Electric centrifugal fluid pump

Abstract

The invention refers to an electric centrifugal fluid pump (10) with a pump wheel (20) rotating around an axial 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 head cover (110) with a pumping chamber wall (110') defining a pumping chamber (119) wherein the pump wheel (20) rotates, an axial-radial fluid inlet channel (120) with an inlet opening flange (122), and a tangential-radial outlet channel (130) with an outlet opening flange (132) being geometrically in-line with the inlet opening flange (122) at a single fluidic mounting axis (M), and wherein the pumping chamber head cover (110) is provided with several axial stiffening ribs (51-58, 61-66) extending distally in axial direction (z) from the pumping chamber wall (110'), and wherein an outlet section (111) of the head cover (110) including the fluid outlet channel (130) is provided with several radial stiffening ribs (51-58) and an inlet section (112) of the head cover (110) including the fluid inlet channel (120) is provided with several transversal parallel stiffening ribs (61-66) being arranged at a right angle with respect to the mounting axis (M).

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 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 channel being in-line with a fluid outlet channel, both being defined by a single plastic pumping chamber head cover. The plastic pumping chamber head cover defines a pumping chamber wherein a pump wheel rotates. Typically, a heating circuit circulation pump is provided at a vertically low position of the heating circuit so that the gravitation pressure of the liquid can be up to 25 bar, even if the building only has a few floor levels. This fact makes it difficult to use inexpensive plastic parts for the fluidic part of the electric centrifugal fluid pump.

[0004] Typical plastic pumping chamber head covers for a high gravitation pressure are known from US 9 624 945 B2 and EP 1 950 420 A2, which both disclose a pumping chamber head cover which is provided with several stiffening ribs extending distally in axial direction from the pumping chamber wall defined by the pumping chamber head cover. The stiffening ribs improve the structural stability of the pumping chamber head cover against high fluidic pressures. All stiffening ribs extend radially from the rotor center in a star-like manner. Therefore, during the manufacturing process of the plastic pumping chamber head cover, the demoulding can only be realized in axial direction so that no axial undercuts are possible or allowed at the pumping chamber head cover. This substantially restricts the structural possibilities for the construction of the pumping chamber head cover. It is an object of the invention to provide an electric centrifugal fluid pump with reduced restrictions in the construction of the pumping chamber head cover.

[0005] This object is solved according to the invention with an electric centrifugal fluid pump with the features of claim 1.

[0006] The electric centrifugal fluid pump is provided with a pump wheel, for example an impeller, rotating around an axial 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 plastic pumping chamber head cover, which is provided with a pumping chamber wall defining a pumping chamber in which the pump wheel rotates and the pumped fluid is accelerated.

[0007] The pumping chamber head cover defines a radial-axial fluid inlet channel with a pump inlet opening flange and defines a tangential-radial outlet channel with a pump outlet opening flange. 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.

[0008] The pumping chamber head cover is provided with several axial stiffening ribs extending distally in axial direction from the pumping chamber wall. The pumping chamber head cover has two sections, i.e. an outlet section including and defining the fluid outlet channel, and an inlet section including and defining the fluid inlet channel. The outlet section of the head cover is provided with several 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 head cover 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.

[0009] 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 head cover body which provides more freedom for the construction of the pumping chamber head cover. In particular, the increased constructural freedom allows to incline the fluidic mounting axis with respect to the horizontal plane of the pumping chamber head cover with a few degrees which can substantially reduce the fluidic resistance of the complete fluidic path of the fluid pump. In particular, the radial-axial fluid inlet channel can have an angle of more than 90° 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 90° between the pump housing inlet opening and the pump wheel inlet opening. Preferably, the fluidic mounting axis is inclined with respect to the horizontal plane by at least 7°.

[0010] Preferably, the radial stiffening ribs of the outlet section are arranged star- like with respect to the rotation axis.

[0011] Preferably, the pumping chamber wall defines a volute surrounding the pump wheel and having an increasing volute cross-section in volutedownstream direction with the highest volute cross-section at the fluidic volute end where the tangential part of the tangential-radial outlet channel begins.

[0012] Preferably, the pumping chamber head cover defines a head cover mounting flange lying in a horizontal plane with respect to the vertical- axial rotation axis of the pump wheel. The mounting flange of the mounting head cover is the mechanical interface between the pumping chamber head cover and the motor housing. At least 50%, and more preferably all of the stiffening ribs extend to the outside radius of the mounting flange.

