EP4705639A1 - An ingress protection element - Google Patents

Abstract

Described and claimed is an ingress protection element for an open end of a stator chamber of a wet-running electric motor. The stator chamber is formed between a stator housing and a rotor can of the wet-running electric motor. The ingress protection element extends in an arc shape about a center axis between an inner edge and an outer edge. The outer edge is formed on an axial ingress protection section of the ingress protection element extending parallel to the center axis. The axial ingress protection section sectionally prevents direct access to the stator of the wet-running electric motor through a drainage opening of the wet-running electric motor. The ingress protection element abuts circumferentially against at least one of the rotor can, a stator support and the stator housing of the electric motor so that the ingress protection element is centered about a rotor axis of the electric motor and the center axis coincides with the rotor axis.

Description

Applicant: GRUNDFOS HOLDING A/S

Title: An ingress protection element

Our Ref.: GP 3724 WO

Description

[01 ] The present invention is directed to an ingress protection element for an open end of a stator chamber of a wet-running electric motor. The invention is further directed to a wet-running electric motor comprising an ingress protection element for an open end of a stator chamber.

[02] Wet-running electric motors are often used to drive impellers of centrifugal pumps. An electric motor is deemed to be wet-running when the pump fluid is not restricted to the pump chamber of the pump but is also present in a rotor chamber of the electric motor, for example, to lubricate the rotor and the drive shaft. The rotor chamber is delimited towards the stator and particularly the live parts of the stator using a rotor can. The rotor can thus prevents any fluid inside the rotor can from coming into contact with the electrically conducting or live parts of the stator. The stator is circumferentially arranged around the rotor can. A stator housing and a motor housing encapsulate both the rotor chamber and the stator chamber.

[03] Especially in cases where the wet-running electric motor is used as a pump for cold liquids in humid conditions, condensation may occur on an outer surface of the rotor can due to the cold pump fluid inside the rotor chamber. This is particularly prevalent in tropic and subtropic regions with high humidity when the pump is used as part of an air conditioning system for pumping cooling media. As the condensation occurs on the outside of the rotor can, i.e., in the stator chamber, condensed water may accumulate near the live parts of the electric motor. To avoid damages to the electric motor, the condensed water needs to be removed from the stator chamber.

[04] To this end, a plurality of drainage openings is commonly provided through which the condensed water can flow out of the stator chamber. For example, the drainage openings may be provided at an interface between the stator housing and the rotor can or in the stator housing. When the pump has been installed, one of the drainage openings needs to be located at the lower most point of the stator chamber so that any water that accumulates inside the stator chamber may flow out of the stator housing through the opening. The drainage opening mitigates the risks of damages to the electric motor which could be caused by condensed water.

[05] The drainage openings provide a potential way for direct ingress of water from the outside of the motor housing into the stator chamber. While such ingress cannot be excluded, the water can also be drained through the existing drainage opening at the lower most point of the stator chamber so that the risk due to ingress of water through the drainage openings is commonly limited.

[06] Furthermore, the drainage openings may not only form a potential pathway forwaterentering the inside of the stator housing but could also be used for inserting parts into the stator housing which could potentially contact conducting parts of the stator damaging the stator or increasing the risk of electrocution. This needs to be prevented for the wet-running electric motor to meet the requirements of ingress protection level IPX4D.

[07] It is, therefore, an object of the present invention to provide a means for mitigating the risk that a solid object inserted through a drainage opening into the stator chamber could potentially contact live parts of the stator. [08] The present invention is directed to on ingress protection element and a wet-running electric motor according to the independent claims. Preferred embodiments of the ingress protection element are the subject matter of the dependent claims.

[09] In a first aspect, an ingress protection element for an open end of a stator chamber of a wet-running electric motor is provided. The stator chamber is formed between a stator housing and a rotor can of the wetrunning electric motor and houses a plurality of stator coils resting on a stator support. The ingress protection element extends in an arc shape about a center axis between an inner edge and an outer edge. The outer edge is formed on an axial ingress protection section of the ingress protection element. The axial ingress protection section extends parallel to the center axis and is configured for sectionally preventing direct access to the stator of the wet-running electric motor through a drainage opening of the wet-running electric motor. The ingress protection element is configured to abut circumferentially against at least one of the rotor can, the stator support and the stator housing of the electric motor so that the ingress protection element is centered about a rotor axis of the electric motor and the center axis coincides with the rotor axis.

[10] In otherwords, in the preferred embodiment an ingress protection element is provided which can be placed at an open end of a stator chamber of wet-running electric motor. The wet-running electric motor comprises at its center a rotor which is rotatable about a rotor axis. The rotor is arranged inside a rotor can which is filled during operation of the electric motor with a liquid. For example, in case the wet-running electric motor is used as a part of a centrifugal pump assembly for driving one or more impellers of the centrifugal pump, the liquid may be the pump liquid. [1 1 ] The rotor chamber is surrounded by the stator of the electric motor which is in turn arranged inside a stator housing. The stator housing may, for example, be generally cup-shaped, i.e., it is based on a cylinder which is closed at one end. At the second end the stator housing is open so that the stator, the rotor can, and the rotor can be inserted into the stator housing. When the electric motor has been assembled, the open end of the stator housing may, for example, be closed by a part of the rotor can extending outwards from the rotor axis and generally perpendicular to the rotor axis. In another example, a dedicated cover is provided for closing the space between the rotor can and the stator housing. A space between the rotor can and the stator housing in which the stator is arranged is referred to as the stator chamber.

