DE102018114822A1 - Electrical machine - Google Patents

Abstract

The invention relates to an electrical machine with a stator with at least two stator teeth, each of which is at least partially wrapped by at least one coil, and with a rotor, which is rotatably received by the stator, the stator and the rotor being formed opposite the rotor to drive the stator by means of electromagnetic interaction, and the stator is at least partially surrounded by a housing which has at least one annular housing element radially and at least one first end plate on the end face. The electrical machine is characterized in that the annular housing element and the first bearing plate are formed at least in sections on the stator as plastic encapsulation.

Description

The invention relates to an electrical machine according to the preamble of patent claim 1 and to a method for producing such an electrical machine according to patent claim 7.

For a long time, electrical machines such as e.g. Electric motors used. Such machines can drive the rotor relative to the stator by means of an electromagnetic interaction between a stator or stator and a rotor or rotor movable relative to the stator. The most widespread is the generation of a rotating or rotating movement which can be transmitted from the rotor to an object to be moved by means of a shaft. The rotor and the stator do not touch each other. Rather, an air gap is formed between the rotor and stator, through which the electromagnetic field can pass.

Depending on the operating principle and design of the electrical machines, coils can be wound in the stator around ferromagnetic stator teeth made of sheet metal in order to form the poles or pole teeth of the stator pack of the electrical machines. The rotor can also have pronounced rotor teeth in order to in turn form poles or pole teeth.

Usually, a rotating electrical machine in the form of an electric motor is essentially formed in that an interior of the electrical machine is enclosed by a housing which accommodates the stator package. The stator back, the stator teeth and coils, which essentially form the stator, are arranged within the housing and are fixedly connected to it. However, the housing can also be assigned to the stator, since the two elements are fixed to one another. The rotor essentially consists of a shaft with the rotor teeth fixedly arranged thereon. The rotor is arranged within the stator and is usually rotatably connected to the stator by two bearings.

The housing can usually be made of aluminum or plastic. The housing can have an annular housing element, which radially surrounds the stator pack and is closed at the end by a substantially circular cover, through which the shaft of the rotor projects. Such lids are also referred to as end shields in electrical machines. In addition to the delimitation of the interior of the electrical machine and the holding of the stator package, the end shields can usually also be used to accommodate the bearings which rotatably connect the shaft of the rotor to the stator.

When assembling the stator pack with its stator teeth and coils, the bearings and the rotor with shaft and rotor packs in the interior of the electrical machine, these elements are usually arranged starting with the stator pack on the radial inside of the annular housing element and thus aligned with it. In other words, these elements are received by the housing with the outer diameter of the stator. As a result, all tolerances from the outer stator diameter to the end shields and bearings, the stator bore and the rotor together with the shaft add up in the radial air gap.

In general, there is a desire to use electrical machines such as to achieve the highest possible power density and the highest possible efficiency values for electric motors. This can be achieved, for example, by making the air gap between the stator and rotor as small as possible.

The problem here is that, in the case of known typical motor housings of electrical machines, a large number of dimensional tolerances, which can affect the radial width of the air gap, can add up due to the production, as already mentioned above. In order to avoid contact between the stator and the rotor, the desired minimum air gap width must be increased by these tolerance widths. This contradicts the goal of an air gap width that is as small as possible in the radial direction and thus prevents or reduces the achievable power density or efficiency. In other words, the tolerances of the dimensions of the individual elements of such an electrical machine can lead to a large dimensional spread of the width of the air gap between the stator and the rotor.

In order to prevent or reduce this, the assembly effort can be increased, but this can also lead to higher production costs. Therefore, such a large radial air gap is usually provided, so that contact with the stator and rotor can be reliably ruled out, taking into account the possible maximum tolerances of all elements. The resulting loss of efficiency and the lower power density of the electrical machines are accepted.

A further disadvantage is that the tolerances of the elements, depending on their combination, can lead to different air gap widths for identical electrical machines. Thus, due to the dimensional scatter of the radial air gap width in the Manufacturing process of identical electrical machines to spread the performance of the electrical machines among themselves.

