DE102019106426A1 - Motor shaft bearing for an electric motor - Google Patents

Abstract

Motor shaft bearing (1) for an electric motor, with a bearing plate (3), a motor shaft (5) with a rotor area (7) for receiving a rotor of the electric motor, two angular contact roller bearings (11) which are arranged in the bearing plate (3) and which store the motor shaft (5), the angular contact roller bearings (11) being arranged in a bearing area (9) of the motor shaft (5) on one side of the rotor area (7).

Description

Field of invention

The disclosure relates to a motor shaft bearing for an electric motor and a method for manufacturing an electric motor.

State of the art

From the prior art, for example from DE 433 54 33 A1 , electric motors with one-sided mounting of the motor shaft are known.

However, the one-sided bearings of the motor shaft known from the prior art are not suitable for absorbing axial and transverse forces from the output or they require a large amount of installation space.

Disclosure of the invention

The object of the disclosure is to specify a motor shaft bearing for an electric motor and a method for producing an electric motor which are improved over the prior art, in particular a space-saving or stable bearing should be specified which should be easy to manufacture.

The object is achieved with a motor shaft bearing for an electric motor according to claim 1 and a method according to the independent claim.

According to one aspect, a motor shaft bearing for an electric motor is specified, with a bearing plate, a motor shaft with a rotor area for receiving a rotor of the electric motor, two angular contact roller bearings which are arranged in the bearing plate and which support the motor shaft, the angular contact roller bearings in a bearing area of the motor shaft are arranged on one side of the rotor area.

According to a further aspect, a method for producing an electric motor with a motor shaft mounted on one side, which has a bearing area and a rotor area, is specified, with assembly of a motor shaft bearing according to one of the embodiments described herein with bearings for the bearing area of the motor shaft in the angular contact roller bearings; and attaching a rotor of the electric motor to the rotor area of the motor shaft.

Typically the rotor area corresponds to axial, i.e. H. along the longitudinal axis of the motor shaft, a section of the motor shaft which is provided for attaching a rotor, wherein the rotor can in particular comprise a rotor carrier or a magnet carrier. The rotor area is typically limited axially in the direction of the bearing area by a first shoulder, for example by a stepped widening of the motor shaft towards the bearing area. The first paragraph can serve as a mechanical stop for the rotor.

In typical embodiments, the angular contact roller bearings are arranged in the bearing area on the output side of the rotor area. Typically, the bearing area of the motor shaft comprises the axial areas of the motor shaft in which the angular contact roller bearings are attached to the motor shaft, and the axial area of the motor shaft that lies between the angular contact roller bearings. In typical embodiments, the end shield is designed as an A end shield. The bearing area of the motor shaft can be delimited axially on the output side by an output flange and axially towards the rotor area by a pretensioning means.

In typical embodiments, each of the two angular contact roller bearings each comprises an inner ring, an outer ring and rolling elements. The inner ring is attached to the motor shaft and provides an inner running surface for the rolling elements on the motor shaft, the outer ring is attached to the end shield and provides an outer running surface for the rolling elements on the end shield.

Typical embodiments of the motor shaft bearing comprise preloading means for preloading the angular contact roller bearings. Typically, a biasing means is arranged on the motor shaft. In typical embodiments, the angular contact roller bearings are preloaded against one another. Typically, the angular contact roller bearings are rigidly preloaded, in particular without a spring or a corrugated washer. In typical embodiments, the preload forces are greater than the permissible axial forces or transverse forces that can be absorbed by the angular roller bearings. Typical embodiments have a motor shaft mounted free of play, which in exemplary embodiments is free of play even under load within the permissible loads.

Forces that are transmitted between the motor shaft and the end shield via the angular contact roller bearings are referred to as axial forces and lateral forces. Axial forces act in the axial direction, i. H. along the longitudinal axis of the motor shaft. On the other hand, transverse forces act perpendicular to the axial direction, i.e. H. perpendicular to the longitudinal axis of the motor shaft. Axial forces and transverse forces can in particular also result from torques which act, for example, on the end shield or on the motor shaft at the output. In this way, lateral forces can arise from a tilting moment acting on the motor shaft.