[12] The stator may, for example, comprises a plurality of coils which are under voltage, i.e., form live parts, when the electric motor is operating. The coils are in an exemplary embodiment provided on a stator support. The stator support may, for example, comprise two stator end caps which delimit the stator in the direction of the rotor axis. The end cap facing towards the closed end of the stator housing may comprise electrical contacts for powering the stator coils whereas the stator end cap facing towards the open end of the stator housing does commonly not comprise any electric contacts. Nevertheless, at least the upper layers of windings forming the coils may be exposed towards the open end of the stator housing so that they can be accessed through the open end of the stator housing when it has not been closed. Note that it is understood that the actual conductors forming the actual windings of the coils will usually be encapsulated in an insulating material.

[13] The wet-running electric motor comprises one or more drainage openings for removing water from the stator chamber. Water may, for example, accumulate inside the stator chamber due to condensation that occurs when a cold pump liquid flows inside the rotor can and the air surrounding the electric motor is humid. Also, water may flow into the stator chamber through the one or more drainage openings. The drainage openings may, for example, be formed at an interface between the stator housing and rotor can. In another example, drainage openings may additionally or alternatively be formed entirely in the stator housing.

[14] The ingress protection element is provided for placement at the open end of the stator chamber to restrict or prevent access to the stator coils through, for example, the drainage openings of the electric motor. The ingress protection element is generally arc-shaped, i.e., the basic shape of the ingress protection element is circular or covers at least a part of a circle. The center of the ingress protection element is defined by a center axis around which the ingress protection element is formed.

[15] The ingress protection element extends between an outer edge and an inner edge. The terms inner edge and outer edge refer to the distance of the respective edge of the ingress protection element from the central axis where the inner edge is closer to the central axis than the outer edge.

[16] The outer edge is formed on a part of the ingress protection element that extends parallel to the center axis and is thus referred to as the axial ingress protection section. The axial ingress protection section may, for example, transition into the outer edge, extends parallel to the center axis and is configured for sectionally preventing direct axis to the stator of the wet-running electric motor through a drainage opening of the wet-running electric motor in a direction extending perpendicular to the center axis.

[17] The ingress protection element is intended to be placed inside the motor housing of a pump assembly. The axial ingress protection section may, for example, be placed or inserted between the stator housing and the stator. Once installed in the motor housing, the location of the ingress protection element is determined by one or more parts of the motor housing against which the ingress protection element abuts. The ingress protection element is in contact with one or more of the rotor can, the stator support or the stator housing. The position of these parts of the electric motor in the motor housing and, in particular, relative to the rotor axis is well defined. The ingress protection element is shaped so that when it has been installed in the motor housing, the central axis of the ingress protection element coincides with the rotor axis of the motor.

[18] Once installed in the motor housing, the ingress protection element surrounds at least part of the live parts of the stator. In this position, the axial ingress protection section prevents an unauthorized person from touching live parts of the stator by inserting an item such as a wire through one of the drainage openings of the electric motor. Other parts of the ingress protection element may also hinder access to the live parts of the stator through the drainage openings. To this end, the ingress protection element is generally formed so that there is no direct line of view or direct line along which the stator windings can be reached through the drainage openings.

[19] The ingress protection element does usually not provide a fluid- tight seal of the stator chamber. Rather, it facilitates drainage of water which has accumulated in the stator chamber. To this end, a gap may be present between the outer edge of the ingress protection element and the stator housing.

[20] In a preferred embodiment, a radial ingress protection section of the ingress protection element extends generally radially away from the center axis between the axial ingress protection section and the inner edge. In other words, the axial ingress protection section generally ex- tends perpendicular to the radial ingress protection section. The inner edge may be formed on the radial ingress protection section or may, for example, delimit the radial ingress protection section towards the rotor can.

[21 ] Further preferably, the inner edge is configured to abut partially and preferably circumferentially against the rotor can of the electric motor so that the ingress protection element is centered by the rotor can about the rotor axis of the electric motor. Thus, the inner edge is configured to abut preferably for its entire length, i.e., over the full arc or even a full circle against the rotor can of the electric motor so that the ingress protection element is centered by the rotor can about the rotor axis of the electric motor. The ingress protection element thus not only surrounds the rotor can but its inner edge is in contact with the rotor can and preferably with an outer surface of a section of the rotor can extending parallel to the rotor axis and surrounding the rotor chamber.

[22] In a preferred embodiment, a plurality of condensation recesses is formed in the outer edge and, further preferably, also the adjacent axial ingress protection section. Thus, in the preferred embodiment the outer edge of the ingress protection element does not extend, for example, along a continuous arc or circle about the center axis but comprises several indentations where the outer edge recedes so that water or other liquid present in the stator chamber can flow out of the stator chamber. For example, the condensation recesses may allow water to pass between the ingress protection element and a stator end cap which may be in contact with the non-receding sections or parts of the outer edge. Thus, the condensation recesses facilitate drainage of water that has accumulated in the stator chamber.

[23] Preferably, the condensation recesses are equidistantly distributed about the circumference of the outer edge. [24] In a preferred embodiment, the outer edge is formed by a circumferential protrusion, wherein the protrusion extends radially away from the center axis. Hence, in the preferred embodiment outer edge is formed by a projection that extends over the entire arc covered by the ingress protection element. The projection is formed on the axial ingress protection section in a direction extending away from the center axis of the ingress protection element. Thus, the outer edge points away from the rotor can when installed in the electric motor. The protrusion advantageously improves protection of the stator from water flowing through the drainage openings into the stator housing.

