DE102022120246A1 - Electromotive drive unit and robot arm - Google Patents

Abstract

The invention relates to an electric motor drive unit (1) comprising an axial flux machine (2) with a driven rotor shaft (3) and a wet-running gear unit (4) which is coupled to the axial flux machine (2) via the rotor shaft (3) in a torque-transmitting manner, wherein a gear unit (4) is located in a radial direction The centrifugal disc (5), which extends in the direction out of the rotor shaft (3), is arranged non-rotatably on the rotor shaft (3) axially between the axial flux machine (2) and the gear unit (4), the centrifugal disc (5) being configured so that it is in operation the electromotive drive unit (1) from the gear unit (4) in the direction of the axial flow machine (2) is hurled radially outwards by centrifugal force.

Description

The present invention relates to an electric motor drive unit comprising an axial flux machine with a driven rotor shaft and a wet-running gear unit coupled to the axial flux machine via the rotor shaft in a torque-transmitting manner. The invention further relates to a robot arm.

Modern robots have a wide range of applications, for example in industry or medicine. Industrial robots are commonly known as programmable machines for handling, assembling or machining workpieces and are used in a variety of industrial processes. They are an essential part of advancing automation.

In this context, electric motor drive units have become known, in which an electric motor and a transmission unit are structurally combined into one unit. Axial flux motors combined with a shaft gear are often used here.

In the DE 10 2018 103 221 A1 a wave gear is described. This wave gear comprises a flexible gear element designed as a collar sleeve, which is held non-rotatably on a housing element, with recesses being located in the collar of the gear element and fastening elements fixed to the housing, namely pins, engaging in the recesses in such a way that there is relative mobility between the housing element and the collar is. To secure the flexible gear element in the axial direction, a cover attached to the housing element is provided, the collar being arranged with play in the axial direction between the cover and an end face of the housing element.

From the DE 102019 105 760 A1 Another wave gear is known. This wave gear comprises a drive wheel, a collar sleeve connected to it, which has a sleeve-shaped section with external teeth and a radially outwardly directed flange, a wave generator which interacts with the collar sleeve and has a flexible outer ring, and an internally toothed output wheel, with one on the The axial stop arranged on the inside of the sleeve-shaped section allows an axial force to be transmitted between the outer ring and the collar sleeve and the axial stop is formed by a separate securing element held on the collar sleeve.

The gears in these drive units are usually wet-running, i.e. they are lubricated with gear grease and/or gear oil. Since leaks of gear grease and/or oil are not permitted in the robot applications mentioned, for example in the medical sector or in clean room applications, very high demands are regularly placed on the tightness of the gear unit. Penetration of gear grease and/or oil into the electrical or electronic components of the drive unit must also be prevented in order to ensure error-free and stable operation of the drive unit.

However, the requirements for high tightness are contrary to the efficiency requirements for drive units.

The object of the invention is therefore to provide an electric motor drive unit with a high sealing effect against the ingress of gear grease and / or oil, which also has a high level of efficiency with low friction losses. It is also the task to realize an optimized robot arm with an electric motor drive unit.

This object is achieved by an electromotive drive unit comprising an axial flux machine with a driven rotor shaft and a wet-running gear unit coupled to the axial flux machine via the rotor shaft in a torque-transmitting manner, with a centrifugal disk extending in the radial direction out of the rotor shaft in a rotationally fixed manner axially between the axial flux machine and the gear unit the rotor shaft is arranged, wherein the centrifugal disc is configured such that, during operation of the electromotive drive unit, it throws hydraulic fluid emerging from the gear unit in the direction of the axial flow machine radially outwards under the effect of centrifugal force.

This has the advantage that the sealing effect can be achieved without frictional contact of the sealant, here the centrifugal disc. This ensures a high sealing effect and high energy efficiency of the electric motor drive unit.

First, the individual elements of the claimed subject matter of the invention are explained in the order in which they are mentioned in the claim sentence and particularly preferred embodiments of the subject matter of the invention are described below.

The magnetic flux in an electric axial flux machine (AFM), as used in the electromotive drive unit, is axial to a rota in the air gap between the stator and rotor direction of the rotor of the axial flux machine.

There are different types of axial flow machines. A known type is a so-called I-arrangement, in which the rotor is arranged axially next to a stator or between two stators, and which is preferred in the context of this invention.

