DE102015223586A1 - Radial bearing in an electric machine - Google Patents

Abstract

A radial bearing in an electrical machine comprises a radial bearing and a housing fixed held Einpassring, wherein the radially inner side of the Einpassrings and the radially outer side of a bearing outer ring of the radial bearing are at an angle to each other.

Description

The invention relates to a radial bearing in an electrical machine for supporting a rotor shaft according to the preamble of claim 1.

State of the art

From the JP 11-264421 A is a radial bearing in an electric machine for supporting the rotor shaft known. The radial bearing comprises a bearing acting as a floating bearing with a bearing inner ring and a bearing outer ring, between which the rolling elements are arranged, wherein the bearing inner ring is seated on the rotor shaft and the bearing outer ring is received in a housing fixedly arranged Einpassring. The outer side of the bearing outer ring is conical, as well as the inner side of the female fitting ring. This design makes it possible during assembly to push the housing component accommodating the fitting ring axially and the rotor shaft with radial bearing into one another until a surface contact between the radial bearing and the press-in ring is achieved. In operation, an axial relative displacement between press-in ring and radial bearing in one axial direction is possible, in the opposite axial direction, however, excluded.

In the WO 2005/042992 A1 a radial bearing is described in which the bearing outer ring and the inside of the Einpassrings are convexly curved, which should be compensated for alignment errors during assembly. The outside of the fitting ring has a conical contour and is accommodated in a corresponding conical housing component with the same cone angle.

Disclosure of the invention

With the radial bearing according to the invention, a rotor shaft can be stored in an electric machine. The radial bearing has a radial bearing with a bearing inner ring which is fixedly arranged on the rotor shaft, and a bearing outer ring, between which rolling bodies are arranged, wherein the bearing outer ring is received in a housing fixed held Einpassring. The mutually facing sides of the bearing outer ring and fitting ring are each rectilinear with respect to the motor longitudinal axis, they thus have a curvature only in the circumferential direction, but not in the direction of the motor longitudinal axis. The radial bearing forms a loose bearing, which supports the rotor shaft in the radial direction, but not fixed in the axial direction. On the axially opposite side, the rotor shaft is received in a fixed bearing with radial and axial bearing.

In the radial bearing according to the invention, the radially outer side of the bearing outer ring and the radially inner side of the fitting ring are at an angle to each other. This angular relative arrangement allows for temperature changes a length compensation without loss of contact between the bearing outer ring of the radial bearing and the Einpassring. The rotor and the stator of the electric machine can have different axial and radial coefficients of thermal expansion and correspondingly perform different thermal expansions in the event of a temperature change, without the contact between the bearing outer ring and the fitting ring being lost. The angular relative arrangement allows at all temperatures an at least approximately linear contact between the radially outer side of the bearing outer ring and the radially inner side of the Einpassrings, with increasing temperature and increasing thermal expansion in the radial and axial direction of the linear contact further radially to migrates outside and at decreasing temperature accordingly in the opposite direction continues to move radially inward. Due to the relative angle creates a conical sliding space, within which the radial bearing can move with contact to the inside of the Einpassrings.

According to an advantageous embodiment, one side is conical and one side is cylindrical, so that the cone angle of the respective side forms the angle at which the inner side of the Einpassrings and the outer side of the bearing outer ring are arranged to each other. According to an advantageous embodiment, the radial bearing is cylindrical, so that the outer side of the bearing outer ring of the radial bearing is cylindrical, whereas the inside of the fitting ring is made conical. This makes it possible to use standard radial bearings, so that only one on the inside conically formed Einpassring must be used. The outside of the Einpassrings is advantageously also cylindrical, so that in the receiving housing component, such as a bearing plate, the electric machine only a cylindrical bore for receiving the Einpassrings must be introduced.

In an alternative embodiment, the outside of the Einpassrings is conical and received in a recess in the housing member.

According to a further alternative embodiment, both facing sides of Einpassring and bearing outer ring are conical, but they differ in their cone angle from each other, so that the sides at an angle to each other taking. In this embodiment, too, it is ensured that at least one line contact between the radial bearing and the fitting ring always remains with thermal expansion or thermal contraction.