[25] In a preferred embodiment, the circumferential protrusion is interrupted wherever the outer edge transitions into a condensation recess of the plurality of condensation recesses. In other words, the protrusion does in the exemplary embodiment does not follow the outer edge wherever it recedes to form one of the condensation recesses but is instead discontinued. Interrupting the circumferential protrusion simplifies manufacture of the ingress protection element. However, it should be noted that it would also be possible to provide a circumferential protraction that extends continuously along the outer edge and the condensation recesses for an improved protection of the stator chamber from fluid entering through the drainage openings of the electric motor.

[26] Preferably, the circumferential protrusion is interrupted for the entirety of each of the condensation recesses, i.e., the circumferential protrusion stops where a condensation recess begins and continuous on the other side of the condensation recess. This embodiment is preferred from a manufacturing point of view, in particular, in case the ingress protection element is manufactured using plastic injection molding.

[27] Alternatively, the circumferential protrusion partially continues along each of the condensation recesses. For example, the protrusion may be interrupted where the outer edge transitions into the condensation recess, continue partially along the recess and be again interrupted where the condensation recess transition back to the outer edge. This embodiment provides a trade-off between a simplified design of the tool required for manufacturing the ingress protection element and an improved protection from water ingress provide by the circumferential protrusion.

[28] Further preferably, a plurality of radially extending indentations is formed on an inner surface of the ingress protection element. The inner surface of the ingress protection element faces towards the stator cham- berwhen the ingress protection element is mounted in an electric motor. The indentations form channels for condensed water. Thus, in the preferred embodiment channels for water are formed on an inner surface of the ingress protection element. The inner surface faces towards the stator of the electric motor once the ingress protection element has been installed and extends generally perpendicular to the center axis, i.e., radially away from the center axis. On this surface a plurality of indentations or depression are formed which extend generally radially away from the center axis. These indentations form channels or flow paths for water that has accumulated inside the stator chamber away from the inner edge of the ingress protection element and towards the outer edge and the ingress protection section. The channels are particularly advantageous in case the inner surface of the ingress protection element should come in (circumferential) contact with a stator end cap of the electric motor as they provide a passageway for water past the stator end cap. Without the passageways water could potentially accumulate inside the stator chamber.

[29] Preferably, each of the plurality of indentations is aligned with one of the plurality of condensation recesses. Hence, in the preferred embodiment each indentation forming a channel for water from the inside of the stator chamber towards the ingress protection section and the condensation recesses is oriented so that it points to one of the condensation recesses. Thereby it is ensured that water from the inside of the stator chamber is directed towards the condensation recesses. Furthermore, in case one of the condensation recesses is arranged in an installed electric motor so that it points downwards, the channel formed by the indentation also points downwards.

[30] In a preferred embodiment, a plurality of radially extending indentations is formed on an outer surface of the ingress protection element. The outer surface of the ingress protection element faces away from the stator chamber when the ingress protection element is mounted in an electric motor. The indentations form channels for condensed water or ingress water. Hence, in the exemplary embodiment corresponding indentations are formed on an outer surface of the ingress protection element which outer surface extends preferably also generally perpendicular to the center axis. The indentations provide a flow path for ingress water or condensation water in case the outer surface of the ingress protection element should be in contact with, for example, a radially outward extending part of the rotor can or another cover for the open end of the stator housing.

[31 ] Preferably, the inner edge of the ingress protection element is formed as a lip extending parallel to the center axis. The lip is configured to be inserted between a rotor can and a stator end cap of an electric motor. Thus, in the present embodiment a lip extending parallel to the center axis is formed which forms the inner edge of the ingress protection element. For example, the lip could be formed on the inner surface of the ingress protection element and point towards the stator when the ingress protection element has been installed in an electric motor. The lip provides more rigid support of the ingress protection element on the rotor can and also improves sealing thereof. [32] In a preferred embodiment, a plurality of spacers is formed on an outer surface of the ingress protection element. The outer surface of the ingress protection element faces away from the stator chamber when the ingress protection element is mounted in an electric motor. The spacers are formed to maintain a minimum distance between an adjacent component of the electric motor and the outer surface so that water can flow between the outer surface and the adjacent component of the electric motor.

[33] Spacers on an outer surface may be used additionally or alternatively to indentations formed on the outer surface. Both ensure that ingress water or condensed water may flow along the outer surface of the ingress protection element so that it can drain out of the motor through drainage openings.

[34] In a preferred embodiment, a plurality of snap-fit projections is formed on the axial ingress protection section. The snap-fit projections are configured for engaging with corresponding snap-fit elements of the electric motor for securing the ingress protection element in a direction of the center axis. Thus, in the preferred embodiment snap-fit projections are provided on the ingress protection element for temporarily interlocking with mating snap-fit elements on a part of the motor, for example, the stator end cap. The snap-fit projections may, for example, be formed on an inner surface of the ingress protection section. The snap-fit projections would thus point inwards towards the center axis. Mating snap-fit elements could be formed, for example, on a stator end cap facing outwards away from the center axis. Alternatively, outward facing snap-fit projections pointing away from the center axis could be provided on an outer surface of the ingress protection section, while mating snap-fit elements are formed on an inner surface of the stator housing facing towards the center axis. The interlock between the snap-fit elements and the snap-fit projections releasably secures the ingress protection element against movement in the axial direction.

[35] In a preferred embodiment, an elongated protrusion protruding radially away from the center axis is formed on the axial ingress protection section. The elongated protrusion is configured for supporting the ingress protection element on the stator housing. The elongated protrusion is preferably interrupted one or more times to enable a flow of condensed water or ingress water on the axial ingress protection section.

