GB1593850A

GB1593850A - Screw pump

Info

Publication number: GB1593850A
Application number: GB42014/76A
Authority: GB
Original assignee: POWERHOUSE ENG Ltd
Current assignee: POWERHOUSE ENG Ltd
Priority date: 1977-10-07
Filing date: 1977-10-07
Publication date: 1981-07-22

Description

(54) SCREW PUMP (71) We, POWERHOUSE ENGINEERING LIMITED, a British Company of 56 High Pavement, Nottingham, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to a screwtype pump used for pumping flowable particulate materials.

It is known to provide a screw pump having a mixing chamber from which particulate material is discharged by compressed air, the pump including a conduit along which particulate material is moved by a screw to be discharged into the mixing chamber.

In order to prevent the compressed air from forcing particulate material back along the conduit it is known to provide an inclined flap valve at the discharge end of the conduit.

Such an arrangement is disclosed in U.K.

patent 402,998.

In the pump disclosed in U.K. patent 402,998, the flap valve has a body which defines the mixing chamber and the flap member of the valve as supported on a shaft which extends through the walls of the body to the exterior thereof. This arrangement is cumbersome and requires the shaft to be sealed against egress of particulate material.

According to the present invention there is provided a screw pump for flowable particulate material including a mixing chamber from which particulate material is discharged by compressed air, a conduit for feeding particulate material into the mixing chamber, and a screw for moving the particulate material along said conduit, the discharge end of the conduit being closed by a flap valve housed within the mixing chamber, the valve having a tubular body portion having a bore which at one end communicates with the conduit and the other end is normally closed by a movable flap member which is pivotally connected to the body portion so as to normally abut against an end abutment face of the body portion surrounding the bore, said end abutment face being planar and being inclinked to the axis of the bore.

Reference is now made to the accompanying drawings, in which: Figure 1 is a longitudinal part crosssectional view of a screw pump according to the present invention; Figure 2 is an enlarged side view of the flap valve shown in Figure 1; Figure 3 is an enlarged side view of the valve of Figure 2; Figure 4 is a part end view of a different flap valve.

In Figure 1 there is shown a screw-pump 10 known as the "Fuller Kinyon Pump" made by GATX-Fuller Limited, Radnor House, London Road, Norbury, London, SW16 4DX. This type of pump is mainly used for pumping flowable particulate materials such as dust or ash. The pump has an inlet hopper 12 and outlet port 13. At the base of hopper 12 is a screw 14 which is mounted on a shaft 15 which is rotatably mounted in the pump casing. The screw 14 is located within a central bore or conduit 17 and the screw 14 has a helically extending flange 18, the peripheral edge of which is in sliding contact with the internal surface of the bore 17.

The discharge end of the bore 17 opens out into a mixing chamber 20 which communicates with the outlet port 13. Particulate material located in chamber 20 is discharged therefrom through outlet port 13 by virtue of compressed air which enters chamber 20 through a plurality of nozzles N from a manifold M. Releasably secured into the end of bore 17 is a flap valve 30 which has a tubular body portion 31. The flap valve 30 serves to prevent the compressed air entering chamber 20 from entering the bore 17 and thus descreasing the feed rate of the screw 14. The body portion 31 has a central bore 32 communicating with bore 17, the inner surfaces of bores 32 and 17 being contiguous.

The tubular body portion 31 has an outwardly radially projecting peripheral flange 33 which is provided with apertures 34 (Figure 3) so that it may be bolted to the housing of the pump to releasably hold the flap valve 30 in position. The end wall 35 of the tubular body portion 31 remote from the end directly communicating with bore 17 is planar, the plane of which is inclined to the axis of the tubular body portion 31.

In the jllustrated embodiment the included angle, , between the plane containing end wall 35 and the axis of the bore is about 75". However this included angle may be in the rarg of 45"--85". The end wall 35 defines a seat or abutment surface against which a flap member 36 normally abuts to close the bore 32.

The flap member 36 is pivotally connected to the peripheral flange 33 by an arm 37 and support plate 38 which is carried by the arm 37.

The support plate 38 is provided with bolt apertures 39 through which bolts 40 extend to be threadedly received in threaded bores 41 formed in the flap member 36. Interposed between the support plate and flap member 36 are shims 43 which may be selectively added or removed for the purpose of adjusting the orientation of the flap member 36 relative to the support plate 38 so as to ensure that flap member 36 can correctly seat upon the abutment surface when in its normal lowermost position.

