DE102019214301A1 - Fluid pump with exposed, axially fixed return ring - Google Patents

Abstract

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 (3), an axle (4) and a rotor (1) arranged on the axle (4). , which has an impeller (8), the axis (4), the stator (3) and the rotor (1) being arranged in a pump housing with an inlet opening and an outlet opening, and the rotor (1) at least one magnet (7 ) and at least one metal ring (2), the metal ring (2) enclosing the magnet (7). The fluid pump is characterized in that the metal ring (2) can be pushed onto an outer circumference (1a) of a rotor base body (10), in the pushed-on state at least partially encloses the outer circumference (1a) and a section of an outer surface (2a) of the rotor (1 ) forms.

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.

Electrically driven fluid pumps are well known in the art and are often used for cooling systems of internal combustion engines. So describes the JP4723906B2 a coolant pump with a multi-part rotor made of plastic.

Permanently excited electric motors are known which consist of a stator with coils and a coaxially aligned rotor with several permanent magnets distributed over the circumference. It is also known to design the pairing of rotor and stator as a so-called external rotor. A ring-shaped rotor envelops the stator, which is arranged in the middle.

In order to strengthen the magnetic field generated by the magnets of the rotor in the area of the stator, a metal ring is often used, which is also referred to as a return ring. For this purpose, the metal ring is positioned on the outside of the magnets and must be fixed in a process-safe and functional manner.

The metal ring is usually fixed to the rotor by overmolding it with a plastic in the so-called plastic injection molding process.

In particular, the different coefficients of expansion of the metal ring on the one hand and the encasing plastic on the other hand must be taken into account. However, the different expansion coefficients have a negative influence on the bond strength of the different materials over the life of the fluid pump.

In a fluid pump it can happen that, due to temperature fluctuations, a gap is formed between the materials, so that water or coolant comes into contact with the magnets, which can lead to corrosion.

Another challenge is to encapsulate the magnets with plastic in such a way that sufficient plastic remains on the outside of the metallic ring during injection molding and, at the same time, no plastic penetrates into the receptacles in which the magnets are located. This can lead, for example, to the magnets being displaced or even damaged, or it can also lead to an undesirable accumulation of mass, which can cause imbalances in the rotor during later operation.

The object of the present invention is therefore to at least partially solve the problems arising from the prior art and, in particular, to provide a fluid pump that is easy to manufacture, has good concentricity and offers improved corrosion protection for the magnets used.

To achieve this object (s), a fluid pump and a production method for a fluid pump according to the independent patent claims are disclosed.

It should be pointed out that the features listed individually in the dependent claims can be combined with one another in any technologically sensible manner and define further configurations of the heat exchanger. In addition, the features specified in the claims are explained and specified in more detail in the description, with further preferred exemplary embodiments of the fluid pump being presented.

A fluid pump with an electric drive, which is set up in particular as a fluid pump for a cooling and / or heating circuit of a motor vehicle, contributes to this. It has a stator, an axis and a rotor arranged on the axis with an impeller, the axis, the stator and the rotor being arranged in a pump housing with an inlet opening and an outlet opening.
The rotor has at least one magnet and at least one metal ring, the metal ring enclosing the magnet. In this fluid pump, the metal ring can be pushed onto an outer circumference of a rotor base body; so that in the pushed-on state it at least partially encloses the outer circumference and forms a section of an outer surface of the rotor.

The main rotor body is the section of the rotor that accommodates the axle and the at least one magnet. The metal ring is the section of the rotor that encompasses the magnets arranged in the main rotor body and that forms an outer surface of the rotor. Seen in the radial direction, the metal ring can optionally form the outer surface of the rotor on the inside or on the outside. The embodiment of the fluid pump described here with a metal ring as the outer surface of the rotor is functional. In particular, plastic encapsulation is no longer necessary, for example in order to align their components with one another and / or to make them durable. Therefore, the "outer surface of the rotor" refers to one Area that is not (directly) covered by a coating or a housing or is inextricably linked to it. Rather, this outer surface is in contact with the ambient air even when the fluid pump is in operation.