[36] Thus, in addition to the outer edge of the ingress protection section element, a further projection is formed on an outer surface of the axial ingress protection section. The projection may be formed by a series of adjacent but spaced apart or interrupted elevations, that serve as spacers for maintaining a distance between an inner surface of the stator housing and the axial ingress protection section so that water can flow between the ingress protection element and the stator housing. The projection may further or alternatively define the position of the ingress protection element in the stator chamber, in particular, in case the ingress protection element lacks a radial ingress protection section. The interruptions may additionally or alternatively be used to correctly positioning the ingress protection element inside the stator housing by engaging corresponding positioning elements formed on the stator housing.

[37] In a preferred embodiment, the ingress protection element is formed as a partial arc extending between a first end and a second end. Hence, in the preferred embodiment the ingress protection element is not ring-shaped and does not extend for a full circle. An ingress protection element covering only part of a full arc may be sufficient if there are only very few drainage openings as it may not be necessary to install an ingress protection element in areas without drainage openings. Limiting the size of the ingress protection element by providing on ingress protection element covering only a partial arc may also reduce the risk of condensation inside the stator chamber on the ingress protection element.

[38] Further preferably, the first end and the second end of the ingress protection element project away from the stator chamber and are configured for preventing a flow of condensed water or ingress water towards the stator chamber, preferably by abutting at least partially against the stator housing. Hence, in the preferred embodiment the first and second end of the ingress protection element delimit the ingress protection element in the circumferential direction. The first end and the second end point away from the axial and/orradial protection element and the stator when the ingress protection element has been installed in the motor housing. In other words, the first and second end of the axial ingress protection section may point radially away from the center axis. And the first and second end of the radial ingress protection section, if available, may point parallel to the center axis and away from the stator.

[39] The first and second ends are shaped to prevent ingress water which entered the motor housing through the drainage opening from the flowing into the stator chamber where the ingress protection elements end in the circumferential direction. The shape of the first and second ends thus essentially delimit the space formed between the stator housing and the ingress protection element. The first and second ends may additionally or alternatively be used to position the ingress protection element inside the stator chamber.

[40] In a preferred embodiment, the ingress protection element extends in a ring shape about the center axis. Hence, in the preferred embodiment the ingress protection element extends for a full arc about the center axis. Thereby, access to the live parts of the stator is prevented equally from all sides of the stator housing. Further, using a circular ingress protection element simplifies the installation thereof in the electric motor as the orientation of the ingress protection element inside the electric motor and about the rotor axis does not have to considered.

[41 ] Preferably, the ingress protection element is formed as a single piece using plastic injection molding. For example, the ingress protection element could be made fora thermoplastic polyester with 30% glass fiber such as 30% glass reinforced modified polyethylene terephthalate resin.

[42] In a second aspect, the invention is directed to a wet-running electric motor comprising a stator chamber formed between a stator housing and a rotor can of the wet-running electric motor and an ingress protection element according to any of the preceding embodiment attached to an open end of the stator chamber. The previously described embodiments of an ingress protection element also apply to the wetrunning electric motor. Also, the advantages of the electric motor correspond to that of the ingress protection element used therein.

[43] Finally, in an exemplary third aspect the invention is directed to a pump assembly comprising a pump housing and a wet-running electric motor according to any of the preceding embodiments. The pump housing comprises at least one impeller arranged on a drive shaft that is driven by the wet-running electric motor.

[44] In the following, exemplary embodiments of an ingress protection element as well as a wet-running electric motor and a pump assembly will be described with reference to the drawings, wherein

Figure 1 shows a sectional view of a pump assembly comprising a wet-running electric motor and a centrifugal pump,

Figure 2a shows a perspective view of a first exemplary embodiment of an ingress protection element, Figure 2b shows another perspective view of the first exemplary embodiment of an ingress protection element,

Figure 2c shows a bottom view of the first exemplary embodiment of an ingress protection element,

Figure 2d shows a top view of the first exemplary embodiment of an ingress protection element,

Figure 3a shows a perspective view of a second exemplary embodiment of an ingress protection element,

Figure 3b shows another perspective view of the second exemplary embodiment of an ingress protection element,

Figure 4a shows a perspective view of a third exemplary embodiment of an ingress protection element,

Figure 4b shows another perspective view of the third exemplary embodiment of an ingress protection element,

Figure 4c shows a partial sectional view of the third exemplary embodiment of an ingress protection element,

Figure 5a shows a perspective view of a fourth exemplary embodiment of an ingress protection element,

Figure 5b shows sectional view of the fourth exemplary embodiment of an ingress protection element,

Figure 5c shows a detail of the sectional view of Figure 5b,

Figure 6a shows a perspective view of a fifth exemplary embodiment of an ingress protection element,

Figure 6b shows a detail of the section view of Figure 6a,

Figure 7a shows a perspective view of a sixth exemplary embodiment of an ingress protection element,

Figure 7b shows a detail of a bottom sectional view of the sixth exemplary embodiment of an ingress protection element,

Figure 8 shows a perspective view of a seventh exemplary embodiment of an ingress protection element,

Figure 9 shows a perspective view of an eighth exemplary embodiment of an ingress protection element, and Figure 10 shows a perspective view of a nineth exemplary embodiment of an ingress protection element.

[45] Figure 1 shows an exemplary embodiment of a pump assembly 1 comprising a wet-running electric motor 3 and a centrifugal pump 5. A pump housing 7 of the centrifugal pump 3 defines an impeller chamber 9 in which an impeller 1 1 is arranged rotatably about a rotor axis 12 on a rotor shaft 13. The pump housing 7 further defines an inlet 15 through which a pump fluid is ingested into the pump 5 and an outlet 17 for dispensing the pressurized pump fluid.

