阅读说明：本技术 轴承组合体 (Bearing assembly ) 是由 马丁·道赫尔 托马斯·福斯特 贝恩德·斯蒂芬 于 2021-05-06 设计创作，主要内容包括：本发明披露一种用于支撑电动机传动轴的轴承组合体(1),包含至少一个内圈(2-1、2-2)、至少一个外圈(4)以及设置在内圈(2-1、2-2)和外圈(4)之间的滚动体(6-1、6-2)。其中,所述轴承组合体(1)是被设置为包含有两列滚动体(6-1、6-2)的角接触球轴承。(The invention discloses a bearing assembly (1) for supporting a motor drive shaft, comprising at least one inner ring (2-1, 2-2), at least one outer ring (4) and rolling bodies (6-1, 6-2) arranged between the inner ring (2-1, 2-2) and the outer ring (4). The bearing assembly (1) is an angular contact ball bearing which is provided with two rows of rolling bodies (6-1, 6-2).)

1. Bearing assembly (1) for supporting a drive shaft of an electric motor, comprising at least one inner ring (2-1, 2-2), at least one outer ring (4) and rolling bodies (6-1, 6-2) arranged between the inner ring (2-1, 2-2) and the outer ring (4), characterized in that: the bearing arrangement (1) is designed as an angular contact ball bearing comprising two rows of rolling bodies (6-1, 6-2).

2. Bearing assembly (1) according to claim 1, wherein: the diameter (D) of the rolling bodies (6-1, 6-2)_w) Between 0.2 and 0.4, in particular between 0.25 and 0.35, wherein D is the outer diameter of the bearing assembly (1) and D is the inner diameter of the bearing assembly (1).

3. Bearing assembly (1) according to any of the preceding claims, wherein: the contact angle (alpha) of the angular contact ball bearing (1) is between 15 DEG and 40 DEG, in particular between 15 DEG and 25 deg.

4. Bearing assembly (1) according to any of the preceding claims, wherein: the contact angles (alpha) of the two rows of rolling bodies (6-1, 6-2) are not the same.

5. Bearing assembly (1) according to claim 4, wherein: the first row (6-1) of rolling elements (6-1, 6-2) has a smaller contact angle (alpha) than the second row (6-2) of rolling elements (6-1, 6-2).

6. Bearing assembly (1) according to any of the preceding claims, wherein: a conductive part, in particular a conductive brush, is arranged between the inner rings (2-1, 2-2) and the outer ring (4).

7. Bearing assembly (1) according to any of the preceding claims, wherein: the bearing assembly (1) comprises two inner rings (2-1, 2-2) and two outer rings (4-1, 4-2), and a row of rolling bodies (6-1, 6-2) are respectively arranged between each inner ring and each outer ring.

8. Bearing assembly (1) according to any of claims 1 to 7, wherein: the bearing assembly (1) comprises two inner rings (2-1, 2-2) and an outer ring (4).

9. A shaft assembly for an electric motor, comprising a shaft supported at both ends by a bearing assembly (1) according to any one of claims 1 to 8.

Technical Field

The present invention relates to a bearing assembly for supporting a drive shaft of an electric motor (electric drive motor). The invention also relates to a shaft assembly (/ shaft assembly/drive shaft assembly) for an electric motor.

Background

Current motors are typically supported by deep groove ball bearings arranged in pairs. Such deep groove ball bearings exhibit a high axial clearance and are not very rigid in the axial direction. The use range of deep groove ball bearings is therefore limited, in particular at high rotational speeds. However, in the development of the present electric machines (especially electric motors), it is crucial to reduce the weight and size of the electric machines. To achieve this, motors have been developed that can be operated at high rotational speeds. Here, a rotation speed of 1,000,000 mm/min or more at n × dm value (rotation speed × pitch circle diameter) can be realized. However, the deep groove ball bearings currently used in electric motors are difficult to withstand such high rotational speeds or n × dm values.

Disclosure of Invention

It is therefore an object of the present invention to provide a bearing assembly (bearing assembly) for supporting a drive shaft (drive shaft) of an electric motor (electric drive motor), which bearing assembly is capable of withstanding very high rotational speeds, in particular rotational speeds of 1,000,000 mm/min or higher n dm values.

This object is achieved by a bearing assembly for supporting a drive shaft of an electric motor according to claim 1 and a shaft assembly according to claim 9 comprising such a bearing assembly.

The bearing assembly comprises at least one inner ring, at least one outer ring and a plurality of rolling elements arranged between the inner ring and the outer ring. In order to be able to support the drive shaft of an electric motor at high rotational speeds, in particular at rotational speeds of 1,000,000 mm/min or more n dm, the bearing assembly according to the invention is an angular contact ball bearing which is provided with two rows of rolling elements, in comparison with previous bearing assemblies comprising deep groove ball bearings. Due to the angular contact ball bearing design, the rigidity of the bearing assembly and thus the motor is increased. Thus, the motor can be used at higher speeds than previously possible with deep groove ball bearings. For the sake of simplicity, in the following description, the n × dm value (rotation speed × pitch circle diameter) that can provide a more precise expression is referred to as a rotation speed.