The invention therefore presents the problem of providing an electrical machine as described in the introduction, in which the tolerances of the elements of the electrical machine, which can affect the width of the air gap between the stator and the rotor, can be reduced and in particular minimized. In other words, the tolerances relevant to the air gap width should be reduced and in particular minimized. At least an alternative to known electrical machines of this type is to be created.

According to the invention, this problem is solved by an electrical machine with the features of patent claim 1 and by a method with the features of patent claim 7. Advantageous refinements and developments of the invention result from the following subclaims.

The present invention thus relates to an electrical machine having a stator with at least two stator teeth, each of which is at least partially wrapped by at least one coil, and with a rotor which is rotatably received by the stator, the stator and the rotor being designed To drive the rotor relative to the stator by means of electromagnetic interaction, and wherein the stator is at least partially surrounded by a housing which has radially at least one annular housing element and at least one first end plate on the end face. Such an electrical machine, which can preferably be an electric motor, was described at the beginning.

The electrical machine according to the invention is characterized in that the annular housing element and the first bearing plate are formed at least in sections on the stator as plastic encapsulation.

The present invention is based on the knowledge that a dimensional tolerance between the stator or its stator teeth and the housing in the form of its ring-shaped housing element and its first bearing plate can be reduced and in particular avoided by jointly directly connecting the ring-shaped housing element and the first bearing plate are sprayed onto the stator or onto its stator teeth made of plastic. As a result, dimensional deviations, in particular in the radial direction between the stator or its stator teeth and the rotor, can be avoided or at least reduced, since the stator or its stator teeth extend radially over the material of the housing radially to a first bearing, which is picked up by the first bearing plate. Dimensional tolerances from the stator or its stator teeth to the first bearing can thus be avoided or at least reduced according to the invention. This can affect the tolerances of the air gap, which can now be made smaller than previously known. This can improve the efficiency and the power density of the electrical machine, which can be reduced by a larger air gap.

The remaining tolerances or dimensional deviations or dimensional inaccuracies can thus be attributed to the injection mold or injection mold used and can thus be reduced or minimized with less effort than the tolerances of the individual elements of the electrical machine to be assembled with one another, as was previously the case is.

It is also advantageous that the possibly remaining dimensional tolerances from the stator or its stator teeth to the first bearing are the same for each electrical machine produced, since these dimensional tolerances result from the injection mold used. Scattering of dimensional tolerances for a series of electrical machines that are manufactured using the same injection mold can thus be avoided.

According to one aspect of the present invention, the annular housing element and the first bearing plate are formed in one piece. Dimensional tolerances between the ring-shaped housing element and the first end shield can hereby be avoided. The hold between the annular housing element and the first bearing plate can also be improved. Furthermore, this can simplify and accelerate production.

According to a further aspect of the present invention, the annular housing element and the first bearing plate are formed, at least in sections, in direct contact with at least the stator package and / or with at least the coil and / or with at least one winding insulation of the coil. As a result, a direct connection and thus a cohesive hold between these elements can be created, which can improve the overall durability of the stator. Dimensional tolerances between these elements can also be reliably avoided in this way.

According to a further aspect of the present invention, the rotor has a shaft, which is rotatably connected to the stator by means of at least one first bearing, the first bearing being received by plastic encapsulation from the first bearing plate. As a result, dimensional tolerances between the first bearing plate and the first bearing can be avoided, as described above. Furthermore, the hold of the first bearing on the stator or on the housing can be improved as described above.

According to a further aspect of the present invention, the rotor has a shaft which is rotatably connected to the stator by means of at least one first bearing, the first bearing plate being formed by plastic encapsulation and the first bearing then being shrink-fitted by the first bearing plate. In this way, an alternative possibility can be created to hold the first bearing securely and with as little or no dimensional tolerances as possible in the first bearing plate.

According to a further aspect of the present invention, the annular housing element has a centering surface for receiving and aligning a second end shield. As a result, the dimensional tolerances between the rotor and the stator, which can affect the width of the air gap, can also be reduced or avoided at this point in the electrical machine.