[46] The rotor shaft 13 further supports a rotor 19 of the wet-running electric motor 3. The rotor 19 is guided by two bearings 21 a, 21 b inside the electric motor 3 and arranged inside a rotor chamber 23. The rotor chamber 23 is defined by a generally cup-shaped rotor can 25 which separates the rotor chamber 23 from the surrounding stator chamber 27. The rotor chamber 23 is filled with the pump liquid which serves as a lubricant and may also provide cooling. A bearing plate 29 closes the rotor chamber 23 towards the impeller chamber 9 and supports one of the bearings 21 a which guide the rotor shaft 13.

[47] The stator chamber 23 is formed by an also generally cup-shaped stator housing 31 in which the stator 33 of the electric motor 3 and also the rotor 19 are arranged. The stator 33 comprises a plurality of coils 35 which are supported on a stator support 37 formed by two stator end caps 37a, 37b and surround the stator lamination 39. The stator end cap 37b arranged in proximity of a closed end 41 of the stator housing 31 provides electrical connections for the stator coils 35. The other stator end cap 37a forms the opposing end of the stator 33 facing towards an open end 43 of the cup-shaped stator housing 31 . In the pump arrangement 1 shown in Figure 1 , the open end of the stator housing 31 is closed by the bearing plate 29 and partly also by a part of the rotor can 25 that extends radially away from the rotor axis 12.

[48] During operation of the pump assembly 1 , the rotor camber 23 is filled with pump liquid. In particular, in case the pump 5 is used for pressurizing a cool pumping fluid such as, for example, cooling liquid of air conditionings system, water may condense inside the stator chamber 27 on the rotor can 25. This effect is particularly prominent in humid regions such as the tropics where air temperatures and humidity are high. In order to avoid damages to the live parts of the stator 33, drainage openings 45 are provided in the electric motor 3. In the exemplary embodiment shown in Figure 1 , the drainage openings 45 are provided at the interface of the stator housing 31 and the rotor can 23.

[49] However, these drainage openings 45 provide an ingress point for (liquid) water and could also be used to insert foreign parts into the stator chamber 27. These foreign parts and the ingress water could come into contact with, for example, the live stator coils 35. The latter are powered during operation of the pump assembly 1 and could be damaged or pose a risk to a person inserting a foreign part into the pump.

[50] To obstruct a direct or straight path from the drainage openings 45 to the live parts of the stator 33, an ingress protection element 47 has been mounted inside the electric motor 3. The ingress protection element 47 comprises an inner edge 49 which is in circumferential contact with an outer surface 51 of the rotor can 25. The outer surface 51 extends parallel to the rotor axis 12. The rotor can 25 thus centers the ingress protection element 47 about the rotor axis 12 that coincides when the ingress protection element 47 has been installed in an electric motor 3 with a center axis 53 of the ingress protection element 47. [51 ] The ingress protection element 47 is delimited on its outer circumference by on outer edge 55 that is, however, in the embodiment shown in Figure 1 not in contact with an inner surface 57 of the stator housing 31 but spaced apart therefrom. The outer edge 55 is formed at an axial ingress protection section 59 of the ingress protection element 47 which extends parallel to the center axis 53 and at least partially prevents direct access through the drainage openings 45 to the stator 33. In the embodiment of Figure 1 , the axial ingress protection section 59 prevents access to the outer stator end cap 37a which is part of a stator support 37.

[52] Furthermore, the ingress protection element 47 also comprises a radial ingress protection section 61 that extends from the inner edge generally radially away towards the axial ingress protection section 59. In the embodiment show in Figure 1 , the radial ingress protection section 61 also prevents access through the drainage openings 45 to stator 33 and, here, in particular, the live parts thereof. The ingress protection element thus prevents foreign parts inserted through one of the drainage openings 45 from reaching the stator 33 and, in particular, the stator coils 35. Also, ingress water spraying or flowing into the electric motor 3 through the drainage openings 45 will not be able to directly reach the live parts of the motor.

[53] During assembly of the electric motor 3, first the stator 33 is placed in the stator housing 31. Afterwards, the ingress protection element 47 is placed onto the outer stator end cap 37a, before the rotor can 25 is inserted for centering the ingress protection element 47. Afterwards, the rotor 19 and the rotor shaft 13 are installed in the electric motor 3 which is eventually closed off using the bearing plate 29.

[54] A detailed description of embodiments of ingress protection elements 47 that can be used in the exemplary embodiment of a pump assembly 1 shown in Figure 1 comprising an exemplary embodiment of a wet-running motor 3 will subsequently be described with reference to the following figures.

[55] Figures 2a to 2d show detailed views of a first exemplary embodiment of an ingress protection element 47 which could be used in the electric motor 2 of Figure 1 . The ingress protection element 47 extends between an inner edge 49 and an outer edge 55 which both extend circumferentially for a full circle or arc about a center axis 53. The outer edge 55 is formed partially by a circumferential protrusion 63 that extends radially away from the center axis 53 and an adjacent axial ingress protection section 59 of the ingress protection element 47. Only some of the circumferential protrusions 63, which are provided to prevent ingress water from flowing part the ingress protection element 47 into the stator chamber 27, have been designate with reference numerals to keep the figures intelligible.

[56] Between the circumferential protrusions 63 condensation recesses 65 are formed which provide a pathway for water from the inside of the stator chamber 27 to flow towards the drainage openings 45 in case the outer edge 55 of the ingress protection element is otherwise in circumferential contact with parts of the electric motor 3, for example, the outer stator end cap 37a. In the embodiment seen shown in Figures 2a to 2d, the circumferential protrusions 63 are interrupted for the full length of the condensation recesses 65 which simplifies production of the ingress protection element 47. Only some of the condensation recesses 65 have been designated with reference numerals to keep the figures intelligible.

