duct-closure members respectively controlling the inlet and outlet sides of a determined volume provided by a section V of the duct 1 between the slides 3 and 4. The slides 3 and 4 are movable together in unison, to this end being integral members of a unitary slide structure 5 in which they are connected by a top cross member 6. Thus in side view, as shown in Fig. 1, the slide structure 5 is of generally rectangular and inverted U-form, with the slides 3 and 4 forming the side limbs of the U and the member 6 forming the intermediate (top) limb thereof. The slide 3 has a rectangular control aperture 7 which matches the controlled rectangular inner cross-section of the duct 1, and the slide structure 5 is vertically movable by a vacuum cylinder 8 (see Fig. 3).

Referring now to Fig. 3, a rest position of the slide structure 5 is shown in Fig. 3(a) in which the upstream slide 3 is in the open position with the aperture 7 aligned with the duct 1. The downstream slide 4 is now in the closed position, and thus the material M can flow past the slide 3 into the duct section V to fill the latter, as shown by the arrow 9. On the application of vacuum to the cylinder 8, the slide structure 5 is raised and passes through an intermediate position shown in Fig. 3(b) in which the slide 3 and 4 respectively close off the inlet and outlet sides of the duct section V, a determined volume of material M thus being trapped in the section V.Further movement of the slide structure 5 by the vacuum cylinder 8 takes it to the limit position shown in Fig. 3(c) in which the inlet side of the volume V remains closed off by the slide 3, whereas the slide 4 is in an open position with the lower free edge thereof just clear of the controlled inner cross-section of the duct 1. Thus the previously trapped volume of material in the duct section V is delivered by gravity past the slide 4 and is discharged from the feeder, as shown by arrow 10 in Figs. 1 and 3(c).

Guide means which guide the sliding movement of the slide structure 5 are illustrated in Fig. 2. For guidance purposes the structure 5 is of open box-like form, with a front wall member 11 extending between the slide members 3 and 4. Thus the slide structure 5 is, as shown in this figure, of rectangular U-shape in horizontal cross-section.

The manner of guidance will be clear without detailed explanation from a consideration of the view of Fig. 2, in which 12 and 13 indicate external vertical guide strips fixed to the duct 1, and 14 indicates an internal guide strip also fixed to the duct 1. The guide strips 12, 13 and 14 are of suitable low-friction material not requiring lubrication, such as PTFE (polytetrafluorethylene).

It will also be clear from the foregoing description that each successive application of vacuum to the cylinder 8 produces a movement of the slide structure 5 resulting in delivery of a discrete volume of the material M which is determined by the duct section V. This determined volume is adjustable, to which end the duct 1 has a movable top wall section 15 which defines the top of the duct 1 between the slides 3 and 4. The wall section 15 is part of an adjustment member 16 which has a section 17 with an adjustment slot, and which is clamped to a vertical side of a fixed structure 18 of the duct by a thumbscrew 19. Fig.

1 illustrates how adjustment of the wall section 15 from the position shown in full lines to a lower position shown in broken lines correspondingly reduces the predetermined volume of the duct section V.

A tension spring 20 anchored between the duct section 15 and the top cross member 6 of the slide structure 5 acts as a return spring, operating to return the slide structure 5 to the rest position of Fig. 3(a) when vacuum is removed from the cylinder 8.

The structure 18 defines an internal void 21 on either side of the slide 3 above a wide gap or opening 22 in the upper wall of the duct 1 through which the slide 3 moves between the open rest position and the limit closed position. Due to the provision of the wide gap 22 instead of a narrow slot closely fitting the slide, thereby providing a substantial clearance (as shown) at each side of the slide 3, particles of the material M cannot be trapped between the lower edge of the slide aperture 7 and the upper wall of the duct 1. Any particles which may be picked up on this lower edge as the slide 3 moves from the rest position towards the limit closed position fall off the slide 3 within the void 21 and fall back on to the mass of material M within the duct 1.

Claims

CLAIMS:

1. A feeder operative to deliver particulate material, comprising a duct and an apertured slide which controls flow along the duct and which moves upwardly towards a closed position through a slot or gap at the upper side of the duct, the width of said slot or gap being such as to provide a substantial clearance at each side of the slide and a void or free space being provided above said slot or gap within which any particles of material picked up by the lower trailing edge of the slide aperture can fall back on to the mass of material within the duct.

2. A feeder according to claim 1, wherein said void is an internal void defined by surrounding fixed structure of the duct.

3. A feeder according to claim 1 or claim 2, wherein the feeder is a metering feeder with said apertured slide disposed at the upstream end of an inclined section of said duct and comprises a further slide at the downstream end of the duct section, both slides being movable transversely of the duct and operable in synchronized fashion so that when one is in an open position the other is in the closed position, and vice versa, whereby to supply the material in discrete amounts determined by the volume of said duct section.

4. A feeder according to claim 3, wherein the slides are directly linked.

5. A feeder according to claim 4, wherein the slides are mounted for parallel movement and directly interconnected.

6. A feeder according to claim 5, wherein the two slides are members of an integral slide structure comprising the two slides and an intermediate connecting member disposed in an inverted generally U-shaped arrangement.

7. A feeder according to claim 6, wherein an operating cylinder is coupled to the intermediate member of the slide structure.

8. A feeder according to claim 6 or claim 7, wherein a return spring is connected to the intermediate member of the slide structure to urge that structure to a rest position.

9. A feeder according to claim 8, wherein said rest position of the slide structure corresponds to the open position of the upstream apertured slide to allow filling of said duct section.

10. A feeder according to any one of claims 4 to 9, wherein the downstream slide is arranged so that a free lower edge thereof clears the controlled cross-section of the duct, when in the open position, to allow delivery of the material previously trapped in said duct section.