EP3779205B1 - Fluid pump with an electrical drive - Google Patents

Description

The present invention relates to a fluid pump with an electric drive, in particular a fluid pump for a cooling and/or heating circuit of a motor vehicle, with a stator, an axle connected to a pump housing and a rotor arranged on the axle, which has an impeller and is mounted on the axle by means of a radially acting first bearing, wherein the axle, the stator and the rotor are arranged in the pump housing and the axle has a radially circumferential groove at a free end on the outer circumference.

Electrically driven fluid pumps are well known in the art. For example, in the DE 4411960 A1 a detailed description of such a pump. The pump shown there has a bell-shaped rotor, in whose cylindrical interior the stator engages. A tube or cup-shaped wall runs between the rotor and stator, with an axis embedded in the bottom of the cup, around which the rotor is mounted so that it can rotate.

Furthermore, the EP 22 73123 A1 an electric automotive coolant pump for cooling an automotive internal combustion engine is known. This coolant pump has a canned motor arrangement in which a rotor with the blades and a plain bearing sleeve is mounted on a fixed metallic axle. The pump blades of the rotor are arranged axially in the area of the plain bearing sleeve. A metallic stop ring is arranged at a distal end of the axle and is welded to the axle. The welded stop ring serves to axially fix the rotor.

The disadvantage of the known solutions is that the rotor is permanently fixed to the axle during assembly. Subsequent replacement of the rotor or repair of the bearing is therefore not possible or only possible with difficulty. In addition, a relatively complex thermal joining process is required during production, which can, for example, be accompanied by undesirable heat input into the component and welding spatter, and components have to be damaged for disassembly.

From the US 2015/184674 A1 An electronic water pump is known. A rotor is secured to an axle via an axial bearing. The axial bearing is supported on the axle via a locking ring.

The object of the present invention is therefore to at least partially solve the problems resulting from the prior art and in particular to provide a fluid pump which is easy to manufacture, has better acoustic properties and, if necessary, can be easily repaired and/or can be easily adapted to different operating conditions.

A fluid pump according to the independently formulated patent claim contributes to the solution of this task(s). It should be noted that the features listed individually in the dependent patent claims can be combined with one another in any technologically reasonable manner and define further embodiments of the invention. In addition, the features specified in the patent claims are explained and specified in more detail in the description, with further preferred embodiments of the invention being presented.

A fluid pump with an electric drive, in particular a fluid pump for a cooling and/or heating circuit of a motor vehicle, contributes to this, which has at least one stator, an axle connected to a pump housing and a rotor arranged on the axle. The rotor has an impeller and is mounted on the axle by means of a radially acting first bearing.

The axle, the stator and the rotor are arranged in the pump housing, with the axle having a radial groove at a free end on the outer circumference. A deformable locking element is arranged in the groove. Furthermore, an axially acting second bearing for the rotor is arranged between the locking element and the rotor, with the second bearing being designed to introduce an axially acting force generated by the rotor into the axle via the deformable locking element.

It was recognized that a second axially acting bearing can be fixed in the axial direction in a particularly advantageous manner by means of a deformable locking element. The deformability in the sense of the present invention can be either plastic or elastic of the locking element. For this purpose, the deformable locking element is in a Groove which extends along the outer circumference of the axle and in its radial direction. The fluid pump designed in this way can be assembled in a particularly simple manner by first placing the rotor together with the first bearing on the axle during assembly. This is followed by the assembly of the second bearing, which prevents the rotor from being pulled off the axle in the axial direction. Finally, in the last step, the second bearing is secured in the axial direction by simply inserting the deformable locking element into the groove. If the locking element were to be inserted in the radial direction, there would be a collision with the blades of the pump wheel or the geometry of the impellers would have to be shortened accordingly. However, the present invention, in conjunction with the other advantages of the invention mentioned, also enables particularly simple axial assembly.

The axial forces generated by the rotor during pump operation can thus be transmitted from the rotor via the bearing or contact point with the second bearing, which is not designed to be deformable, via the contact point of the second bearing with the deformable locking element to the deformable locking element, before the deformable locking element introduces the axial forces into the axle via the groove.