According to a further expedient embodiment, the angle between the mutually facing sides of bearing outer ring and fitting ring is at least 5 °, in particular at least 10 °. The angle can be for example 11.5 °. Advantageously, the angle is within a maximum value range of 15 ° in order to avoid an excessive force component in the axial direction of the radial bearing.

According to yet another expedient embodiment, the fitting ring has a greater axial length than the radial bearing. This ensures thermal expansion sufficient axial clearance for the relative movement of Einpassring and radial bearings without the risk of loss of contact.

The electric machine that is equipped with such a radial bearing is used for example in motor vehicles, for example as a generator or as a belt-driven starter generator.

Further advantages and expedient embodiments can be taken from the further claims, the description of the figures and the drawings. Show it:

1 a partial section longitudinally through an electric machine with a radial bearing for the rotor shaft, wherein a bearing outer ring of a radial bearing is accommodated in a cone-shaped fitting ring,

2 the radial bearing with the radial bearing and the fitting ring in an enlarged view.

In the figures, the same components are provided with the same reference numerals.

In 1 is an electrical machine 1 shown, which is designed as an internal rotor motor and an external stator 2 and an internal rotor 3 with a rotor shaft 4 having. The stator 2 is at its two axial ends of a bearing plate 5 . 6 enclosed, each forming a housing component, wherein in the first bearing plate 5 a camp 7 and in the axially opposite second bearing plate 6 a radial bearing 9 as part of a radial bearing 8th is included.

As 1 combined with 2 refer to the radial bearing 8th the radial bearing 9 and a housing-side fitting ring 10 in the camp sign 6 is firmly recorded and in turn the radial bearing 9 firmly absorbs. The radial bearing 9 includes a bearing inner ring 9a that is on the rotor shaft 4 firmly seated, a bearing outer ring 9b and intermediate rolling elements 9c , The bearing outer ring 9b is in contact with the radially inner side of the fitting ring 10 and is rotationally fixed to the Einpassring 10 held.

The radial bearing 9 including the bearing outer ring 9b is cylindrical, so that the radially outer side of the bearing outer ring 9b forms a cylindrical outer surface. The fitting ring 10 is conically formed on its radially inner side and has opposite the motor longitudinal axis 11 or a parallel to the motor longitudinal axis a cone angle β, under the due to the cylindrical design, the inner side of the fitting ring 10 also opposite the outer side of the bearing outer ring 9b lies. The radially outer side of the fitting ring 10 is cylindrical, as well as the recess in the bearing plate 6 in which the fitting ring 10 is included. Depending on the thermal expansion ratios between the components, the direction of the cone angle can be as in 1 be formed or formed opposite.

The angle β between the bearing outer ring 9b and the fitting ring 10 As a result, the radial bearing 9 only with an outer edge of the bearing outer ring 9b at the Einpassring 10 is applied. As a result, a linear or circular contact over the entire circumference between the radial bearing 9 and the fitting ring 10 given. The angle β allows that at thermal strains in the stator 2 and in the rotor 3 vary in size, a relative displacement between the radial bearing 9 and the fitting ring 10 takes place without the contact between radial bearings 9 and fitting ring 10 get lost. It remains ensured during operation of the electric machine at all temperatures that the bearing outer ring 9b in contact with the fitting ring 10 stands and firmly with the Einpassring 10 is connected, so that a defined bearing of the rotor shaft 4 is given and besides a game between the radial bearing 9 and the fitting ring 10 is avoided.

The angle β between the bearing outer ring 9b and the fitting ring 10 is preferably in an angular range between at least 5 °, in particular between at least 10 ° and a maximum of 15 °, for example at 11.5 °.

