EP3997781A1

EP3997781A1 - Electrical machine with cooled busbars

Info

Publication number: EP3997781A1
Application number: EP20729736.7A
Authority: EP
Inventors: Konstantin Lindenthal; Uwe Knappenberger; Sebastian Hoffmann; Andreas Herzberger; Claus-Christian Oetting; Thomas Bublat
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2019-07-11
Filing date: 2020-05-29
Publication date: 2022-05-18
Also published as: CN114041261A; DE102019210308A1; US20220271609A1; WO2021004693A1

Abstract

The present invention relates to an electrical machine (1) having a rotor (2) and a stator (3) which are at least partially arranged in a machine housing (4), and also having a cooling jacket (5) for cooling the stator (3), a plurality of first cooling ducts (6), which run parallel in relation to one another, in particular in an axial direction with respect to the stator axis, for guiding a cooling medium run through said cooling jacket, wherein the machine housing (4) has at least one end plate (7), which is connected to the cooling jacket (5), for supporting a rotor shaft (8) of the rotor (2), wherein a plurality of second cooling ducts (9) which each connect two, in particular adjacent, first cooling ducts (6) to one another in terms of flow are formed on the end plate (7), wherein the second cooling ducts (9) together with the first cooling ducts (6) produce a coolant path, which is in particular of meandering or serpentine design, through the electrical machine (1), and wherein at least one busbar (10) which is electrically connected to a stator winding (14) of the stator (3) runs on the end plate (7), characterized in that the busbar (10) has a main section (11) and at least one cooling lug (12) which extends from the main section (11), wherein the cooling lug (12) engages into a housing recess (13) of the end plate (7), which housing recess is formed directly adjacent to one of the second cooling ducts (9).

Description

description

title

Electric machine with cooled busbars

State of the art

The present invention relates to an electrical machine. The electrical machine has in particular cooled busbars.

Electrical machines are known from the prior art, for example from EP 1 401 089 A1. Usual electrical machines include a rotor and a stator, the stator having a stator winding in which a magnetic field can be generated in order to drive the rotor. To energize the stator winding, there are busbars that heat up during operation due to their electrical resistance. This heat is given off, for example, via heat conducting pads. For example, part of a housing of the electrical machine or the entire housing of the electrical machine is often made of a metallic material, said heat conducting pads taking the heat from the

Lead off the busbar to the said metallic housing.

Disclosure of the invention

The electrical machine according to the invention enables busbars to be cooled efficiently. Optimized cooling is possible in particular if a housing of the electrical machine is not made from a metallic material and / or from a material that is poorly thermally conductive. The optimized cooling is achieved in that busbars have cooling lugs which dissipate heat directly to a cooling channel, a cooling medium being able to flow in the cooling channel. In this way it can be achieved that a safe and reliable cooling of the busbars takes place. The electrical machine according to the invention has a rotor and a stator. The rotor and stator are at least partially arranged in a machine housing. At least the stator has a stator winding. The rotor can be designed in any way and is set up in particular to interact with the stator. The stator can thus drive the rotor.

The electrical machine also has a cooling jacket for cooling the stator. First cooling channels for guiding a cooling medium run through the cooling jacket. The first cooling channels preferably run parallel, in particular in the axial direction with respect to the stator axis. The cooling medium can be a thermally conductive fluid, for example water.

The machine housing includes an end shield. The end shield is connected to the cooling jacket. Advantageously, there can be several end shields that are connected to the cooling jacket. A rotor shaft of the rotor is mounted on the end shield. In addition, the end shield has second cooling channels. The first cooling channels and the second cooling channels are coupled in particular for fluid communication, with each second cooling channel fluidly connecting two first, preferably adjacent, cooling channels. The electrical machine can be cooled through the first cooling channels and the second cooling channels, in particular the stator can be cooled through the cooling channels. In particular, the first cooling channels and the second cooling channels form a continuous coolant path through the electrical machine. This

The coolant path is preferably designed in a meandering or serpentine shape.

At least one busbar runs on the end shield. The busbar is electrically connected to a stator winding of the stator. This makes it possible, in particular, to energize the stator winding via the busbar.

It is provided that the busbar has a holding section and at least one cooling tab extending from the main section. The

The cooling vane is arranged in the machine housing in such a way that it engages in a housing recess in the end shield. The housing recess is formed directly adjacent to one of the second cooling channels. Thus, there is a heat transfer between the cooling medium that flows into the second cooling channel and the busbar, in particular the cooling vane Power rail, made possible. This allows the cooling vane to cool the busbar by removing the heat from the busbar through the cooling medium.

Such an arrangement and design of the busbar results in a large surface area for heat dissipation from the busbar to the cooling medium. The busbar can be effectively cooled via this area. As a result, with the same electrical load, that is, with the same current, the cross section of the busbar can be reduced. The costs of the electrical machine can thus be reduced compared with electrical machines from the prior art. In addition, a reduction in the cross section of the busbar enables a weight saving.