In typical embodiments, the prestressing means is designed as a shaft nut. Typically, the shaft nut is attached between the rotor area and the angular contact roller bearings. In further embodiments, the shaft nut is attached to the side of the bearing area facing away from the rotor area. In further embodiments, the angular contact roller bearings are preloaded by a housing nut. In further embodiments, the angular contact roller bearings are preloaded by means of a screwed flange or a ring in the end shield. Further embodiments include shims or suitably manufactured components for preloading the angular contact roller bearings.

In typical embodiments, a rotary shaft seal runs on the shaft nut. When the angular contact roller bearings are lubricated with oil, the shaft nut is typically sealed with adhesive. Further embodiments use alternative sealants to seal the storage space.

In a typical embodiment, the pretensioning means is arranged between the rotor area and the two angular contact roller bearings. In further embodiments, the pretensioning means is arranged on the output side of the angular contact roller bearing.

In typical embodiments, the motor shaft is supported exclusively by the two angular contact roller bearings. An encoder with its own bearing can be used; this typically has its own shaft that is attached to the motor shaft.

The respective outer diameters of the angular contact roller bearings are typically the same. The outer diameter of an angular contact roller bearing is given by the outer diameter of an outer ring of the angular contact roller bearing. Typically, the angular contact roller bearings are installed in such a way that the stiffness of the motor shaft bearings for axial forces in both directions, i. H. for tensile and compressive forces in the axial direction, is the same.

In typical embodiments, the axial length of the bearing area is shorter than the length of the rotor, typically shorter than half the length of the rotor. The axial length of the bearing area corresponds to half the length of the bearing area along the longitudinal axis of the motor shaft. In a typical embodiment, the rotor is 150 mm long, for example, and the axial length of the bearing area is 66 mm in this embodiment. In further embodiments, the rotor is 200 mm long and the axial length of the bearing area is 90 mm.

In further embodiments, half the axial length of the bearing area is shorter than the length of the rotor, typically shorter than half the length of the rotor.

In typical embodiments, the axial distance between the angular contact roller bearings is shorter than at least one of the outer diameters of the angular contact roller bearings, in particular less than 50%, typically less than 35% of the typically identical outer diameter of the at least two angular contact roller bearings or the smaller of the two angular contact roller bearings in the case of angular contact roller bearings with different outer diameters. In typical embodiments, the axial distance between the angular contact roller bearings is shorter than the length of the rotor, typically shorter than half the length of the rotor, even more typically shorter than a quarter of the length of the rotor.

The axial distance between the angular contact roller bearings is to be understood as the distance along the longitudinal axis of the motor shaft between two mutually facing surfaces of the inner rings of the angular contact roller bearings. In a typical embodiment, the outer diameter of the angular contact roller bearings is 95 mm, the axial distance between two angular contact roller bearings is 20 mm, the rotor is 150 mm long; in a further embodiment, the respective values are 125 mm and 35 mm, 200 mm.

In typical embodiments, the axial length of the bearing area of the motor shaft corresponds to approximately 2 to 4 times the width of one of the two angular contact roller bearings. The width of an angular contact roller bearing is given by the spatial extent of the angular contact roller bearing along the longitudinal axis of the motor shaft.

In typical embodiments, both angular contact roller bearings have at least essentially the same width. The axial length of the bearing area of the motor shaft is typically more than twice the width of one of the two angular contact roller bearings and less than five times the width, in particular less than three times the width.

In typical embodiments, the angular contact roller bearings are designed as tapered roller bearings, which can have a high load capacity. In other embodiments, the angular contact roller bearings are designed as angular contact ball bearings or needle bearings.

