Drive having an electric motor with a transmission

Abstract

A drive having an electric motor with a transmission, wherein: the electric motor has a rotatably mounted rotor shaft; the transmission has an eccentric transmission stage; the rotor shaft has at least one first eccentric region; and the first eccentric region has a cylindrical outer circumference, the axis of symmetry of the cylinder being parallel to and spaced apart from the axis of rotation of the rotor shaft.

Description

[0001] Drive, comprising an electric motor with gearbox

[0002] Description:

[0003] The invention relates to a drive comprising an electric motor with a gearbox.

[0004] It is generally known that a gearbox has gear stages and can be driven by an electric motor.

[0005] From DE 11 2012 003 027 T5, the closest prior art is a motor arrangement with a speed reducer.

[0006] An electric motor drive is known from CN 2 01 080 990 Y.

[0007] From DE 39 06 053 A1 a transmission in the form of a stress wave transmission is known.

[0008] From DE 102016 101 381 A1 a self-locking back-gear for shaft movements and a composite reduction device with this back-gear are known.

[0009] From DE 102019 002 918 A1 an electric motor with a rotor shaft and a first and second bearing is known.

[0010] A reduction gear is known from JP S62 - 93 565 A.

[0011] A coaxial gear is known from WO 2011 / 027 675 A1.

[0012] A bearing with a sealing arrangement is known from JP 2015 - 10 523 A.

[0013] A coaxial gear is known from WO 2012 / 033 043 A1.

[0014] The invention is therefore based on the object of designing a drive that is as compact and powerful as possible. According to the invention, this object is achieved by the drive according to the features specified in claim 1.

[0015] Important features of the drive, comprising an electric motor with a gearbox, are that the electric motor has a rotatably mounted rotor shaft, wherein the gearbox has an eccentric gear stage, wherein the rotor shaft has at least a first eccentric region, wherein the first eccentric region has a cylindrical outer circumference, the cylinder symmetry axis of which is aligned parallel and spaced from the axis of rotation of the rotor shaft, in particular wherein the rotor shaft is formed integrally and / or in one piece with the first eccentric region.

[0016] The advantage here is that the drive is compact yet still provides a high gear ratio. Furthermore, the rotor shaft is supported on one side by the eccentric gear stage and on the other side by another bearing. This reduces energy loss, eliminates the need for components such as a rotor shaft bearing, and avoids over-determination of the rotor shaft bearing.

[0017] In an advantageous embodiment, the rotor shaft has a second eccentric region, wherein the second eccentric region has a cylindrical outer circumference whose cylindrical symmetry axis is aligned parallel to and spaced from the rotational axis of the rotor shaft. In particular, the plane spanned by the cylindrical symmetry axis of the first eccentric region and the plane spanned by the cylindrical symmetry axis of the second eccentric region, in particular a fictitious plane, contains the rotational axis of the rotor shaft. In particular, the rotor shaft is formed integrally and / or in one piece with the first and second eccentric regions. This is advantageous in that the imbalance can be reduced.

[0018] In an advantageous embodiment, the electric motor has a motor housing which is connected at its first axial end region to a bearing shield and which is connected at its second axial end region to a housing part, wherein an outer ring of a bearing, in particular a ball bearing, is accommodated in the bearing shield, the inner ring of which is placed on the rotor shaft, wherein an inner ring of a first rolling bearing is placed on the first eccentric region of the rotor shaft, wherein first rollers roll on the outer circumference of the outer ring of the first rolling bearing and / or on the radial outer circumference of the first rolling bearing, which first rollers project through respective recesses of a rotatably mounted cage and which are delimited by the cage in the circumferential direction and in the axial direction, wherein the axis of rotation of the rotor shaft is aligned coaxially to the axis of rotation of the cage, wherein the first rollers are arranged on a recess formed on the inside of the housing part,Rolling along the first shaft contour, particularly the one extending in the circumferential direction. The advantage here is that the rotor shaft directly drives the eccentric gear, reducing imbalance.

[0019] In an advantageous embodiment, the cage has a cylindrical extension, with at least one additional bearing being mounted on the extension and accommodated in the housing part, in particular with the inner ring of the additional bearing being mounted on the extension and the outer ring of the additional bearing being accommodated in the housing part. It is advantageous that the cage itself forms the output shaft.