For this purpose, the metal ring is made of a metal that is suitable for aligning the magnetic field generated by the magnets in the area of the rotor. In particular, it is desirable here to build up a particularly high density of magnetic field lines and thus a particularly strong magnetic field around the stator.

Since the pushed-on metal ring forms part of the outer circumference, there is no need to overmold this metal ring with plastic in a further process step. The technically demanding overmoulding with plastic can thus be omitted and the risk of undesired back-injection is avoided.

For this purpose, the metal ring can optionally be formed in one piece or in several pieces. Furthermore, the outer surface of the metal ring can be designed to be closed or open. The influence of the magnetic field generated by the magnets is decisive for the function of the metal ring.

While the fluid pump can already be implemented with a magnet, in particular embodiments can be used in which a plurality of magnets are used, which are regularly distributed over the circumference of the rotor in the, for example, terraced receptacles.

In particular, it can be provided that the metal ring is axially fixed in at least one direction by at least one fixing means.
In a particularly simple embodiment, the fixing means can be designed as a stop that is designed on the rotor base body. This makes it possible to assemble the metal ring in a particularly simple manner, in that it only has to be pushed onto the main rotor body. The metal ring reaches the desired defined end position as soon as it is in contact with the stop. The metal ring can be fixed in the end position, for example, by friction, form fit, material connection, gluing, screws and other known fixing means. While the metal ring is first fixed in a first direction by the stop during assembly, the metal ring can be fixed in a second seal by means of a second fixing means. For example, the first fixing means can limit the movement of the metal ring in its assembly direction. The second fixing means can then limit the movement in the opposite direction, that is to say the dismantling direction, as soon as the metal ring is positioned on the main rotor body.

In particular, it can also be provided that the metal ring has sealing means for the rotor base body at at least one axial end.
The sealant can fulfill two different functions. On the one hand, it can prevent the fluid to be delivered by the fluid pump from entering between the metal ring and the rotor base body and thereby coming into contact with the magnets located in the receptacles. Such contact of the fluid with the magnets would lead to undesirable corrosion over a long period of time. The sealing means can be designed, for example, as an O-ring or as a separately sprayed-on elastomer track.
Another function that the sealant can fulfill is that of fixing the metal ring on the main rotor body. If, for example, the O-ring is inserted into a groove located on the inside of the metal ring and the metal ring is then pushed onto the rotor base, this O-ring fulfills both the sealing function and a fixing function against unintentional twisting of the metal ring and unintentional pulling off of the metal ring relative to the main rotor body.
For this purpose, an O-ring can be provided as a sealing means, for example on one side of the metal ring or also in the area of both end faces of the metal ring. As an alternative or in addition, fixing means can also be used which prevent a rotary movement between the rotor base body and the metal ring by means of a form fit. This can be achieved, for example, by toothing that is provided between the metal ring and the adjacent plastic components.

In particular, the rotor base body can have a receptacle for each magnet. This makes it possible to position each magnet in a defined position relative to the main rotor body. In this way, irregular distributions of masses can be avoided, which, for example, can lead to undesired imbalances during operation of the fluid pump.

For this purpose, the fluid pump is designed, in particular, in such a way that the rotor has a plurality of magnets and receptacles that are evenly distributed over a circumference. The magnets can be arranged distributed over the outer circumference, for example, at regular intervals. Alternatively, however, it is also possible to form groups of magnets and to arrange these groups evenly distributed over the outer circumference.

A particularly simple embodiment provides that the fixing means is designed as an axial contact surface of the rotor base body. The contact surface can, for example, be a simple one radially circumferential web which surrounds the outer circumference of the rotor base body and points outward in the radial direction. Such a web can serve to limit the movement of the metal ring as it acts on the main rotor body as a stop.

