Electrical machine with an oil-cooling system

Abstract

The invention relates to an electrical machine with an oil-cooling system, wherein the electrical machine comprises a stator (1), a stator housing (2) and winding heads (3) on the two axial ends of the stator (1), wherein the oil-cooling system is configured to cool the stator (1) and the winding heads (3) of the electrical machine, wherein the oil is guided axially centrally to the stator (1) through a radial slot (4) in the stator housing (2) and runs along both sides of the stator (1) through oil channels (5) of the stator (1), and the cross section of the oil channel (5) is constricted by the stator housing (2) at at least one axial end of the stator (1) such that the oil passes through the cross section constricted by the stator housing (2) so as to reach a winding head (3).

Description

[0001] Electric machine with oil cooling

[0002] Field of the invention

[0003] The present invention relates to an electric machine with oil cooling, in particular as a drive motor in a motor vehicle.

[0004] State of the art

[0005] Oil-cooled electric machines are known and can be used in motor vehicles, for example, as drive motors. Such an electric machine may comprise a substantially cylindrical stator with a coil winding. At the axial ends of the stator, the coil winding may form a so-called winding head, which represents a large number of current-carrying conductors in a comparatively small volume. Due to the dense arrangement of the current conductors, such a winding head of an electric machine is usually the hottest point of the electric machine and is therefore usually cooled.

[0006] Cooling of a winding head can be achieved, for example, by thermally connecting the winding head to the respective stator package to dissipate the heat loss that occurs and, if necessary, to cooling devices provided there.

[0007] The cooling of the winding heads can also be designed separately from the stator cooling and thus comprise a separate cooling device for each winding head. Summary of the invention

[0008] It is an object of the invention to provide an electrical machine with oil cooling which can be manufactured cost-effectively and at the same time allows efficient cooling of the stator and winding heads.

[0009] The problem is solved by an electrical machine with oil cooling, the electrical machine comprising a stator, a stator housing and winding heads at the two axial ends of the stator, the oil cooling being designed to cool the stator and the winding heads of the electrical machine, the oil being guided axially centrally to the stator via a radial groove in the stator housing, running along the stator on both sides via oil channels of the stator and at at least one axial end of the stator the cross section of the oil channel is tapered by the stator housing, so that the oil reaches a winding head via the cross section tapered by the housing.

[0010] According to the invention, a stator of an electrical machine is thus cooled via oil channels in the stator. The oil reaches the oil channels via a groove in the stator housing, so that the oil can flow in both directions from the outlet into the oil channels along the stator and cool it. A tapered cross-section is formed at at least one axial end of the stator and thus also of the oil channel. The oil flow changes at this tapered cross-section so that it is directed specifically to a winding overhang, preferably to the winding overhangs. Preferably, both the flow velocity and the flow direction, towards the winding overhang, change at the tapered cross-section. The tapered cross-section is formed directly by the stator housing and can therefore be manufactured very easily and cost-effectively. The tapered cross-section is therefore located between the stator housing on the one hand and the stator orthe oil channel formed by the stator. The oil channels are preferably formed integrally through the stator.

[0011] The term "tapered" describes a narrowing, i.e., a reduction in the cross-section. While the reduction in the cross-section can be continuous, it does not have to be. It can therefore also be discontinuous, i.e., stepwise, preferably in the form of a shoulder. It can thus comprise one or more discontinuous reductions in the cross-section exclusively, or in addition to a continuous reduction in the cross-section.

[0012] The term "axially centered" for the oil supply through the radial groove encompasses not only an exactly centered oil supply, but also any supply to the stator located between the two axial ends, so that the oil reaches the axial ends of the stator via oil channels on both sides of the radial groove. Preferably, the axially centered supply is located at least near the geometric center between the axial ends.

[0013] Further developments of the invention are specified in the dependent claims, the description and the accompanying drawings.

[0014] Preferably, at the other axial end of the stator, the cross-section of the oil channel is tapered by a tolerance compensation element, so that the oil flows to a winding head at the other axial end of the stator via the cross-section tapered by the tolerance compensation element. The tolerance compensation element can be spring-loaded against the stator and / or be spring-elastic. A change in the length of the stator can be absorbed or compensated for by the tolerance compensation element, which can extend, for example, from the stator housing to the stator and cover part of the cross-section of an oil channel.

[0015] According to another embodiment, the cross section of the oil channel is also tapered by the stator housing at the other, second axial end of the stator, so that the oil reaches a winding head at the other axial end of the stator via the cross section tapered by the housing.

[0016] Preferably, the oil channels at both axial ends of the stator have tapered cross-sections. Particularly preferably, the two cross-sections are of different sizes, so that different power losses of the two winding heads can be cooled by different and thus adapted oil flows.

[0017] The tapered cross-section of the oil channel can be designed in such a way that the oil flow direction is specifically changed at the tapered cross-section of the oil channel. The oil flow can be specifically redirected to the winding head by appropriately shaping the taper.

[0018] Preferably, the cross-section of the oil channel is tapered at at least one axial end of the stator by a shoulder of the stator housing. At at least one axial end of the stator, the cross-section of the oil channel can be tapered by a shoulder of the tolerance compensation element.

