Electric centrifugal fluid pump

Abstract

The invention refers to electric centrifugal fluid pump (10) with a pump wheel (20) rotating around a vertical rotation axis (R), an electric drive motor (30) driving the pump wheel (20), and a pump housing (100) housing the pump wheel (20) and the electric drive motor (30), wherein the pump housing (100) comprises a pumping chamber housing (110) with a pumping chamber wall (110') defining a pumping chamber (119) in which the pump wheel (20) rotates, a radial-axial fluid inlet conduit (120) with a pump inlet opening flange (122) surrounding a pump inlet opening (12), and a tangential-radial outlet conduit (130) with a pump outlet opening flange (132) surrounding a pump outlet opening (14), whereas the pump inlet opening flange (122) and the pump outlet opening flange (132) have a single linear fluidic mounting axis (M), wherein the fluidic mounting axis (M) is inclined with respect to the horizontal plane (xy) with a mounting axis angle (a) of at least 4°, and wherein the tangential-radial outlet conduit (130) lies in a horizontal plane (xy) lying perpendicular with respect to the rotation axis (R).

Description

[0001] Electric centrifugal fl uid pump

[0002] The invention refers to an electric centrifugal fluid pump, and preferably refers to a circulation pump for a heating and / or cooling liquid circuit of a building.

[0003] A typical electric centrifugal fluid pump being a circulation pump for a heating liquid in a heating liquid circuit is provided with a fluid inlet conduit being in-line with a fluid outlet conduit, both being defined by a pumping chamber housing. The pumping chamber housing also defines a pumping chamber wherein a pump wheel rotates.

[0004] It is typical for a fluid flow pump with a centrifugal pump wheel that the pump chamber inlet opening has an axial orientation and a pump chamber outlet opening has a tangential orientation so that the pump chamber inlet opening and the pump chamber outlet opening are generally not in-line with each other. A typical centrifugal fluid pump for stationary heating liquid circuits is disclosed in DE 68 910 574 DI and is provided with a pump inlet opening and a pump outlet opening being linearly in-line with each other for facilitating the installation of the fluid pump in a linear tube section of the heating circuit. The orientations of the pump inlet opening and the pump outlet opening are exactly rectangular with respect to the rotational axis of the pump wheel. The inlet conduit between the pump inlet opening and the pump chamber inlet opening and the outlet conduit between the pump chamber outlet opening and the pump opening both comprise several curves to provide a linear mounting axis of the pump but cause a substantial fluidic resistance.

[0005] GB 681 295 A and US 2 851 955 A disclose fluid flow pumps with a pump inlet conduit and a pump outlet conduit not being arranged perpendicular to the rotation axis of the pump wheel to reduce the overall fluid resistance. However, the fluid resistance in the outlet conduit is still relatively high because the inclination of the outlet conduit versus the transversal plane of the volute causes substantial flow resistance where the fluid leaving the volute has considerable turbulences.

[0006] It is an object of the invention to provide an in-line type electric flow pump with minimum flow resistance.

[0007] This object is solved according to the invention with an electric centrifugal fluid pump with the features of claim 1.

[0008] The electric centrifugal fluid pump is of the flow-type and is provided with a pump wheel, for example an impeller, rotating around an axial / vertical rotation axis. The fluid pump is provided with an electric drive motor directly driving the pump wheel. The fluid pump is provided with a pump housing which houses the pump wheel and the electric drive motor. The pump housing comprises a separate pumping chamber housing, which is provided with a pumping chamber wall defining a pumping chamber in which the pump wheel rotates and the pumped fluid is accelerated in radial and tangential direction.

[0009] The pumping chamber housing defines a radial-axial fluid inlet conduit with a pump inlet opening flange surrounding a pump inlet opening and defines a tangential-radial outlet conduit with a pump outlet opening flange surrounding a pump outlet opening. The pump inlet opening flange and the pump outlet opening flange are geometrically linearly in-line with each other and thereby define a single linear fluidic mounting axis. The electric centrifugal fluid pump can simply be integrated into a linear fluid tube by simply substituting a linear section of the fluid tube by the electric centrifugal fluid pump.

[0010] The fluidic mounting axis is inclined with respect to the horizontal plane with a mounting axis angle of at least 4°. The inclination of the mounting axis versus the horizontal plane reduces the maximum bending of the inlet conduit between the pump inlet opening and the pump chamber inlet opening to maximally 86° so that the fluid resistance can be reduced in this part of the fluid pump.