Another known type is a so-called H arrangement, in which two rotors are arranged on opposite axial sides of a stator. In principle, it is also possible for a plurality of rotor-stator configurations to be arranged axially next to one another as I-type and/or H-type. In this context, it would also be possible to arrange both one or more rotor-stator configurations of the I-type and one or more rotor-stator configurations of the H-type next to one another in the axial direction. In particular, it is also preferable that the rotor-stator configuration of the H-type and/or the I-type are each designed to be essentially identical, so that they can be put together in a modular manner to form an overall configuration. Such rotor-stator configurations can in particular be arranged coaxially with one another and connected to a common rotor shaft or to several rotor shafts.

The rotor of an electric axial flux machine can preferably be designed, at least in part, as a laminated rotor. A laminated rotor is designed to be layered in the axial direction. The rotor of an axial flux machine can alternatively also have a rotor carrier or rotor body, which is correspondingly equipped with magnetic sheets and/or SMC material and with magnetic elements designed as permanent magnets.

A rotor body preferably has an inner part, via which the rotor can be connected to a shaft in a rotationally fixed manner, and an outer part, which delimits the rotor in the radial direction to the outside. The rotor body can be formed between the inner part and the outer part with a plurality of rotor struts, via which the inner part and the outer part are connected to one another and which, together with the radial outer surface of the inner part and the radial inner surface of the outer part, has a receiving space for receiving the magnetic elements and the flux guide elements of the rotor forms. As an alternative to the receiving space, the magnetic elements can be arranged or placed on the rotor carrier.

A magnetic element can be formed as a permanent magnet in the form of a bar magnet or in the form of smaller magnetic blocks designed as blocks. The magnetic elements are usually arranged in, on or on a rotor carrier. The magnetic element of a rotor of an axial flux machine, designed as a permanent magnet, interacts with a rotating magnetic field which is generated by the stator winding coils, which are generally supplied with a three-phase current.

A rotatably mounted shaft of an electrical machine is referred to as a rotor shaft, to which the rotor or rotor body is coupled in a rotationally fixed manner.

The stator of an electric axial flux machine preferably has a stator body with a plurality of stator windings arranged in the circumferential direction. The stator body can be designed in one piece or segmented in the circumferential direction.

According to an advantageous embodiment of the invention, it can be provided that a first disk-shaped stator body and / or a second disk-shaped stator body are designed as a circuit board, in particular as a printed circuit, which is also referred to as a printed circuit board PCB, whereby the stator body is particularly compact and can be produced inexpensively. The winding of the stator body is formed in one piece with the circuit board. The circuit board is preferably a multilayer circuit board with several copper layers over which the stator windings extend. Another possible embodiment is to design the stator body as a sandwich of several multilayer boards. The circuit board is preferably formed from a composite of epoxy resin and glass fiber.

It is particularly preferred that the first stator body and/or the second stator body are/is formed in the shape of an annular disk. According to a further preferred development of the invention, it can also be provided that at least one of the stator bodies is designed as a multilayer PCB and/or several carrier plates are arranged stacked together in layers.

The transmission unit can preferably comprise a shaft gear transmission. A shaft gear transmission usually consists of a rigid first gear, the so-called circular spline, which has internal teeth. A second externally toothed and flexible gear, the so-called flex spline, is usually arranged in this rigid first gear. The external toothing is locally engaged with the internal toothing of the rigid first gear. The diameter of the external teeth is slightly smaller than the internal teeth, and the internal teeth also have fewer Teeth as the external teeth. A usually oval disk or similar is also provided, which functions as a wave generator and is arranged in the flexible second gear, i.e. the flex spline. This disk is coupled to an external motor, possibly via an intermediate gearbox. A rotation of the disc caused by the motor leads to a deformation of the flex spline, which takes on a shape corresponding to the shape of the disc. This changes the engagement of the two teeth, so that in the end there is a translated rotational movement of the flexible unit, i.e. the flex spline, relative to the rigid, non-moving unit, the circular spline. The output takes place via the flex spline, which rotates in translation.

According to an advantageous embodiment of the invention, it can be provided that the centrifugal disk defines an annular channel together with a housing component of the electromotive drive unit. The advantage of this configuration is that the hydraulic fluid is guided along a defined radial path, which accordingly points away from the axial flow machine.

