GB2554761A

GB2554761A - Pump impeller

Info

Publication number: GB2554761A
Application number: GB1617185.2A
Authority: GB
Inventors: Lawrence Mabon Jack
Original assignee: Aspen Pumps Ltd
Current assignee: Aspen Pumps Ltd
Priority date: 2016-10-10
Filing date: 2016-10-10
Publication date: 2018-04-11
Also published as: WO2018069692A1; GB201617185D0

Abstract

An impeller 120 suitable for a centrifugal pump (100, figure 1) for pumping liquid, the impeller having an axial direction about which it can rotate and a radial direction transverse to the axial direction and comprising first 126 and second 124 axially spaced shroud portions. At least one vane 128 extends radially outward between the first shroud portion and the second shroud portion, and the second shroud portion defines at least one open region 134 radially inward of a radial boundary of the first shroud portion. This prevents retention of air bubbles between the first shroud portion and the second shroud portion when the centrifugal pump is operated with the axial direction substantially aligned with a gravitational direction. Preferably the open region is continuously open to the radial boundary of the first shroud portion. Preferably the centrifugal pump comprising the impeller is used in an air conditioning equipment condensate tank pump.

Description

(71) Applicant(s):

Aspen Pumps Limited (Incorporated in the United Kingdom)

Apex Way, HAILSHAM, East Sussex, BN27 3WA, United Kingdom (72) Inventor(s):

Jack Lawrence Mabon (56) Documents Cited:

DE 010219616 A1 RU 002327903 C1 JPH10227291 (58) Field of Search:

INT CL F04D

Other: WPI and EPODOC

JP 2000045979 A US 20100061841 A1 (74) Agent and/or Address for Service:

HGF Limited

Document Handling - HGF - (London), 1 City Walk, LEEDS, LS11 9DX, United Kingdom (54) Title of the Invention: Pump impeller

Abstract Title: Impeller comprising two shrouds, one including an open region for preventing gas retention (57) An impeller 120 suitable for a centrifugal pump (100, figure 1) for pumping liquid, the impeller having an axial direction about which it can rotate and a radial direction transverse to the axial direction and comprising first 126 and second 124 axially spaced shroud portions. At least one vane 128 extends radially outward between the first shroud portion and the second shroud portion, and the second shroud portion defines at least one open region 134 radially inward of a radial boundary of the first shroud portion. This prevents retention of air bubbles between the first shroud portion and the second shroud portion when the centrifugal pump is operated with the axial direction substantially aligned with a gravitational direction. Preferably the open region is continuously open to the radial boundary of the first shroud portion. Preferably the centrifugal pump comprising the impeller is used in an air conditioning equipment condensate tank pump.

120

1/3

138

FIG. 2

2/3

144

FIG. 4

3/3

Pump Impeller [0001] This invention relates to an impeller for a centrifugal pump for liquids, in particular to an impeller for a centrifugal pump for use in an air conditioner condensate pump.

BACKGROUND [0002] Centrifugal pumps for pumping liquid in air conditioning equipment condensate pump systems are used at least intermittently throughout the duration of operation of the air conditioning equipment to pump liquid condensate away from the air conditioning equipment. Centrifugal pumps operate by rotation of an impeller within the fluid to create a pressure differential across a fluid, whereby to move the fluid from a pump inlet to a pump outlet. The present disclosure provides at least an alternative to impellers of the prior art.

BRIEF SUMMARY OF THE DISCLOSURE [0003] In accordance with the present disclosure there is provided an impeller for a centrifugal pump for pumping liquid. The impeller has an axial direction about which the impeller is arranged to rotate and a radial direction transverse to the axial direction. The impeller comprises: a first shroud portion; a second shroud portion axially spaced from the first shroud portion; and at least one vane extending radially outward between the first shroud portion and the second shroud portion. The second shroud portion defines at least one open region radially inward of a radial boundary of the first shroud portion.

[0004] Thus, there is provided an impeller which substantially prevents the retention of buoyant gas bubbles, for example air bubbles when the liquid is water, between the first shroud portion and the second shroud portion when the centrifugal pump is operated with the axial direction of the impeller substantially aligned with a gravitational direction and when the second shroud portion is above the first shroud portion (i.e., when the axial direction is substantially vertical and the bubbles are buoyant towards the at least one open region of the second shroud portion). Removal of the buoyant gas bubbles provides a smoother fluid flow through the centrifugal pump and reduces an operational noise level of the centrifugal pump due to turbulent interactions between the buoyant gas bubbles and the liquid.