• • Anordnen eines Stators innerhalb einer Spritzgussform, wobei der Stator ein Statorpaket mit wenigstens zwei Statorzähnen aufweist, welche zumindest abschnittsweise von jeweils einer Spule umwickelt sind, und
• • Umspritzen des Stators mittels Kunststoff zur Ausbildung eines Gehäuses, welches den Stator zumindest abschnittsweise umgibt, wobei das Gehäuse radial wenigstens ein ringförmiges Gehäuseelement und stirnseitig wenigstens einen ersten Lagerschild aufweist.

The present invention also relates to a method for producing an electrical machine as described above with at least the following steps:

• Arranging a stator within an injection mold, the stator having a stator package with at least two stator teeth, each of which is wrapped at least in sections by a coil, and
• Injection molding of the stator by means of plastic to form a housing which surrounds the stator at least in sections, the housing having at least one annular housing element radially and at least one first end plate on the end face.

In this way, an electrical machine according to the invention with the properties described above can be created in order to be able to use the resulting properties and advantages.

According to one aspect of the present invention, a cavity is created during the encapsulation for later accommodation of a rotor, preferably and at least a first bearing, by means of a mandrel. In other words, the volume inside the stator, which is later to be taken up by the air gap and the rotor, is kept free of the injection molding material by the mandrel during the process of the injection molding process.

• • Anordnen wenigstens eines ersten Lagers innerhalb der Spritzgussform, so dass das erste Lager beim Umspritzen von dem ersten Lagerschild aufgenommen wird.

According to a further aspect of the present invention, the method has at least the further step:

• • Arranging at least one first bearing within the injection mold, so that the first bearing is received by the first bearing plate during the encapsulation.

In this way, the first bearing can be connected to and surrounded by the first bearing plate directly during the injection molding process, so that, on the one hand, a secure hold can be established between these elements and dimensional tolerances can be avoided at this point in the electrical machine.

• • Anordnen wenigstens eines ersten Lagers in dem ersten Lagerschild, so dass das erste Lager durch Einschrumpfung von dem ersten Lagerschild aufgenommen wird.

According to a further aspect of the present invention, the method has at least the further step:

• Arranging at least one first bearing in the first bearing plate so that the first bearing is received by the first bearing plate by shrinking.

In this way, an alternative possibility can be created to connect the first bearing to the first bearing plate. There is a mandrel for this, which keep the volume free of the injection molding material during the injection molding process, remove it after completing the injection molding process and arrange the first bearing within the first end shield in a timely manner so that the first bearing can be enclosed and held in the area of the first end shield by the shrinking injection molding material , This can ensure a secure hold and as little or no dimensional tolerances as possible.

• 1 eine schematische Schnittdarstellung einer elektrischen Maschine gemäß des Standes der Technik gemäß eines Längsschnitts durch die 2;
• 2 eine schematische Draufsicht auf die elektrische Maschine der 1 von der rechten Seite der Darstellung der 1;
• 3 eine perspektivische schematische Darstellung der elektrischen Maschine der 1 von der linken Seite der Darstellung der 1 von schräg oben;
• 4 eine schematische Schnittdarstellung einer erfindungsgemäßen elektrischen Maschine gemäß einem Längsschnitt durch die 5;
• 5 eine schematische Draufsicht auf die elektrische Maschine der 4 von der rechten Seite der Darstellung der 4; und
• 6 eine perspektivische schematische Darstellung der elektrischen Maschine der 4 von der linken Seite der Darstellung der 4 von schräg oben.

An embodiment of the invention is shown purely schematically in the drawings and is described in more detail below. It shows

• 1 is a schematic sectional view of an electrical machine according to the prior art according to a longitudinal section through the 2 ;
• 2 a schematic plan view of the electrical machine of the 1 from the right side of the illustration of the 1 ;
• 3 a perspective schematic representation of the electrical machine of the 1 from the left of the representation of the 1 from diagonally above;
• 4 is a schematic sectional view of an electrical machine according to the invention according to a longitudinal section through the 5 ;
• 5 a schematic plan view of the electrical machine of the 4 from the right side of the illustration of the 4 ; and
• 6 a perspective schematic representation of the electrical machine of the 4 from the left of the representation of the 4 from diagonally above.

