Device for liquid cooling of an electric machine

Abstract

This invention relates to an apparatus for liquid cooling of an electric motor (EM) having a stator (S) and a rotor (R), the motor (EM) being surrounded on its outer circumference by a cooling jacket (M) having an inlet (M1) and an outlet (M2), wherein, in the mounting position of the motor (EM), the inlet (M1) is spatially arranged below the axis of rotation (RA) of the rotor (R), and the outlet (M2) is spatially arranged above the axis of rotation (RA); the invention also relates to an electric motor (EM) having the above-described apparatus; and the invention further relates to a drive unit for a motor vehicle having the above-described electric motor (EM).

Description

[0001] This application is a divisional application of the invention patent application filed on April 7, 2020, with application number 202010263811.6 and invention title "Apparatus for Liquid Cooling of Motor". Technical Field

[0002] This invention relates to an apparatus for liquid cooling of an electric motor. The invention also relates to an electric motor having such an apparatus, and to a drive unit for a motor vehicle having such an electric motor. Background Technology

[0003] Devices for liquid cooling of motors are known in the prior art. For example, patent application DE 10 2017203 435 A1 describes a cooling jacket assembly for a motor housing. This cooling jacket assembly includes a tubular cooling jacket with an inlet sleeve and an outlet sleeve arranged at opposite ends of the cooling jacket. However, this device increases installation space requirements because corresponding connectors must be provided for the inlet and outlet of the cooling jacket assembly. Summary of the Invention

[0004] Therefore, the object of the present invention is to provide a liquid cooling device for an electric motor, characterized by good cooling effect and small space requirement.

[0005] This objective is achieved through the main features of the invention. Advantageous improvements are derived from other features.

[0006] To achieve this objective, the present invention provides an apparatus for liquid cooling of an electric motor having a stator and a rotor. The motor is surrounded on its outer circumference by a cooling jacket. The cooling jacket has an inlet and an outlet. The cooling jacket is configured to guide a liquid cooling medium from the inlet to the outlet, thereby enabling heat transfer from the motor to the cooling medium. The cooling medium can then flow through a heat exchanger, thereby enabling heat transfer from the cooling medium to the environment or another cooling medium. The cooling medium can circulate in a cooling loop, so that the cooling medium can be returned to the motor after flowing through the heat exchanger.

[0007] According to the present invention, in the installation position of the motor, the inlet is spatially arranged below the rotation axis of the rotor, while the outlet is spatially arranged above the rotation axis.

[0008] The spatial separation between the inlet and outlet of the cooling jacket means that the cooling medium flows from bottom to top. Therefore, a separate connector at the outlet can be eliminated, as the cooling medium exiting at the outlet can collect in the bottom housing area surrounding the motor. This solution also improves the thermal efficiency of the cooling system.

[0009] In the installation location, the outlet is preferably spatially arranged at the highest point of the motor. This arrangement particularly improves the thermal efficiency of the cooling arrangement because the fluid flowing out of the outlet can thus flow downwards through the entire motor.

[0010] The cooling medium flowing out of the outlet preferably flows downwards to the outside of the cooling jacket on the motor. This arrangement ensures that the cooling medium flowing out of the outlet comes into contact with the rotor. If the rotor rotates, the cooling medium will form eddies. This improves the thermal efficiency of the cooling device.

[0011] According to a preferred embodiment, the outlet has at least two discharge openings. These two discharge openings are arranged spaced apart from each other in the axial direction. This arrangement facilitates the flow of cooling medium to both end faces of the motor.

[0012] In the motor mounting location, the inlet is preferably spatially located at the lower third or lower quarter of the motor, thus away from the lowest point of the motor. This configuration does not increase the width of the assembly of the motor together with the cooling jacket.

[0013] The inlet and outlet are preferably arranged at least one-quarter of the circumference of the motor, and particularly preferably at least one-third of the circumference of the motor. This arrangement allows for at least some degree of uniform cooling of the motor.

[0014] The cooling jacket is preferably designed such that, starting from the inlet, the incoming cooling medium is guided to the outlet along two circumferential directions. In other words, the cooling jacket has a first flow path and a second flow path. The first flow path starts from the inlet and extends along the outer circumference of the motor in a first direction to the outlet. The second flow path starts from the inlet and extends along the outer circumference of the motor in a second direction to the outlet. The first and second directions are oriented in opposite directions. This arrangement allows for at least some degree of uniform cooling of the motor. The two flow paths can have different lengths.

[0015] According to a preferred embodiment, the cooling jacket is formed by the stator support of the motor and a covering element surrounding the stator support. With this structure, the cooling jacket can be formed using structural elements that are otherwise necessary (such as the stator support). Therefore, the number of parts required to form the cooling jacket can be reduced.

[0016] The outlet of the cooling jacket is preferably formed by at least one, preferably two, openings in the stator support. The cooling medium can flow out from these openings, thus reaching the stator windings directly. Therefore, the stator windings can be effectively cooled without being surrounded by the cooling jacket.