Alternatively, the effective cooling of the busbar enables higher electrical currents to flow with the same cross-section of the busbar. In addition, as in the prior art, heat-conducting pads are not necessary, as a result of which the assembly effort and thus also the assembly costs are reduced. The advantage of effective cooling is achieved in particular in that an existing cooling circuit of the electrical machine is used. This serves to cool the electrical machine, in particular the stator, particularly preferably a winding head of the stator, and is therefore already present in the electrical machine. Alternatively, there is the possibility of designing a separate cooling circuit, independent of the circuit mentioned above, for cooling the busbars. It is therefore not necessary to take special measures for heat dissipation. In particular, cost-intensive hybrid structures, such as metal in plastic, in particular, can thereby be avoided.

The subclaims show preferred developments of the invention regarding content.

The cooling jacket is advantageously part of the stator or part of the machine housing. In particular, the cooling jacket in one

Be formed stator core. If the cooling jacket is part of the

If the machine housing is, the cooling jacket encloses the stator at least in some areas, in particular completely. The cooling jacket surrounds the stator in particular in the circumferential direction around an axis of rotation of the electrical machine. The stator is advantageously held by the cooling jacket. It is preferably provided that the busbar has two cooling tabs.

Each cooling vane is arranged in its own housing recess in the end shield. One of the second cooling channels runs between the two housing recesses, which means that the two

Housing recesses are formed on both sides of one of the second cooling channels. By arranging the cooling lug on both sides of the cooling channel, the area from which heat can be transferred from the busbar to the cooling medium can be increased. This results in an improved cooling performance. The two extend particularly advantageously

Cooling vanes parallel to each other.

There is advantageously a between the cooling vane and the end shield

Thermally conductive material attached. The heat-conducting material can in particular be a heat-conducting adhesive. This leads to a further improved heat transfer between the busbar and

Cooling medium that flows within the second cooling channels.

It is also advantageously provided that between the cooling vane and

An electrical insulation material is introduced into the bearing shield. In particular, it is an electrically insulating adhesive. The adhesive can particularly advantageously be both electrically insulating and thermally conductive. If the adhesive is electrically insulating, housing parts made of metal can be used, for example, which enable optimal heat conduction, while at the same time the risk of a short circuit via the busbar is minimized. Alternatively or in addition to the adhesive, it can be

Insulation material can also be protective varnish and / or an insert.

The main area of the busbar is advantageously formed in one piece with the cooling lug of the busbar. The busbar is particularly advantageously manufactured as a stamped and bent part. In this way, the busbar can be produced simply and inexpensively, and in this way the

different areas, i.e. the main area and the cooling flag, can be designed simply and with little effort.

In an alternative embodiment, the main area and cooling vane are separate elements. The cooling flag and the main area are via a joining process connected with each other. It is particularly advantageous to be a

Joining process that ensures optimal heat transfer between the cooling flag and the main area. In this way it is achieved that the cooling vane is reliable for cooling the main area and the entire area

Busbar can be used. Due to the separate design of the cooling flag and main area and the subsequent joining of the two

Components, a design of the busbars can be implemented easily and inexpensively in any way. There is thus increased flexibility in the layout and design of the busbar.

It is preferably provided that the main area and the cooling vane

are firmly connected. This is achieved in particular by welding and / or soldering. The main area and the cooling vane can also be coupled by a force-fit connection. The non-positive connection can be achieved in particular by a press connection. Finally, it is alternatively or additionally provided that the main area and cooling vane are connected in a form-fitting manner. This can be implemented particularly advantageously via a rivet connection. All of these different types of connection allow a simple and inexpensive connection of the main area and cooling flag, with heat transfer being made possible between the main area and cooling flag. This ensures that the cooling vane

Main area and the entire busbar can cool.

The stator winding is particularly advantageously a three-phase winding. There are thus three busbars, one of which is electrically connected to a phase of the stator winding. All of these busbars are designed as described above, that is, all of these busbars have a main area and at least one cooling flag. In this way, the busbars can be optimally cooled.

The cooling jacket and / or the bearing plate are preferably made of a metallic material. As an alternative or in addition, the cooling jacket and end shield can also be made from a plastic. If metallic materials are used, thermal conductivity is improved. The formation of the elements from plastic, in turn, enables flexible design and inexpensive manufacture. When forming the plastic bearing shield As an alternative to the mounting solution for the busbar in the end shield, it is also possible to inject the busbar with the cooling flag into the end shield.

The cooling jacket is advantageously designed as a hollow cylinder. The first cooling channel is arranged along a central axis of the hollow cylindrical shape, the end shield closing the cooling jacket at one end face. In particular, an S-shaped course of the cooling medium through the cooling jacket and the end shield can be achieved in this way.

