Gearbox for an electric motor and electric motor

Abstract

The invention relates to a gearbox (10) for an electric motor (100), with a housing (12) in which at least one shaft (21, 22) is rotatably mounted about an axis of rotation (33, 34), wherein the shaft (21, 22) is mounted in a bearing arrangement designed as a tapered roller bearing (44, 46) in the region of a first axial end section (36, 40), wherein an inner ring (48, 50) of the tapered roller bearing (44, 46) radially surrounds the end section (36, 40) of the shaft (21, 22), and wherein an adjusting element (60, 62) arranged concentrically to the axis of rotation (33, 34) acts on an outer ring (52, 54) of the tapered roller bearing (44, 46) to generate an axial preload force (F) and / or to adjust an axially backlash-free tapered roller bearing (44, 46).

Description

Technical area

[0001] The invention relates to a gearbox for an electric motor, in which an axial preload force can be generated on an outer ring of a tapered roller bearing in a particularly advantageous and simple manner to produce a bearing free of axial play. Furthermore, the invention relates to an electric motor with a gearbox designed according to the invention. State of the art

[0002] Gearboxes for electric motors are used in a variety of ways. For example, such gearboxes also serve as a component of a drive train in an electric vehicle. Such a gearbox typically has shafts rotatably mounted in the housing of the electric motor, which, for example, carry gear wheels to transmit torque from an electric motor to a driven wheel. It is also known to mount such shafts in the housing using tapered roller bearings. These tapered roller bearings are characterized by the fact that an axial preload force must be generated between an outer ring and an inner ring of the tapered roller bearing in order to enable the tapered roller bearing to be designed free of play in the axial direction. In the prior art, this is typically done by measuring an axial distance between an end face of the outer ring of the tapered roller bearing and a housing element that interacts with the outer ring.Due to component tolerances, individual distances vary, which are compensated for using individually designed spacer rings as adjustment elements, which enable the required preload force or zero clearance. Therefore, it is necessary to measure the existing axial dimension between the outer ring and the housing element and select an appropriate spacer ring. This requires a relatively high manufacturing effort. Disclosure of the invention

[0003] The gear mechanism according to the invention for an electric motor with the characterizing features of claim 1 has the advantage that it enables easy adjustment of an axial preload force on an outer ring or an axial zero play of the tapered roller bearing in a particularly simple manner using always the same components. The invention is based on the idea of ​​achieving an axial adjustment or positioning of the adjustment element via an adjustment element having a thread, wherein the adjustment element acts on the outer ring of the tapered roller bearing. The thread thus enables a continuously adjustable adjustment path through a corresponding angle of rotation of the adjustment element and thus a continuously adjustable axial preload force on the outer ring or the adjustment of an axial zero play of the tapered roller bearing.

[0004] Against the background of the above explanations, it is therefore provided in a transmission according to the invention for an electric motor with the features of claim 1 that the adjusting element is designed as an axially adjustable adjusting element connected to the housing by means of a thread.

[0005] Advantageous further developments of the transmission according to the invention for an electric motor are listed in the subclaims.

[0006] There are various options regarding the design of the adjustment element. These depend, in particular, on whether the adjustment element is intended to close a housing opening, for example, or whether a (tight) closure is not required. Against this background, it is particularly intended that the adjustment element be designed as a closure cap or as an adjustment sleeve.

[0007] In order to enable a uniform action of the adjusting element on the outer ring of the tapered roller bearing, a further preferred design of the adjusting element provides that a wall section of the adjusting element which runs radially around the axis of rotation of the shaft is arranged with an end face in direct contact with the outer ring.

[0008] In order to be able to adjust the required preload force or the screw-in depth particularly easily and precisely, a further preferred embodiment of the invention has the feature that the adjusting element has an external thread which interacts with an internal thread on the housing, and that the thread is designed as a fine thread.

[0009] In order to avoid a change in the axial preload force after setting the axial preload force or the required screw-in depth over the service life of the gearbox and to maintain the axial positioning of the adjusting element over the service life of the gearbox, it is provided that the adjusting element can be fixed in its final position on the housing. Such fixing can be achieved, for example, by an adhesive arranged between the housing and the thread of the adjusting element. Such an adhesive advantageously seals the interior of the housing against the ingress of media. Alternatively or additionally, a mechanical deformation of the adjusting element and / or the housing can also take place, e.g. by mechanical caulking or so-called punching.

[0010] Preferably, not just one shaft of the transmission is arranged in the manner provided according to the invention, but typically at least two shafts or all shafts of the transmission. Therefore, the transmission thus designed has at least two parallel shafts with tapered roller bearings in the housing, each of which interacts via an adjusting element.

[0011] In order to enable the components of the gearbox to be installed in the housing as easily as possible, it is further provided that the housing has a housing cover in which the adjusting element is arranged.

[0012] Finally, the invention also comprises an electric motor with a transmission designed according to the invention as described so far, wherein the electric motor is designed as a drive motor of an electric vehicle.

[0013] Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments of the invention and from the drawings. Short description of the drawing Fig. 1 shows a longitudinal section in the area of ​​a gearbox of an electric motor that serves as a drive motor for an electric vehicle. Embodiments of the invention

[0014] In the Fig. 1 shows the area of ​​a transmission 10 of an electric motor 100, which is preferably, but not restrictively, designed as a drive motor of an electric vehicle.