[0011] The tangential-radial outlet conduit lies in a horizontal plane being perfectly perpendicular with respect to the vertical rotation axis so that the fluid leaving the volute has a smooth transition from the volute to the outlet conduit. Consequently, the fluid resistance in this part of the fluid pump is reduced to a minimum. As a result, the overall fluid resistance of the electric centrifugal fluid pump is optimized.

[0012] Preferably, the mounting axis of the pump outlet opening flange is inclined with the mounting axis angle with respect to the tangential-radial outlet circuit which lies in a horizontal plane. By angling the pump outlet opening flange with respect to the horizontal outlet conduit, a single linear mounting axis for the pump inlet opening flange and the pump outlet opening flange is realized whereas the total fluidic resistance of the pump is reduced.

[0013] Preferably, the radial part of the radial-axial fluid inlet conduit is inclined with the mounting axis angle, so that the radial part of the fluid inlet conduit is substantially defining the linear fluidic mounting axis of the fluid pump.

[0014] Preferably, the pumping chamber housing is provided with several axial stiffening ribs extending distally in axial direction from the pumping chamber wall. Preferably, the pumping chamber housing is made out of plastic. The axial stiffening ribs make the pumping chamber housing sufficiently stiff against high static pressures which are specific for circulation pumps in a heating liquid circuit of a building.

[0015] Preferably, the pumping chamber housing has two sections, i.e. an outlet section including and defining the fluid outlet conduit, and an inlet section including and defining the fluid inlet conduit. The outlet section of the pumping chamber housing is provided with several, i.e. at least two radially orientated stiffening ribs which have a radial extension with reference to the axial rotation axis of the pump rotor. The inlet section of the pumping chamber housing is provided with several transversal stiffening ribs being parallel to each other and being arranged substantially orthogonal with respect to the linear mounting axis defined by the inlet opening flange and the outlet opening flange. Preferably, the outlet section and the inlet section each define substantially half of the circumference of the pumping chamber.

[0016] The outlet section with the radial stiffening ribs only allows an axial- vertical deforming direction, whereas the inlet section with the transversal parallel stiffening ribs allows a horizontal or an axial-vertical deforming direction. As a consequence, axial undercuts are possible at the pumping chamber housing body which provides more freedom for the construction of the pumping chamber housing. In particular, the increased constructural freedom allows to incline the fluidic mounting axis with respect to the horizontal plane of the pumping chamber housing with a few degrees which can substantially reduce the fluidic resistance of the complete fluidic path of the fluid pump.

[0017] The radial part of the radial-axial fluid inlet conduit has an angle of more than 94° with respect to the horizontal plane of the axial inlet opening of the pump wheel so that the incoming fluid is deflected by less than 86° between the pump housing inlet opening and the pump wheel inlet opening.

[0018] Preferably, the radial stiffening ribs of the outlet section are arranged star- like with respect to the rotation axis.

[0019] The pumping chamber wall defines a volute surrounding the pump wheel and having an increasing volute cross-section in volute-downstream direction with the highest volute cross-section at the fluidic volute end where the tangential part of the tangential-radial outlet conduit begins. Preferably, the pumping chamber housing defines a pumping chamber housing mounting flange lying in a horizontal plane with respect to the vertical rotation axis of the pump wheel. The mounting flange of the pumping chamber housing is the mechanical interface between the pumping chamber housing and the motor housing. At least 50%, and more preferably all of the stiffening ribs extend to the outside radius of the mounting flange.

[0020] Preferably, the pumping chamber housing defines at least two fixation bodies each defining an axial fixation bore for mounting and fixing the pumping chamber housing to the motor housing by a bolt, a screw or another axial fixation means. The fixation bodies have to withstand the high axial fixation forces caused by the internal fluid pressure of up to 25 bar. The stiffening ribs extend to each of the fixation bodies so that the fixation bodies have a massive mechanical support.

[0021] Preferably two fixation bodies are provided at the outlet section and two fixation bodies are provided at the inlet section of the pumping chamber housing. More preferably, the fixation bodies are arranged equidistantly at the mounting flange in angles of, for example 90° with respect to each other.

[0022] Preferably the stiffening ribs have a minimum axial extension of 5 mm. Preferably, at least five radial stiffening ribs are provided.