[57] The axial ingress protection section 59 merges into a radial ingress protections section 61 that extends generally radially away from the centeraxis 53. On an outer surface 67 of the radial ingress protections section 61 shown in Figures 2b and 2c indentations 69 are formed. Similar indentations 71 are formed on an inner surface 73 of the radial ingress protec- tions section 61 . The inner surface 73 faces towards the stator 33 when the ingress protection element 47 has been mounted in an electric motor 3 and the outer surface 67 faces away from the stator 33.

[58] The radially extending indentations 69, 71 on either surface 67, 73 forms channels for water such as ingress water or condensed water in case either of the surface should be in extended contact with other parts of the electric motor 3. For example, the inner surface 73 could be in circumferential contact with the outer stator end cap 37a and the indentations 71 on the inner surface 73 allow water from the stator chamber 27 to flow past the stator end cap 37a which prevents an accumulation of relevant amounts of water inside the stator chamber 27. Similarly, the indentations 69 on the outer surface 67 allow water to flow past areas of the outer surface 67 that are in extended contact, for example, with a radial part of the rotor can 25 or a cover for the open end of the 43 of the stator housing 31. Only some of the indentations 69, 71 have been labelled with reference numerals to keep the figures intelligible.

[59] Note that the indentations 71 on the inner surface 73 are aligned with the condensation recesses 65 to direct the water directly to the recesses 65 so that it can flow out of the stator chamber27. To the contrary, the indentations recesses 69 on the outer surface 67 are aligned with the circumferential protrusion 63 which prevent water flowing along the outer surface 67 of the ingress protection element 47 from flowing into the stator chamber 27.

[60] Finally, the inner edge 49 of the ingress protection element 47 is formed as a lip 75 that extends axially to support the ingress protection cap 47 on a rotor can 25 and provide an improved sealing with regard thereto. [61 ] Figures 3a and 3b show a simplified second exemplary embodiment of an ingress protection element 47. Only the differences with regard to the embodiment of Figures 2a to 2d will be described subsequently. Throughout the following description of the different embodiment, like elements will be designated will like reference numerals. Also, where multiple elements would be designed with the same reference numeral in figures, reference numerals may have been omitted to keep the figures intelligible.

[62] In the second exemplary embodiment, no indentations are provided on the inner and outer surfaces 67, 73 of the radial ingress protection section 61. Also, the condensation recesses 65 are shaped differently.

[63] Figures 4a, 4b and 4c show a third exemplary embodiment of an ingress protection element 47. Only the differences with regard to the embodiment of Figures 2a to 2d will be described subsequently. In this embodiment, neither condensation recesses 65 are formed along the outer edge 55 nor any indentations 69, 71 are provided in the radial ingress protection section 61 .

[64] To facilitate water flow between the outer surface 67 of the radial ingress protection section 61 and an adjacent radial section of a rotor can 25, spacer elements 77 are formed on the outer surface 67. Furthermore, an extended collar 79 is formed at the inner edge 49 of the ingress protection element 47. The extended collar 79 extends parallel to the center axis 53 and can be used for placing an O-ring or another seal between the ingress protection element 47 and a rotor can 25 for preventing water from entering the stator chamber 27 by flowing along an outer surface 51 of the rotor can 25. The collar 79 is supported by a plurality of ribs 81 . [65] The outer surface 51 of the rotor can 25 is the most likely place for condensation as it cooled by the liquid inside the rotor chamber 23. Thus, a seal placed at the interface of the rotor can 25 and the ingress protection element 47 will prevent condensed water from flowing into the stator chamber 27. Thus, the need for draining the inside of the stator chamber 27 will be further reduced.

[66] A fourth exemplary embodiment of an ingress protection element 47 is shown in Figures 5a to 5c. Again, only the differences with regard to the embodiment of Figures 2a to 2d will be described subsequently.

[67] In this embodiment, snap-fit projections 83 are formed on an inner surface 85 of the axial ingress protection section 59 which faces towards the stator chamber 27 when the ingress protection element 47 is mounted in an electric motor 3. The snap-fit projections 83 point towards the center axis 53 and are provided for interlocking with corresponding snap-fit elements 87 on outer stator end caps 37a which are shown for reference in Figures 5b and 5c. The snap-fit connection between the stator end cap 37a and the ingress protection element 47 secures the ingress protection element 47 in a direction extending parallel to the rotor axis 12. In all other embodiments, the ingress protection element 47 is only secured in the radial direction by its form-fit connection with the rotor can 25.

[68] A fifth exemplary embodiment of an ingress protection element 47 is shown in Figures 6a and 6b. Again, only the differences with regard to the embodiment of Figures 2a to 2d will be described subsequently.

[69] In the fifth exemplary embodiment, the circumferential protrusion 63 on the outer edge 55 is not interrupted for the condensation recesses 65 but follows along the condensation recesses. This results in an im- proved protection from ingress water but is more difficult to manufacture.

[70] A sixth exemplary embodiment of an ingress protection element 47 is shown in Figures 7a and 7b. Again, only the differences with regard to the embodiment of Figures 2a to 2d will be described subsequently.

[71 ] In the sixth exemplary embodiment, the circumferential protrusion 63 on the outer edge 55 is interrupted where the outer edge 55 transitions into a condensation recess 65 and then continues along the condensation recess 65. As compared to the fifth embodiment, similar protection from ingress water is achieved but at a reduced manufacturing effort.