[0020] In an advantageous embodiment, an inner ring of a second rolling bearing is placed on the second eccentric region of the rotor shaft, wherein second rollers roll on the outer circumference of the outer ring of the second rolling bearing and / or on the radial outer circumference of the second rolling bearing, which second rollers project through respective recesses of a rotatably mounted cage and which are delimited by the cage in the circumferential direction and in the axial direction, wherein the second rollers roll on a second shaft contour formed on the inside of the housing part, in particular extending in the circumferential direction, in particular wherein the first shaft contour is axially spaced from the second shaft contour in the axial direction or adjoins the second shaft contour and / or wherein the axis of rotation of the second rolling bearing is spaced from the axis of rotation of the first rolling bearing and the axis of rotation of the first rolling bearing,The rotational axis of the second rolling bearing and the rotational axis of the rotor shaft are arranged together in a fictitious plane. This has the advantage of reducing the imbalance.

[0021] In an advantageous embodiment, the rotor shaft has a shaft collar against which the inner ring of the first rolling bearing is positioned. This is advantageous because it allows for a robust design.

[0022] In an advantageous embodiment, a continuously circumferential annular groove is arranged in the outer circumference of the shaft collar. This has the advantage of reducing the formation of high-frequency vibrations.

[0023] In an advantageous embodiment, one or more radial bores are introduced into the shaft collar or one or more radial bores are introduced into the eccentric regions, in particular wherein the radial bore or bores are arranged at the axial position of the annular groove, in particular and open into the annular groove, in particular wherein the inner ring of the first rolling bearing covers at least one radial bore and / or wherein the inner ring of the second rolling bearing covers at least one radial bore. The advantage here is that the formation of vibration resonances is made more difficult and the transmission can be operated more robustly. In particular, quieter operation can thus be achieved.

[0024] In an advantageous embodiment, a sealing cover attached, in particular clamped, to an axial projection of the housing part seals against the rotor shaft, in particular wherein the sealing cover is designed as a rubberized sheet metal part. This is advantageous because lubricants such as grease do not enter the area of ​​the stator winding.

[0025] In an advantageous embodiment, the respective roller protrudes radially through the respective recess of the cage, in particular with the rotational axis of the shaft and the rotational axis of the cage aligned coaxially with each other. This is advantageous because the eccentric gear is easy to manufacture.

[0026] In an advantageous embodiment, the shaft contour has a radial spacing that runs periodically in the circumferential direction. This is advantageous because the shaft contour is easy to manufacture and has a high overload capacity.

[0027] In an advantageous embodiment, the rotational axis of the first rolling bearing is aligned parallel to the rotational axis of the rotor shaft and spaced from the rotational axis of the rotor shaft. In particular, the rotational axis of the first rolling bearing executes a circular motion around the rotational axis of the rotor shaft during operation of the eccentric gear stage. In particular, the rotational axis of the second rolling bearing executes a circular motion around the rotational axis of the rotor shaft during operation of the eccentric gear stage. This allows for simple manufacturing.

[0028] In an advantageous embodiment, the housing part of the gearbox is centered on the motor housing and connected and / or fastened to the housing part, in particular with screws. The advantage here is that a high level of precision can be achieved. In an advantageous embodiment, the eccentric position of the first eccentric region is shifted by 180° in the circumferential direction relative to the eccentric position of the second eccentric region. The advantage here is that the imbalance is reduced. Further advantages arise from the subclaims. The invention is not limited to the combination of features of the claims. Those skilled in the art will recognize further useful combinations of claims and / or individual claim features and / or features of the description and / or the figures, in particular from the problem and / or the problem arising from a comparison with the prior art.

[0029] The invention will now be explained in more detail using schematic illustrations:

[0030] Figure 1 shows an electric motor according to the invention with an integrated eccentric gear stage in a cut-away oblique view.

[0031] The electric motor has a gear stage which is surrounded by the housing of the electric motor.

[0032] The housing of the electric motor has a motor housing 1, in particular a stator housing, which radially surrounds the stator winding of the electric motor.

[0033] The axial direction is aligned parallel to the direction of the rotational axis of the rotor shaft 4. The radial direction is related to the rotational axis of the rotor shaft 4, as are the radial direction and the circumferential direction.

[0034] The rotatably mounted rotor shaft 4 of the electric motor drives the gear stage.

[0035] The motor housing 1 is connected at its first axial end region to a housing part 5 which radially surrounds the gear stage.

[0036] At its second axial end region, a bearing shield is connected to the motor housing 1, wherein a bearing is accommodated in the bearing shield, by means of which the rotor shaft 4 is rotatably mounted and which thus functions as the first bearing.

[0037] The second bearing of the rotor shaft 4 is via the gear stage.