In particular, however, it can also be provided that the fixing means is designed as a separate component that is connected to the rotor base body via a connecting means. Any means that is suitable for establishing a permanent connection between the separate component and the rotor base body can be used as the connecting means. In particular, the fixing means can be a separate component that is designed as a stop ring. For example, it can be dimensioned so that it can be plugged onto the rotor base body and thereby fix the metal ring on the rotor base body. The separate component can be made by means of known methods, such as laser welding, gluing or pressing on or pressing. Depending on the method used, the inner diameter of the separate component can have a slight oversize or a slight undersize with respect to the rotor base body. Laser welding, for example, has the advantage that no mechanical or unnecessarily high thermal loads are introduced into the components during manufacture.

Instead of using plastic encapsulation as was the case with previous fixings, separately manufactured components, such as stop rings, can now be used, making the manufacturing process significantly more robust and producing significantly fewer rejects.

In addition to metals, plastics can also be used to produce the fixatives. For example, the separate annular component can be designed as a stop ring which is made from a plastic. This plastic ring is inexpensive to manufacture and can be permanently connected to the main rotor body in a particularly simple manner, for example by friction welding or laser welding. For this purpose, only a radial laser weld is required, for example. A separate annular component designed in this way is referred to below as a stop ring.

For example, the return ring can be axially fixed in one direction by a step located on the rotor base body and in a direction opposite thereto by a separate stop ring.

For a connection of the fixing means with the rotor base body, it can be provided in particular that the stop ring of the fixing means is made of a laser-transparent plastic.

A laser-transparent plastic, which allows the light used by the laser to shine through with the appropriate wavelength, facilitates the welding between the fixing means and the rotor base body. For example, the stop ring can be made from a laser-transparent PPS with a low fiber content and the rotor base body from a standard PPS with a fiber content or a PPA. In the past, PPS in particular has proven itself for use in connection with coolants in that this material shows no or only a very slight tendency to swell when it comes into contact with coolants and is also characterized by high strength and rigidity.

In order to ensure a correctly formed welded joint, gap-free contact between the two joining partners is also required. Such a gap-free contact can be achieved, for example, in that the stop ring has a transition fit up to a slight press fit with respect to the rotor base body or with respect to elevations on the outside of the rotor base body.

In particular, it can be provided for this purpose that opposing centering surfaces are provided at at least three points on at least one inside of the stop ring or on the outside circumference of the rotor base body. The centering surfaces serve to center the stop ring relative to the main rotor body. The at least three raised points with the opposing centering surfaces are arranged offset by 120 ° over the outer circumference of the rotor base body or the inner circumference of the stop ring on the other hand. In this way, a self-centering arrangement of the stop ring on the rotor base body can be achieved by means of the centering surfaces.

While it is very difficult to produce a weld over the entire circumference due to different diameters and habits between the main rotor body and the stop ring, a defined weld can be implemented reliably and at defined locations using the present weld at three points.
In particularly simple embodiments, the raised centering surfaces can only be provided on the rotor base body or on the stop ring.

In other embodiments, both on the rotor base body and on the stop ring each raised centering surfaces are provided. The raised centering surfaces are overdimensioned with respect to one another. I. E. the outer diameter of the centering surfaces of the rotor base body is larger than the inner diameter of the centering surfaces of the stop ring. As a result, the stop ring is initially assembled in such a way that the raised centering surfaces of the stop ring are fitted in a rotated position relative to the raised centering surfaces of the rotor base body about the axis of the rotor base body. As soon as the raised centering surfaces of the stop ring, viewed in the axial direction, are at the same height as the raised centering surfaces of the rotor base body, the stop ring and the rotor base body are rotated relative to one another, so that the raised centering surfaces of both components rest against one another and the stop ring is centered relative to the rotor base body. In particular, it can be provided for this purpose that the raised centering surfaces have run-up bevels which support self-centering during the relative rotation of the two components with respect to one another. The run-up bevels can in particular be wedge-shaped in order to support the centering of the stop ring during the relative rotation to the rotor base body.
The stop ring centered in this way can then be permanently connected to the rotor base body.

1. a) Fertigung eines Rotorgrundkörpers mit Aufnahmen für Magnete;
2. b) Anordnen von Magneten in den Aufnahmen;
3. c) Anordnen wenigstens eines Metallrings über den Magneten.

