Electric fluid pump

Abstract

The invention refers to a An electric fluid pump (10) with a pump housing comprising a plastic pump housing part (12) which integrally defines a threaded fluid connector (20, 20'), whereas the fluid connector (20, 20') comprises a ring flange body (21') defining a ring flange (21) with a ring flange surface (24) lying in a flange plane and surrounding a connector opening (22), wherein the ring flange body (21') has a radial ring flange body width (t21) of more than 3.5 mm, an outer connector thread (26) adjacent to the ring flange (21), wherein the outer connector thread (26) has at least two thread turns (26a–26e) and has a thread depth (d26) of at least 1.0 mm, and at least one radial thread interruption recess (31, 32, 33, 31', 32', 33') which is provided at the ring flange body (21'), circumferentially interrupts at least one thread turn (26b, 26c, 26d) of the outer connector thread (26), has a radial recess depth (d3) being higher than the thread depth (d26), and has a pocket bottom (34) with a radial bottom wall thickness (t3) of at least 1.0 mm.

Description

[0001] - 1 - PP.P.23009. WO / EB 08.11.2024

[0002] Electric fluid pump

[0003] The invention refers to an electric fluid pump, preferably to a stationary electric water pump being part of a stationary house heating system.

[0004] Electric fluid pumps for applications in stationary heating systems have standardized fluid connectors with a ring flange body defining a ring flange surface lying in a cross plane. The ring flange body also is provided with a defined outer connector thread and a defined connector opening, whereas the radial thickness of the ring flange body can be 4 mm up to almost 8 mm, or even more.

[0005] Stationary electric fluid pumps are provided with a pump housing part which defines the fluid connectors, i.e. an inlet fluid connector and an outlet fluid connector. Normally, the pump housing part defining the fluid connectors is made of metal. However, the more complex this pump housing part is, the more expensive is the manufacturing thereof.

[0006] Alternatively, the pump housing part being geometrically complex and defining the fluid connectors can be made from plastic. However, relatively thick plastic portions of more than 3 mm thickness are difficult if not impossible to be precisely produced by a plastic injection molding process because of the inhomogeneous cooling behavior of relatively thick plastic portions and the geometric distortions resulting therefrom. Geometric distortions are not acceptable in particular at the connectors ring flange body of which the ring flange surface as well as the outer - 2 - PP.P.23009. WO / EB 08.11.2024 connector thread is highly relevant for a reliable sealing quality when the connector flange body is connected to a connecting fluid pipe.

[0007] It is an object of the invention to provide an inexpensive electric fluid pump with good sealing quality of the fluid connectors.

[0008] This object is, according to the invention, solved with an electric fluid pump with the features of claim 1.

[0009] The electric fluid pump according to the invention is provided with a pump housing comprising a plastic pump housing part which integrally defines at least one threaded fluid connector. Preferably, the plastic pump housing part defines an inlet fluid connector and an outlet fluid connector.

[0010] The fluid connector comprises a ring flange body defining a ring flange with a ring flange surface lying in a cross plane which is the flange plane. The connector's ring flange body surrounds a connector opening and is provided with an outer connector thread, which thread has at least two thread turns and which thread has a thread depth of at least 1.0 mm.

[0011] The ring flange body has a radial thickness of more than 3.5 mm, which radial thickness is the radial ring flange body width without the connector thread. In stationary heating system applications, the radial ring flange body width of the electric fluid pump can not be optimized because the geometric parameters of the threaded fluid connector including the ring flange body with the outer thread are standardized. - 3 - PP.P.23009. WO / EB 08.11.2024

[0012] The fluid connector is provided with at least one radial thread interruption recess which circumferentially interrupts at least one thread turn of the outer connector thread and which has a recess depth being higher than the thread depth so that the radial thread interruption recess not only interrupts the at least one thread but also protrudes into the ring flange body radially inside of the outer connector thread. The radial thread interruption recess has a pocket bottom, whereas the material strength at the pocket bottom, i.e. the radial bottom wall thickness, is at least 1.0 mm, preferably at least 3.0 mm.

[0013] The radial thread interruption recess locally massively reduces the radial thickness of the ring flange body so that the ring flange body can cool down faster right after the injection molding process step. As a result, the cooling behavior of the plastic ring flange right after the injection molding step is more homogenous and the geometric distortions resulting therefrom are reduced. This allows to provide an electric fluid pump with a standardized fluid connector with a radially relatively thick ring flange body made of plastic and having a sufficient precision to provide sufficient sealing qualities.

