DE102017203156A1 - Electric machine for a motor vehicle - Google Patents

Abstract

Electric machine (1) for a motor vehicle comprising a housing (2), a stator (3), wherein the stator (3) can be cooled via a stator cooling circuit, wherein the stator cooling circuit is connected to an external cooling circuit and has a cooling jacket (4), which is arranged on the stator (3), and a rotor (5), wherein the rotor is cooled by a rotor cooling circuit, wherein the rotor cooling circuit is an internal, closed cooling circuit having a heat exchanger (6), wherein the heat exchanger (6) the cooling jacket (4) of the stator cooling circuit is formed.

Description

Field of the invention

The present invention relates to an electric machine for a motor vehicle comprising a housing, a stator, wherein the stator is cooled by a stator cooling circuit, wherein the stator cooling circuit is connected to an external cooling circuit, and a rotor, wherein the rotor is cooled via a rotor cooling circuit, wherein the rotor cooling circuit is an internal, closed cooling circuit.

State of the art

Electric machines, asynchronous machines, such as synchronous machines, generate heat due to the dielectric loss during their operation - electrical energy is converted into heat, which, on the one hand, causes a deterioration in the efficiency of the electric machine and, on the other hand, adversely affects a reliable operation of the electric machine over its lifetime. Therefore, a cooling device is generally provided in electrical machines, which cools the stator and / or the rotor of the electric machine.

Numerous measures for cooling electrical machines are known from the prior art. However, the most common types of cooling are air cooling and liquid cooling. As a rule, cooling channels associated with the cooling are connected to an external cooling circuit, such as, for example, the cooling circuit of a water-cooled internal combustion engine.

The document DE 43 15 280 A1 describes, for example, an electric machine with an external rotor which is rotatably mounted on a stand. In the interior of the stator, namely radially below the stator lamination stack, at least one cooling jacket through which cooling fluid flows is arranged. Radially further inside, the stator has at least one cooling channel through which a circulating internal cooling medium, preferably air, flows. Thus, at least one cooling jacket for the cooling liquid and at least one cooling channel for the cooling air are shown.

The document US 2014/0368064 A1 discloses a cooling system for an electric motor having at least one heat pipe in a hollow portion of the rotor shaft of the electric motor. One end of the heat pipe extends beyond one end of the rotor shaft and is coupled to a heat exchanger, for example to a heat sink whose fins are designed as fan blades.

Summary of the invention

It is an object of the invention to provide an electric machine with an alternative, need-based cooling, which is characterized by a component-optimized and thus cost-reduced structure.

The object is achieved by an electrical machine for a motor vehicle comprising a housing, a stator, wherein the stator is cooled by a stator cooling circuit, the stator cooling circuit is connected to an external cooling circuit and having a cooling jacket, which is arranged on the stator, and a Rotor, wherein the rotor is cooled via a rotor cooling circuit, wherein the rotor cooling circuit is an internal, closed cooling circuit having a heat exchanger, wherein the heat exchanger is formed by the cooling jacket of the stator cooling circuit.

According to the invention, the electric machine comprises a housing, a stator and a rotor.

According to the present invention, the stator is cooled via a stator cooling circuit and the rotor via a rotor cooling circuit. That If necessary, the stator cooling circuit serves to cool the stator of the electric machine, and the rotor cooling circuit serves as needed to cool the rotor of the electric machine.

The stator cooling circuit according to the invention is connected to an external cooling circuit and has a cooling jacket, which is arranged on the stator. The external cooling circuit can be, for example, the cooling circuit of a water-cooled internal combustion engine. The external cooling circuit may also serve to cool other vehicle components, such as an inverter. The external cooling circuit uses a cooling device for cooling a coolant. This cooling device can be designed, for example, as a heat exchanger, a liquid circuit or an air cooling system.

A coolant is to be understood as meaning any coolant known to the person skilled in the art which can be used for cooling electrical machines.

The rotor cooling circuit according to the invention is an internal, closed cooling circuit which has a heat exchanger. The term "internal, closed cooling circuit" is to be understood in particular a cooling circuit, which is not connected to an external cooling circuit and the material not coupled with another cooling circuit, here the stator cooling circuit.

Both the stator cooling circuit and the rotor cooling circuit are to be understood as integral components of the electrical machine.

According to the present invention, the heat exchanger of the rotor cooling circuit is formed by the cooling jacket of the stator cooling circuit.

