Liquid pump with optimized cooling and heat dissipation

Abstract

Liquid pump, comprising a housing (1) in which a wound stator (2) and electronics (3) are arranged in a dry chamber (4), a permanent magnet rotor (5) arranged in a wet chamber (6), an axle (7) held on one side in a pump head (8) and on the other side in an axle receptacle (9) in a containment shell (10), wherein the containment shell (10) separates the dry chamber (4) from the wet chamber (6) and includes at least one bearing (11) which is incorporated in the permanent magnet rotor (5) and rotatably mounts it on the axle (7), the permanent magnet rotor (5) comprising a plastic insert (12) and a permanent magnet (13), and in that at least one fluid channel (14) is formed on the plastic insert (12), characterized in that the plastic insert (12) has axially parallel grooves (18) on its outer circumferential surface (17),the plastic insert (12) is overmolded with permanent magnetic material and thereby forms the permanent magnet rotor (5), that during the overmolding of the plastic insert (12) at least one groove (18) is also filled with permanent magnetic material, and that the fluid channel (14) is formed by at least one opening (19) in the impeller (16) and a corresponding groove (18) on the plastic insert (12).

Description

The invention relates to a liquid pump according to the preamble of claim 1 and to a method for producing a liquid pump according to claim 10.Known liquid pumps have a multi-part housing in which a dry chamber and a wet chamber are formed. A rotor is arranged in the wet chamber, around which a fluid flows. A containment shell separates the wet chamber from the dry chamber and contains the circulated rotor. The stator is arranged in the drying space. Furthermore, most known liquid pumps have an additional electronics space in which the control electronics are accommodated. The fluid is conducted via an impeller into the wet chamber and washes around the rotor. It is known to additionally form axial fluid channels in the form of recesses in the region of a radial bearing. A disadvantage of this is a reduced force distribution due to the consequently smaller bearing surface. In addition, dirt particles and foreign bodies from the fluid stream can be transported directly unintentionally into the storage means and can settle there, which can lead to damage to the pump. It is also known to form fluid channels which are produced during assembly. The disadvantage of this is that additional assembly effort is created and the area for force-fit connections is reduced.DE 100 51 239 A1 discloses a liquid pump, having a housing in which a wound stator and electronics are arranged in a dry space, a permanent magnet rotor which is arranged in a wet space, an axle which is held on the one hand in a pump head and on the other hand in an axle receptacle in a containment shell, wherein the containment shell separates the dry space from the wet space.DE 10 2012 209 487 A1 discloses a hydrodynamic pump, in particular a cooling water pump for an internal combustion engine, having a pump wheel which is directly driven by an electric motor arrangement and is designed in the manner of a turbine or blade wheel and operates in a pump working space between at least one suction connection piece and a pressure connection piece of a pump housing, wherein the electric motor arrangement has a rotor designed as an internal rotor and / or a stator arranged in or on the pump housing. The blades of the axial section of the pump wheel provided as a rotor consist of magnetizable material or are sheathed with such material. The axial section of the pump wheel provided as a rotor has a core region K made of magnetizable sheets or laminated cores, and this core region is covered with respect to the pump medium by a coating made of plastic material which is mixed with a magnetizable powder.DE 10 2011 079 226 A1 discloses a liquid pump, in particular a water pump, having an axle on which a permanent-magnetic rotor of an electric motor with an axially adjoining disk and an axially adjoining impeller of the liquid pump is mounted via a bearing region of the rotor, wherein the impeller and the disk are integral with a hollow shaft which consists of a non-magnetic material and wherein a substantially annular plastic-bonded permanent magnet is arranged radially around the hollow shaft, axially with respect to the disk, and is fixedly connected to the disk and / or the hollow shaft and wherein the bearing region of the rotor radially adjoins the axle.DE 10 2006 021 244 A1 discloses a permanent magnet rotor which has a shaft, a hollow cylindrical permanent magnet and an elastic connecting medium between the shaft and the permanent magnet. The permanent magnet is arranged coaxially around the shaft. The object of the invention is to ensure that the permanent magnet is securely mounted, that it is not damaged in the event of great temperature fluctuations and that it is not excessively deflected from the axis of rotation under severe radial loading. In this case, a simple and cost-effective installation method is used, in which a secure mechanical connection between shaft and permanent magnet is ensured over the entire service life. According to the invention, this object is achieved in that an elastic connecting medium is arranged along the circumference of the shaft at a plurality of first regions in which the distance between the shaft and the permanent magnet is increased. These first regions are separated from the second regions in which the distance between the shaft and the permanent magnet is minimized but is not zero.DE 10 2015 010 650 A1 discloses a rotor of an electric pump including a body including an inner circumferential surface surrounding a shaft and a magnet located in a motor chamber of an accommodation space of the pump and arranged to be separated from an outer circumferential surface of the body with a clearance therebetween and separated from a stator of the pump with a clearance therebetween. The clearance between the magnet and the body may connect the motor chamber and a pump chamber of the accommodation space. The body may include a groove extending from an end of the inner circumferential surface of the body to the pump chamber. The rotor may further include a wall disposed in the clearance between the magnet and the outer circumferential surface of the body and at a position different from