In the event of repairs, only the deformable locking element needs to be removed in order to be able to disassemble the fluid pump into its individual components. This allows easy access to the bearing points or, for example, a simple replacement of the rotor or pump wheel.

In addition, the rotor and the second bearing can be acoustically decoupled from the axle by the deformable locking element, which has a positive effect on noise during operation, i.e. reduces it. In addition, fluid pumps constructed in this way can be varied in a particularly simple manner according to a modular principle and adapted to the respective operating conditions. For example, under low loads, individual or all components such as the housing, impeller, rotor or the second bearing can be made and used from plastic. Furthermore, these components can be replaced by metal or ceramic components as required, for example under higher thermal loads. This means that a wide variety of fluid pump variants can be created using the modular principle. Last but not least, it is possible to use plastic for the components by avoiding heat input during production of the fluid pump.

The second bearing can have an opening to accommodate the axle. In this case, the second bearing can be pushed onto the axle in a particularly simple manner during assembly, whereby the axle can then protrude through the opening.

For particularly reliable transmission of the axial forces, the invention provides that the opening has opening cross-sections of different sizes in the axial direction of the axis. The opening cross-sections of different sizes of the opening in the second bearing make it possible to exert a force acting in the radial direction to the axis from the second bearing onto the deformable locking element. This can result in an axial force introduced into the second bearing being diverted into a radial force and the deformable locking element being pressed in the direction of the groove by means of this radial force. Consequently, the greater the axial force exerted by the rotor via the second bearing, the greater the radial drive force that holds the deformable locking element in the groove. If the opening is also circular, the second bearing can self-center on the deformable locking element when installed. For example, a stop ring welded to the shaft, as is known from the prior art, has the disadvantage that this stop ring is not centered on the axis and is also fixed in a position inclined to the axis due to the uneven heat input of the welding process. The present invention enables self-centering of the second bearing on the deformable locking element. At the same time, the bearing surface of the second bearing automatically aligns itself at right angles to the longitudinal axis of the axis. Furthermore, the deformable locking element can even compensate for positional deviations of the pump wheel caused by tolerances between the first bearing and the pump wheel. If, for example, the center axis of the pump wheel is slightly inclined to the axis due to the tolerances, the second bearing can compensate for this inclination via the deformable locking element.

It is particularly advantageous if the opening is designed as a (continuous or) flat transition between two opening cross-sections of different sizes and axially spaced apart from each other.

In another particularly simple embodiment, for example, a simple stepped bore can be provided which has a larger and a smaller diameter in the axial direction (immediately) one after the other. Preferably, the different diameters pass through corresponding roundings of the jump edges as smoothly as possible in order not to damage the deformable locking element during assembly and to avoid generating unnecessarily large material stresses in the contact area with the second bearing when installed.

If the diameters are selected so that the opening cross-sections of the opening become smaller with increasing distance from the free end, the force component exerted by the second bearing in the radial direction on the locking element increases when the second bearing is moved towards the free end. The system can therefore be designed to be self-clamping or self-locking.

It can also be provided that the opening is designed as a conical bore section. The angle of the cone is between 5° and 60°, preferably between 10° and 50°, in relation to the longitudinal axis of the axle or in relation to the center axis of the opening. By means of a cone, the axial force exerted can be particularly effectively redirected into a radial force in order to press the deformable locking element into the groove.

In this way, even larger axial forces can be easily absorbed.

The opening can be designed as a conical bore section or as a bore with a molded-on chamfer, whereby the chamfer or cone can preferably extend from one end face of the second bearing to the (smallest) bore section. Such a chamfer or cone can be produced particularly cheaply in terms of manufacturing technology and the function corresponds to that of the previously described conical bore section.

