Technical Field

[001] The invention relates to a cutting part for a pump, a pump casing including a cutting part and a pump including the pump casing and the cutting part.

Background

[002] Pumps are often subject to fluids that may contain solids and stringy material. For example, pumps used the sewage industry may encounter large solids, such as material being in the size range of about 20mm to 80mm, and also stringy material such as lengths of cloth, rope or line.

[003] A problem encountered with such pumps is that large solid material may become clogged within the pump, such as becoming caught at an inlet of the pump or within a volute of the pump, and the stringy material may become tangled around an impeller of the pump.

[004] Accordingly, when the pump becomes clogged or the impeller becomes tangled with stringy material the pump can become inefficient and may need to be shutdown for maintenance. The clogging solid material and/or the stringy material then needs to be manually removed via maintenance personal before the pump is again operated. A problem with shutting down the pump for manual maintenance is that such maintenance and downtime is both time consuming and costly.

[005] In an attempt to address the problem of stringy material "chopper" type pumps have been developed which include a cutting arrangement located upstream or at the inlet to the main pump impeller. The cutting arrangement includes a housing having a fixed cutting bar and a rotating agitation bar which moves past the fixed cutting bar to create a cutting action to cut or shred material entering the housing. A problem with these types of "chopper" pumps is that the cutting arrangement acts on all materials passing into the inlet of the pump and as such the cutting arrangement may become clogged with large solids. Accordingly, the solids handling ability of the pump is limited. Another problem is that the rotating agitation bar is required to spin through the incoming fluid that may cause inefficiencies and/or the agitation bar to strike a large solid object and become damaged.

[006] The invention disclosed herein seeks to overcome one or more of the above identified problems or at least provide a useful alternative.

Summary

[007] In accordance with a first aspect there is provided, a pump including a casing having a volute and an impeller arranged substantially centrally of the volute to urge fluid through the volute between an inlet and an outlet of the volute, the volute including a circumferential face extending from a first side of a throat of the outlet around the impeller to a second opposing side of the throat of the outlet, wherein a cutting element is located relative to the circumferential face so as to extend at least partially into a gap between the circumferential face and a blade of the impeller such that a cutting action is provided between the cutting element and the blade of the impeller during rotation of the impeller.

[008] In one aspect, the cutting element is elongate and is arranged in a lengthwise circumferential direction along the circumferential face.

[009] In another aspect, the cutting element is located toward the first side of the throat.

[0010] In yet another aspect, the cutting element includes a cutting edge.

[0011] In yet another aspect, cutting edge is curved so as to maintain a substantially fixed spacing between the cutting edge and the blade of the impeller. [0012] In yet another aspect, the throat is defined by a tongue on the first side of the throat, and wherein the cutting element is arranged to extend from a location adjacent the tongue at least partially along the circumferential face.

[0013] In yet another aspect, the circumferential face includes a mounting portion adapted to couple with the cutting element.

[0014] In yet another aspect, the cutting element is supported by a base which is adapted to releasably couple with the mounting portion.

[0015] In yet another aspect, the base supports at least two spaced apart cutting elements which are arranged substantially parallel to one another.

[0016] In yet another aspect, the base supports three spaced apart cutting elements.

[0017] In yet another aspect, the base and the mounting portion include likewise arranged apertures arranged to receive a fastener to couple the base to the mounting portion.

[0018] In yet another aspect, the length of the cutting element is in the range of about 1/4 to 1/8 of the diameter of the impeller.

[0019] In yet another aspect, the pump includes a wear plate coupled to the casing proximate the inlet, the wear plate having a surface facing the impeller, the surface including at least one pocket arranged to create a further cutting action between the impeller and the at least one pocket during rotation of the impellor.

[0020] In accordance with a second aspect there is provided, a cutting part for fitting with a volute of a centrifugal pump, the volute including an inlet arranged substantially centrally of the volute, an outlet extending from the volute and an impeller arranged adjacent the inlet to urge fluid through the volute between the inlet and the outlet, the volute including a circumferential face extending from a first side of a throat of the outlet around the impeller to a second opposing side of the throat of the outlet; and wherein a cutting element is located relative to the circumferential face with the cutting element extending at least partially into a gap between the circumferential face and a blade of the impeller such that a cutting action is provided between the cutting element and the blade of the impeller during rotation of the impeller.

[0021] In one aspect, the cutting element includes an elongate cutting edge configured to extend in a lengthwise circumferential direction along the circumferential face.