the groove in a rotational direction of the rotor.From US 2016 0 025 095 A1 an electric pump is known, comprising a housing, a shaft element fixed to the housing, a cylinder bearing inserted on the outside of the shaft element, a rotor formed as a rod separate from the bearing and configured to rotate integrally with the bearing, and an impeller fixed to an end of the rotor, wherein an outlet path is formed between the bearing and the rotor along an axial direction and allows the liquid to return through it to the impeller, wherein the liquid flows from the outer periphery of the impeller into the housing and circulates in the housing.It is an object of the invention to propose a liquid pump which overcomes the above-mentioned disadvantages and ensures optimum cooling and heat dissipation. In addition, a higher temperature resistance is to be ensured without influencing the dirt load capacity or the storage quality.This object is achieved by the features according to claim 1 and by the features according to the method according to claim 10.A liquid pump comprises a housing in which a wound stator and an electronics are arranged in a dry chamber, a permanent magnet rotor arranged in a wet chamber, an axle which is held on the one hand in a pump head and on the other hand in an axle receptacle in a containment shell. The split pot separates the drying space from the wet space. In addition, the liquid pump has at least one bearing which is introduced in the permanent magnet rotor, for example by pressing in, injection or by force and form locking. The bearing rotatably locates the permanent magnet rotor on the axle. The permanent magnet rotor includes a resin insert and a permanent magnet. At least one fluid channel is formed on the plastic insert. The at least one fluid channel is introduced directly in the tool in the plastic insert. In addition, a clearance is introduced in the inner region of the permanent magnet. This forms a fluid channel which forms a connection from the fluid region of an impeller to an inner wall of the containment shell which is arranged on a printed circuit board. This increases the fluid exchange and improves the cooling performance on the printed circuit board.It is advantageous that the fluid channel is thus not formed in the region of the radial bearing. Consequently, the area for force-fit connections is increased, the quality of the rotor rotation is improved, a higher possible radial load is made possible by a larger running surface and a higher dirt load capacity is ensured, since the fluid exchange does not take place via the bearing.The plastic insert has on its outer circumferential surface axially parallel grooves. These grooves can be formed on the entire or only partially on the outer circumferential surface. The plastic insert is encapsulated with permanent magnetic material and thereby forms the permanent magnet rotor.When the plastic insert is injection-molded, at least one groove is also filled with permanent magnetic material. Alternatively, all the grooves except for a groove which forms the fluid channel can be filled with permanent magnetic material or none of the grooves can be filled with permanent magnetic material. The formation of grooves on the outer circumferential surface of the plastic insert improves the positive fit between the overmolding with permanent magnetic material and the plastic insert.The fluid channel is formed by at least one aperture in the impeller and an associated corresponding groove on the plastic insert. It is advantageous in that the fluid channel is not formed in the region of the radial bearing. This increases the surface area for force-fit connections, improves the quality of the rotor rotation, enables a higher possible radial load through a larger running surface, and ensures a higher dirt load capacity, since the fluid exchange does not take place via the bearing.In a preferred embodiment, the plastic insert has a receiving contour for the axle and the at least one bearing in the inner region. The inner region is formed in a precisely fitting or shape-fitting manner on the axis to be received and the at least one bearing during the injection molding process.In a further development, the plastic insert is formed integrally with an impeller made of the same material. Here, the resin insert and the impeller are preferably formed of a non-magnetic material such as PPS (polyphenylene sulfide) or another thermoplastic material known to those skilled in the art.In a development, the plastic insert is formed at least as long in its length as the permanent magnet. The plastic insert is preferably shorter so as not to be placed on the axle receptacle of the containment shell, i.e. the plastic insert does not contact the containment shell base. However, it would also be conceivable for the plastic insert to be longer than the permanent magnet.In a further development, a cover disk with at least one through-opening is arranged on the impeller and forms the fluid channel with the opening in the impeller and the groove. Dirt particles or foreign bodies are discharged from the fluid stream through the through-opening in the cover plate and cannot enter the fluid channel.Furthermore, it can advantageously be provided that a fluid flows around the permanent magnet rotor within the containment shell. The fluid flow around the permanent magnet within the containment shell forms a main cooling path. The fluid additionally serves as a lubricant for the at least one bearing. A venting at the at least one bearing is advantageously ensured by the fluid channel.In a further embodiment, the fluid channel in the plastic insert conveys the fluid via a secondary flow path. The secondary flow path serves for heat dissipation and for cooling the electronics on the printed circuit board via the containment shell and the fluid. The containment shell base is in direct contact with the printed circuit board. In addition, a heat-conducting foil or a heat-conducting paste can be arranged between the containment shell base and the printed circuit board, which permits better heat dissipation. It is important here that no air gap is formed between the containment shell and the printed circuit board or the printed circuit board, the heat-conducting foil or heat-conducting paste and the containment shell base.In a further development, a projection of the containment shell together with the pump head and a motor