For safe and reliable production, it is advantageously provided that the axle has symmetrically designed and/or arranged radial circumferential grooves at both ends. The axles designed in this way can thus be fixed in the housing in both positions, i.e. either with the first end or the second end, without this leading to a manufacturing error. The axles can be pressed, glued, screwed and/or injected into the pump housing. All suitable manufacturing processes known in the state of the art are available for this purpose.

In order to improve the durability of the deformable locking element and/or to facilitate assembly, it can also be advantageously provided that the groove has at least partially rounded edges. The rounded edges facilitate the assembly (at least partial penetration into the groove) of the deformable locking element and prevent damage to the locking element from sharp edges. All edges of the groove can be rounded, or only those with which the deformable locking element comes into contact during assembly or disassembly.

Particularly favorable deformable properties are achieved if the locking element is at least partially made of an elastomer. Elastomers suitable for use in a heating and/or cooling circuit are, for example, HNBR or EPDM. These can be used advantageously, for example, for axles with diameters of 3-10 mm and especially for axles with diameters of 6-8 mm.

In other embodiments of the invention, particularly with larger axle diameters, locking elements made of spring steel can also be used. Such locking elements can be formed, for example, from a helically wound wire whose turns lie against one another. Such a locking element can be temporarily expanded radially for mounting in the groove of the axle, similar to a ring on a bunch of keys, without it undergoing plastic deformation.

It is particularly advantageous if the locking element is made of an incompressible material. While the invention can already be implemented with compressible and foamed elastomers, provided that they have sufficient strength or hardness (e.g. Shore hardness), it is even more advantageous if the selected elastomer is incompressible. In this case, the deformable locking element can be moved particularly effectively into the groove by the radial forces exerted by the second bearing, thus ensuring that the second bearing is held particularly securely on the axle.

For particularly long-lasting fluid pumps, a preferred embodiment of the present invention provides that the second bearing is made of a ceramic material. The second bearing can thus form a particularly smooth and low-friction contact point with the rotor. In addition to the low coefficient of friction, the contact point also has a particularly high level of wear resistance. The fluid pump designed in this way is therefore particularly low-wear, energy-saving and long-lasting. When manufacturing the second bearing from a ceramic material, in addition to the In addition to the low-friction contact point with the rotor, a contact surface that is in contact with the deformable locking element can be designed with increased roughness. The increased surface roughness between the deformable locking element and the second bearing prevents the second bearing from accidentally turning relative to the deformable locking element during operation of the fluid pump. Such a permanent relative movement between the two components would lead to unnecessary wear and tear in the long term, thus premature wear on one of the components or even on both components. However, this can be reliably prevented.

In another particularly inexpensive embodiment, the second bearing is made of a plastic material. Thermosets and thermoplastics are preferably used as plastic materials. Unreinforced thermosets, reinforced thermoplastics or thermoset-bonded graphite can be used particularly advantageously for the present invention. Such plastic materials can be used if, for example, only small axial forces need to be supported.

In another advantageous embodiment, the second bearing is made of a metallic material. If the fluid pump is to be used at very high temperatures, for example, it can be advantageous to make the second bearing out of metal. Metals are harder than plastics, are temperature-resistant and can be processed inexpensively into second bearings. This can be done by punching, clamping processes or sintering powder metals. Alternatively, the metals can also be processed using a metal injection process, also known as metal injection molding (MIM).

In addition, metallic materials have a relatively high surface roughness in their untreated state, which prevents unintentional relative movement between the second bearing and the deformable locking element.

To further prevent this relative movement, a rotary brake can advantageously be arranged between the second bearing and the locking element. Such a rotary brake can be formed, for example, by radial webs on the contact surface of the second bearing to the deformable locking element or by targeted burr formation or roughness on stamped metallic second bearings. In addition to burr formation, it is also possible to form depressions or notches in the metal during stamping, which then form-fit into the complementary shaped Locking element and thereby act as a rotary brake. This can reliably prevent unintentional relative movement between the deformable locking element and the second bearing.

