Pressure Wall for a Fluid Pump and a Pump Including the Pressure Wall

Abstract

The present invention relates to a pressure wall for a centrifugal pump for fluid having substantially the shape of a disc, the disc-shaped pressure wall having a central axis, the pressure wall comprising: a top surface; and a bottom surface opposing the top surface; wherein the top surface includes an inner surface section and an outer surface section, wherein the inner surface section extends radially from the central axis and is recessed to form a central recess; and wherein the outer surface section includes an inner circumferential edge portion and an outer circumferential edge portion, wherein the inner circumferential edge portion is located closer to the central axis than the outer circumferential edge portion, and wherein the outer circumferential edge portion is located higher than the inner circumferential edge portion with respect to a plane perpendicular to the central axis and passing through the inner circumferential edge portion.

Claims

1. A pressure wall for a centrifugal pump for fluid having substantially the shape of a disc, the disc-shaped pressure wall having a central axis, the pressure wall comprising: a top surface; and a bottom surface opposing the top surface; wherein the top surface includes an inner surface section and an outer surface section, wherein the inner surface section extends radially from the central axis and is recessed to form a central recess; and wherein the outer surface section includes an inner circumferential edge portion and an outer circumferential edge portion, wherein the inner circumferential edge portion is located closer to the central axis than the outer circumferential edge portion, and wherein the outer circumferential edge portion is located higher than the inner circumferential edge portion with respect to a plane perpendicular to the central axis and passing through the inner circumferential edge portion.

2. The pressure wall according to claim 1, wherein the pressure wall further comprises a central through hole extending at least substantially along the central axis for bearing an impeller of the pump.

3. The pressure wall according to claim 1, wherein the height of the outer surface section measured from the inner circumferential edge portion to the outer circumferential edge portion increases in the direction perpendicular to the central axis of the pressure wall, preferably increases steadily.

4. The pressure wall according to claim 1, wherein the outer surface section is inclined towards the central axis of the pressure wall.

5. The pressure wall according to claim 1, wherein an inclination angle formed between the outer surface section and the plane perpendicular to the central axis is larger than 0° and less than or equal to 30°, preferably less than or equal to 20°, and more preferably less than or equal to 10°.

6. The pressure wall according to claim 1, wherein the outer surface section has a concave shape extending substantially around the entire circumference of the outer surface section.

7. The pressure wall according to claim 1, wherein the outer surface section further has a helical shape extending substantially in the direction of the central axis of the pressure wall.

8. The pressure wall according to claim 7, wherein the helical shape extending substantially around the entire circumference of the outer surface section.

9. The pressure wall according to claim 7, wherein the helical shape of the outer surface section extends over a major portion of the circumference of the outer surface section with the remaining portion connecting the end portions of the outer surface section together.

10. The pressure wall according to claim 1, wherein the pressure wall is a deep-drawn part.

11. The pressure wall according to claim 1, wherein the pressure wall is made of a metal, preferably a corrosion-resistant metal, such as stainless steel or high-alloy steel.

12. The pressure wall according to claim 1, wherein the bottom surface is recessed to form a chamber for receiving a rotor of a motor of the pump.

13. The pressure wall according to claim 1, wherein the bottom surface comprises an outer circumferential edge to connect with a casing portion of the pump.

14. The pressure wall according to claim 1, wherein the central recess has a cylindrical shape which substantially matches the outer contour of an impeller.

15. A pump, in particular for domestic appliances such as dishwashers, comprising: a pumping chamber including a central axial fluid inlet and a tangential fluid outlet, a heating unit for heating the fluid, an impeller for conveying fluid, wherein the impeller rotating within the pumping chamber, a motor for driving the impeller, and a pressure wall according to claim 1 for deflecting the fluid flowing out of the impeller towards the heating unit of the pump.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0063] FIG. 1a is a perspective view of an impeller according to the state of art.

[0064] FIG. 1b is a sectional top view cut along a plane perpendicular to the rotational axis of the impeller of FIG. 1a.

[0065] FIG. 2a is a perspective view of an impeller according to an embodiment of the present invention.