[0038] The housing part 5 is centered and attached to the motor housing 1.

[0039] The housing part 5 surrounds the gear stage driven by the rotor shaft 4, which is designed as an eccentric gear stage.

[0040] The eccentric gear stage drives a device not shown in the figures, such as another gear. For this purpose, a cage 2 of the eccentric gear stage has a shaft stub on the output side, which enables a keyed connection for driving a shaft of the device to be driven. In particular, a keyway is formed in the shaft stub of the cage 2, into which a key is inserted, rotationally fixedly connected to a cage 2 of the eccentric gear stage. Instead of the keyed connection, a spline connection can also be used.

[0041] The eccentric gear stage interacts with eccentric regions (13, 14) formed on the rotor shaft 4. In particular, the rotor shaft 4 is formed integrally with its eccentric regions (13, 14). The eccentric regions are each formed as a cylindrical section, although the cylinder axis is arranged parallel to and spaced from the rotational axis of the rotor shaft 4. The cylinder axes of the two eccentric regions (13, 14) are arranged in a fictitious mathematical plane in which the rotational axis of the rotor shaft 4 is also located.

[0042] A first bearing 8 is mounted on a first eccentric region 14, in particular an eccentric region of these eccentric regions (13, 14) of the rotor shaft 4, the first bearing 8 having its axis of rotation aligned parallel to the axis of rotation of the rotor shaft 4 and spaced apart from the axis of rotation of the rotor shaft 4. Rollers 7 of a first row of rollers, spaced apart from one another in the circumferential direction, roll on the radial outer circumference of the first bearing 8. The rollers 7 are delimited in the circumferential direction and / or in the axial direction by a recess in a cage 2, in particular a cage 2 which can be connected in a rotationally fixed manner to the shaft of the device to be driven.

[0043] Due to the eccentric arrangement of the first bearing 8, the distance between the rollers 7 is variable during the rotational movement of the cage 2.

[0044] Depending on the eccentric position, the rollers 7 roll radially outwards on the radial inside of the housing part 5, which has a wave contour, in particular a clear inner diameter and / or clear radial distance that is periodically dependent on the circumferential position.

[0045] Further rollers 10 of a second row are axially displaced from the rollers 7 of the first row.

[0046] They are spaced apart in the same direction and roll radially inward on the radial outer circumference of a bearing 9, which is mounted on a further eccentric region 13 of the rotor shaft 4, in particular wherein the eccentric position is shifted by 180° in the circumferential direction compared to the first eccentric region 14. The further rollers 10 of the second row are also each delimited by the cage 2 in the axial direction and in the circumferential direction. The further rollers 10 also roll radially outward on the same or alternatively on a further shaft contour on the inside of the housing part 5.

[0047] During the rotational movement of the rotor shaft 4, the cage 2 is thus set in rotational movement and in this way the shaft of the device to be driven, which is not shown in the figures and is connected to the cage 2, is driven, whereby a very high transmission ratio can be achieved with little space requirement.

[0048] Since the rotor shaft 4 is supported by means of two bearings accommodated in the motor housing 1 and, in addition, the rollers 7 and 10 are supported on the inside of the housing part 5 and also press on the rotor shaft 4 via the bearings 8 and 9, the mechanical overdetermination is mitigated and / or tolerable by suitably designed tolerances.

[0049] The housing part 5 has the shaft contour of the eccentric gear stage on its inner side. The housing part 5 is formed in one piece. The shaft contour is preferably cycloidal in the circumferential direction and is therefore fundamentally different from an involute-toothed ring gear.

[0050] Preferably, the rollers 7 are offset from the rollers 10 in the circumferential direction, in particular by 180° in the circumferential direction, where N is the number of rollers in the first row and the number of rollers in the first row is equal to the number of rollers in the second row. This improves synchronization and also reduces a higher moment of imbalance. Alternatively, the rollers 7 are offset from the rollers 10 in the circumferential direction by 180°.

[0051] Since the interior region of the gearbox comprising the eccentric areas (13, 14) is at least partially filled with lubricant, a sealing disc 11, in particular a Nilos ring or rubberized sheet metal part, is received on an axial projection of the housing part 5, so that the sealing disc 11 seals off the rotor shaft 4. The cage has a stub-shaped extension which is rotatably mounted via two bearings 12 which are received in the housing part 5. The outer rings of the bearings 12 are received in the housing part 5, and the inner rings of the bearings 12 are placed on the stub-shaped extension of the rotor shaft 12.