[0023] One embodiment of the invention is described with reference to the enclosed drawings, wherein figure 1 shows a side view of an electric centrifugal fluid pump with a pump housing including a pumping chamber housing, figure 2 shows a top view of the pumping chamber housing of the fluid pump of figure 1, figure 3 shows a perspective view of the pumping chamber housing of figures 1 and 2, and figure 4 shows a bottom view of the pumping chamber housing of figures 1 to 3.

[0024] Figures 1 and 3 show an electric centrifugal fluid pump 10 which is suitable to be a circulation pump for pumping a heating liquid, for example water, in a heating liquid circuit of a building with several floor levels. Generally, a heating circulation pump is located at a vertically low position of the heating circuit so that the static gravitation pressure in the fluid pump 10 typically is in the range of 10 to 20 bar.

[0025] The fluid pump 10 is provided with a pump housing 100 comprising a separate plastic pumping chamber housing 110 and a separate motor housing 190. The motor housing 190 encloses an electric drive motor 30 having an electromagnetic motor stator 32 and a permanently magnetized motor rotor 34. The electric drive motor 30 is designed as a canned motor.

[0026] The plastic pumping chamber housing 110 is made of a single fiber- reinforced plastic body and houses a centrifugal pump wheel 20 which is designed as an impeller with a central axial inlet opening and a ring-like radial outlet opening. The rotor comprising the pump rotor 20 and the corotating motor rotor 34 rotates around a rotation axis R. having a vertical orientation z.

[0027] The pumping chamber housing 110 has a pumping chamber wall 110' which surrounds a pumping chamber 119 including an outlet volute 90. The pump wheel 20 rotates within the pumping chamber 119 and is radially surrounded by the outlet volute 90. The outlet volute 90 has an increasing cross-section in upstream direction.

[0028] The pumping chamber housing 110 also defines a radial-axial fluid inlet conduit 120 with an inlet opening flange 122 and a tangential-radial outlet conduit 130 with an outlet opening flange 132. The inlet opening flange 122 surrounds a pump inlet opening 12 and the outlet opening flange 132 surrounds a pump outlet opening 14. The inlet opening flange 122 and the outlet opening flange 132 are geometrically perfectly in-line with each other at a linear fluidic mounting axis M. The fluidic mounting axis M is inclined with respect to the horizontal plane xy with an inclination angle of about 15°.

[0029] The tangential-radial outlet conduit 130 lies in a horizontal plane xyl30 being perpendicular with respect to the vertical rotation axis R. The mounting axis M of the pump outlet opening flange 132 is inclined with the mounting axis angle a with respect to the horizontal plane xyl30 of the tangential-radial outlet conduit 130. The radial part 120R of the radial- axial fluid inlet conduit 120 is inclined with the mounting axis angle a with respect to the horizontal plane xyl30 of the tangential-radial outlet conduit 130.

[0030] The pumping chamber housing 110 is provided with several axial stiffening ribs 51-58, 61-66 extending distally in axial direction z from the pumping chamber wall 110'. With reference to the orientation of the stiffening ribs 51-58, 61-66, the pumping chamber housing 110 is divided into two sections: the outlet section 111 including the complete fluid outlet conduit 130 and the inlet section 112 including the fluid inlet conduit 120. The virtual vertical plane separating the outlet section 111 from the inlet section 112 includes the rotation axis R and is orientated at right angle with respect to the fluidic mounting axis M. In the inlet section 112, the six axially extending stiffening ribs 61 - 66 at both lateral sides of the inlet conduit 120 are vertical transversal stiffening ribs 61 - 66, which are parallel to each other and which are arranged in vertical transversal planes yz at right angles with respect to the mounting axis M, respectively. In the outlet section 111, the seven stiffening ribs are radial stiffening ribs 51-58 which are orientated not in transversal vertical planes yz, i.e. not in a right angle to the mounting axis M, but are orientated radially with respect to the rotation axis R and together define a star -like rib structure. The pumping chamber housing 110 defines an axial pump chamber inlet opening 92 lying in a horizontal plane xy and also defines a ring-like pumping chamber housing mounting flange 140 lying in another horizontal plane xy. Radially outside of the ring-like portion of the mounting flange 140, four massive fixation bodies 81-84 are provided, each of them defining an axial fixation bore 85. The pumping chamber housing fixation bodies 81 - 84 vertically correspond with four fixation bodies 81', 82' at the motor housing 190. The motor housing 190 and the pumping chamber housing 110 are held together by four screws 88 extending through the motor housing fixation bodies 81', 82' and being screwed into the pumping chamber housing mounting bodies 81 - 84.