In typical embodiments, the angular contact roller bearings are designed to transmit axial forces and transverse forces between the motor shaft and the end shield. In typical embodiments, the maximum axial force that can be transmitted via the angular contact roller bearings is at least 50% of the maximum transverse force that can be transmitted. In typical embodiments, the maximum axial force that can be transmitted via the angular contact roller bearings is at least 70% or at least 90% of the maximum transverse force that can be transmitted.

In typical embodiments, the end shield is formed in one piece. The end shield is typically manufactured as a turned or milled part. Solid material as well as a forged or cast blank can be used as the basis for manufacturing the end shield. Further typical embodiments are equipped with a multi-part bearing plate, for example a mounting flange can be pressed onto the bearing plate.

In typical embodiments, the end shield comprises an outer mounting flange, in particular a radially outer mounting flange. The mounting flange is provided, for example, for connection to a work machine or to a stationary machine element. Typically, the mounting flange is made in one piece with the end shield. In other embodiments, the mounting flange is screwed onto the end shield. Typically the mounting flange is arranged axially in the bearing area.

Typically, the end shield comprises an external housing flange for fastening the end shield to a housing of an electric motor.

In typical embodiments, the motor shaft has a shoulder, the shoulder being designed in particular radially, for example as a stepped widening of the motor shaft. Typically, the motor shaft has a first shoulder between the rotor area and the bearing area, wherein the shoulder, which is especially designed radially, can be designed as a mechanical stop for the rotor.

In typical embodiments, the motor shaft has an output flange. The output flange is typically made in one piece with the motor shaft. The output flange is typically arranged on the output side of the bearing area. In typical embodiments, the output flange has a second shoulder, which can be designed as a mechanical stop, in particular as an axial mechanical stop, for one of the two angular roller bearings, in particular for an inner ring of an angular roller bearing.

In typical embodiments, the output flange has axially executed drill holes, in particular drill holes with a thread, on the output side.

The motor shaft can have a tapered area at the end of the motor shaft opposite the output flange, which can make it easier to bring the motor shaft together, for example, with the inner rings of the angular contact roller bearings, the end shield, a shaft nut or the rotor.

In typical embodiments, the motor shaft has a threaded area between the rotor area and the bearing area which can be provided for screwing on a shaft nut.

In typical embodiments, the motor shaft has a centering bore on the output side for introducing forces. The centering hole is typically designed axially. In typical embodiments, the centering hole is designed as a blind hole. In further typical embodiments, the centering bore runs axially continuously through the motor shaft.

A typical embodiment of the invention comprises an electric motor with a motor shaft bearing according to one of the embodiments described herein and a rotor arranged on the motor shaft in the rotor area.

In typical embodiments, a pinion, in particular a helically toothed pinion, is attached to the output side of the motor shaft for use in a rack-and-pinion drive. The pinion is attached to the motor shaft, for example by fitting with the centering hole. In particular, the mounting flange on the bearing plate is designed for connection to a slide or a stationary machine element. The motor shaft bearing is designed to absorb the axial forces and transverse forces introduced by the tooth contact between the pinion and the rack without play.

In typical embodiments, the electric motor is designed as a permanent magnet synchronous motor (PMSM).

In typical processes for manufacturing an electric motor, the outer rings of the angular contact roller bearings are pressed into the end shield. Typically, a first inner ring and first rolling elements, for example a first set of rolling elements, are pressed onto the motor shaft in the bearing area of the motor shaft, the first inner ring and the first rolling elements being assigned to the angular contact roller bearing of the two angular contact roller bearings further away from the rotor area. The motor shaft is then typically inserted into the end shield, for example with the rotor area first. Typically, a second inner ring and second rolling elements, for example a second set of rolling elements, are then pushed over the rotor area of the motor shaft and arranged in the bearing area of the motor shaft, the second inner ring and the second rolling elements being assigned to the angular contact roller bearing of the two angular contact roller bearings that is closer to the rotor area .

In typical embodiments of the method, a shaft nut is then pushed over the rotor area onto the motor shaft and arranged on the second inner ring. Typically, the shaft nut is screwed onto the motor shaft with a defined tightening torque, whereby the angular contact roller bearings are preloaded against one another.