bestimmt werden, worin das Verhältnis der radialen zur axialen Relativdehnung zwischen Stator und Rotor im Falle einer Temperaturänderung ΔT zum Ausdruck kommt. Das Verhältnis lässt sich unter Berücksichtigung von Geometriegrößen und thermischen Kenngrößen gemäß ΔD_ges = ΔD_G – 2Δr_EPR – ΔD_L Δr_EPR = α_EPR·ΔT·r_EPR ΔD_L = α_L·ΔT·D_L ΔD_G = α_G·ΔT·D_G ΔL_ges = ΔL_Stat – ΔL_Rot ΔL_Stat = α_Stat·ΔT·L_Stat ΔL_Rot = α_Rot·ΔT·L_Rot ausdrücken. Hierin werden die Wärmedehnungskoeffizienten α_L für das Radiallager, α_G für das Gehäuse (Lagerschild), α_Stat für den Stator, α_Rot für den Rotor und α_EPR für den Einpassring berücksichtigt, darüber hinaus die mittlere radiale Dicke r_EPR des Einpassrings, der Außendurchmesser D_L des Lagers, der Außendurchmesser D_G des Gehäuses, die axiale Länge L_Stat des Stators, und die axiale Länge L_Rot des Rotors. Erfüllt der Winkel β die vorgenannte Ungleichung, werden zu hohe Kräfte auf das Radiallager vermieden.The angle β must have a minimum value in order to avoid excessive forces on the radial bearing. The angle β can be calculated from the inequality

are determined, wherein the ratio of the radial to the axial relative expansion between stator and rotor in the case of a temperature change .DELTA.T is expressed. The ratio can be calculated taking into account geometry parameters and thermal characteristics according to ΔD _ges = ΔD _G - 2Δr _EPR - ΔD _L .Delta..sub.R _EPR = α · _EPR .DELTA.T · r _EPR ΔD _L = α _L · ΔT · D _L ΔD _G = α _G · ΔT · D _G ΔL _ges = ΔL _Stat - ΔL _Red ΔL _Stat = α _Stat · ΔT · L _Stat ΔL _Red = α _Red · ΔT · L _Red express. Herein, the thermal expansion coefficients α _L for the radial bearing, α _G for the housing (end shield), α _Stat for the stator, α _red for the rotor and α _EPR for the fitting ring taken into account, beyond the mean radial thickness r _{EPR of} the fitting ring, the Outer diameter D _{L of} the bearing, the outer diameter D _{G of} the housing, the axial length L _{Stat of} the stator, and the axial length L _{Red of} the rotor. If the angle β satisfies the aforementioned inequality, excessive forces on the radial bearing are avoided.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• JP 11-264421 A [0002]
• WO 2005/042992 Al [0003]

Claims (10)

Radial bearing in an electrical machine ( 1 ) for supporting a rotor shaft ( 4 ), with a radial bearing ( 9 ) housed in a housing-tight fitting ring ( 10 ), wherein the radially inner side of the fitting ring ( 10 ) and the radially outer side of a bearing outer ring ( 9b ) relative to the motor longitudinal axis ( 11 ) are each formed in a straight line, characterized in that the radially inner side of the fitting ring ( 10 ) and the radially outer side of the bearing outer ring ( 9b ) are at an angle (β) to each other. Radial bearing according to claim 1, characterized in that one side ( 10 ) conical and one side ( 9b ) is cylindrical. Radial bearing according to claim 2, characterized in that the inside of the fitting ring ( 10 ) conical and the outside of the bearing outer ring ( 9b ) are cylindrical. Radial bearing according to claim 3, characterized in that the outside of the fitting ring ( 10 ) is cylindrical. Radial bearing according to claim 1, characterized in that both sides are conical. Radial bearing according to one of claims 1 to 5, characterized in that the angle (β) between the radially inner side of the fitting ring ( 10 ) and the radially outer side of the bearing outer ring ( 9b ) is at least 5 °, in particular at least 10 °. Radial bearing according to one of claims 1 to 6, characterized in that the angle (β) between the radially inner side of the Einpassrings ( 10 ) and the radially outer side of the bearing outer ring ( 9b ) is maximum 15 °. Radial bearing according to claim 6 or 7, characterized in that the angle (β) between the radially inner side of the Einpassrings ( 10 ) and the radially outer side of the bearing outer ring ( 9b ) Is 11.5 °. Radial bearing according to one of claims 1 to 8, characterized in that the fitting ring ( 10 ) has a greater axial length than the radial bearing ( 9 ). Electric machine with a radial bearing ( 8th ) according to one of claims 1 to 9.

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