[0005] The open region may be continuously open to the radial boundary of the first shroud portion.

[0006] Viewed from another aspect, the present disclosure provides an impeller for a centrifugal pump for pumping liquid. The impeller has an axial direction about which the impeller is arranged to rotate and a radial direction transverse to the axial direction. The impeller comprises: a first shroud portion; a second shroud portion axially spaced from the first shroud portion; and at least one vane extending radially outward between the first shroud portion and the second shroud portion. The impeller is formed to substantially prevent retention of air bubbles between the first shroud portion and the second shroud portion when the centrifugal pump is operated with the axial direction substantially aligned with a gravitational direction.

[0007] The or each vane may define a non-straight profile in a radial plane of the impeller. The non-straight profile may be a curved profile.

[0008] The or each vane may extend axially from the first shroud portion to the second shroud portion.

[0009] The first shroud portion may be formed as a substantially circular disk. The second shroud portion may be formed as a substantially circular disk.

[0010] The first shroud portion may extend substantially radially outwards. The second shroud portion may extend substantially radially outwards.

[0011] The impeller may further comprise a central portion from which extends the first shroud portion. The second shroud portion may extend from the central portion. The second shroud portion may extend radially outward from the central portion. The or each vane may extend radially outward from the central portion.

[0012] The first shroud portion and the second shroud portion may each be centred on the central portion.

[0013] A shaft insert opening may be defined within the central portion.

[0014] The shaft insert opening may be non-circular, whereby to substantially prevent rotation of the impeller relative to a non-circular shaft member in use.

[0015] The impeller may further comprise a fluid inlet arranged to provide fluid to a pumping region defined between the first shroud portion and the second shroud portion. The fluid inlet may be provided adjacent to a root of the or each vane. The fluid inlet may be defined in the first shroud portion.

[0016] The or each vane may be formed from a plurality of substantially planar plates stacked in the axial direction.

[0017] The second shroud portion may comprise a substantially filled region radially inward of the open region. The impeller may define a closed pumping region radially inward of the open region of the second shroud portion.

[0018] The closed pumping region may be bounded by one or more surfaces of the vane, and inner facing surfaces of the first shroud portion and the second shroud portion.

[0019] The impeller may define a semi-open pumping region axially adjacent to the open region of the second shroud portion.

[0020] The or each vane may extend beyond a radial extent of the second shroud portion. The or each vane may extend to a radial extent of the first shroud portion.

[0021] A radially innermost boundary of the open region may be spaced from a radial centre of the impeller by at least 10% of the radius of the first shroud portion. The radially innermost boundary of the open region may be spaced from the radial centre of the impeller by at least 25% of the radius of the first shroud portion. The radially innermost boundary of the open region may be spaced from the radial centre of the impeller by at least 50% of the radius of the first shroud portion. The radially innermost boundary of the open region may be spaced from the radial centre of the impeller by less than 90% of the radius of the first shroud portion. The radially innermost boundary of the open region may be spaced from the radial centre of the impeller by less than 70% of the radius of the first shroud portion.

[0022] The diameter of the first shroud portion may be less than 10 centimetres. The diameter of the first shroud portion may be less than 6 centimetres. The diameter of the first shroud portion may be greater than 2 centimetres.

[0023] The present disclosure extends to centrifugal pump apparatus comprising the impeller as described herein.

[0024] The present disclosure extends to air conditioning equipment condensate tank pump apparatus comprising the centrifugal pump apparatus as described herein.

BRIEF DESCRIPTION OF THE DRAWINGS [0025] Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which:

Figure 1 is an illustration of a section through an air conditioning equipment condensate tank pump as disclosed herein;

Figure 2 is an illustration of the impeller for the centrifugal pump shown in the air conditioning equipment condensate tank pump shown in Figure 1;

Figure 3 is a top-down view of the impeller shown in Figure 2;

Figure 4 is an illustration of a lower portion of the impeller shown in Figures 2 and

3; and

Figure 5 is an illustration of an upper portion of the impeller shown in Figures 2 and 3.