[0066] FIG. 2b is a sectional top view cut along a plane perpendicular to the rotational axis of the impeller of FIG. 2a.

[0067] FIG. 3a is a perspective view of an impeller according to a further embodiment of the present invention.

[0068] FIG. 3b is a sectional side view cut along a plane parallel to the rotational axis of the impeller of FIG. 3a.

[0069] FIG. 3c is a sectional top view cut along a plane perpendicular to the rotational axis of the impeller of FIG. 3a.

[0070] FIG. 3d is a perspective sectional view cut along a plane parallel to the rotational axis of the impeller of FIG. 3a.

[0071] FIG. 4a is a perspective view of a blade according to the embodiment shown in FIGS. 3a to 3d.

[0072] FIG. 4b is another perspective view of the blade shown in FIG. 4a.

[0073] FIG. 5a is a perspective view of an impeller according to another embodiment of the present invention.

[0074] FIG. 5b is a sectional side view cut along a plane parallel to the rotational axis of the impeller of FIG. 5a.

[0075] FIG. 6a is a perspective view of an impeller according to a further embodiment of the present invention.

[0076] FIG. 6b is a sectional side view cut along a plane parallel to the rotational axis of the impeller of FIG. 6a.

[0077] FIG. 7a is a perspective view of a pump according to an embodiment of the present invention.

[0078] FIG. 7b is a sectional view cut along a plane parallel to the rotational axis of the impeller of the pump of FIG. 7a.

[0079] FIG. 8a is a perspective view of a pressure wall according to an embodiment of the present invention.

[0080] FIG. 8b is a perspective sectional side view cut along a plane parallel to the central axis of the pressure wall of FIG. 8a.

[0081] FIG. 9a is a perspective view of a pressure wall according to a further embodiment of the present invention.

[0082] FIG. 9b is a sectional side view cut along a plane parallel to the central axis of the pressure wall of FIG. 9a.

[0083] FIG. 10a is a perspective view of a pressure bushing according to an embodiment of the present invention.

[0084] FIG. 10b is a sectional side view cut along a plane parallel to the central axis of the pressure bushing of FIG. 10a.

[0085] FIG. 11 is a sectional side view of an impeller cut along a plane parallel to the rotational axis of the impeller according to a further embodiment of the present invention.

[0086] FIG. 12 is a sectional view of a pressure bushing according to a further embodiment of the present invention.

[0087] FIG. 13 is a sectional view of a pump according to another embodiment of the present invention including the pressure bushing of FIG. 12.

DETAILED DESCRIPTION

[0088] FIG. 1a depicts a perspective view of an impeller 10 according to the state of art. Impeller 10 includes a top plate 20 having a central opening and an opposing bottom plate 30, wherein vertical aligned blades 40 are arranged therebetween. A rotor shaft (not shown) is coupled to a central recess of bottom plate 30 to rotate impeller 10 about its rotational axis. Blades 40 are curved in a direction perpendicular to the rotational axis of impeller 10 to form a C-shape, seen from a top sectional view of FIG. 1b, wherein blades 40 extend from the center to an outer circumference of top plate 20 and bottom plate 30, respectively. According to this, fluid enters impeller 10 at the central opening, flows through an interior formed by top plate 20 and bottom plate 30, and out in the direction perpendicular to the rotational axis of impeller 10 at the outer circumference of top plate 20 and bottom plate 30. As can be best seen in FIG. 1b, showing a sectional top view cut along a plane perpendicular to the rotational axis of impeller 10 of FIG. 1a, blades 40 are curved to form a C-shape. Further, a respective sub-blade 50 is arranged between two subsequently blades 40.

[0089] FIG. 2a shows a perspective view of an impeller 100 according to an embodiment of the present invention. Impeller 100 for a fluid pump comprises a lower pump plate 110 having at least one coupling section 112 configured to be coupled to a rotor shaft RS for driving impeller 100 about its rotational axis R. Impeller 100 further comprises an upper pump plate 120 opposing lower pump plate 110 and having a central opening 122 for providing an inlet for a fluid to be pumped. A plurality of blades 130 are arranged between lower pump plate 110 and upper pump plate 120. Lower pump plate 110 and upper pump plate 120 both have an outer circumference forming an outlet for the pumped fluid. According to this, the fluid flows in a fluid flow direction F from the fluid inlet through a pump interior formed by lower 110 and upper pump plate 120, and out at the fluid outlet.