[0052] The rotor shaft 4 is supported on the one hand by a bearing not shown in the figures and on the other hand by rollers 7 and 10 rolling on the rolling bearings 8 and 9. Thus, the rotor shaft 4 is supported at two locations, with the stator winding of the electric motor arranged axially between these locations.

[0053] The inner ring of bearing 9 is positioned against a shaft collar 3 of the rotor shaft 4. Radial bores can be drilled into the shaft collar and / or into the eccentric areas 13 and 14. An annular groove is provided in the shaft collar, preferably axially centered, and runs continuously in the circumferential direction. If a radial bore is drilled into the shaft collar 3, it opens into the annular groove.

[0054] In further embodiments according to the invention, an eccentric disc having the eccentric regions 13 and 14 is placed on the rotor shaft 4 and is connected to the rotor shaft 4 in a rotationally fixed manner by means of a key connection.

[0055] Preferably, the eccentric disc has on its radial outer circumference an outer collar projecting axially on both sides and uninterrupted in the circumferential direction and an inner collar projecting axially on both sides and uninterrupted in the circumferential direction.

[0056] The inner collar is arranged radially spaced from the outer collar and / or radially within the outer collar. Radially between the inner collar and the outer collar, on each side, there is a respective recess formed in the eccentric disc in the axial direction, which is interrupted in the circumferential direction by a thickened portion of the eccentric disc. Each recess preferably extends over more than 180°. Axial bores are formed in each thickened portion.

[0057] The thickened portions are diametrically opposed in the circumferential direction, making it easy to avoid imbalance. Alternatively, the thickened portions can also be arranged at the same circumferential angle, which requires precise balancing, especially at higher torques. The recesses are C-shaped.

[0058] Preferably, the axial bores are all arranged at the same radial distance, i.e., at the same distance from the rotational axis of the rotor shaft 4. In particular, the axial bores are evenly spaced from one another in the circumferential direction.

[0059] The respective rolling bearings 8 and 9 are mounted on the outer collar. The inner collar allows for an axially expanded connection area with the rotor shaft 4.

[0060] In further embodiments according to the invention, the bearing of the rotor shaft 4 accommodated in the flange part is omitted, and thus the electric motor is designed with only a single bearing for the rotor shaft 4. When assembling the electric motor with the gearbox, the rotor shaft 4 is inserted into the eccentric disc 3, in particular connected in a rotationally fixed manner by means of a keyway, and thus also mounted within the gearbox via the eccentric disc 3. The tolerance of the rollers (7, 10) can then be selected such that the rotor shaft 4 is mounted on the one hand via the rollers 7 and 10 and on the other hand via a bearing of the electric motor, in particular on the B-side, which acts as the only bearing for the rotor shaft within the motor housing 1 of the electric motor. This also avoids any mechanical overdetermination. However, the electric motor cannot function without the gearbox.

[0061] List of reference symbols

[0062] 1 engine housing

[0063] 2 cages

[0064] 3 eccentric disc

[0065] 4 Rotor shaft

[0066] 5 Housing part

[0067] 6 Radial bore

[0068] 7 front row roles

[0069] 8 first camp

[0070] 9 second camp

[0071] 10 second-row roles

[0072] 11 Sealing disc, in particular Nilos ring or rubberized sheet metal part

[0073] 12 camps

[0074] 13 second eccentric area

[0075] 14 first eccentric area

Claims

Patent claims:

1. Drive, comprising an electric motor with a gear, wherein the electric motor has a rotatably mounted rotor shaft, wherein the gear has an eccentric gear stage, wherein the rotor shaft has at least one first eccentric region, wherein the first eccentric region has a cylindrical outer circumference, the cylinder symmetry axis of which is aligned parallel and spaced from the axis of rotation of the rotor shaft, in particular - wherein the rotor shaft has a base rotor shaft, in particular one which is continuously rotationally symmetrical to the axis of rotation of the rotor shaft, and a sleeve which is fitted onto the base rotor shaft and has an eccentric bore, which provides the eccentric region, or wherein the rotor shaft is formed integrally and / or in one piece with the first eccentric region, in particular wherein an inner ring of a first rolling bearing is fitted onto the first eccentric region of the rotor shaft and wherein one or more radial bores are introduced into the shaft collar to make it more difficult to form Vibration resonances and more robust operability of the gearbox.