Each cooling vane is particularly preferably designed in such a way that it extends parallel to a central axis of the rotor.

Brief description of the drawing

Exemplary embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing is:

Figure 1 is a schematic illustration of an electrical machine according to an embodiment of the invention,

Figure 2 shows a schematic detailed view of the electrical machine according to the embodiment of the invention,

Figure 3 is a schematic sectional view of a bearing plate of the

Machine housing of the electrical machine,

FIG. 4 shows a schematic sectional view of at least a partial area of the electrical machine, and FIG

Figure 5 is a schematic detailed view of a portion of a

Busbar of the electrical machine according to the

Embodiment of the invention.

Embodiment of the invention

Figure 1 shows schematically an electrical machine 1 according to a

Embodiment of the invention. The electrical machine 1 has a Rotor 2 and a stator 3. The rotor 2 comprises a rotor shaft 8 which can be rotated about a central axis 100.

The rotor 2 can be driven via the stator 3. It is provided that the stator 3 can be cooled through cooling channels 6, 9. The cooling channels 6, 9 are arranged in a machine housing 4 of the electrical machine 1.

The machine housing 4 comprises a cooling jacket 5 and at least one bearing plate 7 for mounting the rotor shaft 8, two bearing plates being shown in FIG. Alternatively, the cooling jacket 5 can also be part of the stator 3.

The cooling jacket 5 is designed in the shape of a hollow cylinder and additionally has a plurality of first cooling channels 6, each of which extends parallel to one

Extend central axis of the hollow cylindrical shape. Fluid can flow within the first cooling channels, in particular in order to cool a stator winding 14 (see FIG. 4).

The end shields 7 also have cooling channels, the following second ones

Cooling channels 9 are called. The second cooling channels 9 each connect two, for example adjacent, first cooling channels 6 to one another, so that the second cooling channels 9 with the first cooling channels 6 create a coolant path through the electrical machine 1, which is for example meandering or

Is formed serpentine. For this purpose, a flow deflector is formed in each of the second cooling channels 9, for example.

The rotor shaft 8 is mounted on the end shields 7 via bearings 15. Each end shield 7 is attached to an end face of the hollow cylindrical cooling jacket 5.

Figure 2 shows schematically a course of three busbars 10. These

Bus bars 10 are electrically connected to the stator winding 14 (see FIG. 4). Thus, by energizing the busbars 10 a

The stator winding 14 is energized. The busbars 10 are arranged in particular on the bearing plate 7.

FIG. 3 shows a schematic detailed view of the end shield 7. It is shown that the end shield 7 on both sides of the second cooling channels 9

Has housing recesses 13. In these housing recesses 13 cooling tabs 12, which extend from a main region 11 of busbars 10, engage. It is provided in particular that the busbar is manufactured as a stamped and bent part. Thus, the

Manufacture cooling tabs 12 easily and with little effort. At the same time, optimal heat transfer between main section 11 and cooling vane 12 is made possible.

Through the housing recesses directly on one of the second

Cooling channels 9 and the arrangement of the cooling lugs 12 on both sides of the second cooling channels 9 can create a large area over which one

Heat transfer from the busbar 10 to the cooling medium is made possible within the second cooling channel. As a result, the bus bar 10 can be cooled effectively. This enables either higher currents to be carried than without such cooling or, alternatively, the design of the busbars 10 with smaller cross-sections. Through the housing recesses 13 is a

Assembly of the busbars 10 enables simple and easy.

To improve the heat transfer, it is advantageously provided that in the housing recesses 13 between the cooling lug 12 and

End shield 7 is attached a heat conducting material. In particular, it can be a thermally conductive adhesive. Thus, in a heat-optimized manner, from the busbars 10, in particular from the cooling lugs 12 of the busbars 10, via the end shield 7 to the cooling medium within the second cooling channels 9.

FIG. 4 schematically shows a section through at least part of the electrical machine 1. In particular, the coupling of one of the first cooling channels 6 to one of the second cooling channels 9 is shown in FIG. It is also shown that the cooling jacket 5 extends around the stator 3. The stator 3 in turn has the stator winding 14, which is electrically contacted by the busbars 10. In particular, it is a three-phase stator winding 14, so that each of the busbars 10 is provided for energizing one phase of the stator winding 14.

Cooling medium that flows through the first cooling channel 6 and the second cooling channel 9 also automatically reaches that area of the second

Cooling channel 9 which is framed by cooling lugs 12. Alternatively, if only one cooling vane 12 is still present, the cooling medium could also flow into the corresponding second cooling channel 9 are guided past the remaining cooling flag 12. In any case, heat can be transferred between the cooling vane 12 and the cooling medium, so that the busbar 10 is cooled.