[0090] Each of blades 130 has a suction surface 131, a pressure surface 132 opposing suction surface 131, side edges 133, 134, 135, 136 and a longitudinal axis extending at least substantially in fluid flow direction F: a first longitudinal side edge 133 of each blade 130 being attached to upper pump plate 120, a second longitudinal side edge 134 of each blade 130 opposing first longitudinal side edge 133, and being attached to lower pump plate 110, an inflow side edge 135 of each blade 130 being arranged at least substantially in the opposite direction of the fluid flow F, and an outflow side edge 136 opposing inflow side edge 135, and being arranged at least substantially in the direction of fluid flow F.

[0091] Further, as can be best seen in FIG. 2a, an angle is formed between outflow side edge 136 and lower pump plate 110, which is an acute angle. An acute angle is an angle that measures between 90° and 0°, meaning it is smaller than a right angle (an “L” shape) but has at least some space between the two lines that form it. In this particular case, the angle between outflow side edge 136 and lower pump plate 110 is approximately 60°.

[0092] Moreover, lower pump plate 110 comprises a cross-section which corresponds to a hat-like trapezoid with rounded edges, and wherein the hat-like trapezoid with rounded edges corresponds to a bell-like trapezoid with rounded edges. Upper pump plate 120 comprises a cross-section which decreases steadily, in particular exponentially, from the inside to the outside.

[0093] Referring to FIG. 2b, each blade 130 of impeller 100 is circularly arranged in regular intervals from each other between lower pump plate 110 and upper pump plate 120. According to the embodiment shown in FIGS. 2a and 2b, impeller 100 includes five blades 130. Moreover, impeller 100 further comprises a plurality of sub-blades 140, i.e. five in this particular embodiment, arranged between lower pump plate 110 and upper pump plate 120, and extending from the outer circumference of lower pump plate 110 and upper pump plate 120 to the interior formed by lower pump plate 110 and upper pump plate 120. Thus, impeller 100 comprises five blades 130 and five corresponding sub-blades 140. The radial extension of sub-blades 140 is less than the radial extension of blades 130. Sub-blades 140 are used to increase the pressure inside impeller 100 and thereby enhancing efficiency of a pump including impeller 100. Each sub-blade 140 opposing two blades 130 and is associated to a respective blade 130, wherein a distance between a sub-blade 140 to an associated blade 130 is different to another opposing blade 130. Further, each blade 130 is torqued or rather twisted in the direction perpendicular to rotational axis R of impeller 100. Additionally, each blade 130 and sub-blade 140 of impeller 100 is tapered towards respective inflow side edge 135.

[0094] An upper section 137 of each blade 130, formed between first longitudinal side edge 133 and inflow side edge 135, extends at least partially into central opening 122 of upper pump plate 120, thereby upper section 137 of each blade 130 has a substantially frustum shape with a rounded outer circumference.

[0095] Besides, the height of each blade 130 measured from first longitudinal side edge 133 to second longitudinal side edge 134 decreases steadily in the direction perpendicular to rotational axis R of impeller 100 form the inside to the outside. Furthermore, each blade 130 terminates at the outer circumference of lower pump plate 110 and upper pump plate 120.

[0096] FIG. 3a depicts a perspective view of an impeller 200 according to a further embodiment of the present invention. Moreover, FIG. 3b is a sectional side view cut along a plane parallel to rotational axis R of impeller 200 of FIG. 3a.

[0097] Impeller 200 for a fluid pump P comprises a lower pump plate 210 having at least one coupling section 212 configured to be coupled to a rotor shaft RS (not shown) for driving impeller 200 about its rotational axis R. Impeller 200 further comprises an upper pump plate 220 opposing lower pump plate 210 and having a central opening 222 for providing an inlet for a fluid to be pumped, and a plurality of blades 230 arranged between lower pump plate 210 and upper pump plate 220. Lower pump plate 210 and upper pump plate 220 both have an outer circumference forming an outlet for the pumped fluid. According to this, the fluid flows in a fluid flow direction F from the fluid inlet through a pump interior formed by lower pump plate 210 and upper pump plate 220, and out at the fluid outlet.