The advantages achieved by the invention are in particular that the electric machine can be represented with respect to efficient cooling of the stator as well as the rotor with minimal component and thus cost. In particular, by the use of the cooling jacket of Statorkühlkreislaufs as a heat exchanger for the rotor cooling circuit can generate a synergy effect that allows generating a component and cost-optimized design of the electric machine and continue to provide a needs-based cooling of the stator and the rotor safely. In addition, the interfaces to an external cooling circuit are minimized, thus reducing the risk of unwanted contamination of the coolant within the cooling circuits, whereby a reliable operation of the electrical machine can be ensured.

Further developments of the invention are specified in the dependent claims, the description and the accompanying drawings.

Preferably, the electric machine is designed in an inner rotor design with a radially outer stator, wherein the cooling jacket surrounding the stator at least partially, preferably over a range of 180 ° to 300 °, the outer circumference. In such a structure, the rotor is therefore circumferentially surrounded by the stator from radially inward to radially outward, the cooling jacket of the stator cooling circuit is embodied on the outside of the stator and the housing of the electrical machine in turn surrounds the cooling jacket of the stator on the outside.

In a preferred embodiment of the electric machine according to the invention, the rotor cooling circuit has a first cooling channel for guiding a coolant through the rotor with at least one first coolant inlet and at least one first coolant outlet. Furthermore, the rotor cooling circuit preferably has a second cooling channel for guiding the coolant along the heat exchanger, namely the cooling jacket of the stator cooling circuit, the rotor cooling circuit with at least one second coolant inlet and at least one second coolant outlet. Preferably, the second coolant outlet of the second cooling channel is fluidly connected to the first coolant inlet of the first cooling channel via a first coolant line and the first coolant outlet of the first cooling channel via a second coolant line to the second coolant inlet of the second cooling channel.

Preferably, the first cooling channel is formed in a rotor shaft of the rotor and extends at least partially substantially axially through the rotor shaft.

The term "axial" describes a direction along or parallel to a rotational axis of the rotor shaft of the rotor.

The term "radial" describes a direction normal to the axis of rotation of the rotor shaft of the rotor.

abgeschätzt werden, wobei ω die Winkelgeschwindigkeit des Rotors, ρ die Dichte des zur Kühlung verwendeten Kühlmittels und r_E und r_A die jeweilige radiale Position des ersten Kühlmitteleinlasses und des ersten Kühlmittelauslasses bezeichnen.The first coolant outlet preferably has a greater radial distance to the axis of rotation of the rotor shaft of the rotor than the first coolant inlet. The arrangement of the first coolant outlet at a greater radial distance from the axis of rotation than the first coolant inlet establishes a speed-dependent pressure difference and thus a speed-dependent mass flow in the first cooling channel and the second cooling channel. The cooling channels can be designed in all components of the rotor. The shape and size of the cooling channels depends on the required mass flow and the dissipated heat output. The pressure difference between the first coolant inlet and the first coolant outlet can be understood from the context $$\mathrm{\Delta }p={\mathrm{<figure-callout\; id="2"\; label="\omega "\; filenames="DE102017203156A1\_0002.png,DE102017203156A1\_0003.png"\; state="\{\{state\}\}">\omega </figure-callout>}}^2\cdot \rho \cdot \left(r_A^2-r_e^2\right)$$

where ω is the angular velocity of the rotor, ρ is the density of the coolant used for cooling, and r _E and r _{A are} the respective radial positions of the first coolant inlet and the first coolant outlet.

Preferably, the second cooling channel is formed in the housing of the electric machine.

In an advantageous embodiment of the electric machine according to the invention, a spiral-shaped collecting geometry is arranged on or in the housing of the electric machine in the region of the first coolant outlet. The spiral collecting geometry converts the kinetic energy of the coolant flowing out of the coolant outlet into a pressure increase at the end of the spiral and thus increases the mass flow rate of the closed rotor cooling circuit with the same energy expenditure. Furthermore, a conversion of the rotational energy of the coolant, imprinted by the rotation of the rotor shaft of the rotor, in a translatory movement.

list of figures

• 1 ist eine Schnittansicht einer erfindungsgemäßen elektrischen Maschine.
• 2 zeigt eine erste perspektivische Ansicht einer erfindungsgemäßen elektrischen Maschine.
• 3 zeigt eine zweite perspektivische Ansicht einer erfindungsgemäßen elektrischen Maschine.
• 4 zeigt eine dritte perspektivische Ansicht einer erfindungsgemäßen elektrischen Maschine.
• 5 zeigt eine erste perspektivische Ansicht einer spiralförmigen Auffanggeometrie.
• 6 zeigt eine zweite perspektivische Ansicht einer spiralförmigen Auffanggeometrie.

The invention will now be described by way of example with reference to the drawings.