The present object is also achieved by a method for manufacturing a fluid pump, which has the following steps:

1. a) Manufacture of a rotor base body with mounts for magnets;
2. b) arranging magnets in the receptacles;
3. c) placing at least one metal ring over the magnet.

The arrangement of the metal ring as part of the outer surface of the rotor on the one hand protects the magnets arranged underneath and holds them securely in the intended receptacles. At the same time, the metal ring is easy to assemble and, as a return ring, effects the desired arrangement or alignment of the magnetic field generated by the magnets.

In this case, after step c), the metal ring can be connected to the rotor base body at least by a form fit, friction fit, material fit or force fit. This connection can be represented in a process-reliable, inexpensive and highly automated manner.

In addition, during or between steps a) to c), sealing means can be arranged between the metal ring and the rotor base body in such a way that the magnets are tightly enclosed in the receptacles. The magnets are thereby shielded from the fluid to be conveyed by the fluid pump, as a result of which, for example, corrosion damage is avoided if the medium to be conveyed is water.

Finally, it can also be provided that the metal ring is fixed on the rotor base body by a stop ring (fixing means) and the stop ring is pushed onto the rotor base body in the axial direction after step c) and centered relative to the rotor base body by means of a rotary movement by means of centering surfaces and then fixed to the rotor base body is connected. This enables secure fixing of the metal ring and reliable centering of the stop ring.

As a precaution, it should be noted that the numerals used here (“first”, “second”, ...) primarily (only) serve to differentiate between several similar objects, sizes or processes, so in particular no dependency and / or sequence of these objects, sizes or prescribe processes to each other. Should a dependency and / or sequence be required, this is explicitly stated here or it is obvious to a person skilled in the art when studying the specifically described embodiment.

• 1: eine Schrägansicht eines Rotors und Stators;
• 2: eine teilweise geschnittene Schrägansicht eines Rotors;
• 3 eine teilweise geschnittene Seitenansicht eines Rotors;
• 4 einen schematischen Radialschnitt durch einen Rotorgrundkörper und einen ersten Anschlagring; und
• 5 einen schematischen Radialschnitt durch einen Rotorgrundkörper und einen zweiten Anschlagring in zwei Zuständen.

The invention and the technical environment are explained in more detail below with reference to the accompanying figures. It should be pointed out that the invention is not intended to be restricted by the exemplary embodiments cited. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and to combine them with other components and findings from the present description. In particular, it should be pointed out that the figures and in particular the size relationships shown are only schematic. In the drawing show:

• 1 : an oblique view of a rotor and stator;
• 2 : a partially sectioned oblique view of a rotor;
• 3 a partially sectioned side view of a rotor;
• 4th a schematic radial section through a rotor base body and a first stop ring; and
• 5 a schematic radial section through a rotor base body and a second stop ring in two states.

In 1 is one embodiment of a rotor 1 with a metal ring 2 and one Rotor body 10 shown as an external rotor around a stator 3 rotate. All components rotate around an axis 4th . Inside the stator 3 are coils 5 arranged that can generate alternating magnetic fields. The rotor 1 points on its outer circumference 1a Recordings 6th on where magnets 7th are arranged. The ones in the recordings 6th arranged magnets 7th are from the metal ring 2 tightly enclosed. On an underside of the rotor 1 is an impeller 8th provided when the rotor rotates 1 cause the promotion of the fluid to be pumped. During the operation of a fluid pump, not shown, the stator remains 3 immobile in a pump housing of the fluid pump, while the rotor 1 together with the metal ring 2 and the blades of the impeller 8th and the axis 4th rotates. The drive of the rotor 1 takes place via the changing magnetic fields of the coils 5 on the magnets 7th exerted magnetic forces. When assembled, the metal ring forms 2 a portion of an exterior surface 2a of the rotor 1 .

The 2 shows a partially cut-away oblique view of a rotor 1 . It is easy to see how the magnets 7th under the metal ring 2 are arranged. There are the magnets 7th in groups of two magnets each 7th evenly around a circumference of the rotor 1 arranged distributed. The metal ring 2 was mounted on the rotor from bottom to top during assembly 1 attached. A circumferential web acts as a fixing means 9 and limits the push-on movement of the metal ring 2 so that it comes to rest on the bridge.