According to a further preferred development of the invention, it can also be provided that the housing component is arranged in a non-rotating manner relative to the centrifugal disk. This can ensure that the hydraulic fluid thrown in the radial direction by centrifugal force flows off in the direction of gravity when it hits the stationary housing wall and is thus kept away from the axial flow machine.

Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the centrifugal disk has a conical section pointing in the direction of the gear unit at its radially outer end. The advantageous effect of this design is that the sealing effect of the centrifugal disc can be further optimized.

According to a further particularly preferred embodiment of the invention, it can be provided that the centrifugal disk is connected in a rotationally fixed manner to a hollow cylindrical section which extends in the axial direction and from which the centrifugal disk extends radially outwards. In this way, the effect can be achieved in particular that the centrifugal disc can be placed particularly easily on the rotor shaft. The centrifugal disk can basically be connected to the rotor shaft using various connection techniques, such as pressing, welding, gluing or the like.

Furthermore, the invention can also be further developed in such a way that the centrifugal disk and the hollow cylindrical section are designed in one piece, in particular monolithically. The advantage of this configuration is that the production of the component is particularly favorable in terms of production and costs.

In a likewise preferred embodiment variant of the invention, it can also be provided that the centrifugal disk and the hollow cylindrical section are designed in two pieces. The two-part design saves costs and simplifies assembly.

It can also be advantageous to further develop the invention in such a way that a roller bearing for supporting the rotor shaft relative to the housing component is arranged in the axial direction between the centrifugal disk and the gear unit. The advantage that can be achieved in this way is that the bearing is lubricated by the grease in the gearbox and acts as an additional barrier against grease escape.

According to a further preferred embodiment of the subject matter of the invention, it can be provided that no seal is provided in the axial direction between the roller bearing and the centrifugal disk. This can support a particularly high energy efficiency of the drive unit.

The hydraulic fluid in the sense of this application can be a gear grease or a gear oil. In particular, a hydraulic fluid can also include one or more components of a gear grease.

The electromotive drive unit can in particular also be designed as a pre-assembled articulated arm unit for a robot arm, in which case an electric motor, a wave gear, an output bearing and an optionally integrated torque sensor form a structural unit.

Finally, the object of the invention can also be achieved by a robot arm for a robot comprising an electromotive drive unit according to one of claims 1-9.

The invention will be explained in more detail below using figures without restricting the general idea of the invention.

• 1 Elektromotorische Antriebseinheit in einer schematischen Axialschnittdarstellung und
• 2 einen Roboterarm mit einer elektromotorischen Antriebseinheit in einer perspektivischen, teilgeschnittenen Darstellung.

It shows:

• 1 Electromotive drive unit in a schematic axial sectional view and
• 2 a robot arm with an electric motor drive unit in a perspective, partially cutaway view.

The 1 shows an electromotive drive unit 1 comprising an axial flux machine 2 with a driven rotor shaft 3 and a wet-running gear unit 4 coupled to the axial flux machine 2 via the rotor shaft 3 in a torque-transmitting manner.

A centrifugal disk 5, which extends in the radial direction out of the rotor shaft 3, is arranged on the rotor shaft 3 in a rotationally fixed manner between the axial flux machine 2 and the gear unit 4. The centrifugal disc 5 is configured in such a way that, during operation of the electromotive drive unit 1, it throws hydraulic fluid 6 emerging from the gear unit 4 in the direction of the axial flow machine 2 radially outwards using centrifugal force, which is clearly shown by the arrows in the 1 can be understood.

The centrifugal disk 5, together with a housing component 7 of the electromotive drive unit 1, defines an annular channel 8, although the housing component 7 is not arranged to rotate relative to the centrifugal disk 5. As a result, hydraulic fluid 6 thrown onto the housing component 7 can flow away due to gravity.

Like in the 1 shown, the centrifugal disk 5 has at its radially outer end 9 a conical section 10 pointing in the direction of the gear unit 4. This allows the channel 8 to be designed in a labyrinth-like manner, which further improves the sealing effect.