[0098] FIGS. 4a and 4b show different perspective views of a blade 230 used in impeller 200 depicted in FIGS. 3a to 3d. Each of blades 230 has a suction surface 231, a pressure surface 232 opposing suction surface 231, side edges 233, 234, 235, 236 and a longitudinal axis extending at least substantially in fluid flow direction F: a first longitudinal side edge 233 of each blade 230 being attached to upper pump plate 220, a second longitudinal side edge 234 of each blade 230 opposing first longitudinal side edge 233, and being attached to lower pump plate 210, an inflow side edge 235 of each blade 230 being arranged at least substantially in the opposite direction of the fluid flow F, and an outflow side edge 236 opposing inflow side edge 235, and being arranged at least substantially in the direction of the fluid flow F.

[0099] Further, as can be best seen in FIG. 3a, an angle is formed between outflow side edge 236 and lower pump plate 210, which is an acute angle. In this particular case, the angle between outflow side edge 236 and lower pump plate 210 is approximately 60°.

[0100] Additionally, suction surface 231 of each blade 230 has at least partially a convex curvature extending at least substantially in the direction of rotational axis R of impeller 200. As a result, efficiency of impeller 200 may be enhanced even further. Pressure surface 232 of each blade 230 has at least partially a concave curvature extending at least substantially in the direction of rotational axis R of impeller 200. The convex and/or concave curvatures extend substantially along the entire surface of each blade 230 in direction of the longitudinal axis extending at least substantially in fluid flow direction F.

[0101] Additionally, inflow side edge 235 and outflow side edge 236 of each blade 230 is curved substantially in the direction of rotational axis R of impeller 200.

[0102] Lower pump plate 210 and upper pump plate 220 of impeller 200 depicted in FIGS. 3a to 3d correspond to lower pump plate 110 and upper pump plate 120 of impeller 100 shown in the embodiment of FIGS. 2a and 2b.

[0103] Thus, as can be best seen in FIG. 3b, lower pump plate 210 comprises a cross-section which corresponds to a hat-like trapezoid with rounded edges, and wherein the hat-like trapezoid with rounded edges corresponds to a bell-like trapezoid with rounded edges. Upper pump plate 220 comprises a cross-section which decreases steadily, in particular exponentially, from the inside to the outside.

[0104] FIG. 3c is a sectional top view cut along a plane perpendicular to rotational axis R of impeller 200 of FIG. 3a. Each blade 230 is torqued in the direction perpendicular to rotational axis R of impeller 200. Additionally, each blade 230 and sub-blade 240 of impeller 200 is tapered towards the respective inflow side edge 235.

[0105] As can be best seen in FIG. 3d, which is a perspective sectional view cut along a plane parallel to rotational axis R of impeller 200 of FIG. 3a, inflow side edge 235 of each blade 230 is curved substantially in the direction of rotational axis R of impeller 200.

[0106] FIG. 5a shows a perspective view of an impeller 300 according to another embodiment of the present invention, wherein FIG. 5b is a corresponding sectional side view cut along a plane parallel to rotational axis R of impeller 300 of FIG. 5a.

[0107] The embodiment of impeller 300 shown in FIGS. 5a and 5b mostly corresponds to that depicted in FIGS. 3a to 3d with the exception that each blade 330 and each sub-blade 340 comprises a cross-section which has a wave-form or rather a fin-form, wherein the wave-form includes an upward portion and a downward portion.

[0108] FIG. 6a depicts a perspective view of an impeller 400 according to a further embodiment of the present invention. FIG. 6b is a sectional side view cut along a plane parallel to rotational axis R of impeller 400 of FIG. 6a.

[0109] The embodiment of impeller 400 shown in FIGS. 6a and 6b mostly corresponds to that depicted in FIGS. 5a to 5b with the exception that the outer circumference of lower pump plate 410 is larger than the outer circumference of upper pump plate 420. This increases the outlet surface of the fluid outlet.