In the 3 Figure 3 is a side view, partially in section, of a rotor 1 shown. The rotor 1 has a metal ring in this embodiment 2 on, which in the course of assembly from top to bottom on a rotor base body 10 has been postponed. Between the metal ring 2 and the bar (fixative 9 ) of the rotor 1 is a first sealant 11 arranged which the of the metal ring 2 covered magnets 7th against fluid that seals the metal ring 2 and the rotor 1 flows around the fluid pump during operation. Furthermore, is on an upper side of the metal ring 2 a second sealant 12th provided which the metal ring 2 against a stop ring 13th sealed. Both the first sealant 11 as well as the second sealant 12th are made of an elastomer and serve on the one hand to make the metal ring 2 to seal tightly against the fluid to be conveyed and on the other hand an unintentional twisting of the metal ring 2 relative to the rotor body 10 to prevent. For this are the sealants 11 and 12th dimensioned so that the between the sealants 11 and 12th one hand and the metal ring 2 and the rotor base 10 on the other hand occurring frictional forces are high enough to safely prevent this relative movement in all operating states.

The stop ring 13th is after assembling the metal ring 2 from above onto the rotor base 10 been postponed. By means of a welded connection 14th is the stop ring 13th firmly to the rotor body 10 connected and thus acts as a second fixing means for the metal ring 2 . In the present embodiment, the first fixing means limits the movement of the metal ring 2 down and the second fixation means the movement of the metal ring 2 up. The stop ring 13th is made in the embodiment shown from a translucent or laser-transparent plastic, so that the welded connection 14th between the stop ring 13th and the rotor base 10 by laser welding in the direction of the arrows shown 15th can be produced.

According to 4th Figure 3 is a radial sectional view through another embodiment of the invention. The rotor body 10 is from the stop ring 13th includes. At three evenly over the circumference of the rotor body 10 distributed surveys 16 becomes the stop ring 13th above the rotor body 10 centered. On the elevations, each offset by 120 ° 16 becomes the stop ring 13th by means of three welded joints 14th with the rotor body 10 firmly connected.

Finally shows 5 a radial sectional view through a further embodiment of the invention in two different states. On the left of the 5 the state is shown in which the stop ring 13th on the rotor body 10 is attached. On the right-hand side, the assembled state is shown after the stop ring 13th in the direction of the arrow 17th has been rotated relative to the rotor base body. Both the rotor body 10 as well as the stop ring 13th each have three surveys 16 with wedge-shaped bevels 18th on that as centering surfaces 19th serve. During the rotation of the stop ring 13th around the rotor body 10 these run-up bevels slide 18th on each other and center the stop ring 13th on the rotor body 10 , whereby a zero gap is achieved between the two components. After the assembly has been carried out in this way, both components can then additionally be connected to one another by means of a joining process such as laser welding, friction welding, ultrasonic welding or also by means of an adhesive process.

List of reference symbols

1

List of reference symbols rotor

1a

Outer circumference

2

Metal ring

2a

Exterior surface

3

stator

4th

axis

5

Kitchen sink

6th

admission

7th

magnet

8th

Impeller

9

fixer

10

Rotor body

11

first sealant

12th

second sealant

13th

Stop ring

14th

Welded joint

15th

Arrows

16

Elevation

17th

arrow

18th

Approach slope

19th

Centering surfaces

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• JP 4723906 B2 [0002]

Claims (1)

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 (3), an axle (4) and a rotor (1) arranged on the axle (4). , which has an impeller (8), the axis (4), the stator (3) and the rotor (1) being arranged in a pump housing with an inlet opening and an outlet opening, and the rotor (1) at least one magnet (7 ) and at least one metal ring (2), the metal ring (2) enclosing the magnet (7). The fluid pump is characterized in that the metal ring (2) can be pushed onto an outer circumference (1a) of a rotor base body (10), in the pushed-on state at least partially encloses the outer circumference (1a) and a section of an outer surface (2a) of the rotor (1 ) forms.

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