[0022] In another aspect, the cutting edge is curved so as to maintain a substantially even spacing between the cutting edge and the blade of the impeller as the blade passes the cutting edge.

[0023] In yet another aspect, the circumferential face includes a mounting portion adapted to couple with the cutting element, and wherein the cutting part includes a base supporting the cutting element, the base being adapted to releasably couple with the mounting portion.

[0024] In yet another aspect, the base supports at least two spaced apart cutting elements which are arranged substantially parallel to one another.

[0025] In yet another aspect, the base supports three spaced apart cutting elements.

[0026] In yet another aspect, the base includes at least one aperture arranged to receive a faster to couple cutting part to the mounting portion.

[0027] In yet another aspect, the length of the cutting element is in the range of about 1/4 to 1/8 of the diameter of the impeller.

[0028] In accordance with a third aspect there is provided, a pump casing including a volute, the volute including a recessed mounting portion located in a circumferential face of the volute, the recessed mounting portion being shaped to at least partially receive and coupled with a cutting part as defined above. [0029] In accordance with a fourth aspect there is provided, a pump including a casing and an impeller arranged substantially centrally of the casing to urge fluid through the casing between an inlet and an outlet of the casing, the casing including a circumferential face extending from a first side of a throat of the outlet around the impeller to a second opposing side of the throat of the outlet, wherein a cutting element is located so as to extend at least partially into a gap between the circumferential face and a blade of the impeller such that a cutting action is provided between the cutting element and the blade of the impeller during rotation of the impeller.

[0030] In accordance with a fifth aspect there is provided, a method of cutting stringy material within the volute of a pump, the method including the steps of: arranging a cutting element between a circumferential face of the volute and the impellor such that a cutting action is provided between the cutting element and the blade of the impeller during rotation of the impeller; and rotating the impeller to cut the stringy material.

Brief Description of the Figures

[0031] The invention is described, by way of non-limiting example only, by reference to the accompanying figures, in which;

[0032] Figure 1 is an isometric view illustrating a pump casing including a volute with a mounting side being open to reveal a cutting part fitted to the volute;

[0033] Figure 2 is an isometric view illustrating the pump casing shown in Figure 1 with the a cutting part removed from the volute to reveal a mounting portion to which the cutting part is coupled;

[0034] Figure 3 is an end cut-away view illustrating the pump casing showing the cutting part fitted to the volute, and an inlet assembly fitted to the inlet;

[0035] Figure 4 is a side sectional view illustrating the pump casing and the arrangement of the cutting part within the volute; [0036] Figure 5a is a top view illustrating the cutting part; [0037] Figure 5b is an isometric view illustrating the cutting part; [0038] Figure 5c is a end view illustrating the cutting part; [0039] Figure 5d is a side view illustrating the cutting part;

[0040] Figure 6a is a side sectional view illustrating a blade of the impeller at a position prior to sweeping past the cutting part;

[0041] Figure 6b is a side sectional view illustrating a blade of the impeller at a position after the cutting part has passed the cutting element;

[0042] Figure 7a is perspective front view illustrating a second example of the cutting part;

[0043] Figure 7b is perspective underside view illustrating the second example of the cutting part;

[0044] Figure 7c front view illustrating the second example of the cutting part;

[0045] Figure 7d is a top view illustrating the second example of the cutting part;

[0046] Figure 7e is a rear view illustrating the second example of the cutting part;

[0047] Figure 8a is a perspective front view illustrating a third example of the cutting part;

[0048] Figure 8b is a side view illustrating the third example of the cutting part;

[0049] Figure 9 is a sectional view illustrating a pump end including the pump casing and cutting part fitted therein; [0050] Figure 10a is a front perspective view illustrating a front wear plate for the pump casing;

[0051] Figure 10b is a rear perspective view illustrating the front wear plate; [0052] Figure 10c is a front view illustrating the front wear plate; [0053] Figure lOd is a side view illustrating the front wear plate; and [0054] Figure lOe is a rear view illustrating the front wear plate. Detailed Description

[0055] Referring to Figures 1 to 4, there is shown a pump 5 including centrifugal pump casing 10 having a volute 12, an inlet 14 arranged substantially centrally of the volute 12, an outlet 16 extending from the volute 12 and an impeller 18 arranged substantially centrally of the volute 12 and adjacent the inlet 14 to urge fluid through the volute 12 from the inlet 14 to the outlet 16. In this example, the impeller 18 is a solids handling impeller having two curved blades or vanes 34 which are spaced apart from one another to create an opening 35, and are arranged around the inlet 14 so as to allow the passage of relatively large solids into the volute 12. The pump casing 10 includes a ring shaped coupling face 21 to which an inlet assembly 77 (shown in Figure 9) that carries a front wear plate 90 (shown in Figures 9 and 10a to lOe) is coupled in use.