DETAILED DESCRIPTION [0026] Figure 1 is an illustration of a section through an air conditioning equipment condensate tank pump 100 as disclosed herein. The air conditioning equipment condensate tank pump 100 comprises a housing 102. The housing 102 defines a fluid chamber 104 for containing condensate to be pumped out of the air conditioning equipment condensate tank pump 100. The housing 102 further defines a centrifugal pump chamber 106 in fluid communication with the fluid chamber 104 via a pump inlet 108. In this example, the fluid chamber 104 and the centrifugal pump chamber 106 are part of the same chamber. Fluid is expelled from the centrifugal pump chamber 106 through a pump outlet 110. Typically, the centrifugal pump chamber 106 is provided at a lower end of the fluid chamber 104. Thus, during filling of the air conditioning equipment condensate tank pump 100 with fluid (e.g. water), the centrifugal pump chamber 106 may be substantially completely filled with fluid during an initial filling process of the fluid chamber 104 and the air conditioning equipment condensate tank pump 100 can operate to remove any further fluid from the fluid chamber 104.

[0027] The centrifugal pump chamber 106 contains therein at least an impeller 120. The impeller 120 defines an axial direction, about which the impeller 120 is arranged to rotate to pump fluid through the centrifugal pump chamber 106. The impeller 120 further defines a radial direction substantially transverse to the axial direction, and comprises a central portion 122 from which extends a first shroud portion in the form of an upper shroud member 124. An internal surface of the central portion 122 to an underside surface of the upper shroud member 124 defines a substantially curved profile. The impeller 120 further comprises a second shroud portion in the form of a lower shroud member 126 axially spaced from the upper shroud member 124. The upper shroud member 124 and the lower shroud member 126 each extend substantially parallel with the radial direction. A plurality of vanes 128 extend radially outward between the upper shroud member 124 and the lower shroud member 126. In this example, each vane 128 extends axially from the upper shroud member 124 to the lower shroud member 126.

[0028] The impeller 120 further comprises an impeller inlet 130 defined within an inner region of the lower shroud member 126. Thus, fluid may enter the centrifugal pump chamber 106 through the pump inlet 108. The fluid may further pass through the impeller inlet 130 to a region between the upper shroud member 124 and the lower shroud member 126. The central portion 122 of the impeller 120 defines a shaft opening (see Figure 2) to receive a driving shaft 140. The driving shaft 140 is connected to a motor (not shown) to cause rotation of the impeller 120 about the axial direction. In this example, the impeller 120 rotates in a clockwise direction when viewed along a direction from the upper shroud member 124 to the lower shroud member 126. It will be understood that the impeller 120 could alternatively be arranged for rotation in a counter-clockwise direction (with appropriate modification ofthe vanes 128).

[0029] A cover 150 is provided over an opening in the fluid chamber 104, through which the driving shaft 140 is arranged to pass. The cover 150 substantially separates the fluid within the fluid chamber 104 from the fluid within the centrifugal pump chamber 106 and the impeller 120. It will be understood that no seal between the driving shaft 140 and the cover 150 will be perfect, and some fluid or air may pass between the centrifugal pump chamber 106 and the fluid chamber 104 during operation of the air conditioning equipment condensate tank pump 100. It will be understood that during typical operation of the air conditioning equipment condensate tank pump 100, a pressure within the centrifugal pump chamber 106 will be greater than a pressure within the fluid chamber 104. In this way, air or fluid cannot be drawn into the centrifugal pump chamber 106 from the fluid chamber 104 through the opening in the fluid chamber 104 through which the driving shaft 140 is arranged to pass. During rotation ofthe impeller 120, the fluid within the impeller 120 (between the upper shroud member 124 and the lower shroud member 126) is pushed radially outwards and exits the centrifugal pump chamber 106 through the pump outlet 110. Further fluid is drawn into the centrifugal pump chamber 106 from the fluid chamber 104 through the pump inlet 108 to replace the fluid removed through the pump outlet 110.

In this way, the air conditioning equipment condensate tank pump 100 can be operated to pump fluid from the fluid chamber 104 out of the air conditioning equipment condensate tank pump 100 through the pump outlet 110.