[0014] Preferably, the most distal threat turn is not interrupted by any radial thread interruption recess. The most distal threat turn is the threat turn which initially engages with an inner thread of a connecting means, for example of a coupling nut which is provided with a complementary inner thread. Since the most distal threat turn is not interrupted, the initial screwing of the complementary connecting means is not complicated by the threat interruption recess. - 4 - PP.P.23009. WO / EB 08.11.2024

[0015] Every threat interruption recess is a direct axial fluidic shortcut through the outer connector thread. Since the most distal threat turn of the outer connector thread is not interrupted by any radial threat interruption recess, a sufficient fluidic tightness of the threat connection can be ensured.

[0016] Preferably, the most proximal threat turn is not interrupted by any radial threat interruption recess so that the fluidic tightness of the threat connection is improved accordingly.

[0017] Preferably, the circumferential recess width angle of the radial threat interruption recess is less than 20°. The circumferential width of the radial threat interruption recess is limited to 20° so that the affected thread turns are interrupted locally with a maximum interruption of 20° by the corresponding threat interruption recess. As a consequence, also the interrupted threat turns of the outer connector thread keep their functionality and ensure a smooth and reliable screwing.

[0018] Preferably, the number of threat interruption recesses at the ring flange body is at least four and is maximally eight. The threat interruption recesses are not necessarily distributed all over the ring flange body circumference equidistantly. However, the circumferential distance of neighboring threat interruption recesses preferably is at least equal to the circumferential extension of the threat interruption recess. - 5 - PP.P.23009. WO / EB 08.11.2024

[0019] Preferably, all threat interruption recesses are free of undercuts seen from one radial demoulding direction or from the exactly opposite demoulding direction. All circumferential side wall surfaces of all threat interruption recesses have no undercuts, seen from the corresponding demoulding axis. As a geometric consequence, the axis' of symmetry of the threat interruption recesses do not necessarily have a precise radial orientation. This geometric concept allows to provide numerous threat interruption recesses at a plastic ring flange body manufactured by injection molding.

[0020] Preferably, the threat interruption recesses are slightly conical. In particular, the side wall surfaces of the threat interruption recesses define a conical shape.

[0021] Preferably the electric fluid pump is a centrifugal flow-type pump, and the plastic pump housing part defines a substantial part of a flow pump volute. The plastic pump housing part thereby can define many different structural features in one single part which allows to provide an inexpensive electric fluid pump.

[0022] One embodiment of the electric fluid pump according to the invention is described with reference to the enclosed drawings, wherein figure 1 shows a radial side view of the electric fluid pump with a plastic pump housing part defining an inlet fluid connector and an outlet fluid connector of which the connector ring flange bodies are provided with radial threat interruption recesses, - 6 - PP.P.23009. WO / EB 08.11.2024 figure 2 shows an axial bottom view of the electric fluid pump of figure 1, figure 3 shows an axial top view of the electric fluid pump of figures 1 and 2, and figure 4 shows a cross-section IV-IV of a connector ring flange of one of the fluid connectors of the electric fluid pump of figures 1 to 3.

[0023] Figures 1 to 3 show an electric centrifugal flow-type fluid pump 10 which is suitable to be a stationary circulation pump for pumping a heating liquid in a stationary heating liquid circuit of a building. Generally, a heating circulation pump is located at a vertically low position of the heating circuit so that the static gravitation pressure in the electric fluid pump 10 is always typically in the range of 10 to 20 bar. This requires a high sealing quality and durability of the fluid connections of the electric fluid pump 10 being a part of the heating liquid circuit.

[0024] The electric fluid pump is provided with a pump housing comprising a plastic pump housing part 12 and a separate plastic motor housing part 14. The motor housing part 14 encloses an electric drive motor having an electromagnetic motor stator and a permanently magnetized motor rotor.

[0025] The plastic pump housing part 12 is made of a single fiber-reinforced plastic body and substantially defines a flow pump volute 18 and houses a centrifugal pump wheel. The plastic pump housing part 12 integrally - 7 - PP.P.23009. WO / EB 08.11.2024 defines a threaded inlet fluid connector 20 and a threaded outlet fluid connector 20'.

[0026] Both fluid connectors 20, 20' are basically identical with each other and are provided with a ring flange body 21' defining a circular ring flange 21 with a plane ring flange surface 24 lying in a flange plane and surrounding a circular connector opening 22. The fluid connector 20, 20' comprises an outer connector thread 26 provided adjacent to the ring flange surface 24, which connector thread 26 has five thread turns 26a - 26e and has a thread depth d26 of about 2.0 mm.