[0056] As is best shown in Figure 4, the volute 12 includes a circumferential face 20 extending from a first side 22 of a throat 24 of the outlet 16 around the impeller 18 to a second opposing side 26 of the throat 24 of the outlet 16. The throat 24 is defined by a tongue 25 on the first side 22 of the throat 24. The tongue 25 provides a cut-water 29 to split or direct the outlet water stream toward the outlet 16. The tongue 25 has a pointed leading edge 27 oriented toward the oncoming fluid flow as shown by arrow [0057] The tongue 25 forms the entry into the circumferential face 20 of the volute 12 which extends from the tongue 25 around the impeller 18, in the direction indicated by arrow "R" to the second opposing side 26 of the throat 24. The outlet 16 includes a diffusor 17 which extends from the throat 24 to a flange 19 for coupling to further pipe work.

[0058] A cutting part or arrangement 28 is coupled to or located at the circumferential face 20 such that cutting elements 30 of the cutting part 28 extend at least partially into a gap 32 (shown best in Figure 4) between the circumferential face 20 and the blades 34 of the impeller 18. The cutting elements 30 are each elongate and extend in a circumferential lengthwise direction along the circumferential face 20, as best shown in Figures 1 and 3. In this arrangement, the cutting elements 30 are substantially parallel to the direction of fluid flow and therefore present minimal interference to the passing fluid. The cutting part 28 includes a base 36 that supports the cutting elements 30. The base 36 is adapted to couple with or to a mounting portion 38 of the circumferential face 20 of the volute 12.

[0059] As is best shown in Figure 2, the mounting portion 38 includes a cut-out or recess 39 in or at the circumferential face 20 of the volute 12 to which the base 36 is at least partially received. The recess 39 is arranged to present a generally flat surface 41 against which the base 36 may be seated and the flat surface 41 extends into the circumferential face 20 in a direction away from the tongue 25 so that a ledge or step 43 is provided between the mounting portion 38 and the circumferential face 20.

[0060] The base 36 includes apertures 40 which are arranged to align with corresponding apertures 42 of the mounting portion 38 such that fasteners 44 may be passed through apertures 40, 42 to releasably secure the cutting part 28 to the volute 12. The apertures 40 are counter-sunk and the depth of the recess 39 is such that an exposed face 44 of the base 36 is substantially flush with or slightly recessed relative to the adjacent circumferential face 20 of the volute 12. The mounting portion 38 may be cast with the volute 12 or machined into the circumferential face 20 of the volute 12. The volute 12 being formed from a metal material or suitable alternative.

[0061] The cutting part 28 and the mounting portion 38 are located toward or at the tongue 25 at the first side 22 of the throat 24. In this example, the recess 39 extends from a location near or at the tip 27 to the step 43 and the base 36 of the cutting part 28 is located or abutted against the step 43 and terminates just short of the tip 27. Accordingly, the cutting part 28 and the associated cutting elements 30 extend from or adjacent to the tongue 25 at least partially along the circumferential face 20.

[0062] The location of the cutting part 28 near or at the tongue 25 which provides the cut-water 29 is advantageous as the flow velocity at this location of the volute 12 is at a minimum and as such the flow disturbance caused by the cutting part 28 and associated energy loss or efficiency losses are minimised. Further advantageously, the gap 32 between the circumferential face 20 of the volute 12 the blades 34 of the impeller 18 is at a minimum toward the tongue 25. Accordingly, the height "FT of the cutting elements 30 (as shown below in Figures 5a to 5d) may be relatively short to reach the blades 34 and allows the cutting elements 30 to cut any material such as stringy material caught or carried by the blades 34. The relatively short height "FT of the cutting elements 30 also assist to minimise flow disturbance and allows the cutting part 28 to be relatively compact thereby saving on wear and material costs.

[0063] Referring now to Figures 5a to 5d, the cutting part 28 includes three spaced apart cutting elements 30 which are arranged substantially parallel to one another. The cutting elements 30 are equally spaced apart from one another and extend substantially perpendicularly from the base 36. The base 36 includes a flat plate 50 which is seated on the flat surface 41 of the mounting portion 38. The apertures 40 are located between the spaced apart cutting elements 30. The base 36 includes a leading end 52 and a trailing end 53 between which the cutting elements 30 extend and, first and second opposing sides 54, 56.