To provide the pivotal connection between arm 37 and flange 33, two laterally spaced support members 47 are located on flange 33 between which extend a shaft 46. A pair of spacing washers 46a are provided to restrict lateral movement of the shaft between support members 47.

The arm 37 received on shaft 46 and is located between the support members 47.

Locking means in the form of a small bolt 48 is provided which fixedly locates the arm 37 onto shaft 46. The shaft 46 is loosely received at either end in apertures 49, the loose fitment of the shaft 46 in apertures 49 being such as to permit free pivotal movement between arm 37 and flange 33 during working conditions.

Consequently, the flap member 36 is gravity biased to abut against the abutment surface.

In the embodiment of Figure 4, similar parts have been designated by similar reference numerals. In figure 4 the arm 37 is provided with a bore 37a which is in alignment with a bore 46b formed in shaft 46.

Locking means in the form of a spring dowel 48a is received in aligned bores 37a and 46b to fixedly locate the arm 37 onto shaft 46. In the embodiment of figure 4 the spacing washers 46a have been dispensed with.

In use, flowable material to be pumped is introduced into the inlet hopper and the screw is rotated to transfer the material along bore 17 towards the flap valve 30.

Initially there is a build up of material behind the flap member 36 and when the pressure of this material is sufficient to raise this flap member, material flows into chamber 20. Once the pressure of the material behind the flap valve drops below a predetermined minimum, the flap member falls and seats upon the abutment surface.

The above described flap valve has the following advantages over conventional flap valves used in such pumps: a) Since the valve seat is inclined there is a greater volume between the end of the screw shaft.

b) The flap member in its seated position is inclined and thus a greater force is required to open it than if it hung vertically as in conventional flap valves. This is particularly advantageous as it results in a build up of material behind the flap valve which forms a 'solid plug' of material which provides an effective seal to ingress of air from chamber 20.

c) In conventional flap valves the flap member is rotatably received on a fixed shaft and wear between the shaft and flap member rapidly occurs due to the dust laden environment within chamber 20. In the present flap valve, the flap member is fixedly mounted on a shaft which is rotatably received in two spaced bearings providing a greater bearing area, so that the flap valve has a longer working life.

d) In a conventional flap valve the flap member hangs vertically and a condition known as 'chattering' between, the flap and seat occurs which is induced by vibration due to rotation of the screw. Such a condition shortens the life of a valve. In the present flap valve 'chattering' is substantially reduced or avoided since the flap member in its seated position is inclined and is therefore gravity biased into pressure contact with its seat.

WHAT WE CLAIM IS: 1. A screw pump for flowable particulate material including a mixing chamber from which particulate material is discharged by compressed air, a conduit for feeding particulate material into the mixing chamber, and a screw for moving the particulate material along said conduit, the discharge end of the conduit being closed by a flap valve housed within the mixing chamber, the valve having a tubular body portion having a bore which at one end communicates with the conduit and the other end is normally closed by a movable flap member which is pivotally connected to the body portion so as to normally abut against an end abutment face of the body portion surrounding the bore, said end abutment face being planar and being inclined to the axis of the bore.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

33 which is provided with apertures 34 (Figure 3) so that it may be bolted to the housing of the pump to releasably hold the flap valve 30 in position. The end wall 35 of the tubular body portion 31 remote from the end directly communicating with bore 17 is planar, the plane of which is inclined to the axis of the tubular body portion 31.

In the jllustrated embodiment the included angle, , between the plane containing end wall 35 and the axis of the bore is about 75". However this included angle may be in the rarg of 45"--85". The end wall 35 defines a seat or abutment surface against which a flap member 36 normally abuts to close the bore 32.

The flap member 36 is pivotally connected to the peripheral flange 33 by an arm 37 and support plate 38 which is carried by the arm 37.

The support plate 38 is provided with bolt apertures 39 through which bolts 40 extend to be threadedly received in threaded bores 41 formed in the flap member 36. Interposed between the support plate and flap member 36 are shims 43 which may be selectively added or removed for the purpose of adjusting the orientation of the flap member 36 relative to the support plate 38 so as to ensure that flap member 36 can correctly seat upon the abutment surface when in its normal lowermost position.

To provide the pivotal connection between arm 37 and flange 33, two laterally spaced support members 47 are located on flange 33 between which extend a shaft 46. A pair of spacing washers 46a are provided to restrict lateral movement of the shaft between support members 47.

The arm 37 received on shaft 46 and is located between the support members 47.