[0110] FIG. 7a depicts a perspective view of a pump P according to an embodiment of the present invention and FIG. 7b is a perspective sectional view cut along a plane parallel to rotational axis R of impeller of pump P of FIG. 7a.

[0111] As best seen in FIG. 7b, pump P comprises a pumping chamber including a central axial fluid inlet and a tangential fluid outlet, and an impeller 10; 100; 200; 300; 400 for conveying fluid. Impeller 10; 100; 200; 300; 400 rotating within the pumping chamber. Pump P further comprises a motor (not shown) including a rotor shaft RS, wherein the rotor shaft RS is attached to the at least one coupling section 112; 212; 312; 412 of impeller 10; 100; 200; 300; 400. A heating unit H is arranged near the inner circumference of pumping chamber for heating the fluid.

[0112] As can be inferred from FIG. 7b, pump P further includes a pressure wall 500 arranged underneath impeller 10; 100; 200; 300; 400. Pressure wall 500 is described in more detail with respect to FIGS. 8a, 8b, 9a and 9b below. Pump P further comprises a pressure bushing 600 arranged on top of central opening 122; 222; 322; 422 of upper pump plate 20; 120; 220; 320; 420 of impeller 100; 200; 300; 400, and which is used for guiding fluid towards inlet of impeller 10; 100; 200; 300; 400. Pressure bushing 600 is described in detail with respect to FIGS. 10a and 10b below. Pressure wall 500 and pressure bushing 600 can be used with any conventional pump.

[0113] FIG. 8a depicts a perspective view of a pressure wall 500 according to an embodiment of the present invention. FIG. 8b is a perspective sectional side view cut along a plane parallel to the central axis A of pressure wall 500 of FIG. 8a. As can be best seen in FIG. 7b, pressure wall 500 is arranged underneath impeller 10; 100; 200; 300; 400 of pump P. Pressure wall 500 is used to guide fluid conveyed out of impeller 10; 100; 200; 300; 400 to an outlet port of pump P.

[0114] According to this, pressure wall 500 has substantially the shape of a disc. Disc-shaped pressure wall 500 has a central axis A. Pressure wall 500 comprises a top surface 510, and a bottom surface 520 opposing top surface 510, wherein top surface 510 includes an inner surface section 512 and an outer surface section 514. Inner surface section 512 extends radially from central axis A and is recessed to form a central recess 516. Outer surface section 514 includes an inner circumferential edge portion 518 and an outer circumferential edge portion 519, wherein inner circumferential edge portion 518 is located closer to central axis A than outer circumferential edge portion 519. Outer circumferential edge portion 519 is located higher than the inner circumferential edge portion 518 with respect to a plane perpendicular to central axis A and passing through inner circumferential edge portion 518. Further, pressure wall 500 comprises a cylindrical side surface 530.

[0115] Pressure wall 500 further comprises a central through hole 540 extending at least substantially along central axis A for bearing an impeller 10; 100; 200; 300; 400 of pump P. The height of outer surface section 514 measured from inner circumferential edge portion 518 to outer circumferential edge portion 519 increases in the direction perpendicular to central axis A of pressure wall 500. Outer surface section 514 is inclined towards central axis A of pressure wall 500. Moreover, outer surface section 514 has a concave shape extending substantially around the entire circumference of outer surface section 514.

[0116] FIG. 9a is a perspective view of a pressure wall 500 according to a further embodiment of the present invention. FIG. 9b is a sectional side view cut along a plane parallel to the central axis A of pressure wall 500 of FIG. 9a.

[0117] The embodiment of pressure wall 500 shown in FIGS. 9a and 9b mostly corresponds to that depicted in FIGS. 8a and 8b with the exception that outer surface section 514 of top surface 510 of pressure wall 500 has in addition to the concave shape a helical shape which extends in direction towards central axis A of pressure wall 500. Helical shape extends almost entirely around the entire circumference of outer surface section 514 of top surface 510 of pressure wall 500.

[0118] FIG. 10a shows a perspective view of a pressure bushing 600 according to an embodiment of the present invention. FIG. 10b depicts a sectional side view cut along a plane parallel to the central axis A of pressure bushing 600 of FIG. 10a.