[0064] A first of the cutting elements 30 located at the first side 54 is arranged to end from and flush with the first side 54, and a third of the cutting elements 30 is located toward but inwardly offset from the second side 56. A second intermediate one of the cutting elements is located between the first and second of the cutting elements 30. The third of the cutting elements 30 being offset from the second side 56 allows provides lateral spacing between the third of the cutting elements 30 and casing 10 and/or impeller 18. [0065] Turning to the cutting elements 30 in more detail, each of the cutting elements 30 includes an elongate cutting edge 57 extending lengthwise along the cutting element 30. The cutting edge 57 has a chamfered edge so as to be shaped to cut commonly encountered material such as stringy material such a rope and lengths of cloth. The cutting edges 57 of each of the cutting elements 30 are curved or radiused, as best shown in Figure 5c, so as to maintain a fixed or constant spacing between the cutting edge 57 and the blade 34 of the impeller 18. The curve may be concave or scalloped in appearance.

[0066] Referring additionally to Figures 6a and 6b, the curve of the cutting elements 30 is matched to the outer diameter traced by blades 34 of the impeller. The height "FT of the cutting elements 30 is arranged such that there is only a small spacing between the cutting edges 57 and the passing blade tips 58 of the blades 34. The spacing may be in the order of only 1mm to 5mm, preferably about 2mm. Accordingly, when the blades 34 move past the fixed cutting part 28, as shown in the sequence of Figures 6a and 6b, any stringy material being carried by the blades 34 or caught on the cutting part 28 is cut or shredded by the relative movement. The cut or shredded material may then be passed through the volute 12 and out of the outlet 16.

[0067] The length of the cutting elements 30 may in some examples be in the range of about 1/3 to 1/8 of the diameter of the impeller. In this example, the diameter of the impeller 18 is about 285mm and the length "L" of the cutting elements is about 60mm being 1 :4.75 of the impeller 18 diameter. The maximum edge height "Ft" of the cutting elements 30 is about 25mm and the width "W" of the base 36 is about 90 mm. The cutting part 28 may be formed form a steal material such as cast or stainless steal. Advantageously, in this example, the cutting part 28 is removable from the volute 12 that allows the cutting part 28 to be maintained or replaced.

[0068] Referring now to Figures 7a to 7f there is shown a further example of the cutting part 28 in which like numerals are used to denote like parts. The overall configuration and functionally is similar to that described above with reference to Figures 5a to 5d. However, in this example, the cutting elements 30 stand lower toward the leading end 52 and are relatively raised toward the trailing end 53. [0069] Accordingly, the cutting edges 57 of the cutting elements 30 have a more pronounced curvature between opposing ends 31, 33 of the cutting elements 30. In this example, the leading end 52 also includes a pointed tip or leading edge 35 arranged to meet the circumferential face 20 of the volute 12 and provide a streamlined surface to direct fluid over and through the cutting part 28. The cutting elements 30 are also symmetrically arranged with the two outer cutting element 30 being at and flush with the respective sides 54, 56. In this example, the cutting part 28 has a width of about 80 mm, a length of about 80 mm and the cutting elements 30 have a maximum height of about 30mm.

[0070] Referring to Figure 8a and 8b, there is shown yet another example, of cutting part 28 in which like numerals are used to denote like parts. This example shows yet another geometric variation of the cutting elements 30 with the cutting edges 57 of the cutting elements 30 have a less pronounced curvature, in comparison to that shown in Figures 7a to 7f, between opposing ends 31, 33 of the cutting elements 30. This geometric variation is to fit the cutting part 28 with a volute having a different scroll shape and/or size in comparison to, for example, the cutting part 28 as shown in Figures 7a to 7f.

[0071] Accordingly, in view of the examples shown in Figures 5a to 5d, Figures 7a to 7f, and Figures 8a and 8b, it may be appreciated that shape of the cutting part 28, in particular of the cutting edges 57 of the cutting elements 30 may be modified to suit a variety of volute shapes, sizes and impeller configurations so to allow close positioning of the cutting edges 57 with the impeller 18 as it passes the cutting edges 57.