Deep groove ball bearings have been used in bearing assemblies for propeller shafts, which are indeed more economical, but can only withstand low rotational speeds, in particular rotational speeds below 700,000 mm/min n dm. However, the inventors have found that despite the higher cost, the use of angular contact ball bearings is advantageous because these motors can be developed with higher rotational speeds. Due to these high rotational speeds, the electric machine can be constructed more lightweight and compact, thereby gaining benefits over the higher cost of angular contact ball bearings. In addition to higher rotational speeds, angular contact ball bearings also offer an advantage: even at higher rotational speeds, they are more stable than the deep groove ball bearings used hitherto. This also has the positive effect of making the motor or drive shaft more stable.

The diameter of the rolling elements may be between 0.2 and 0.4 and in particular between 0.25 and 0.35. Here, D represents an outer diameter of the bearing assembly, and D represents an inner diameter of the bearing assembly. The rolling elements, in particular the balls, are therefore also smaller than in the case of normal angular contact ball bearings. For example, according to the present embodiment, the diameter of the rolling element may be 0.33 × D in two single row angular contact ball bearings arranged in pair, and 0.303 × D in a double row angular contact ball bearing.

By using smaller rolling elements, the stiffness of the bearing assembly is increased, since with smaller rolling elements more rolling elements can be used per bearing. A bearing comprising a plurality of small rolling elements is more rigid than a bearing comprising a few large rolling elements.

According to a further embodiment, the contact angle of the angular ball bearing is between 15 ° and 40 °, in particular between 15 ° and 25 °. A smaller contact angle is particularly suitable for high rotational speeds, since the change in contact angle caused by centrifugal forces is very small, as a result of which the wear is reduced.

In one embodiment, the contact angles of the two rows of rolling elements may be the same as each other.

Alternatively, the contact angles of the two rows of rolling elements may be different. In particular, the rolling elements of the first row have a smaller contact angle than the rolling elements of the second row. This has the advantage that rows of rolling elements with smaller contact angles result in a high radial stiffness and rows of rolling elements with larger contact angles result in a high axial stiffness. In this manner, both the axial and radial stiffness of the bearing assembly is enhanced.

The bearing with the smaller contact angle should be located inside the electrical machine (/ motor). The radial support force is mainly provided by the bearing. Being disposed at an inboard position, the strut width is reduced and the axial bending is reduced.

The rolling bodies can be made of metal (in particular steel) or ceramic material. The choice of material depends inter alia on the speed and the conductive requirements. The rolling elements are preferably made of ceramic, since this protects the rolling elements, the bearing rings and the lubricant from galvanic corrosion.

The bearing assembly may further comprise an electrically conductive element, in particular an electrically conductive brush, arranged between the inner ring and the outer ring. Such a conductive brush can be used in particular with rolling bodies made of ceramic for electrically connecting the inner and outer rings to one another. Such a conductive element can thus ensure that no static voltage is built up in the bearing assembly, since the static voltage can be eliminated by the electrical connection between the inner and outer rings. A rotor with static electricity presents a safety risk, since during contact the current may be discharged through the body.

According to one embodiment, the bearing assembly comprises two inner rings and two outer rings, each set having a row of rolling elements disposed therebetween. The bearing assembly is thus provided as a set of paired angular contact ball bearings, which may be provided in a back-to-back (back-to-back) or face-to-face (face-to-face) arrangement. Two single-row angular contact ball bearings arranged in pairs can additionally exert axial preload with springs.

According to another embodiment, the bearing assembly comprises two inner rings and one outer ring. Such a double-row angular contact ball bearing can further increase the possible rotational speeds, since it has a higher axial stiffness than a double-row angular contact ball bearing comprising an integral inner ring.

In general, one-piece cages (e.g., made of plastic or metal) ideal for high speeds can be used for the bearing assembly proposed here. The pockets of the cage may be uniformly or non-uniformly circumferentially spaced. The non-uniform spacing here has the advantage that the ball through flow frequency (ball through flow frequency) does not excite surrounding components, compared to the case of equal spacing.

According to a further aspect, the invention also proposes a shaft assembly (shaft assembly) for an electric motor. The shaft assembly includes a drive shaft (drive shaft) supported at both ends on the bearing assembly.

Further advantages and preferred embodiments of the invention will be described in the description, drawings and claims. The combination of features, which is set forth in particular in the description and the drawings, is purely exemplary in nature and these features may be present individually or in any other combination.