[0017] Preferably, a mechanism for distributing coolant into the cooling jacket is formed or arranged on the stator support. This mechanism may be, for example, a flow aid, such as an orifice, a guide element, or the like. This allows for a uniform distribution of the cooling medium entering the cooling jacket.

[0018] The aforementioned device for liquid cooling is preferably a component of the motor. In other words, the device can form a common structural unit together with the electromagnetically activated elements of the motor.

[0019] The motor equipped with the aforementioned device can be a component of a drive unit for a motor vehicle. The drive unit can be, for example, formed by a vehicle axle unit, a transmission, or a hybrid power module arranged between an internal combustion engine and a transmission. The transmission can be a multi-stage transmission or a continuously variable transmission (CVT). Attached Figure Description

[0020] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The drawings show: Figures 1 to 3 These are different drive trains used in motor vehicles; and Figure 4 and Figure 5 These are cross-sectional views of the motor. Detailed Implementation

[0021] Figure 1 A drivetrain for a motor vehicle is schematically illustrated. The drivetrain has an internal combustion engine VM, the output of which is connected to the input shaft GW1 of a transmission G. The transmission G forms the drivetrain unit of the drivetrain. The output shaft GW2 of the transmission G is connected to a differential AG. The differential gear AG is designed to distribute the power applied to the output shaft GW2 to the drive wheels DW that drive the motor vehicle. The transmission G has a gear set RS, which is connected to a gear not in the differential gear set. Figure 1 The shifting elements shown are arranged together between the input shaft GW1 and the output shaft GW2 to provide different gear ratios. The transmission G has a motor EM connected to the input shaft GW1. This motor EM is configured to drive the input shaft GW1.

[0022] Figure 2 The drivetrain is schematically illustrated, in which the electric motor is not included in the transmission G. Instead, a hybrid power module HY is arranged between the internal combustion engine VM and the transmission G. The hybrid power module HY has an electric motor EM.

[0023] Figure 3 The diagram schematically illustrates a transmission system used in a motor vehicle, and... Figure 1 and Figure 2Compared to the illustrated embodiment, this drivetrain is a purely electric drivetrain. The drivetrain has a vehicle axle unit EA. The axle unit EA has a motor EM, which is configured to drive axle W. Axle W is connected to a differential AG. The differential gear AG is designed to distribute the power applied to axle W to the vehicle's drive wheels DW.

[0024] Figures 1 to 3 The transmission system shown is only considered as an example. For example, according to Figure 1 and Figure 2 The drivetrain can also be oriented laterally to the direction of travel. This drivetrain can be used to drive passenger cars, freight cars, or rail vehicles.

[0025] The use of liquid cooling devices for motors (EM) is advantageous for this application, especially in order to increase their maximum available continuous power. Figure 4 and Figure 5 The arrangement of this liquid cooling device is illustrated schematically.

[0026] Figure 4 A schematic cross-sectional view of an electric motor EM having a stator S and a rotor R is shown, wherein the cutting plane is arranged perpendicular to the axis of rotation RA of the rotor R. The electric motor EM is designed, for example, as an internal rotor motor, that is, a motor with a rotor R arranged radially inside the stator S. However, the liquid cooling device described herein can also be used in an external rotor motor, in which the rotor R is arranged radially outside the stator S.

[0027] The motor EM is shown in its installed position, with the vertical line indicated by the directional arrow z. The stator S is held by a stator support ST. The stator support ST can be manufactured, for example, as an aluminum die-casting. The stator S can be pressed into the stator support ST. The stator support ST is surrounded by a cover element C, forming a gap between the inner surface of the cover element C and the outer surface of the stator support ST. This gap forms a cooling jacket M through which a liquid cooling medium, such as water or oil, can flow. The cooling medium can absorb heat from the stator support ST, which is preheated by the stator S, and dissipate it to the environment or another cooling medium via a heat exchanger (not shown).

[0028] The cooling jacket M has an inlet M1 and an outlet M2. The inlet M1 is spatially positioned below the rotation axis RA, specifically at the lower quarter of the motor EM. The inlet M1 is intentionally positioned away from the lowest point of the motor EM in space to avoid increasing the installation height of the motor EM. The outlet M2 is spatially positioned above the rotation axis RA, more precisely at the highest point of the motor EM in space. The inlet M1 and outlet M2 are spaced approximately one-third of the circumference of the stator support ST. The arrows indicate the path of the cooling medium from inlet M1 to outlet M2.

[0029] The cooling jacket M has a first flow path S1 and a second flow path S2. The cooling medium flowing into the inlet M1 is divided into two flow paths S1 and S2 by a separating element X connected to the stator support ST. These two flow paths S1 and S2 lead to the outlet M2 in the circumferential direction, wherein the first flow path S1 is shorter than the second flow path S2.