[0030] In some impellers of the prior art, it has been found that one or more air bubbles may become trapped within an impeller during a filling ofthe fluid chamber 104. In particular, an air bubble may become trapped against an underside surface of an upper shroud member of the impeller, adjacent to a central portion provided at an axial root of the upper shroud member. During operation of the air conditioning equipment condensate tank pump, the air bubble may not be dislodged from the system. In particular, operation of the pump causes a pressure gradient to form within the liquid. The pressure of the liquid increases as the liquid moves from the pump inlet 108 to the pump outlet 110. One effect of this pressure gradient is to impart a radially inward force on the air bubble, effectively pinning the air bubble against the central portion. Trapped air bubbles may reduce the efficiency of the air conditioning equipment condensate tank pump. The trapped air bubbles may also increase the operating noise of the air conditioning equipment condensate tank pump. The trapped air bubbles may further lead to increased wear on the air conditioning equipment condensate tank pump, resulting in increased maintenance costs for the air conditioning equipment.

[0031] Figure 2 is an illustration of the impeller 120 for the centrifugal pump shown in the air conditioning equipment condensate tank pump 100 shown in Figure 1. Figure 3 is a top-down view of the impeller shown in Figure 2. It will be understood that impeller 120 at least attempts to overcome some otthe problems with prior art impellers identified hereinbefore. Much otthe impeller 120 has been described in relation to Figure 1.

However, further features of the impeller 120 will be described with reference to the view of the impeller 120 shown in Figures 2 and 3. The lower shroud member 126 is formed as a substantially circular disk and extends to a lower shroud member radial extent. The upper shroud member 124 defines an open region 134 radially inwards otthe lower shroud member radial extent. In this example, the open region 134 otthe upper shroud member 124 is continuously open to the lower shroud member radial extent.

[0032] The impeller 120 comprises a plurality of vanes in the form of five vanes 128 each extending radially outward between the upper shroud member 124 and the lower shroud member 126. Each vane 128 defines a curved profile when viewed in an axial direction of the impeller 120. Each vane 128 extends radially outwards substantially to the lower shroud member radial extent. In this example, each vane 128 also extends in a counterclockwise direction whereby to cause clockwise rotation otthe impeller 120 in use. A closed pumping region 136 is defined by the impeller 120 and is enclosed by both the upper shroud member 124 and the lower shroud member 126. The closed pumping region 136 is also enclosed circumferentially by adjacent vanes 128. A semi-closed pumping region 138 is defined radially outwards otthe closed pumping region 136 and is open on an upper side. In this example, the upper shroud member 124 comprises an inner portion 140 defining the closed pumping region 136. The inner portion 140 is formed as a substantially circular disk. The upper shroud member 124 further comprises an outer portion 142 which extends over an upper surface of each of the vanes 128. The outer portion 142 of the upper shroud member 124 is shaped to follow a shape of the vanes 128.

[0033] By providing the open region 134 in the upper shroud member 124 radially inwards of the lower shroud member radial extent, one or more air bubbles which would otherwise be trapped within the impeller 120 during operation of the air conditioning equipment condensate tank pump 100 may escape the impeller 120 either during filling or operation of the air conditioning equipment condensate tank pump 100. It is believed that this is due to a reduction in the force required to act radially outwards on the air bubble to move the air bubble to a boundary of the open region 134 of the upper shroud member

124, compared to an amount of force which would be required to move the air bubble radially outwards to the boundary of the upper shroud member 124 if the upper shroud member 124 extended to substantially the same radial extent as the lower shroud member 126. Once the air bubble is released from within the impeller 120, the air bubble will escape from the centrifugal pump chamber 106 through an upper opening provided in an upper surface of the centrifugal pump chamber 106 for passage therethrough of the driving shaft 140.

[0034] In this example, the lower shroud member 126 is formed to have a diameter of approximately 75 millimetres. The inner portion 140 of the upper shroud member 124 is formed to have a diameter of approximately 42 millimetres. The axial spacing between the upper shroud member 124 and the lower shroud member 126 is approximately 4.5 millimetres. An axial thickness of the upper shroud member 124 is approximately 1.5 millimetres. An axial thickness of the lower shroud member 126 is approximately 1.2 millimetres. Therefore, a total axial extent between outer surfaces of the upper shroud member 124 and the lower shroud member 126 is approximately 7.2 millimetres.