Drawings

The invention is described in detail below with reference to exemplary embodiments depicted in the accompanying drawings. The exemplary embodiments and combinations of features presented in the exemplary embodiments are purely exemplary in nature and are not intended to limit the scope of the invention. The scope of the invention is only limited by the appended claims.

FIG. 1 shows a cross-sectional view of a first embodiment of a bearing assembly for supporting a drive shaft of an electric motor;

figure 2 shows a cross-sectional view of a second embodiment of a bearing assembly for supporting a drive shaft of an electric motor.

List of reference numerals

1 bearing assembly

2 inner ring

4 outer ring

6 rolling element

8 holding rack

10 seal

Alpha contact angle

D_wDiameter of rolling element

Detailed Description

In the following description, identical or functionally equivalent parts are given the same reference numerals.

Fig. 1 shows a cross-sectional view of a first embodiment of a bearing assembly 1 for supporting a drive shaft of an electric motor. The bearing assembly 1 is configured as a double row angular contact ball bearing comprising split (/ split) (split) inner rings 2-1, 2-2. The bearing assembly 1 further comprises a single common outer ring 4. Two rows of rolling bodies 6-1 and 6-2 are arranged between the split inner rings 2-1, 2-2 and the outer ring 4.

Since the angular ball bearing 1 is used to support the drive shaft of the motor, the motor can achieve a higher rotation speed than a bearing assembly using a deep groove ball bearing before. Due to the use of angular contact ball bearings 1, it is possible to operate the drive shaft and the motor supported thereby at very high rotational speeds up to values of 1,500,000 mm/min and even higher n dm. If deep groove ball bearings which are still used up to now are used, the rotational speeds can only reach 700,000 mm/min. Due to the higher rotational speed, the motor can be constructed smaller and lighter than before.

In the angular ball bearing 1 shown in fig. 1, the contact angle α is 30 °. The two identical contact angles shown in the figures may also be replaced by different contact angles. This has the advantage that rows of rolling elements with smaller contact angles result in a greater radial stiffness, while rows of rolling elements with larger contact angles result in a greater axial stiffness.

The angular ball bearing 1 is used to support a drive shaft of an electric motor. For this purpose, each end of the drive shaft is supported by a bearing assembly as shown in fig. 1 or 2. The inner rings 2-1, 2-2 of the angular contact ball bearing 1 are arranged on the drive shaft, while the outer ring 4 is arranged in a housing (housing) of the electric motor for supporting the drive shaft in said housing.

The diameter D of the rolling elements 6-1, 6-2 is comparable to that of conventional angular contact ball bearings_wMay be selected to be relatively small. In particular, the diameter D of such a double-row angular contact bearing 1_wMay be 0.303 x (D-D), where D is the bearing outer diameter and D is the bearing inner diameter.

The rolling bodies 6-1, 6-2 can be held by respective cages 8-1, 8-2. In particular, these cages may be one-piece cages (one-piece cages). The holders 8-1, 8-2 may be made of plastic or metal. The bearing assembly 1 can be closed off on the outside by a corresponding seal (/ seal assembly) 10.

As shown in fig. 2, two single-row angular contact ball bearings 1-1, 1-2 may also be used instead of one double-row angular contact ball bearing. Here, two single-row angular contact ball bearings 1-1, 1-2 are mounted in pairs. Unlike the double-row angular contact ball bearing 1 shown in fig. 1, the angular contact ball bearing 1 is provided in this case with two inner rings 2-1, 2-2 and two outer rings 4-1, 4-2.

In the illustrated embodiment, the two angular contact ball shafts 1-1, 1-2 are shown in a back-to-back (back-to-back) arrangement. Alternatively, the two single-row angular contact ball bearings 1-1, 1-2 may be mounted in a face-to-face (face-to-face) mode.

In this case, the diameter D of the rolling elements 6-1, 6-2_wPreferably 0.33 x (D-D). The rolling bodies 6-1, 6-2 can be held by cages 8-1, 8-2, respectively.

In this bearing assembly 1, the contact angle α is also 30 °. It is important to note, however, that the contact angle of the angular contact ball bearing of fig. 1 and 2 may be between 15 ° and 40 °. A smaller contact angle has the advantage that the bearing assembly 1 can be subjected to higher rotational speeds. The contact angles of the two rows of rolling elements 6-1, 6-2 can also differ. Rolling rows with smaller contact angles increase the radial stiffness, while rolling rows with larger contact angles increase the axial stiffness.

As mentioned above, in an electrical machine supporting a drive shaft with a bearing assembly, the bearing assembly proposed by the present invention is capable of achieving extremely high rotational speeds up to values of 1,500,000 mm/min and even higher n dm. This is achieved by replacing the deep groove ball bearings used in the past with angular contact ball bearings. The motor can then be constructed more lightweight and compact due to the higher rotational speeds used.