[0119] As can be best seen in FIG. 10b, pressure bushing 600 comprises a bottom portion 610, an outer side portion 620 and an inner side portion 630. Bottom portion 610 is configured to match the contour of upper pump plate 20; 120; 220; 320; 420 of impeller 10; 100; 200; 300; 400 and can be attached thereto. This is particularly shown in pump P of FIGS. 7a and 7b.

[0120] Inner side portion 630 of pressure bushing 600 has an inner circumference, which tapers towards bottom portion 610 of pressure bushing 600, i.e. towards upper pump plate 20; 120; 220; 320; 420 of impeller 10; 100; 200; 300; 400 of pump P in an assembled configuration. In the embodiment shown in FIGS. 10a and 10b, inner circumference of inner side portion 630 of pressure bushing 600 tapers towards bottom portion 610 by the method of tensile triangles, with the resulting edges rounded. As shown in sectional view of FIG. 10b, the cross-section of inner side portion 630 of pressure bushing 600 is defined by three tensile triangles 640.

[0121] FIG. 11 depicts a sectional side view of an impeller 200 cut along a plane parallel to rotational axis R of impeller 200 according to a further embodiment of the present invention.

[0122] The embodiment of impeller 200 shown in FIG. 11 mostly corresponds to that depicted in FIGS. 3a to 3d with the exception that a circumferential upper ring plate 238 is formed near the outer circumference of upper pump plate 220 and a circumferential lower ring plate 238 is formed near the outer circumference of lower pump plate 210. Ring plates 238, 239 are attached to the outer surfaces of pump plates 210, 220 of impeller 200, respectively.

[0123] FIG. 12 shows a sectional view of a pressure bushing 600 according to a further embodiment of the present invention. The embodiment of pressure bushing 600 depicted in FIG. 12 mostly corresponds to that shown in FIGS. 10a and 10b with the exception that bottom portion 610 further comprises a pressure ring 650 attached to the outer circumference of bottom portion 610 of pressure bushing 600.

[0124] FIG. 13 depicts a sectional view of a pump P according to another embodiment of the present invention including pressure bushing 600 of FIG. 12. As can be inferred from FIG. 13, pressure ring 650 protrudes over upper pump plate 220 of impeller 200 and thereby reduces the gap between pressure bushing 600 and impeller 200.

REFERENCE SIGNS

[0125] 10 impeller

[0126] 20 top plate

[0127] 30 bottom plate

[0128] 40 blades

[0129] 50 sub-blades

[0130] 100; 200; 300; 400 impeller

[0131] 110; 210; 310; 410 lower pump plate

[0132] 112; 212; 312; 412 coupling section

[0133] 120; 220; 320; 420 upper pump plate

[0134] 122; 222; 322; 422 central opening

[0135] 130; 230; 330; 430 blades

[0136] 131; 231; 331; 431 suction surface

[0137] 132; 232; 332; 432 pressure surface

[0138] 133; 233; 333; 433 first longitudinal side edge

[0139] 134; 234; 334; 434 second longitudinal side edge

[0140] 135; 235; 335; 435 inflow side edge

[0141] 136; 236; 336; 436 outflow side edge

[0142] 137; 237; 337; 437 upper section

[0143] 138; 238; 338; 438 upper ring plate

[0144] 139; 239; 339; 439 lower ring plate

[0145] 140; 240; 340; 440 sub-blades

[0146] 500 pressure wall

[0147] 510 top surface

[0148] 512 inner surface section

[0149] 514 outer surface section

[0150] 516 central cylindrical recess

[0151] 518 inner circumferential edge portion

[0152] 519 outer circumferential edge portion

[0153] 520 bottom surface

[0154] 530 cylindrical side surface

[0155] 540 central through hole

[0156] 600 pressure bushing

[0157] 610 bottom portion

[0158] 620 outer side portion

[0159] 630 inner side portion

[0160] 640 tensile triangles

[0161] 650 pressure ring

[0162] A central axis

[0163] F fluid flow direction

[0164] H heating unit

[0165] P pump

[0166] R rotational axis

[0167] RS rotor shaft