The cooling jacket 5 and the bearing plate 7 can consist of a metallic

Material and / or made of plastic. A metallic material in particular enables better conductivity, with due to the

Arrangement of the busbar 10 along one of the second cooling channels 9 enables optimal heat dissipation by means of the coolant. If the end shield is made of a metallic material, it is provided that an electrical insulation material is present between the end shield 7 and the busbar 10. In particular, it can be an electrically insulating adhesive and / or a protective lacquer and / or an insert.

FIG. 5 schematically shows a partial view of the busbar 10. This has a main section 11 and two cooling lugs 12 connected to it. The cooling tabs 12 and the main section 11 can be designed in one piece, in which case the busbar 10 is advantageously a stamped and bent part, as shown in particular in FIG. Alternatively, the

Cooling lugs 12 are separate elements that are connected to the main area 11 by means of a joining process. Such a method can in particular be a mechanical method such as riveting and / or press-fit connection; alternatively, a thermal method such as soldering and / or

Welding a connection between main section 11 and cooling tabs 12 can be made.

The busbars 10 can thus be manufactured and assembled easily and inexpensively. At the same time, the busbars 10 allow safe and reliable heat dissipation via the cooling medium that is passed through the first

Cooling channels 6 and the second cooling channels 9 flows.

Claims

Expectations

1. Electrical machine (1) having a rotor (2) and a stator (3), which are at least partially arranged in a machine housing (4), and a cooling jacket (5) for cooling the stator (3) through which several to each other parallel, in particular running in the axial direction with respect to the stator axis, first cooling channels (6) for guiding a

Coolant run,

• wherein the machine housing (4) has at least one bearing plate (7) connected to the cooling jacket (5) for supporting a rotor shaft (8) of the rotor (2),

• with several second cooling channels (9) on the bearing plate (7)

are formed, which in each case flow-connect two, in particular adjacent, first cooling channels (6) to one another,

• wherein the second cooling channels (9) with the first cooling channels (6) to produce a coolant path through the electrical machine (1), which is in particular designed in a meandering or serpentine shape, and

• at least one busbar (10) running on the bearing plate (7), which is electrically connected to a stator winding (14) of the stator (3),

characterized in that

the busbar (10) has a main section (11) and at least one cooling lug (12) extending from the main section (11), the cooling lug (12) engaging in a housing recess (13) of the end shield (7) which is immediately adjacent to one of the second cooling channels (9) is formed.

2. Electrical machine (1) according to claim 1, characterized in that the cooling jacket (5) a part of the stator (3), in particular a stator core, or a part of the machine housing (4) which at least partially encloses the stator (3) , is

3. Electrical machine (1) according to one of the preceding claims, characterized in that the busbar (10) has two cooling vanes (12) which are each arranged in their own housing recess (13), the two housing recesses (13) being formed on both sides of one of the second cooling channels (9).

4. Electrical machine (1) according to one of the preceding claims, characterized in that a thermally conductive material, in particular a thermally conductive adhesive, is introduced between the cooling vane (12) and the bearing plate (7).

5. Electrical machine (1) according to one of the preceding claims, characterized in that an electrical insulation material, in particular an electrically insulating adhesive and / or a protective varnish and / or an insert, is introduced between the cooling vane (12) and the end shield (7).

6. Electrical machine (1) according to one of the preceding claims, characterized in that the main area (11) of the busbar (10) with the cooling lug (12) of the busbar (10) is formed in one piece, the busbar (10) in particular as Stamped and bent part is manufactured.

7. Electrical machine (1) according to one of claims 1 to 5, characterized

characterized in that the main area (11) of the busbar (10) and the cooling lug (12) of the busbar (10) are separate elements which are connected to one another by a joining process.

8. Electrical machine (1) according to claim 7, characterized in that the main area (11) and the cooling vane (12) materially connected, in particular soldered and / or welded, and / or non-positively connected, in particular via a press connection, and / or are positively connected, in particular via a rivet connection.

9. Electrical machine (1) according to one of the preceding claims, characterized in that the stator winding (14) is a three-phase winding, three busbars (10) are present, one of which is electrically connected to a phase of the stator winding (14) is.

10. Electrical machine (1) according to one of the preceding claims, characterized in that the cooling jacket (5) and / or the

End shield (7) made of a metallic material and / or a

Are made of plastic.

11. Electrical machine (1) according to one of the preceding claims,

characterized in that the cooling jacket (5) is designed in the shape of a hollow cylinder, the first cooling channels (6) being arranged along a central axis of the hollow cylinder shape, and the end shield (7) being the

Cooling jacket (5) closes on one end face.

12. Electrical machine (1) according to one of the preceding claims, characterized in that the busbar (10) with cooling flag (12) are injected into the end shield (7).