[0072] Referring to Figure 9, the pump casing 10 may form part of a pump assembly 70 (also referred to as a pump head 70) including a drive assembly 72 having a drive shaft 74 for coupling to an external motor (not shown), a outlet assembly 76 coupled to the outlet 16 and an inlet assembly 78 coupled to the inlet 14. The inlet assembly 78 includes a flange 77 that is coupled with the ring shaped coupling face 21 that skirts the inlet 14. The inlet assembly 78 carries the front wear plate 90 with the front wear plate 90 being at least partially received by the ring shaped coupling face 21. The front wear plate 90 is further described below with reference to Figures 10a to lOe.

[0073] The drive assembly 72 includes a bearing housing 80 supporting the drive shaft 74 and a motor coupling flange 82 for coupling with the external motor. In use, the motor drives the shaft 74 which in turn drives the impeller 18 to urge fluid from the inlet 14, through the volute 12, to the outlet 16. An example of a particular configuration of pump to which the pump casing 10 including the cutting part 28 may be fitted is a SW150 pump provided by AllightSykes Pty Ltd having a maximum pump power consumption of max 62 kW, a maximum capacity of 130 litres per second, and a maximum pump head of 46m. However, other sizes, styles and types of pumps may also be utilised, as appropriate.

[0074] Referring now to Figures 10a to lOe, there is shown an example of a configuration of the front wear plate 90 including a ring shaped body 91 having a circumferential skirting edge 93 and a central inlet aperture 97 having an inner aperture edge 94. In more detail, the ring shaped body 91 includes a front or wear face 95 that, in use, faces the impeller 18 and a rear or coupling face 96 that, in use, couples to the inlet assembly 78. The front face 95 slopes or is chamfered inwardly from the skirting edge 93 toward the inner aperture edge 94 and radial cutting slots or cutting pockets 92 are provided in the front face 95 extending between the inner aperture edge 94 toward the circumferential skirting edge 93. The slots 92 include a rounded end 98 toward the outer skirting edge 93 and terminate an open end 99 that is open to the inner aperture edge 94. Walls 87 of the slots or pockets 92 provide cutting edges 89.

[0075] The cutting slots 92, in particular the cutting edges 89, function to create a cutting action with the impeller 18 to further assist with cutting solid material that enters the inlet 14. For example, the cutting slots 92 assist cutting of solid material such as garden hoses, sticks and O-rings and other larger or long solid objects that may enter the inlet 14 and may not be easily passable. The cutting elements 28 then assisting to cut any stringy material inside the volute 12 and around the impeller 18. The front wear plate 92 may be formed from any suitable material such as a metal material having the slots 92 machined or cast into the front face 95. [0076] Advantageously, there has been described a cutting part which is fitted within the volute of a pump casing of a pump. The cutting part is sized, shaped and positioned at or near the cut-water or entry into the volute to minimise flow disturbance and also allow relatively short cutting elements to be used and position very near to the tips of the pump blade to allow a cutting action between the cutting elements and the passing pump blade. This cutting action allows the shredding or cutting of stringy material caught by or on the pump blade. Once the material is shredded or cut, the material may be passed through the pump without becoming caught or causing damage.

[0077] Further advantageously, the position of the cutting part adjacent to the cutwater still allows the volute to handle large solid materials. For example, the pump disclosed herein, the SW150, is able to pass solids up to about 90mm. The large solids enter the inlet, pass through the spaced apart blades of the impeller and pass around the volute and out of the outlet. Once within the volute, the large solids are inhibited from re-entering or cycling within the volute by the cutwater. This also inhibits the cutting part from impacting with or becoming worn by large solids. Accordingly, in view of the above, the cutting part enables a centrifugal pump to be configured to handle large solids and also shred or cut stringy material to avoid downtime and maintenance cause by the tangling of stringy material around the impeller.

[0078] The pump may also be fitted with an advantageous front wear plate including cutting pockets that impose a further cutting action on solids material entering the pump that may be too large or long to be passed and are also too large to be acted on by the cutting elements. For example, the cutting pockets may cut up a section of garden hose into smaller pieces that may then be passed through the pump. Accordingly, the cutting elements and cutting pockets may function together as a cutting system to assist with the overall handling of solids and stringy material passing through the pump.

[0079] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0080] The reference in this specification to any known matter or any prior publication is not, and should not be taken to be, an acknowledgment or admission or suggestion that the known matter or prior art publication forms part of the common general knowledge in the field to which this specification relates.

[0081] While specific examples of the invention have been described, it will be understood that the invention extends to alternative combinations of the features disclosed or evident from the disclosure provided herein.

[0082] Many and various modifications will be apparent to those skilled in the art without departing from the scope of the invention disclosed or evident from the disclosure provided herein.