[0013] Preferably, the pumping chamber head cover defines at least two fixation bodies each defining an axial fixation bore for mounting and fixing the pumping chamber head cover 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.

[0014] Preferably two fixation bodies are provided at the outlet section and two fixation bodies are provided at the inlet section of the pumping chamber head cover. More preferably, the fixation bodies are arranged equidistantly at the mounting flange in angles of, for example 90° with respect to each other.

[0015] Preferably the stiffening ribs have a minimum axial extension of 5 mm. Preferably, at least five radial stiffening ribs are provided.

[0016] Preferably, the fluidic mounting axis is inclined with respect to the horizonal plane with at least 4° .

[0017] 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 head cover, figure 2 shows a top view of the pumping chamber head cover of the fluid pump of figure 1, figure 3 shows a perspective view of the pumping chamber head cover of figures 1 and 2, and figure 4 shows a bottom view of the pumping chamber head cover of figures 1 to 3.

[0018] Figures 1 and 3 show an electric centrifugal fluid pump 10 which is suitable to be a circulation pump for pumping a heating liquid 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.

[0019] The fluid pump 10 is provided with a pump housing 100 comprising a plastic pumping chamber head cover 110 and a separate motor housing part 190. The motor housing part 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.

[0020] The plastic pumping chamber head cover 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- axial orientation z.

[0021] The pumping chamber head cover 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.

[0022] The pumping chamber head cover 110 also defines a radial-axial fluid inlet channel 120 with an inlet opening flange 122 and a tangential-radial outlet channel 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°.

[0023] The pumping chamber head cover 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 head cover 110 is divided into two sections: the outlet section 111 including the complete fluid outlet channel 130 and the inlet section 112 including the fluid inlet channel 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 channel 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.

[0024] The pumping chamber head cover 110 defines an axial pump chamber inlet opening 92 lying in a horizontal plane xy and also defines a ring-like head cover 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 head cover fixation bodies 81 - 84 vertically correspond with four fixation bodies 81', 82' at the motor housing part 190. The motor housing part 190 and the pumping chamber head cover 110 are held together by four screws 88 extending through the motor housing fixation bodies 81', 82' and being screwed into the pumping chamber head cover mounting bodies 81-84.

[0025] 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 head cover mounting flange 140. The axial extension of the stiffening ribs 51-66 is at least 5 mm.

[0026] The pumping chamber head cover 110 is provided with three circumferential stiffening ribs 71, 72, 73 which lie in horizontal planes xy parallel to each other and which substantially surround the circumferential wall 110' of the volute 90.

[0027] 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

CLAIMS1. 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 head cover (110) with a pumping chamber wall (110') defining a pumping chamber (119) in which the pump wheel (20) rotates, an axial-radial fluid inlet channel (120) with an inlet opening flange (122), and a tangential-radial outlet channel (130) with an outlet opening flange (132) being geometrically in-line with the inlet opening flange (122) at a single linear fluidic mounting axis (M), and wherein the pumping chamber head cover (110) is provided with several axial stiffening ribs (51-58, 61-66) extending distally in axial direction (z) from the pumping chamber wall (110'), characterized in that an outlet section (111) of the head cover (110) including the fluid outlet channel (130) is provided with several radial stiffening ribs (51-58) and an inlet section (112) of the head cover (110) including the fluid inlet channel (120) is provided with several transversal parallel stiffening ribs (61-66) beingarranged substantially orthogonal with respect to the mounting axis (M).

2. The electric centrifugal fluid pump (10) according to claim 1, wherein the radial stiffening ribs (51-58) are arranged star-like with respect to the rotation axis (R).

3. The electric centrifugal fluid pump (10) of one of the preceding claims, wherein the pumping chamber wall (110') defines a volute (90).

4. The electric centrifugal fluid pump (10) of one of the preceding claims, wherein the pumping chamber head cover (110) defines a head cover 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 head cover mounting flange (140).

5. The electric centrifugal fluid pump (10) of one of the preceding claims, wherein the pumping chamber head cover (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.

6. The electric centrifugal fluid pump (10) of claim 5, 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 (112) of the head cover (110).

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

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

9. The electric centrifugal fluid pump (10) of one of the preceding claims, wherein the fluidic mounting axis (M) is inclined with respect to the horizontal plane (xy) with at least 4°.

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