[72] Figure 8 shows a seventh exemplary embodiment of an ingress protection element 47. Again, only the differences to the exemplary embodiment shown in Figures 2a to 2d will be described in detail below to avoid unnecessary repetitions.

[73] The ingress protection element 47 depicted in Figure 8 differs from the embodiment shown in Figures 2a to 2d in particular in that it is arcshaped but does not cover a full arc or full circle. Rather, the ingress protection element 47 extends between a first end 89 and a second end 91 in the circumferential direction. The first end 89 and the second end 91 are formed as protrusions that extend away from the stator 33 when the ingress protection element 47 has been installed in a stator housing 31. For a stator housing 31 that has only a limited number of drainage openings 45, using an ingress protection element 47 covering only part of a circle is sufficient as there is no need to prevent access to the live parts of the stator 33 when there are no drainage openings 45. However, in this case it is necessary to orient the ingress protection element 47 correctly in the stator housing 31 so that all drainage openings 45 are covered. [74] The first end 89 and the second end 91 are partially formed by the axial ingress protection section 59 and partially by the radial ingress protection section 61. The part of the first end 89 and the second end 91 formed by the axial ingress protection section 59 extends radially away from the center axis 53. The part of the first end 89 and the second end 91 formed by the radial ingress protection section 61 extends parallel to the center axis 53. In each case the parts extend perpendicular to the respective section 59, 61 of the ingress protection element 47 on which they are formed. The raised ends 89, 91 prevent ingress water from flowing out of the space formed between the stator housing 31 and the ingress protection element 47.

[75] Figure 9 shows an eighth exemplary embodiment of an ingress protection element 47. Only the differences to the exemplary embodiment shown in Figure 8 will be described in detail below to avoid unnecessary repetitions.

[76] The ingress protection element 47 also covers only a partial arc and extends circumferentially between a first end 89 and a second end 91. Further, the ingress protection element 47 also lacks a radial ingress protection section. In other words, the ingress protection element 47 is primarily made up from the axial ingress protection section 59. Not using a radial ingress protection section reduces the risk of condensation inside the stator 33. The axial ingress protection section 59 comprises in addition to the circumferential protrusion 63 an extended elongated protrusion 93 that is formed on an outer surface 95 of the axial ingress protection section 59.

[77] The extended elongated protrusion 93 delimits the space formed between the axial ingress protection section 59 and the stator housing 31 to prevent ingress water from flowing towards the live parts of the stator 33. Additionally, the elongated protrusion is also in extended contact with the stator housing 31 to define the distance of the ingress protection element 47 with respect to the rotor axis 12. To ensure that the ingress protection element 47 is correctly positioned in the stator housing 31 , both the elongated protrusion 93 and the circumferential protrusion 63 comprises one or more cut-outs or recesses 95 that are provided for engaging mating elements formed on an innersurface of the stator housing 31.

[78] Finally, a nineth exemplary embodiment of an ingress protection element 47 is shown in Figure 10. This embodiment is based on the exemplary embodiment shown in Figure 9. For the sake of brevity only the differences to the embodiment shown in Figure 9 will therefore be described in detail.

[79] Contrary to the embodiment shown in Figure 9, the ingress protection element 47 shown in Figure 10 comprises an axial ingress protection section 59 extending for a full arc as the first to sixth exemplary embodiment. Using a full arc as compared to a partial arc simplifies mounting of the ingress protection element 47 in the stator housing. The axial ingress protection section 59 also features an elongated protrusion 93 with multiple positioning recesses 95. However, the elongated protrusion 93 does not extend around the full arc but is restricted to an area that is subsequently positioned adjacent to the drainage openings 45 in the stator housing 31 to limit the risk of ingress water flowing towards the live parts of the stator 33.

[80] In the circumferential direction the elongated protrusion 93 is delimited by double webs 95 which form barriers preventing ingress water from leaking out of the space formed in the region of the drainage opening 45 between the ingress protection element 47 and the stator housing 31 . The double webs 95 can further be used for aligning the orientation of the ingress protection element 47 with the stator housing. To this end, mating elements that engage the double webs 95 are provided on the stator housing 31 .

[81 ] Elements of different exemplary embodiments can be combined unless the embodiments are mutually exclusive.

Reference numerals

I pump assembly

3 wet-running electric motor

5 centrifugal pump

7 pump housing

9 impeller chamber

I I impeller

12 rotor axis

13 rotor shaft

15 inlet

17 outlet

19 rotor

21 a, 21 b bearings

23 rotor chamber

25 rotor can

27 stator chamber

29 bearing plate

31 stator housing

33 stator

35 stator coils

37 stator support

37a, 37b stator end cap

39 stator lamination

41 closed end of the stator housing

43 open end of the stator housing

45 drainage openings

47 ingress protection element

49 inner edge of ingress protection element

51 outer surface of rotor can

53 center axis of ingress protection element

55 outer edge of the ingress protection element inner surface of the stator housing axial ingress protection section radial ingress protection section circumferential protrusion condensation recesses outer surface indentations on outer surface indentation on inner surface inner surface lip spacer elements collar rib snap-fit projection inner surface of axial ingress protection section snap-fit element first end second end elongated protrusion recess double web

Claims

Claims

1 . An ingress protection element (47) for an open end (43) of a stator chamber (27) of a wet-running electric motor ( 1 ), wherein the stator chamber (27) is formed between a stator housing (31 ) and a rotor can (25) of the wet-running electric motor ( 1 ) and a plurality of stator coils (35) resting on a stator support (37, 37a, 37b), wherein the ingress protection element (47) extends in an arc shape about a center axis (53) between an inner edge (49) and an outer edge (55), wherein the outer edge (55) is formed on an axial ingress protection section (59) of the ingress protection element (47), wherein the axial ingress protection section (59) extends parallel to the center axis (53) and is configured for sectionally preventing direct access to the stator (33) of the wet-running electric motor ( 1 ) through a drainage opening (45) of the wet-running electric motor ( 1 ), and wherein the ingress protection element (47) is configured to abut circumferentially against at least one of the rotor can (25), the stator support (37, 37a) and the stator housing (31 ) of the electric motor (1 ) so that the ingress protection element (47) is centered about a rotor axis (12) of the electric motor ( 1 ) and the center axis (53) coincides with the rotor axis (12).