2. Drive according to claim 1, characterized in that the rotor shaft has a second eccentric region, wherein the second eccentric region has a cylindrical outer circumference, the cylindrical symmetry axis of which is aligned parallel and spaced from the axis of rotation of the rotor shaft, in particular wherein the plane spanned by the cylindrical symmetry axis of the first eccentric region and by the cylindrical symmetry axis of the second eccentric region, in particular fictitious, contains the axis of rotation of the rotor shaft, in particular wherein the rotor shaft is formed integrally and / or in one piece with the first and second eccentric region.

3. Drive according to one of the preceding claims, characterized in that the electric motor has a motor housing which is connected at its first axial end region to a bearing shield and which is connected at its second axial end region to a housing part, wherein an outer ring of a bearing, in particular a ball bearing, is received in the bearing shield, the inner ring of which is placed on the rotor shaft, wherein an inner ring of a first rolling bearing is placed on the first eccentric region of the rotor shaft, wherein first rollers roll on the outer circumference of the outer ring of the first rolling bearing and / or on the radial outer circumference of the first rolling bearing, which first rollers project through respective recesses of a rotatably mounted cage and which are delimited by the cage in the circumferential direction and in the axial direction, wherein the axis of rotation of the rotor shaft is aligned coaxially with the axis of rotation of the cage,wherein the first rollers roll on a first shaft contour formed on the inside of the housing part, in particular extending in the circumferential direction.

4. Drive according to one of the preceding claims, characterized in that the cage has a cylindrical extension, wherein at least one further bearing is placed on the extension and accommodated in the housing part, in particular wherein the inner ring of the further bearing is placed on the extension and the outer ring of the further bearing is accommodated in the housing part.

5. Drive according to one of the preceding claims, characterized in that an inner ring of a second rolling bearing is placed on the second eccentric region of the rotor shaft, wherein second rollers roll on the outer circumference of the outer ring of the second rolling bearing and / or on the radial outer circumference of the second rolling bearing, which second rollers project through respective recesses of a rotatably mounted cage and which are delimited by the cage in the circumferential direction and in the axial direction, wherein the second rollers roll on a second shaft contour formed on the inside of the housing part, in particular extending in the circumferential direction,in particular, either wherein the first shaft contour and the second shaft contour are the same shaft contour or wherein the first shaft contour is axially spaced from the second shaft contour in the axial direction or adjoins the second shaft contour and / or wherein the axis of rotation of the second rolling bearing is spaced from the axis of rotation of the first rolling bearing and the axis of rotation of the first rolling bearing, the axis of rotation of the second rolling bearing and the axis of rotation of the rotor shaft are arranged together in a particularly fictitious plane.

6. Drive according to one of the preceding claims, characterized in that the rotor shaft has a shaft collar against which the inner ring of the first rolling bearing is positioned.

7. Drive according to one of the preceding claims, characterized in that a continuously circumferential annular groove is arranged in the outer circumference of the shaft collar.

8. Drive according to one of the preceding claims, characterized in that one or more radial bores are introduced into the shaft collar or that one or more radial bores are introduced into the eccentric regions, in particular wherein the radial bore or the radial bores are arranged at the axial position of the annular groove, in particular and open into the annular groove, in particular wherein the inner ring of the first rolling bearing covers at least one radial bore and / or wherein the inner ring of the second rolling bearing covers at least one radial bore.

9. Drive according to one of the preceding claims, characterized in that a sealing cover fastened, in particular clamped, to an axial projection of the housing part seals towards the rotor shaft, in particular wherein the sealing cover is designed as a rubberized sheet metal part.

10. Drive according to one of the preceding claims, characterized in that the respective roller projects in the radial direction through the respective recess of the cage, in particular wherein the axis of rotation of the shaft and the axis of rotation of the cage are aligned coaxially with each other.

11. Drive according to one of the preceding claims, characterized in that the shaft contour has a radial distance which runs periodically in the circumferential direction.

12. Drive according to one of the preceding claims, characterized in that the axis of rotation of the first rolling bearing is aligned parallel to the axis of rotation of the rotor shaft and is spaced from the axis of rotation of the rotor shaft, in particular wherein the axis of rotation of the first rolling bearing during operation of the Eccentric gear stage performs a circular movement around the axis of rotation of the rotor shaft, in particular wherein the axis of rotation of the second rolling bearing during operation of the Eccentric gear stage performs a circular movement around the axis of rotation of the rotor shaft.

13. Drive according to one of the preceding claims, characterized in that the housing part of the gear is centered on the motor housing and is connected and / or fastened to the housing part, in particular with screws.

14. Drive according to one of the preceding claims, characterized in that the eccentric position of the first eccentric region is shifted in the circumferential direction by 180° relative to the eccentric position of the second eccentric region.

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