• 1 is a sectional view of an electric machine according to the invention.
• 2 shows a first perspective view of an electric machine according to the invention.
• 3 shows a second perspective view of an electric machine according to the invention.
• 4 shows a third perspective view of an electrical machine according to the invention.
• 5 shows a first perspective view of a spiral collecting geometry.
• 6 shows a second perspective view of a spiral collecting geometry.

Detailed description of the invention

In 1 is a sectional view of an exemplary electrical machine according to the invention 1 shown.

The electric machine 1 has a housing 2 , a stator 3 and a rotor 4. The stator 3 as well as the rotor 5 the electric machine 1 are essentially in the housing 2 the electric machine 1 arranged.

The electric machine 1 is designed in internal rotor design, ie the stator 3 surrounds the rotor 5 outer circumference. The electric machine 1 can be operated both as an electric motor and as a generator. The features of cooling the electrical machine described in this document 1 However, they can also be used with differently constructed electrical machines.

Because the structure and function of a stator 3 and a rotor 5 the skilled person is well known, will be made to a detailed description of the structure of these components of the electric machine 1 waived.

The stator 3 the electric machine 1 is cooled by a stator cooling circuit. The rotor 5 the electric machine 1 is coolable via a rotor cooling circuit.

The stator cooling circuit is connected to an external cooling circuit (not shown) which supplies the stator cooling circuit with a cooled coolant. The stator cooling circuit has a cooling jacket 4 on. The cooling jacket 4 is outside of the stator 3 , between the stator 3 and the housing 2 , arranged and serves primarily the cooling of the stator 3 the electric machine 1 , The cooling jacket 4 has several coolant-carrying channels 18 on. These coolant-carrying channels 18 are supplied with coolant via the external cooling circuit. The cooling of the stator 3 takes place via the inside 19 of the cooling jacket 4 the stator cooling circuit.

The rotor cooling circuit is an internal, closed cooling circuit that is filled with a coolant. The coolant of the rotor cooling circuit is not materially coupled with the coolant of the stator cooling circuit. The rotor cooling circuit comprises a first cooling channel 7 , a second cooling channel 8th , a first coolant line 13, a second coolant line 14 and a heat exchanger 6 ( 1 . 2 . 3 . 4 ). The heat exchanger 6 the rotor cooling circuit is through the cooling jacket 4 the stator cooling circuit is formed.

The first cooling channel 7 the rotor cooling circuit is in a rotor shaft 15 of the rotor 5 trained and instructed, in 1 Visible, a first coolant inlet 9 , a first coolant outlet 11 and another first coolant outlet 11 ' on. The first coolant outlet 11 and the other first coolant outlet 11 ' have a greater radial distance to a rotation axis 16 the rotor shaft 15 of the rotor 5 on as the first coolant inlet 9 , The first coolant inlet 9 is centric to the axis of rotation 16 the rotor shaft 15 executed.

The first coolant inlet 9 of the first cooling channel 7 extends substantially in the axial direction partially through the rotor shaft 15 of the rotor 5 , At a reversal point 20 the first cooling channel takes place 7 an inversion in the axial direction and the coolant leaves via the first two coolant outlets 11 . 11 ' the rotor shaft 15 at the same end of the shaft 21 where it is in the rotor shaft 15 over the first coolant inlet 9 entry. The first cooling channel 7 can after the reversal point 20 by on a peripheral surface of the rotor shaft 15 substantially axially extending grooves leading to a laminated core 23 of the rotor 5 through a sleeve 22 are sealed, be formed ( 1 ), or be formed by directly in the laminated core substantially axially extending grooves. A structural design in the first cooling channel 7 completely through the rotor shaft 15 extends and at both distal shaft ends a coolant outlet 11 . 11 ' has, is also conceivable.

The term "axial" describes a direction along or parallel to the axis of rotation 16 the rotor shaft 15 ,

The term "radial" describes a direction normal to the axis of rotation 16 the rotor shaft 15 ,

The second cooling channel 8th the rotor cooling circuit is total in the housing 2 the electric machine 1 trained and divided in the in 1 illustrated embodiment in three mutually parallel channels, which are in fluid communication with each other. The second cooling channel 8th has a second coolant inlet 10 and a second coolant outlet 12 on.