The above figures are viewed in cylindrical coordinates. A longitudinal axis extends X , Perpendicular to the longitudinal axis X extends a radial direction R from the longitudinal axis X path. Perpendicular to the radial direction R and around the longitudinal axis X a circumferential direction extends around U ,

The 1 to 3 make an electrical machine 0 according to the prior art, as described above. The electrical machine 0 is a rotary or rotating electric machine 0 which, therefore, as well as rotary electric motor 0 can be designated. The electrical machine 0 has a stator 1 as well as a rotor 2 on which is inside the stator 1 recorded and opposite the stator 1 is rotatable or rotatable. The electrical supply of the electrical machine 0 takes place via electrical contacts 4 of the electrical machine 0 ,

The electrical machine 0 also has a housing 10 on which consists of an annular housing element 10a , from a first location sign 10b , which is also the first camp seat 10b can be referred to, and from a second bearing plate 10c which also serves as a second bearing seat 10b can be designated. The second end shield 10c as well as the annular housing element 10a are made by four screws 15 on the first end shield 10b and held together, see e.g. 1 and 3 ,

Inside the case 10 is the stator 1 arranged. The stator 1 has several - in this case four - stator teeth 11 made of sheet metal, which in the circumferential direction U are spaced from each other. The 1 shows a longitudinal section through two of the stator teeth 11 , which also as pole teeth 11 of the stator 1 can be designated. Every stator tooth 11 is from a coil 12 wrapped, see 1 , The spools 12 are made in sections by winding insulation 16 surrounded and thereby electrically by the stator teeth 11 Cut.

The rotor 2 points a wave 20 on which several rotor teeth 21 are arranged from sheets, which the pole teeth 21 of the rotor 2 form, see 1 , The wave 20 is about a first camp 13 and a second camp 14 rotatably supported with the stator 1 connected. Between the rotor teeth 21 and the stator teeth 11 there is a radial distance in the form of an air gap 3 ,

In such a known electrical machine 0 must have an air gap 3 be provided with a significantly greater radial distance than is actually required for the function of the electrical machine, since the fluctuations in the dimensions of the components of the stator described above 1 , the rotor 2 as well as the housing 10 must be taken into account. In other words, if the dimensional accuracy of these components were higher, the air gap could 3 designed according to its actually required dimension and thereby the power density and the efficiency of the electrical machine 0 be increased.

To achieve this, the electrical machine according to the invention 0 which in the 4 to 6 is shown, the annular housing element 10a and the first end shield 10b of the housing 10 on the stator 1 designed as plastic encapsulation. In other words, the stator 1 or its stator teeth 11 including coils 12 arranged within an injection mold and overmolded by means of a plastic, so that the annular housing element 10a and the first end shield 10b in one piece as a plastic injection molded part directly on the stator 1 or on its stator teeth 11 including coils 12 can be trained. The winding insulation 16 is also overmolded.

In this way, it is not only possible to hold the ring-shaped housing element securely in a cohesive manner 10a and the first end shield 10b on the stator 1 can be achieved. At the same time, dimensional tolerances between these elements are avoided, since the plastic material of the injection molding process is in direct contact with the elements of the stator 1 can apply and harden there. This can result in inaccuracies in the dimensions, which affect the radial extension of the air gap 3 can affect between the stator 1 or its stator teeth 11 and coil 12 and the annular housing element 10a and the first end shield 10b be avoided.

Preferably the first camp 13 together with the stator 1 or its stator teeth 11 and coil 12 arranged in the injection mold and overmolded. In this way, dimensional inaccuracies can also be avoided at this point. Alternatively, the first camp 13 also immediately after the injection molding process in the first bearing plate 10b be positioned so that the first camp 13 in the first end shield 10b can be shrunk, which can bring about the same advantages as described above.

In the housing manufactured as described above 10 including stator 1 the rotor can now 2 be introduced so that the wave 20 from the first camp 13 can be held and rotatably supported. On the opposite side of the electrical machine 0 can then the interior of the housing 10 with the second end shield 10c be closed, which was manufactured separately and a second warehouse 14 for rotatable bearing of the shaft 20 having.