[0035] In this example, the plurality of vanes 128 are formed by injection moulding. The plurality of vanes 128 are integrally formed with the lower shroud member 126 in a first impeller member 144 as shown in Figure 4. The upper shroud member 124 is separately formed by injection moulding in a second impeller member 146 as shown in Figure 5. This provides an impeller 120 which is simple to manufacture from two moulded components. In this example, the first impeller member 146 and the second impeller member 144 are formed from a plastics material.

[0036] Figure 4 is an illustration of a first impeller member 146 of the impeller shown in Figures 2 and 3. The first impeller member 146 comprises the lower shroud member 126 and the plurality of vanes 128 as described in relation to Figures 2 and 3 previously. An upper surface of two of the vanes 128 comprises a locating nub 148.

[0037] Figure 5 is an illustration of a second impeller member 148 of the impeller shown in Figures 2 and 3. The second impeller member 148 comprises the upper shroud member 124. The upper shroud member 124 has defined therein mounting holes in the form of two mounting holes 132. In this example, the mounting holes 132 extend through the entire thickness of the upper shroud member 124. As will be understood, the mounting holes 132 align and engage with the locating nubs 148 during manufacture of the impeller 120.

[0038] Returning to Figures 2 and 3, the central portion 122 of the impeller 120 defines a shaft opening 123 to receive a driving shaft (see Figure 1). The shaft opening 123 is formed to have a non-circular shape whereby to engage with a correspondingly shaped driving shaft and prevent mutual rotation of the impeller 120 relative to the driving shaft.

[0039] In summary, there is provided an impeller (120) for a centrifugal pump for pumping liquid. The impeller (120) has an axial direction about which the impeller is arranged to rotate and a radial direction transverse to the axial direction. The impeller (120) comprises: a first shroud portion (126); a second shroud portion (124) axially spaced from the first shroud portion (126); and at least one vane (128) extending radially outward between the first shroud portion (126) and the second shroud portion (124). The second shroud portion (124) defines at least one open region (134) radially inward of a radial boundary of the first shroud portion (126).

[0040] Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0041] Features, integers or characteristics described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. An impeller for a centrifugal pump for pumping liquid, the impeller having an axial direction about which the impeller is arranged to rotate and a radial direction transverse to the axial direction, the impeller comprising:

a first shroud portion;

a second shroud portion axially spaced from the first shroud portion; and at least one vane extending radially outward between the first shroud portion and the second shroud portion, wherein the second shroud portion defines at least one open region radially inward of a radial boundary of the first shroud portion.

2. An impeller as claimed in claim 1, wherein the open region is continuously open to the radial boundary of the first shroud portion.

3. An impeller for a centrifugal pump for pumping liquid, the impeller having an axial direction about which the impeller is arranged to rotate and a radial direction transverse to the axial direction, and the impeller comprising:

a first shroud portion;

a second shroud portion axially spaced from the first shroud portion; and at least one vane extending radially outward between the first shroud portion and the second shroud portion, wherein the impeller is formed to substantially prevent retention of air bubbles between the first shroud portion and the second shroud portion when the centrifugal pump is operated with the axial direction substantially aligned with a gravitational direction.

4. An impeller as claimed in any preceding claim, wherein the or each vane defines a curved profile in a radial plane of the impeller.

5. An impeller as claimed in any preceding claim, wherein the or each vane extends axially from the first shroud portion to the second shroud portion.

6. An impeller as claimed in any preceding claim, wherein the first shroud portion is formed as a substantially circular disk.

7. An impeller as claimed in any preceding claim further comprises a central portion from which extends the first shroud portion.

8. An impeller as claimed in any preceding claim, wherein the impeller further comprises a fluid inlet arranged to provide fluid to a pumping region defined between the first shroud portion and the second shroud portion.

9. An impeller as claimed in claim 8, wherein the fluid inlet is provided adjacent to a

5 root of the or each vane.

10. An impeller as claimed in claim 9, wherein the fluid inlet is defined in the first shroud portion.

11. Centrifugal pump apparatus comprising the impeller as claimed in any preceding claim.

10

12. Air conditioning equipment condensate tank pump apparatus comprising the centrifugal pump apparatus as claimed in claim 11.

13. An impeller substantially as described in relation to Figures 1 to 3.

Intellectual

Property

Office

Application No: Claims searched:

GB1617185.2

1-12