housing forms the housing. The projection of the containment shell, the pump head and the motor housing are screwed together. A seal is introduced between the individual housing parts. Alternatively to screwing the housing parts together, they can also be welded to one another or connected to one another by means of another material-locking, form-locking or force-locking method known to the person skilled in the art.It can be provided in particular that the liquid pump is used in water pumps, oil pumps, fuel pumps, SCR pumps in the motor vehicle sector or in the domestic sector.A method for producing a liquid pump is also provided, comprising the following method steps: a) A plastic insert with an impeller is injection-molded in one piece from the same material; b) During injection molding, grooves parallel to the axis are formed on the outer circumferential surface of the plastic insert; c) Subsequently, the plastic insert is encapsulated with permanent magnetic material and thereby forms the permanent magnet rotor (5); d) During the encapsulation of the plastic insert, at least one groove is also filled with permanent magnetic material.By forming the at least one groove on the outer circumferential surface of the plastic insert, the rotor is balanced before being encapsulated with the permanent magnetic material by injection molding. This ensures optimum rotational circulation of the rotor. In addition, the grooves result in a better positive fit between the plastic insert and the permanent magnetic material during the injection molding.List of reference characters1 Housing 2 Stator 3 Electronics 4 Dry chamber 5 Permanent magnet rotor 6 Wet chamber 7 Axis 8 Pump head 9 Axis receptacle 10 Containment shell 11 Bearing 12 Plastic insert 13 Permanent magnet 14 Fluid channel 15 Receiving contour 16 Impeller 17 Outer circumferential surface 18 Grooves 19 Aperture 20 Cover disk 21 Through opening 22 Fluid 23 Projection 24 Motor housing 25 Liquid pumpThe invention is explained in more detail below on the basis of exemplary embodiments with reference to the appended drawings. The following are shown: FIG. 1 is an overview of a liquid pump according to an embodiment, FIG. 2 shows a sectional illustration of a permanent magnet rotor according to FIG. 1, FIG. 3 is a plan view of a permanent magnet rotor according to an embodiment, FIG. 4 is an isometric view of a permanent magnet rotor according to an embodiment, FIG. 5 shows a plan view of a cover pane according to an embodiment, FIG. 6 is a sectional view of a liquid pump according to an embodiment.FIG. 1 shows an overview of a liquid pump ( 25) according to one embodiment. The liquid pump (25) comprises a housing (1) in which a wound stator (2) and an electronics (3) are arranged in a drying space (4). The liquid pump (25) further comprises a permanent magnet rotor (5) which is arranged in a wet chamber (6) and an axle (7) which is held on the one hand in a pump head (8) and on the other hand in an axle receptacle (9) in a containment shell (10). The containment shell (10) separates the drying chamber (4) from the wet chamber (6). Furthermore, at least one bearing (11) is provided, which is introduced into the permanent magnet rotor (5) and rotatably arranges the latter on the axis (7). The permanent magnet rotor (5) comprises a plastic insert (12) and a permanent magnet (13). Furthermore, at least one fluid channel (14) is formed on the plastic insert (12). The individual housing parts can be screwed, welded or connected to one another by means of another material-locking, form-locking or force-locking method known to the person skilled in the art. In particular, a connection can be realized by a projection ( 23) of the containment shell ( 10), which together with the pump head ( 8) and a motor housing ( 24) forms the housing.FIG. 2 shows a sectional illustration of a permanent magnet rotor according to FIG. 1, the plastic insert (12) is formed integrally with an impeller (16) made of the same material and forms the permanent magnet rotor (5) by injection molding with permanent magnetic material. In particular, the plastic insert (12) and one or the permanent magnet (13) are designed as finished parts which are mounted one inside the other in a force-fit or material-fit or form-fit manner and thereby form the permanent magnet rotor (5). The plastic insert (12) is at least as long in its length as the permanent magnet (13), but can also be shorter or longer. The fluid channel (14) is formed by at least one aperture (19) in the impeller (16) and an associated corresponding groove (18) on the plastic insert part (12). In the inner region, the plastic insert part (12) has a receiving contour (15) for the axle (7) and the at least one bearing (11).FIG. 3 shows a plan view of a permanent magnet rotor according to an embodiment, in which it is disclosed that the plastic insert part ( 12) has axially parallel grooves ( 18) on its outer circumferential surface ( 17). These grooves can be formed on the entire or only partially on the outer circumferential surface. During injection molding of the plastic insert (12), at least one groove (18) is filled with permanent magnetic material.In the isometric view of a permanent magnet rotor ( 5) according to FIG. 4, it can also be seen that the fluid channel ( 14) can lead through the complete permanent magnet rotor ( 5) or the plastic insert ( 12) in order to cool (not shown) electronics underneath.FIG. 5 shows a plan view of a cover disk (20) according to an embodiment, which is arranged on the impeller (16). The cover disk (20) comprises at least one through-opening (21) and forms the fluid channel (14) with the aperture (19) in the impeller (16) and the groove (18). Dirt particles or foreign bodies are discharged from the fluid stream through the through-opening (21) in the cover plate (20) and cannot enter the fluid channel (14).FIG. 6 shows a sectional view of a liquid pump according to an embodiment. A fluid ( 22) can be seen, which flows around the permanent magnet rotor ( 5) within the containment shell ( 10). This is a main cooling path which is fed from the aperture ( 19). Furthermore, the fluid (22) is conveyed through the fluid channel (14) in the plastic insert part (12) via a secondary flow path. The secondary flow path serves for heat dissipation and for cooling the electronics on the printed circuit board via the containment shell ( 10) and the fluid ( 22).