In order to achieve the highest possible dimensional accuracy at this point, the ring-shaped housing element has 10a the second end shield 10c facing a centering surface 10d which is formed, the second bearing plate 10c with respect to the longitudinal axis X of the electrical machine 0 center such that the high dimensional accuracy provided by the first bearing 13 , the first end shield 10b as well as the annular housing element 10a on the right side of the 4 is also available on the left side of the 4 at the second end shield 10c can be achieved.

LIST OF REFERENCE NUMBERS

A

Longitudinal section through 5

B

Longitudinal section through 2

R

radial direction

U

circumferentially

X

longitudinal axis

0

(rotary) electrical machine; (rotary) electric motor

1

Electric machine stator 0

10

casing

10a

annular housing element

10b

first end shield; first camp seat

10c

second end shield; second camp seat

10d

Centering surface of the annular housing element 10a for second end shield 10c

11

stator teeth; Pole teeth of the stator 1

12

Do the washing up

13

first camp

14

second camp

15

screw

16

winding insulation

2

Electric machine rotor 0

20

wave

21

Rotor teeth, pole teeth of the rotor 2

3

air gap

4

electrical contacts

Claims (10)

Electrical machine (0), with a stator (1) with at least two stator teeth (11), each of which is at least partially wrapped by at least one coil (12), and with a rotor (2) which is rotatable by the stator (1) is recorded, the stator (1) and the rotor (2) being designed to drive the rotor (2) with respect to the stator (1) by means of electromagnetic interaction, and the stator (1) at least in sections by a housing (10) is surrounded, which has radially at least one annular housing element (10a) and at least one first bearing plate (10b) on the end face, characterized in that the ring-shaped housing element (10a) and the first bearing plate (10b) are at least in sections on the stator (1) as plastic encapsulation are trained. Electrical machine (0) after Claim 1 , characterized in that the annular housing element (10a) and the first bearing plate (10b) are integrally formed. Electrical machine (0) after Claim 1 or 2 , characterized in that the annular housing element (10a) and the first bearing plate (10b) at least in sections in direct contact with at least the stator teeth (11) and / or with at least the coil (12) and / or with at least one winding insulation (16) the coil (12) are formed. Electrical machine (0) according to one of the preceding claims, characterized in that the rotor (2) has a shaft (20) which is rotatably connected to the stator (1) by means of at least one first bearing (13), the first bearing (13) is received by plastic overmolding from the first bearing plate (10b). Electrical machine (0) according to one of the Claims 1 to 4 characterized in that the rotor (2) has a shaft (20) which is rotatably connected to the stator (1) by means of at least one first bearing (13), wherein the first bearing plate (10b) is formed by plastic injection molding and then the first bearing (13) is received by shrinking the first bearing plate (10b). Electrical machine (0) according to one of the preceding claims, characterized in that the annular housing element (10a) has a centering surface (10d) for receiving and aligning a second bearing plate (10c). Method for producing an electrical machine (0) according to one of the preceding claims, with at least the steps: Arranging a stator (1) within an injection mold, the stator (1) having at least two stator teeth (11), each of which is at least partially wrapped by at least one coil (12), and Injection molding of the stator (1) by means of plastic to form a housing (10) which surrounds the stator (1) at least in sections, the housing (10) having at least one annular housing element (10a) radially and at least one first bearing plate (10b) on the end face , Procedure according to Claim 7 , characterized in that, during the extrusion coating process, a cavity is created for later accommodation of a rotor (2), preferably and at least one first bearing (13), using a mandrel. Procedure according to Claim 7 or 8th , characterized by at least the further step before the encapsulation: arranging at least one first bearing (13) within the injection mold, so that the first bearing (13) is received by the first end shield (10b) during encapsulation. Procedure according to Claim 7 or 8th , characterized by at least the further step after the extrusion coating: arranging at least one first bearing (13) in the first bearing plate (10b), so that the first bearing (13) is received by shrinking the first bearing plate (10b).

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