The method steps described above for mounting the bearing area of the motor shaft in the angular contact roller bearings are not to be understood as limitations in relation to the method claimed in the independent claim. Rather, the method steps described above describe a typical embodiment by way of example. In further embodiments in which, for example, a housing nut is used as a pretensioning means, the process steps for mounting the bearing area of the motor shaft in the angular contact roller bearings are carried out in a correspondingly modified form and sequence.

Typically, a cavity, also referred to as a storage space, which surrounds the angular contact roller bearings, is sealed by attaching at least two radial shaft sealing rings. With oil lubrication of the angular contact roller bearings, the angular contact roller bearings are filled with oil between the attachment of a first radial shaft seal and a second radial shaft seal.

In typical methods of manufacturing an electric motor, after the motor shaft bearing has been assembled, the bearing area of the motor shaft being supported in the angular contact roller bearings, the rotor of the electric motor is attached to the rotor area of the motor shaft. Typically, a motor shaft bearing with rotor is then connected to a stator mounted in the housing, in particular via a housing flange. Typically, the method for manufacturing an electric motor also includes the assembly of an encoder housing, an encoder and an additional radial shaft sealing ring as well as the wiring of the electrical connections.

Typical embodiments of the electric motor offer the advantage over the prior art that axial forces and transverse forces introduced via the motor shaft are derived from the output via the angular contact roller bearings, the end shield and the mounting flange without having to be transmitted to the housing of an electric motor, for example. Typical embodiments of the motor shaft bearing offer the advantage that they do not require a bearing bracket or a gearbox to absorb axial forces. As a result, typical embodiments require less installation space, for example. Typical rack and pinion drives, which have a motor shaft in one of the embodiments described herein, are bearing block-free or gear-free.

Figure list

• 1 zeigt eine schematische Schnittansicht einer typischen Motorwellenlagerung;
• 2 zeigt eine schematische Schnittansicht eines Elektromotors mit einer typischen Motorwellenlagerung; und
• 3 zeigt schematisch ein Verfahren zur Herstellung eines Elektromotors.

Further advantages and features of preferred embodiments of the invention are explained below with reference to the accompanying drawings, the figures showing:

• 1 shows a schematic sectional view of a typical motor shaft bearing;
• 2 shows a schematic sectional view of an electric motor with a typical motor shaft bearing; and
• 3 shows schematically a method for manufacturing an electric motor.

Description of embodiments

Typical embodiments are described below with reference to the figures, the invention not being restricted to the exemplary embodiments, rather the scope of the invention is determined by the claims.

In the description of the figures, the same reference symbols are used for the same or similar parts. In some cases, features that have already been described in connection with other figures are not described again for the sake of clarity.

1 shows a schematic sectional view of a typical motor shaft bearing 1 with an end shield 3 and a motor shaft 5 . The motor shaft 5 is by means of two angular contact roller bearings 11 in the end shield 3 stored.

The motor shaft 5 includes a rotor area 7th , which is intended to accommodate a rotor of an electric motor (see 2 ), and a storage area 9 in which the motor shaft 5 in the end shield 3 is stored. The storage area 9 includes the axial area of the motor shaft 5 by the two angular contact roller bearings 11 is edged. The angular contact roller bearings 11 in the storage area 9 are on one side of the rotor area 7th arranged.

In 1 are the angular contact roller bearings 11 designed as a tapered roller bearing. The angular contact roller bearings 11 include rolling elements 15th , Inner rings 17th and outer rings 19th which are the inner running surfaces or outer running surfaces for the rolling elements 15th provide. In the embodiment of 1 are the inner running surfaces on the inner rings 17th of the two angular contact roller bearings 11 inclined to each other.

In typical further embodiments, the running surfaces of the inner rings of the two angular contact roller bearings are inclined away from one another. In summary, embodiments with an X arrangement of the angular roller bearings and embodiments with an O arrangement of the angular roller bearings are possible.