• Fig. 1: eine schematische Schnittansicht einer erfindungsgemäßen Fluidpumpe;
• Fig. 2: eine Schnittansicht durch ein zweites Lager mit deformierbarem Sperrelement;
• Fig. 3a: eine erste Ausführungsform eines zweiten Lagers;
• Fig. 3b: eine zweite Ausführungsform eines zweiten Lagers; und
• Fig. 4: eine weitere erfindungsgemäße Ausführungsform mit verrundeter Nut.

The invention and the technical environment are explained in more detail below with reference to the figures. It should be noted that the figures show particularly preferred embodiments of the invention, to which it is not limited, however. In the drawing:

• Fig.1 : a schematic sectional view of a fluid pump according to the invention;
• Fig.2 : a sectional view through a second bearing with deformable locking element;
• Fig. 3a : a first embodiment of a second bearing;
• Fig. 3b : a second embodiment of a second bearing; and
• Fig.4 : another embodiment according to the invention with rounded groove.

In Figure 1 a fluid pump 1 according to the invention is shown in an axial sectional view. The fluid pump 1 comprises a pump housing 2 with an inlet nozzle 3 and an outlet nozzle 4. A stator 5 is arranged in the pump housing 2 and is separated from the liquid-carrying area of the fluid pump 1 by a wall or a hood 6. An axis 7 is fixedly mounted in the hood 6. A rotor 8 is mounted on the axis 7 and is connected to an impeller 9 and is supported and guided in the radial direction to the axis 7 by means of a first bearing 10. During operation of the fluid pump 1, fluid is sucked in via the inlet nozzle 3 and deflected by the rotating blades of the impeller 9 in the direction of the outlet nozzle 4. The impeller 9 generates an axial force in the direction of the arrow 11. A second bearing 12 is arranged on the axis 7 to absorb the axial force and support it. The second bearing 12 is disk-shaped and serves to axially support the impeller 9 and at the same time to introduce the axial force into the axle 7. For this purpose, a deformable locking element 13 is provided at a free end 15 of the axle 7 in a groove 14. In the embodiment shown, the deformable locking element 13 is designed as an O-ring which is inserted into the upper groove 14 and has a high coefficient of friction with respect to the axle 7 and the second bearing 12. The axle 7 can have a further groove opposite the mounted end 23, via which the axle 7 is secured in the cover 6, whereby the two grooves can be of the same design.

It is clearly visible that the axis 7 is symmetrical and has two circumferential grooves 14, so that an incorrectly positioned installation of the axis 7 is not possible.

The Figure 2 shows an enlarged view of another embodiment according to the invention, in which the axle 7 has a conical or trapezoidal groove 14. The deformable locking element 13, which is designed as an elastomer O-ring, is inserted in the groove 14. The impeller 9 exerts an axial force (arrow 11) on the second bearing 12 via the first bearing 10. The second bearing 12 is ring-shaped and has a cylindrical bore section 16, a conical bore section 17 and an upper edge 18. The cylindrical bore section 16 and the conical bore section 17 form an opening 19 through which the axle 7 protrudes. If the second bearing 12 is now moved in the direction of the arrow 11 due to the axial force, the conical bore section 17 first comes into contact with the deformable locking element 13.

When this contact state is reached, the axial force is diverted via the conical bore section 17 in a radial direction acting at a right angle thereto and presses the deformable locking element 13 into the groove 14 with increasing movement of the second bearing 12 in the direction of the arrow 11 in the radial direction. Consequently, the greater the axial force, the greater the holding force of the locking element 13 pressed into the groove 14. Since the deformable locking element 13 is designed as an incompressible O-ring and the cross-sectional area of the O-ring is larger than that of the associated groove 14, there is always a projection of the O-ring over the groove 14 in the installed state, via which the axial forces of the impeller 9 can be introduced into the axis 7.