[0030] The outlet M2 is formed by an opening M2a constructed in the stator support ST. Now, the cooling medium flowing out at the opening M2a flows downward at the motor EM under the action of gravity and is collected in the bottom shell area (not shown).

[0031] Figure 5 Another schematic cross-sectional view of the motor EM is shown, in which the outlet M2 can be seen. The section plane is now formed by the axis of rotation RA and the perpendicular line z. The motor EM is shown in its mounting position. For greater clarity, Figure 5 Only the upper half of the cross-section is shown. Figure 5 As can be seen, each of the flow paths S1 and S2 is equipped with its own discharge openings M2a and M2b. These discharge openings M2a and M2b are axially spaced apart. The cooling medium flowing from the discharge openings M2a and M2b flows through the gap between the stator support ST and the stator S, passing through the winding head of the stator S. The cooling medium flowing out in this way drips onto the rotor R. As the rotor R rotates, the cooling medium forms vortices and is thrown out. This significantly improves the thermal efficiency of the cooling device. Finally, the cooling medium drips down and collects in the bottom shell area (not shown).

[0032] If the cooling medium is oil, the dripping cooling medium can also be used for lubrication, for example for lubricating rolling bearings, by means of which the rotor R is supported relative to the housing (not shown).

[0033] List of reference numerals in the attached diagram: EM motor S stator ST stator support C Covering element R rotor The axis of rotation of the RA rotor M Cooling jacket M1 entrance S1 First Flow Path S2 Second Flow Path X Distribution Agency M2 Export M2a Discharge Opening M2b discharge opening VM internal combustion engine G housing GW1 input shaft GW2 output shaft RS gear set AG differential DW drive wheel HY hybrid power module EA vehicle axle unit W axis

Claims

1. An apparatus for liquid cooling of an electric motor (EM) having a stator (S) and a rotor (R), wherein the electric motor (EM) is surrounded on its outer circumference by a cooling jacket (M) having an inlet (M1) and an outlet (M2), wherein the cooling jacket (M) is arranged such that a cooling medium entering the cooling jacket (M) at the inlet (M1) is directed to the outlet (M2). Its features are, In the installation position of the motor (EM), the inlet (M1) is spatially arranged below the rotation axis (RA) of the rotor (R), while the outlet (M2) is spatially arranged above the rotation axis (RA). The cooling jacket (M) is configured such that the cooling medium entering the cooling jacket (M) is guided to the outlet (M2) along two circumferential directions starting from the inlet (M1). The cooling jacket (M) has a first flow path and a second flow path (S1, S2), wherein the first flow path (S1) extends from the inlet (M1) along a first direction along the outer circumference of the motor (EM) to the outlet (M2), and wherein the second flow path (S2) extends from the inlet (M1) along a second direction along the outer circumference of the motor (EM) to the outlet (M2), wherein the first and second directions are opposite; and The two flow paths (S1, S2) have different lengths.

2. The apparatus according to claim 1, characterized in that, The outlet (M2) is spatially positioned at the highest point of the motor (EM) in the installation location.

3. The apparatus according to claim 1 or 2, characterized in that, The cooling medium flowing out at the outlet (M2) flows downward on the motor (EM) outside the cooling jacket (M).

4. The apparatus according to claim 1 or 2, characterized in that, The outlet (M2) has at least two discharge openings (M2a, M2b) arranged spaced apart from each other in the axial direction.

5. The apparatus according to claim 1 or 2, characterized in that, The inlet (M1) is spatially located at the lower third or lower quarter of the motor (EM) in the installation position, wherein the inlet (M1) is spatially located at the lowest point away from the motor (EM).

6. The apparatus according to claim 1 or 2, characterized in that, The inlet (M1) and the outlet (M2) are arranged at least one-quarter of the circumference of the motor (EM) apart from each other, and particularly preferably at least one-third of the circumference of the motor apart from each other.

7. The apparatus according to any one of claims 1, characterized in that, The cooling jacket (M) consists of the stator support (ST) of the motor (EM) and a covering element (C) surrounding the stator support (ST).

8. The apparatus according to claim 7, characterized in that, The outlet (M2) is formed by at least one opening (M2a, M2b) constructed in the stator carrier (ST).

9. The apparatus according to claim 7, characterized in that, The mechanism (X) for distributing the coolant entering at the inlet (M1) is constructed or arranged on the stator support (ST).

10. An electric motor (EM), characterized in that, The device is provided for liquid cooling of an electric motor (EM) according to any one of claims 1 to 9.

11. A drive unit for a motor vehicle, characterized in that, The motor (EM) according to claim 10 is provided, and the motor is configured to drive the motor vehicle.

12. The driving unit according to claim 11, characterized in that, The drive unit consists of a vehicle axle unit (EA), a transmission (G), or a hybrid power module (HY) arranged between the internal combustion engine (VM) and the transmission (G).

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