[0027] In the present embodiment, the connector thread 26 of the fluid connectors 20, 20' is in accordance with the Whitworth standard and defines a G I1 / *" thread with an outer thread diameter of about 48 mm and an inner thread diameter of about 44 mm. The inner diameter d22 of the connector opening 22 is about 34 mm, so that the radial ring flange body width t21 is about 5 mm and the total radial flange width t26 including the ring flange body 21' and the connector threat 26 is about 7 mm.

[0028] Every fluid connector 20, 20' is provided with six radial threat interruption recesses 31, 32, 33, 31', 32', 33' which are provided in two lateral groups, wherein each group has three threat interruption recesses

[0029] 31, 32, 33 and 31', 32', 33'. Every radial thread interruption recess 31,

[0030] 32, 33, 31', 32', 33' is provided at radial the outside of the ring flange body 21' and circumferentially interrupts the three middle threat turns 26b, 26c, 26d of the outer connector thread 26, so that the most proximal threat turn 26a as well as the most distal threat turn 26e are - 8 - PP.P.23009. WO / EB 08.11.2024 not interrupted by any threat interruption recess. Every threat interruption recess 31, 32, 33, 31', 32', 33' as a substantially identical circumferential recess width angle a3 of about 10° and has a total radial recess depth d3 of about 3.5 mm so that the radial bottom wall thickness t3 of a recess bottom wall 34 is about 3.5 mm.

[0031] Seen in radial direction, the openings of the threat interruption recesses 31, 32, 33, 31', 32', 33' are substantially square in shape. The sidewalls of the interruption recesses 31, 32, 33, 31', 32', 33' are slightly conical seen from the corresponding radial demoulding direction xdl, xd2 so that all threat interruption recesses 31, 32, 33, 31', 32', 33', and in particular their circumferential sidewalls 300, are free of any undercurrents, seen from the corresponding radial demoulding direction xdl, xd2.

Claims

- 9 - PP.P.23009. WO / EB 08.11.2024CLAIMS1. An electric fluid pump (10) with a pump housing comprising a plastic pump housing part (12) which integrally defines a threaded fluid connector (20, 20'), whereas the fluid connector (20, 20') comprises a ring flange body (21') defining a ring flange (21) with a ring flange surface (24) lying in a flange plane and surrounding a connector opening (22), wherein the ring flange body (21') has a radial ring flange body width (t21) of more than 3.5 mm, an outer connector thread (26) adjacent to the ring flange (21), wherein the outer connector thread (26) has at least two thread turns (26a-26e) and has a thread depth (d26) of at least 1.0 mm, and at least one radial thread interruption recess (31, 32, 33, 31', 32', 33') which thread interruption recess (31, 32, 33, 31', 32', 33') is provided at the ring flange body (21'), circumferentially interrupts at least one thread turn (26b, 26c, 26d) of the outer connector thread (26), has a radial recess depth (d3) being higher than the thread depth (d26), and has a pocket bottom (34) with a radial bottom wall thickness (t3) of at least 1.0 mm.- 10 - PP.P.23009. WO / EB 08.11.20242. The electric fluid pump (10) of claim 1, wherein the most distal threat turn (26e) is not interrupted by any radial thread interruption recess (31, 32,33, 31', 32', 33').

3. The electric fluid pump (10) of one of the preceding claims, wherein the most proximal threat turn (26a) is not interrupted by any radial thread interruption recess (31, 32,33, 31', 32', 33').

4. The electric fluid pump (10) of one of the preceding claims, wherein the circumferential recess width angle (a3) of the radial thread interruption recess (31, 32,33, 31', 32', 33') is less than 20°.

5. The electric fluid pump (10) of one of the preceding claims, wherein the number of thread interruption recesses (31, 32,33, 31', 32', 33') is at least four and is maximally eight.

6. The electric fluid pump (10) of the preceding claim, wherein all thread interruption recesses (31, 32,33, 31', 32', 33') are free of undercuts seen from one radial demoulding direction (xdl) or the opposite demoulding direction (xd2).

7. The electric fluid pump (10) of one of the preceding claims, wherein the thread interruption recess (31, 32,33, 31', 32', 33') is slightly conical.- 11 - PP.P.23009. WO / EB 08.11.20248. The electric fluid pump (10) of one of the preceding claims, wherein the plastic pump housing part (12) defines an inlet fluid connector (20) and an outlet fluid connector (20').

9. The electric fluid pump (10) of one of the preceding claims, wherein the electric fluid pump (10) is a flow-type pump, and the plastic pump housing part (12) substantially defines a flow pump volute (18).

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