In Figure 3a a further embodiment of a second bearing 12 according to the invention is shown in a partial axial sectional view. The second bearing 12 is again ring-shaped with an opening 19 and encloses the axis 7. Between the axis 7 and the second bearing 12, a deformable locking element 13 is pressed by the second bearing 12 in the radial direction 20 into the groove 14. In this embodiment, the opening 19 is designed as a conical bore section 16. The cone used is opened at an angle 22 in the direction of the free end 15. This means that an opening cross-section of the opening 19 in the region of the upper edge 18 is larger than the opening cross-section of the opening 19 in the region of a lower edge 21. The opening cross-section is viewed in a plane whose normal direction is aligned parallel to the longitudinal axis of the axis 7. In order to make assembly as simple as possible, the opening 19 in the area of the lower edge 21 can have a slight oversize compared to the axis 7. This oversize makes it easier to attach the second bearing to the axis 7 and can be compensated for by the tolerance compensation of the deformable locking element 13.

The Figure 3b shows a further embodiment in which the second bearing 12 has an opening 19, which is designed in the lower area as a cylindrical bore section 16. This cylindrical bore section 16 ends, however, before reaching the upper edge 18, wherein in order to overcome a jump in diameter from the smaller diameter in the area of the lower edge 21 to the larger diameter in the area of the upper edge 18, a free-form flat, for example dome-shaped transition is provided, which is contoured in such a way that the locking element 13 is tightly enclosed by it and is pressed into the groove 14 with increasing movement of the second bearing 12 in the direction of the arrow 11.

Finally, in Figure 4 Another embodiment is shown in which the groove 14 has rounded edges. The edges are rounded with a radius R so that the locking element 13 can be assembled or disassembled easily and without damage.

List of reference symbols

1

Fluid pump

2

Pump housing

3

Inlet nozzle

4

Drain nozzle

5

stator

6

hood

7

axis

8

rotor

9

Impeller

10

first camp

11

Arrow

12

second camp

13

Locking element

14

Groove

15

free end

16

cylindrical bore section

17

conical bore section

18

Top edge

19

breakthrough

20

radial direction

21

Bottom edge

22

angle

23

mounted end

R

radius

Claims (8)

1. Fluid pump (1) with an electric drive, in particular a fluid pump (1) for a cooling circuit and/or heating circuit of a motor vehicle, with a stator (5), with a shaft (7) which is connected to a pump housing (2), and with a rotor (8) which is arranged on the shaft (7), said rotor having an impeller (9) and being mounted on the shaft (7) by means of a radially acting first bearing (10), wherein the shaft (7), the stator (5) and the rotor (8) are arranged in the pump housing (2) and the shaft (7) has an encircling groove (14) at a free end (15), wherein a deformable blocking element (13) is arranged in the groove (14) and an axially acting second bearing (12) for the rotor (8) is arranged between the blocking element (13) and the rotor (8), and wherein the second bearing (12) is configured to introduce an axially acting force (11) generated by the rotor (8) into the shaft (7) via the deformable blocking element (13); characterized in that the second bearing (12) has an aperture (19) for receiving the rotationally fixed shaft (7), and, over its extent along the axial direction of the shaft (7), the aperture (19) has opening cross sections of different sizes; wherein the opening cross sections of the aperture (19) decrease in size as the distance from the free end (15) increases; wherein, owing to the differently sized opening cross sections of the aperture (19), a force acting in a radial direction (20) with respect to the shaft (7) from the second bearing (12) to the deformable blocking element (13) is able to be exerted.
2. Fluid pump (1) according to Claim 1, wherein the aperture is configured as a conical bore section (16) .
3. Fluid pump (1) according to either of the preceding claims, wherein the blocking element (13) consists at least partially of an elastomer.
4. Fluid pump (1) according to either of Claims 1 and 2, wherein the blocking element (13) consists of an incompressible material.
5. Fluid pump (1) according to one of the preceding claims, wherein the second bearing (12) consists of a ceramic material.
6. Fluid pump (1) according to one of Claims 1 to 4, wherein the second bearing (12) consists of a plastic material.
7. Fluid pump (1) according to one of Claims 1 to 4, wherein the second bearing (12) consists of a metallic material.
8. Fluid pump (1) according to one of the preceding claims, wherein a rotary brake is arranged between the second bearing (12) and the blocking element (13) .

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