The centrifugal disk 5 is connected in a rotationally fixed manner to a hollow cylindrical section 11 which extends in the axial direction and from which the centrifugal disk 5 extends radially outwards. The section 11 is in turn connected to the rotor shaft 3 in a rotationally fixed manner, for example by a press fit. In the embodiment shown, the centrifugal disc 5 and the hollow cylindrical section 11 are formed in one piece, in particular monolithically. The rotor 15 of the axial flux machine 2 can lie radially outside the section 11 and be connected to it in a torque-transmitting manner. In principle, it would of course also be conceivable for the rotor 15 and the rotor shaft 3 to be directly connected to one another without the interposition of the section 11.

A rolling bearing 12 for supporting the rotor shaft 3 relative to the housing component 7 is arranged in the axial direction between the centrifugal disk 5 and the gear unit 4. It is clear from the 1 It's good that no seal is provided in the axial direction between the roller bearing 12 and the centrifugal disk 5.

Finally, it shows 2 a robot arm 13 for a robot 14 comprising an electromotive drive unit 1 as shown in 1 is known.

The terms “radial”, “axial”, “tangential” and “circumferential direction” used in this application always refer to the axis of rotation of the rotor shaft 3. The terms “left”, “right”, “top”, “bottom”, “ “above” and “below” only serve to clarify which areas of the illustrations are currently being described in the text. The later embodiment of the invention can also be arranged differently. Furthermore, the invention is not limited to the embodiments shown in the figures. The foregoing description is therefore not to be viewed as limiting but rather as illustrative. The following patent claims are to be understood as meaning that a stated feature is present in at least one embodiment of the invention. This does not exclude the presence of other features. If the patent claims and the above description define 'first' and 'second' features, this designation serves to distinguish two similar features without establishing a ranking.

Reference symbol list

1

Drive unit

2

Axial flow machine

3

Rotor shaft

4

Gear unit

5

slingshot disc

6

Hydraulic fluid

7

Housing component

8th

channel

9

End

10

Section

11

Section

12

roller bearing

13

Robot arm

14

robot

15

rotor

QUOTES INCLUDED IN THE DESCRIPTION

This list of 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.

Cited patent literature

• DE 102018103221 A1 [0004]
• DE 102019105760 A1 [0005]

Claims (10)

Electromotive drive unit (1) comprising an axial flux machine (2) with a driven rotor shaft (3) and a wet-running gear unit (4) coupled to the axial flux machine (2) via the rotor shaft (3) in a torque-transmitting manner, characterized in that one is in the radial direction The centrifugal disc (5) extending from the rotor shaft (3) is arranged axially between the axial flux machine (2) and the gear unit (4) in a rotationally fixed manner on the rotor shaft (3), the centrifugal disc (5) being configured in such a way that it is in operation electromotive drive unit (1) from the gear unit (4) in the direction of the axial flow machine (2) is hurled radially outwards by centrifugal force. Electric motor drive unit (1). Claim 1 , characterized in that the centrifugal disk (5) defines an annular channel (8) together with a housing component (7) of the electromotive drive unit (1). Electric motor drive unit (1). Claim 2 , characterized in that the housing component (7) is arranged in a non-rotating manner relative to the centrifugal disk (5). Electromotive drive unit (1) according to one of the preceding claims, characterized in that the centrifugal disk (5) has a conical section (10) pointing in the direction of the gear unit (4) at its radially outer end (9). Electric motor drive unit (1) according to one of the preceding claims, characterized in that the centrifugal disk (5) is connected in a rotationally fixed manner to a hollow cylindrical section (11) which extends in the axial direction and from which the centrifugal disk (5) extends radially outwards. Electric motor drive unit (1). Claim 5 , characterized in that the centrifugal disk (5) and the hollow cylindrical section (11) are formed in one piece, in particular monolithically. Electric motor drive unit (1). Claim 5 , characterized in that the centrifugal disk (5) and the hollow cylindrical section (11) are designed in two pieces. Electric motor drive unit (1) according to one of the preceding claims, characterized in that a rolling bearing (12) for supporting the rotor shaft (3) relative to the housing component (7) is arranged in the axial direction between the centrifugal disk (5) and the gear unit (4). . Electric motor drive unit (1). Claim 8 , characterized in that no seal is provided in the axial direction between the rolling bearing (12) and the centrifugal disk (5). Robot arm (13) for a robot (14) comprising an electric motor drive unit (1) according to one of the preceding claims.

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