The angular contact roller bearings 11 are by means of a pretensioning device 13 , in 1 designed as a shaft nut, preloaded. The pretensioning means 13 is on the motor shaft 5 screwed, making the angular contact roller bearings 11 are biased against each other. The angular contact roller bearings 11 are in both axial directions by means of a radial shaft seal 23 sealed. In the embodiment of 1 a radial shaft seal is running 23 on the biasing means 13 . In typical embodiments, it is through the radial shaft seals 23 sealed space filled with oil.

The motor shaft 5 typically has a center hole 25th on. The embodiment of the 1 includes a motor shaft 5 as a continuous hollow shaft.

In further typical embodiments, the centering hole 25th be designed as a blind hole. In further typical embodiments, the motor shaft 5 be designed as a solid shaft.

The motor shaft of the 1 has a radial first shoulder 28 on, which can serve as a mechanical stop for a rotor, in particular for a rotor arm of the rotor. In 1 limited the first paragraph 28 the rotor area 7th axially in the direction of the bearing area 9 .

The motor shaft 5 is typically in one piece with an output flange 26th designed and has drill holes executed therein 27 with thread on. The output flange 26th has a second paragraph 29 as a mechanical stop for an inner ring of the inner rings 17th the angular contact roller bearing 11 serves.

The bearing shield 3 typically includes a mounting flange 21st , for example to connect the end shield 3 with a working machine or with a fixed machine element. The one in the 1 The embodiment shown is the mounting flange 21st integral with the end shield 3 executed and axially in the bearing area 9 arranged. Due to the one-piece design of the end shield 3 and mounting flange 21st ensure high stability of the motor shaft bearings 1 and a direct transmission of axial forces and lateral forces from the output via the motor shaft 5 who have favourited angular contact roller bearings 11 , the bearing shield 3 and the mounting flange 21st guaranteed.

In embodiments, the end shield comprises a housing flange 22nd for connection to a housing. In typical embodiments, the housing flange is 22nd integral with the end shield 3 executed. In further embodiments, the mounting flange or the housing flange are designed as separate components and are attached to the end shield.

2 shows an electric motor 31 with a typical motor shaft bearing 1 . Typically that comes in connection with 1 Motor shaft bearing shown also in the 2 for use.

On the motor shaft 5 is in the rotor area 7th a rotor 33 appropriate. The motor shaft 5 is about the angular contact roller bearings 11 on the end shield 3 one side of the rotor area 7th stored.

The electric motor 31 typically includes a housing 37 . In typical embodiments, as in 2 shown is the housing 37 via the housing flange 22nd with the end shield 3 screwed. The electric motor 31 includes a stator 35 , which on the housing 37 and around the rotor 33 is appropriate.

As in 2 shown, the electric motor 31 still electrical connections 39 , an encoder housing 41 , an encoder 43 , another radial shaft seal 45 , a housing cover 47 or a wiring of the electrical components.

3 shows schematically the sequence of a typical method for producing one of the typical embodiments described herein, for example the electric motor 31 , which in the 2 is shown.

At 100 the two outer rings 19th the angular contact roller bearing 11 in the end shield 3 pressed in.

At 110 becomes a first inner ring of the inner rings 17th and first rolling elements of the rolling elements 15th on the motor shaft 5 pressed, the first inner ring and the first rolling elements being that of the rotor area 7th farther away the angular contact roller bearings 11 assigned.

At 120 becomes the motor shaft 5 with the rotor area 7th ahead in the end shield 3 plugged.

Then in one process step 130 a second inner ring of the inner rings 17th and second rolling elements of the rolling elements 15th in the storage area 9 the motor shaft 5 arranged, the second inner ring and the second rolling element closer to the rotor area 7th located angular contact roller bearings of the angular contact roller bearings 11 assigned.