The first cooling channel 7 On the one hand, there is a first coolant line 13 and secondly via a second coolant line 14 with the second cooling channel 8th fluidly connected - the second coolant outlet 12 of the second cooling channel 8th is about the first coolant line 13 with the first coolant inlet 9 of the first cooling channel 7 and the first coolant outlet 11 of the first cooling channel 7 via a second coolant line 14 with the second coolant inlet 10 of the second cooling channel 8th fluidly connected. The two coolant lines 13 . 14 run in the housing 2 the electric machine 1 ,

The promotion of the coolant within the rotor cooling circuit via the rotation of the rotor shaft 15 ie the pumping action for cooling the rotor 5 is done by the rotary's own rotary motion. The iron losses in the rotor 5 the electric machine 1 are just like the rotor cooling circuit dependent on the speed of the rotor shaft 15 , Such can be a demand-controlled cooling of the rotor 5 respectively. By flowing through the rotor shaft 15 with coolant, the heat dissipation takes place on the rotor 5 ,

In the area of the first two coolant outlets 11 . 11 ' , in the present embodiment in the region of the shaft end 21 , is in the case 2 a spiral collecting geometry 17 educated. The coolant is via the first coolant line 13 from the first cooling channel 7 in the second cooling channel 8th inside the case 2 promoted and there within the housing 2 around the cooling jacket 4 the stator cooling circuit of the stator 3 guided and cooled. The temperature of the coolant within the stator cooling circuit of the stator 3 is below the temperature level of the coolant within the rotor cooling circuit of the rotor 5 , Due to the temperature difference between the two coolants, namely the coolant within the stator cooling circuit and the coolant within the rotor cooling circuit, the cooling jacket functions 4 as a heat exchanger 6 , After the coolant of the rotor cooling circuit of the rotor 5 its heat to the coolant of the stator cooling circuit of the stator 3 has left this the second cooling channel 8th inside the case 2 via the second coolant outlet 12 and is via the second coolant line 14 back in the first cooling channel 7 within the rotor shaft 15 promoted and the described cooling process begins again.

LIST OF REFERENCE NUMBERS

1

Electric machine

2

casing

3

stator

4

cooling jacket

5

rotor

6

heat exchangers

7

First cooling channel

8th

Second cooling channel

9

First coolant inlet

10

Second coolant inlet

11

First coolant outlet

11 '

Another first coolant outlet

12

Second coolant outlet

13

First coolant line

14

Second coolant line

15

rotor shaft

16

Rotary axis (the rotor shaft)

17

Spiral collecting geometry

18

Coolant carrying duct (of the cooling jacket)

19

Inside (of the cooling jacket)

20

turning point

21

shaft end

22

shell

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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 4315280 A1 [0004]
• US 2014/0368064 A1 [0005]

Claims (7)

Comprising an electric machine (1) for a motor vehicle a housing (2), - A stator (3), wherein the stator (3) via a stator cooling circuit is cooled, wherein the stator cooling circuit is connected to an external cooling circuit and a cooling jacket (4) which is arranged on the stator (3), and - A rotor (5), wherein the rotor is cooled by a rotor cooling circuit, wherein the rotor cooling circuit is an internal, closed cooling circuit having a heat exchanger (6), wherein the heat exchanger (6) through the cooling jacket (4) of the stator cooling circuit is formed , Electric machine (1) after Claim 1 , characterized in that the electrical machine (1) is designed in internal rotor construction with a radially outer stator (3), wherein the cooling jacket (4) surrounds the stator (3) at least partially on the outside. Electric machine (1) after Claim 1 or 2 characterized in that the rotor cooling circuit comprises a first cooling passage (7) having at least a first coolant inlet (9) and at least a first coolant outlet (11) for guiding a coolant through the rotor (5) and a second cooling passage (8) with at least a second cooling passage Coolant inlet (10) and at least a second coolant outlet (12) for guiding the coolant to the heat exchanger (6) of the rotor cooling circuit, namely the cooling jacket (4) of the stator cooling circuit, wherein the second coolant outlet (12) of the second cooling channel (8) via a first coolant line (13) with the first coolant inlet (9) of the first cooling channel (7) and the first coolant outlet (11) of the first cooling channel (7) via a second coolant line (14) with the second coolant inlet (10) of the second cooling channel ( 8) is fluidly connected. Electric machine (1) after Claim 3 , characterized in that the first cooling channel (7) in a rotor shaft (15) of the rotor (5) is formed and at least partially extends substantially axially through the rotor shaft (15). Electric machine (1) after Claim 4 , characterized in that the first cooling channel (7) is designed such that the first coolant outlet (11) has a greater radial distance from a rotation axis (16) of the rotor shaft (15) of the rotor (5) than the first coolant inlet (9) , Electric machine (1) after Claim 3 . 4 or 5 , characterized in that the second cooling channel (8) in the housing (2) of the electric machine (1) is formed. Electric machine (1) according to one of Claims 3 to 6 , characterized in that on or in the housing (2) of the electric machine (1) in the region of the first coolant outlet (11) a spiral-shaped collecting geometry (17) is arranged.

Images