[0019] Short description of the drawing

[0020] The invention is described below by way of example with reference to the drawing. Figure 1 is a schematic partial representation of an electrical machine according to the invention with oil cooling.

[0021] Detailed description of the invention

[0022] The figure shows part of an electrical machine according to the invention with an oil cooling system.

[0023] The electrical machine comprises a cylindrical stator 1 with coil windings in a stator housing 2 and winding heads 3 at the two axial ends of the stator 1.

[0024] An oil cooling system is designed to cool the stator 1 and the winding heads 3 of the electric machine. The oil flow of the oil cooling system is indicated by arrows in the figure.

[0025] The oil is guided axially centrally to the stator 1 via a radial groove 4 in the stator housing 2. The oil then flows along the stator 1 on both sides via oil channels 5 of the stator 1 and cools the stator.

[0026] At at least one axial end of the stator 1 - shown on the right in the figure - the cross section of the oil channel 5 is tapered by a shoulder of the stator housing 2, so that the oil reaches a winding head 3 (also on the right in the figure) via the cross section tapered by the stator housing 2.

[0027] At the other axial end of the stator 1, the cross-section of the oil channel 5 is tapered by a tolerance compensation element 6, so that the oil flows to the winding head 3 at the other axial end of the stator 1 (left in the figure) via the cross-section tapered by the tolerance compensation element 6. The cross-section of the oil channel 5 is tapered by a shoulder of the tolerance compensation element 6. The tolerance compensation element 6 rests against the stator 1 in a spring-loaded manner.

[0028] The tapered cross section of the oil channel 5 is designed at both axial ends in such a way that the flow direction of the oil is specifically changed in the direction of the winding heads 3 at the tapered cross sections of the oil channels 5.

[0029] Thus, oil is supplied to the stator 1 as centrally as possible via a radial groove 4. The oil is distributed to the left and right within the stator 1 via integrated oil channels 5. The channels can be tapered in cross-section on one side by a housing geometry. This increases the oil flow velocity. By adapting the geometry, the oil can be supplied specifically to the stator winding head 3, thereby cooling it.

[0030] On the other hand, a tolerance compensation element 6 can optionally be used for this purpose, following the same principle. The tolerance compensation element 6 compensates for the stator's longitudinal tolerance by securely holding the flow-relevant geometry against the stator 1 by means of a spring effect.

[0031] Alternatively, the cross-section of the oil channel 5 can be tapered on both sides by means of a housing geometry, particularly to reduce costs when the stator longitudinal tolerance is reduced or a lower cooling performance is sufficient. The geometry of the stator housing 2 and the geometry of the tolerance compensation element 6 can also be designed differently depending on the power losses of the two winding heads 3. For example, a winding head 3 with a phase connection can have a higher power loss.

[0032] The invention thus provides a cost-effective option for oil stator cooling with integrated winding head cooling. The cooling can operate independently of tolerances, since both geometries can be applied to stator 1.

[0033] List of reference symbols

[0034] stator

[0035] Stator housing

[0036] Winding head radial groove

[0037] oil channel

[0038] Tolerance compensation element

Claims

Patent claims 1. An electrical machine with oil cooling, the electrical machine comprising a stator (1), a stator housing (2) and winding heads (3) at the two axial ends of the stator (1), the oil cooling being designed to cool the stator (1) and the winding heads (3) of the electrical machine, characterized in that the oil is guided axially centrally to the stator (1) via a radial groove (4) in the stator housing (2), runs along the stator (1) on both sides via oil channels (5) of the stator (1), and at at least one axial end of the stator (1) the cross section of the oil channel (5) is tapered by the stator housing (2), so that the oil reaches a winding head (3) via the cross section tapered by the stator housing (2).

2. Electrical machine according to claim 1, characterized in that at the other axial end of the stator (1) the cross section of the oil channel (5) is tapered by a tolerance compensation element (6), so that the oil reaches a winding head (3) at the other axial end of the stator (1) via the cross section tapered by the tolerance compensation element (6).

3. Electrical machine according to claim 2, characterized in that the tolerance compensation element (6) rests against the stator (1) in a spring-loaded manner and / or is designed to be spring-elastic.

4. Electrical machine according to claim 1, characterized in that the cross section of the oil channel (5) is also tapered by the stator housing (2) at the other axial end of the stator (1), so that the oil reaches a winding head (3) at the other axial end of the stator (1) via the cross section tapered by the stator housing (2).

5. Electrical machine according to at least one of the preceding claims, characterized in that at both axial ends of the stator (1) the oil channels (5) have tapered cross sections, the two cross sections being of different sizes.

6. Electrical machine according to at least one of the preceding claims, characterized in that the tapered cross section of the oil channel (5) is designed such that the flow direction of the oil is specifically changed at the tapered cross section of the oil channel (5).

7. Electrical machine according to at least one of the preceding claims, characterized in that at least one axial end of the stator (1) the cross section of the oil channel (5) is tapered by a shoulder of the stator housing (2) and / or that at least one axial end of the stator (1) the cross section of the oil channel (5) is tapered by a shoulder of the tolerance compensation element (6).

Images