Locking means in the form of a small bolt 48 is provided which fixedly locates the arm 37 onto shaft 46. The shaft 46 is loosely received at either end in apertures 49, the loose fitment of the shaft 46 in apertures 49 being such as to permit free pivotal movement between arm 37 and flange 33 during working conditions.

Consequently, the flap member 36 is gravity biased to abut against the abutment surface.

In the embodiment of Figure 4, similar parts have been designated by similar reference numerals. In figure 4 the arm 37 is provided with a bore 37a which is in alignment with a bore 46b formed in shaft 46.

Locking means in the form of a spring dowel 48a is received in aligned bores 37a and 46b to fixedly locate the arm 37 onto shaft 46. In the embodiment of figure 4 the spacing washers 46a have been dispensed with.

In use, flowable material to be pumped is introduced into the inlet hopper and the screw is rotated to transfer the material along bore 17 towards the flap valve 30.

Initially there is a build up of material behind the flap member 36 and when the pressure of this material is sufficient to raise this flap member, material flows into chamber 20. Once the pressure of the material behind the flap valve drops below a predetermined minimum, the flap member falls and seats upon the abutment surface.

The above described flap valve has the following advantages over conventional flap valves used in such pumps: a) Since the valve seat is inclined there is a greater volume between the end of the screw shaft.

b) The flap member in its seated position is inclined and thus a greater force is required to open it than if it hung vertically as in conventional flap valves. This is particularly advantageous as it results in a build up of material behind the flap valve which forms a 'solid plug' of material which provides an effective seal to ingress of air from chamber 20.

c) In conventional flap valves the flap member is rotatably received on a fixed shaft and wear between the shaft and flap member rapidly occurs due to the dust laden environment within chamber 20. In the present flap valve, the flap member is fixedly mounted on a shaft which is rotatably received in two spaced bearings providing a greater bearing area, so that the flap valve has a longer working life.

d) In a conventional flap valve the flap member hangs vertically and a condition known as 'chattering' between, the flap and seat occurs which is induced by vibration due to rotation of the screw. Such a condition shortens the life of a valve. In the present flap valve 'chattering' is substantially reduced or avoided since the flap member in its seated position is inclined and is therefore gravity biased into pressure contact with its seat.

WHAT WE CLAIM IS: 1. A screw pump for flowable particulate material including a mixing chamber from which particulate material is discharged by compressed air, a conduit for feeding particulate material into the mixing chamber, and a screw for moving the particulate material along said conduit, the discharge end of the conduit being closed by a flap valve housed within the mixing chamber, the valve having a tubular body portion having a bore which at one end communicates with the conduit and the other end is normally closed by a movable flap member which is pivotally connected to the body portion so as to normally abut against an end abutment face of the body portion surrounding the bore, said end abutment face being planar and being inclined to the axis of the bore.
2. A screw pump according to Claim 1

wherein the body portion has a peripheral flange projecting from its external surface which is adapted for releasable attachment to the conduit.
3. A screw pump according to Claim 2 wherein the flap member is pivotally connected to the peripheral flange.
4. A screw pump according to Claim 1, 2 or 3 wherein the pivotal connection is provided by an arm which at one end supports the flap member and at the other end is provided with a pair of lateral projections which are each rotatably supported by the body portion.
5. A screw pump according to Claim 4 wherein the pair of lateral projections are defined by a shaft extending through a lateral bore in said arm, the shaft being releasably held in said arm by locking means.
6. A screw pump according to Claim 5 wherein the arm includes an internally threaded bore communicating with said lateral bore, the locking means being a bolt threadedly received in said threaded bore and being movable for locking engagement with said shaft.
7. A screw pump according to Claim 5 wherein the locking means is in the form of a dowel received in a bore located in the arm and which is in alignment with a bore formed in the shaft.
8. A screw pump according to any of Claims 4 to 7 wherein the flap member is releasably attached to the arm.
9. A screw pump according to Claim 8 wherein the arm is provided with a support plate projecting laterally from the arm, the support plate being provided with apertures through which bolts pass to be threadedly received in the flap member.
10. A screw pump according to Claim 9 wherein shims are located between the support plate and the flap member to enable the orientation of the flap member relative to the abutment face to be adjusted.
11. A screw pump according to any preceding claim wherein the included angle between the planar abutment face and the axis of the bore of the body portion is in the flange 45"--85".
12. A screw pump according to Claim 11 wherein said included angle is about 75".
13. A screw pump substantially as described with reference to and as illustrated in any of the accompanying drawings.