Claims

Liquid pump, having a housing (1) in which a wound stator (2) and an electronics (3) are arranged in a dry space (4), a permanent magnet rotor (5) which is arranged in a wet space (6), an axle (7) which is held on the one hand in a pump head (8) and on the other hand in an axle receptacle (9) in a containment shell (10), wherein the containment shell (10) separates the dry space (4) from the wet space (6) and at least one bearing (11) which is introduced in the permanent magnet rotor (5) and rotatably arranges the latter on the axle (7), the permanent magnet rotor (5) comprises a plastics insert part (12) and a permanent magnet (13), and in that at least one fluid duct (14) is formed on the plastics insert part (12), characterized in that, the plastic insert (12) has on its outer circumferential surface (17) axially parallel grooves (18), the plastic insert (12) is injection-molded with permanent magnetic material and thereby forms the permanent magnet rotor (5), that when the plastic insert (12) is injection-molded at least one groove (18) is also filled with permanent magnetic material and that the fluid channel (14) is formed by at least one aperture (19) in the impeller (16) and an associated corresponding groove (18) on the plastic insert (12).Liquid pump according to claim 1, characterised in that the plastics insert (12) has in the inner region a receiving contour (15) for the axle (7) and the at least one bearing (11).Liquid pump according to one of the preceding claims, characterized in that the plastics insert (12) is formed integrally with the impeller (16) from the same material.Liquid pump according to one of the preceding claims, characterized in that the plastic insert (12) is formed at least as long in its length as the permanent magnet (13).Liquid pump according to one of the preceding claims, characterized in that a cover disc (20) with at least one through-opening (21) is arranged on the impeller (16) and forms the fluid channel (14) with the aperture (19) in the impeller (16) and the groove (18).Liquid pump according to one of the preceding claims, characterized in that a fluid (22) flows around the permanent magnet rotor (5) within the containment shell (10).Liquid pump according to claim 6, characterised in that the fluid channel (14) in the plastic insert part (12) conveys the fluid (22) via a secondary flow path.Liquid pump according to one of the preceding claims, characterized in that a projection (23) of the containment shell (10) forms the housing (1) together with the pump head (8) and a motor housing (24).Liquid pump according to one of the preceding claims, characterized in that the liquid pump is used in water pumps, oil pumps, fuel pumps, SCR pumps in the motor vehicle sector or in the domestic sector.Method for producing a liquid pump according to one of the preceding claims, characterized in that - the plastics insert (12) is injection-moulded integrally with the impeller (16) from the same material; - during injection moulding, axially parallel grooves (18) are formed on the outer circumferential surface (17) of the plastics insert (12); - subsequently the plastics insert (12) is injection-moulded with permanent magnetic material and thereby forms the permanent magnet rotor (5), and - during injection-moulding of the plastics insert (12), at least one groove (18) is also filled with permanent magnetic material.

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