2. Ingress protection element (47) according to claim 1 , wherein a radial ingress protection section (61 ) of the ingress protection element (47) extends generally radially away from the center axis (53) between the axial ingress protection section (59) and the inner edge (49).

3. Ingress protection element (47) according to claim 2, wherein the inner edge (49) is configured to abut partially and preferably circumferentially against the rotor can (25) of the electric motor ( 1 ) so that the ingress protection element (47) is centered by the rotor can (25) about the rotor axis (12) of the electric motor (1 ).

4. Ingress protection element (47) according to any of the preceding claims, wherein a plurality of condensation recesses (65) is formed in the outer edge (55) and preferably also the adjacent axial ingress protection section (59), wherein the axial ingress protection section (59) transitions into the outer edge (55), wherein the condensation recesses (65) are preferably equidistantly distributed about the circumference of the outer edge (55).

5. Ingress protection element (47) according to any of the preceding claims, wherein the outer edge (55) is formed by a circumferential protrusion (63), wherein the protrusion (63) extends radially away from the center axis (53).

6. Ingress protection element (47) according to claims 4 and 5, wherein the protrusion (63) is interrupted wherever the outer edge (55) transitions into a condensation recess (65) of the plurality of condensation recesses (65), wherein the protrusion (63) is preferably interrupted for the entirety of each of the condensation recesses (65) or wherein the protrusion (63) preferably partially continues along each of the condensation recesses (65).

7. Ingress protection element (47) according to any of the preceding claims, wherein a plurality of radially extending indentations (71 ) is formed on an inner surface (73) of the ingress protection element (47), wherein the inner surface (73) of the ingress protection element (47) faces towards the stator chamber (27) when the ingress protection element (47) is mounted in on electric motor (1 ) and wherein the indentations (71 ) form channels for condensed water.

8. Ingress protection element (47) according to claims 4 and 7, wherein each of the plurality of indentations (71 ) is aligned with one of the plurality of condensation recesses (65).

9. Ingress protection element (47) according to any of the preceding claims, wherein a plurality of radially extending indentations (69) is formed on an outer surface (67) of the ingress protection element (47), wherein the outer surface (67) of the ingress protection element (47) faces away from the stator chamber (27) when the ingress protection element (47) is mounted in an electric motor (1 ) and wherein the indentations (69) form channels for condensed water or ingress water.

10. Ingress protection element (47) according to any of the preceding claims, wherein the inner edge (49) of the ingress protection element (47) is formed as a lip (75) extending parallel to the center axis (53), wherein the lip (75) is configured to be inserted between a rotor can (25) and a stator support (37a) of an electric motor (1 ).

1 1 . Ingress protection element (47) according to any of the preceding claims, wherein a plurality of spacers (77) is formed on an outer surface (67) of the ingress protection element (47), wherein the outer surface (67) of the ingress protection element (47) faces away from the stator chamber (27) when the ingress protection element (47) is mounted in an electric motor (1 ) and wherein the spacers (77) are formed to maintain a minimum distance between an adjacent component of the electric motor (1 ) and the outer surface (67) so that water can flow between the outer surface (67) and the adjacent component of the electric motor ( 1 ) .

12. Ingress protection element (47) according to any of the preceding claims, wherein a plurality of snap-fit projections (83) is formed on the axial ingress protection section (59), wherein the snap-fit projections (83) are configured for engaging with corresponding snap-fit elements (87) of the electric motor (1 ) for securing the ingress protection element (47) in a direction of the center axis (53).

13. Ingress protection element (47) according to any of the preceding claims, wherein an elongated protrusion (93) protruding radially away from the center axis (53) is formed on the axial ingress protection section (59), wherein the elongated protrusion (93) is configured for supporting the ingress protection element (47) on the stator housing (31 ), wherein the elongated protrusion (93) is preferably interrupted one or more times to enable a flow of condensed water or ingress water on the axial ingress protection section (59).

14. Ingress protection element (47) according to any of the preceding claims, wherein the ingress protection element (47) is formed as a partial arc extending between a first end (89) and a second end (91 ).

15. Ingress protection element (47) according to claim 14, wherein the first end (89) and the second end (91 ) of the ingress protection element (47) project away from the stator (31 ) and are configured for preventing a flow of condensed water or ingress water towards the stator chamber (27), preferably by abutting at least partially against the stator housing (31 ).

16. Ingress protection element according to any of claims 1 to 13, wherein the ingress protection element (47) extends in a ring shape about the center axis (53).

17. Ingress protection element (47) according to any of the preceding claims, wherein the ingress protection element (47) is formed as a single piece using plastic injection molding.

18. A wet-running electric motor (1 ) comprising a stator chamber (27) formed between a stator housing (31 ) and a rotor can (25) of the wet-running electric motor (1 ) and an ingress protection element (47) according to any of the preceding claims attached to an open end (43) of the stator chamber (27).