Then in one process step 140 the pretensioning means 13 arranged on the second inner ring. In typical embodiments, the biasing means 13 in a thread area of the motor shaft 5 on the motor shaft 5 to the second inner ring of the inner rings 17th screwed down. In typical embodiments, at 140, the area of contact between the biasing means 13 and the motor shaft 5 , especially between biasing means 13 and the threaded area, filled with an adhesive. In this way, both sealing of the cavity and securing of the prestressing means can be achieved. Then at 150 the pretensioning means 13 on the motor shaft 5 tightened with a defined torque, typically with a torque wrench. The angular contact roller bearings 11 biased.

In one process step 160 the radial shaft seals 23 attached, between the attachment of a first radial shaft seal of the radial shaft seals 23 and attaching a second radial oil seal of the radial oil seals 23 the angular contact roller bearings 11 can be filled with oil.

Thereupon in one process step 170 the rotor 33 of the electric motor 31 at the rotor area 7th the motor shaft 5 appropriate.

Typically, in a further process step 180 the electric motor 31 completed. This procedural step 180 typically involves joining the end shield 3 with the case 37 , typically via the housing flange 22nd . With the case 37 are or will typically be additional components of the electric motor 31 connected, especially the stator 35 who have favourited electrical connections 39 , the encoder housing 41 , the encoder 43 or the additional radial shaft seal 45 .

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

• DE 4335433 A1 [0002]

Claims (15)

Motor shaft bearing (1) for an electric motor, with • a bearing plate (3), • a motor shaft (5) with a rotor area (7) for receiving a rotor of the electric motor, • two angular contact roller bearings (11) which are arranged in the end shield (3) and which support the motor shaft (5), • the angular contact roller bearings (11) being arranged in a bearing area (9) of the motor shaft (5) on one side of the rotor area (7). Motor shaft bearing (1) Claim 1 , with a preload means (13) for preloading the angular contact roller bearings (11). Motor shaft bearing (1) Claim 2 , wherein the pretensioning means (13) is designed as a shaft nut. Motor shaft bearing (1) Claim 2 or 3 , wherein the pretensioning means (13) is arranged between the rotor area (7) and the two angular contact roller bearings (11). Motor shaft bearing (1) according to one of the preceding claims, wherein the motor shaft (5) is supported exclusively by the two angular contact roller bearings (11). Motor shaft bearing (1) according to one of the preceding claims, wherein the respective outer diameters of the angular contact roller bearings (11) are of the same size. Motor shaft bearing (1) according to one of the preceding claims, wherein the axial length of the bearing area (9) is shorter than half the length of the rotor. Motor shaft bearing (1) according to one of the preceding claims, wherein the axial distance between the angular contact roller bearings (11) is shorter than at least one of the outer diameters of the angular contact roller bearings (11). Motor shaft bearing (1) according to one of the preceding claims, wherein the angular roller bearings (11) are designed as tapered roller bearings. Motor shaft bearing (1) according to one of the preceding claims, wherein the maximum axial force which can be transmitted via the angular contact roller bearings (11) is at least 50% of the maximum transverse force which can be transmitted. Motor shaft bearing (1) according to one of the preceding claims, wherein the end shield (3) is formed in one piece. Motor shaft bearing (1) according to one of the preceding claims, wherein the bearing plate (3) comprises an external mounting flange (21). Motor shaft bearing (1) according to one of the preceding claims, wherein the motor shaft (5) has a centering bore (25) on the output side for introducing forces. Electric motor (31) with a motor shaft bearing (1) according to one of the preceding claims and a rotor (33) arranged on the motor shaft (5) in the rotor region (7). Method for producing an electric motor (31) with a motor shaft (5) mounted on one side, which has a bearing area (9) and a rotor area (7), with • assembly of a motor shaft bearing (1) according to one of the Claims 1 to 13 with bearings of the bearing area (9) of the motor shaft (5) in the angular contact roller bearings (11); and • attaching a rotor (33) of the electric motor (31) to the rotor area (7) of the motor shaft (5).

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