[0031] As shown in figure 2, the corresponding stiffening ribs 53, 57, 63, 66 radially extent to each of the four fixation bodies 81-84 so that the fixation bodies 81-84 are axially supported by the corresponding stiffening ribs 53, 57, 63, 66. All stiffening ribs 51-66 radially extent to the outside radius of the pumping chamber housing mounting flange 140. The axial extension of the stiffening ribs 51-66 is at least 5 mm.

[0032] The pumping chamber housing 110 is provided with three circumferential ring-like stiffening ribs 71, 72, 73 which lie in horizontal planes xy parallel to each other and which substantially surround and stiffen the circumferential pumping chamber wall 110' defining the volute 90.

[0033] The terms "horizontal" and "vertical" in the present context always do not refer to terrestrial planes but generally refer to the rotation axis R which is defined to be the vertical axis in the present context.

Claims

CLAI MS1. An electric centrifugal fluid pump (10) with a pump wheel (20) rotating around a vertical rotation axis (R), an electric drive motor (30) driving the pump wheel (20), and a pump housing (100) housing the pump wheel (20) and the electric drive motor (30), wherein the pump housing (100) comprises a pumping chamber housing (110) with a pumping chamber wall (110') defining a pumping chamber (119) in which the pump wheel (20) rotates, a radial-axial fluid inlet conduit (120) with a pump inlet opening flange (122) surrounding a pump inlet opening (12), and a tangential-radial outlet conduit (130) with a pump outlet opening flange (132) surrounding a pump outlet opening (14), whereas the pump inlet opening flange (122) and the pump outlet opening flange (132) have a single linear fluidic mounting axis (M), wherein the fluidic mounting axis (M) is inclined with respect to the horizontal plane (xy) with a mounting axis angle (a) of at least 4°, and wherein the tangential-radial outlet conduit (130) lies in a horizontal plane (xyl30) lying perpendicular with respect to the rotation axis (R).

2. The electric centrifugal fluid pump (10) of claim 1, wherein the mounting axis (M) of the pump outlet opening flange (132) is inclined with the mounting axis angle (a) with respect to the tangential-radial outlet conduit (130).

3. The electric centrifugal fluid pump (10) of one of the preceding claims, wherein the radial part (120R.) of the radial-axial fluid inlet conduit (120) is inclined with the mounting axis angle (a).

4. The electric centrifugal fluid pump (10) of one of the preceding claims, wherein the pumping chamber housing (110) is provided with several axial stiffening ribs (51-58, 61-66) extending distally in axial direction (z) from the pumping chamber wall (110').

5. The electric centrifugal fluid pump (10) of one of the preceding claims, wherein an outlet section (111) of the pumping chamber housing (110) including the fluid outlet conduit (130) is provided with several radial stiffening ribs (51-58) and an inlet section (112) of the pumping chamber housing (110) including the fluid inlet conduit (120) is provided with several transversal parallel stiffening ribs (61-66) being arranged, substantially orthogonal with respect to the mounting axis (M).

6. The electric centrifugal fluid pump (10) of claim 5, wherein the radial stiffening ribs (51-58) are arranged star-like with respect to the rotation axis (R).

7. The electric centrifugal fluid pump (10) of one of the preceding claims 5 or 6, wherein the pumping chamber housing (110) defines a pumping chamber housing mounting flange (140) lying in a horizontal plane (xy) and wherein at least 50% of the stiffening ribs (51-58, 61-66) extend to the outside radius of the pumping chamber housing mounting flange (140).

8. The electric centrifugal fluid pump (10) of one of the preceding claims 4 to 7, wherein the pumping chamber housing (110) defines at least two fixation bodies (81-84) each defining an axial fixation bore (85), whereas the stiffening ribs (53, 63, 66, 56) axially extend to the fixation bodies (81-84), respectively.

9. The electric centrifugal fluid pump (10) of claim 8, wherein at least four fixation bodies (81-84) are provided, whereas two fixation bodies (81, 84) are provided at the outlet section (111) and two fixation bodies (82, 83) are provided at the inlet section (H2) of the pumping chamber housing (110).

10. The electric centrifugal fluid pump (10) of one of the preceding claims 5 to 9, wherein the stiffening ribs (51-58, 61-66) have a minimum axial extension of 5 mm.

11. The electric centrifugal fluid pump (10) of one of the preceding claims 6 to 10, wherein at least five radial stiffening ribs (51-58) are provided.

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