[0015] The transmission 10 is arranged in a multi-part housing 12. In particular, the housing 12 comprises at least one housing base body 14 for forming an interior space for the transmission components and a housing cover 16, which closes the housing base body 14 or delimits and surrounds the interior of the housing 12. The housing cover 16 is sealingly connected to the housing base body 14, in particular by means of housing screws 18.

[0016] Two parallel shafts 21, 22 are provided in the interior of the housing 12. The first shaft 21 is connected via a gear 24 to an output pinion 26 of a drive shaft of the electric motor 100. The first shaft 21 meshes with an external toothing region 28 arranged at an axial distance from the gear 24, with an external toothing of a gear 30 connected to the second shaft 22. The second shaft 22 is part of a differential 32, which in turn is connected to the driven wheels of the motor vehicle.

[0017] The two shafts 21, 22 are each arranged to be rotatable about a rotational axis 33, 34. The bearings of the shafts 21, 22 are each provided by two tapered roller bearings 44, 45 and 46, 47 arranged at axial end sections 36, 38 and 40, 42. To ensure the functionality of the tapered roller bearings 44, 45 and 46, 47, it is necessary to mount at least one of the mentioned tapered roller bearings 44 to 47 on each of the shafts 21, 22, in the illustrated embodiment the two in the drawing plane of the Fig. 1 tapered roller bearings 44 and 46 arranged on the top side, to be arranged without axial play.

[0018] The two tapered roller bearings 44 and 46 each have an inner ring 48, 50 and an outer ring 52, 54. The inner ring 48, 50 is pressed onto the outer circumference of the end section 36, 40 of the respective shaft 21, 22 or radially encloses it. The respective outer ring 52, 54 is arranged in a recess 56, 58 of the housing cover 16 for axial adjustment. In order to generate an axial preload force F acting in the direction of the shaft 21, 22 on the outer ring 52, 54 or the zero clearance between the outer ring 52, 54 and the inner ring 48, 50, the two shafts 21, 22 are each arranged in operative connection with an adjusting element 60, 62.

[0019] The adjustment element 60 is designed as a closure cover 64, while the adjustment element 62 is designed as an adjustment sleeve 66. The two adjustment elements 60, 62 each have an external thread that interacts with an internal thread on the housing cover 16. The external and internal threads each form a fine thread 68, 70.

[0020] The end faces 76, 78 of the adjusting elements 60, 62 facing the outer ring 52, 54 rest directly against the corresponding end faces of the outer rings 52, 54. To adjust the preload force F or the zero clearance, the screw-in depth of the adjusting element 60, 62 is individually adjusted, for example, using a torque wrench (not shown). When a target torque is reached, the presence of the required preload force F or the zero clearance is determined.

[0021] As soon as the adjusting element 60, 62 has reached its screw-in depth or axial end position, the adjusting element 60, 62 is fixed either by an adhesive arranged between the internal threads and external threads of the fine threads 68, 70, or by mechanical adjustment or deformation.

[0022] The transmission 10 described so far can be modified or altered in many different ways without deviating from the inventive concept.

Claims

[1] Gearbox (10) for an electric motor (100), comprising a housing (12) in which at least one shaft (21, 22) is mounted rotatably about an axis of rotation (33, 34), wherein the shaft (21, 22) is mounted in the region of a first axial end portion (36, 40) in a bearing device designed as a tapered roller bearing (44, 46), wherein an inner ring (48, 50) of the tapered roller bearing (44, 46) radially engages around the end portion (36, 40) of the shaft (21, 22), and wherein an adjusting element (60, 62) arranged concentrically to the axis of rotation (33, 34) acts on an outer ring (52, 54) of the tapered roller bearing (44, 46) for generating an axial preload force (F) and / or for adjusting an axially play-free tapered roller bearing (44, 46), characterized by that the adjusting element (60, 62) is designed as an axially adjustable adjusting element (60, 62) connected to the housing (12) by means of a thread (68, 70). [2] Transmission according to claim 1, characterized bythat the adjusting element (60, 62) is designed as a closure cover (64) or as an adjusting sleeve (66). [3] Transmission according to claim 1 or 2, characterized by that an end face (76, 78) of the adjusting element (60, 62) which runs radially around the axis of rotation (33, 34) of the shaft (21, 22) is arranged in direct contact with the outer ring (52, 54). [4] Transmission according to one of claims 1 to 3, characterized by that the adjusting element (60, 62) has an external thread which cooperates with an internal thread on the housing (12), and that the thread (68, 70) is designed as a fine thread. [5] Transmission according to one of claims 1 to 4, characterized by that the adjusting element (60, 62) can be fixed in its axial end position on the housing (12). [6] Transmission according to claim 5, characterized bythat the fixing is effected by an adhesive between the housing (12) and the thread of the adjusting element (60, 62) and / or a mechanical deformation of the adjusting element (60, 62) and / or the housing (12). [7] Transmission according to one of claims 1 to 6, characterized by that in the housing (12) two shafts (21, 22) arranged parallel to one another with tapered roller bearings (44 to 47) are provided, each of which interacts with an adjusting element (60, 62). [8] Transmission according to one of claims 1 to 7, characterized by that the housing (12) has a housing cover (16) in which the adjusting element (60, 62) is arranged. [9] Electric motor (100) with a transmission (10) designed according to one of claims 1 to 8, characterized by that the electric motor (100) is designed as a drive motor of an electric vehicle.

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