Motor with rotor cooling

Abstract

The invention provides an electric machine (1) having a stator (2) and a rotor (3), wherein the rotor (3) has a rotor laminated core (9) mounted on a shaft, wherein the shaft includes an oil passage (10), and the rotor laminated core has a passage (5) parallel to the axis (A) of the shaft (8) and end plates (6, 7) at the ends, wherein the oil passage (10) has transverse holes (11, 12) which are arranged in planes (E1, E2) spaced apart from each other axially on the front side (V) of the electric machine (1).

Description

Field of the Invention

[0001] The invention relates to an electric machine having a stator and a rotor, wherein the rotor has a rotor laminated core mounted on a shaft, wherein the shaft includes an oil passage, and the rotor laminated core has a passage parallel to the axis of the shaft and a terminal plate at an end, and the oil passage has a lateral opening. Background Art

[0002] Permanent magnets with rare earths are used in electric machines. If the permanent magnets overheat, there is a risk of demagnetization, whereby the electric machine may suffer irreparable damage. Therefore, in hybrid vehicles, cooling of the electric machine is a necessary factor regardless of the specific installation situation.

[0003] Thermal management in a 2.5 hybrid system is particularly problematic. An example of such a transmission can be found in DE 10 2010 004 711 C5. Due to the specific connection, the electric machine experiences higher speeds during driving at higher vehicle speeds, and these higher speeds are likely to last for several minutes.

[0004] Due to the higher losses occurring in the electric machine, the temperature is in a range where it is already critical for the magnets. Therefore, heat must be actively removed from the rotor laminations and the area near the magnets in order to be able to operate the electrical system without restrictions for a longer time.

[0005] Document JP 2011 254 580 A describes an electric machine having a stator and a rotor. A coolant flow path is provided along the rotor axis, wherein the coolant leaves the rotor shaft via an opening and flows in the end plate to a longitudinal passage in the rotor lamination.

[0006] Document JP 2009-118 686A includes an electric machine having a stator and a rotor, wherein the rotor has a rotor laminated core mounted on a shaft, wherein the shaft includes an oil passage, and wherein the rotor laminated core has a passage parallel to the axis of the shaft and a terminal plate at the end of the rotor laminated core, and the oil passage has lateral holes which are arranged in planes spaced apart from each other axially on the front side of the electric machine and supply oil to a first cooling oil path and a second cooling oil path. The cooling path arranged in the second plane extends via the oil passage and a distributor port in the rotor shaft and via a switching unit pre-tensioned by a spring. If the spring keeps the distributor port open, the coolant can flow into the passage of the rotor laminated core. However, the oil flows in the two cooling paths are not parallel or not always simultaneous. Instead, the two cooling paths are controlled such that one or the other cooling oil path is operative.

[0007] The document WO 2019 / 049 397 A1 describes a cooling system with cooling channels, the cooling channels having a single feed via a connecting opening. The coolant is not extracted via the rotor shaft, but the coolant can be specifically used for the rotor channels by means of a pump. Oil is not ejected from the holes onto the shoulder due to centrifugal force.

[0008] The document JP 2019-30 051 A likewise deflects the incoming coolant conveyed by a pump. Here, the coolant flows against a recessed structural member such that the rotor channels are supplied with coolant.

[0009] Likewise, in JP 2018-191 363 A, only cooling for the rotor is provided, wherein the rotor channels are directly supplied with coolant via a pump. For distribution, the side plates of the rotor are utilized and the side plates of the rotor have grooves and openings.

[0010] The object of the present invention is to create an electric machine with a cooling system that effectively cools the rotor while at the same time maintaining stator cooling. Summary of the Invention

[0011] This object is achieved by an electric machine having a stator and a rotor, wherein the rotor has a rotor laminated core mounted on a shaft, wherein the shaft includes an oil channel, and the rotor laminated core has a channel parallel to the axis of the shaft and a terminal plate at the end, wherein the oil channel has lateral openings which are arranged in planes spaced apart from each other axially on the front side of the electric machine.

[0012] Due to the arrangement of the lateral openings, axially offset oil jets are formed which jet out away from the shaft.

[0013] In order to cool both the stator and the rotor, a first plane is provided within the thickness of the terminal plate of the rotor laminated core located on the front side of the electric machine, the terminal plate being designed as a balancing disk, and a second plane is provided outside the balancing disk, in the region of the winding ends of the stator.

[0014] The oil jets jetting away in an axially offset manner travel on the one hand through the balancing disk and on the other hand directly into the internal structure of the balancing disk.

[0015] This results in a first cooling oil path which extends along the oil channel, passes through the lateral holes in the front and rear sides of the electric machine, and the exiting cooling oil jets out onto the winding ends.

[0016] A second cooling oil path is guided via the oil channel, the lateral holes on the front side, and the balancing disk into the channel of the rotor laminated core.

[0017] The balancing disk is designed such that it has at least one circumferential shoulder, in which apertures or recesses leading to channels in the rotor laminated core are provided along the periphery of the shoulder.

[0018] The depth of the shoulder region is up to half of the thickness of the balancing disk.

[0019] Alternatively, one or more shoulders can also be provided, which have staggered depths and are arranged at a certain distance from each other in the radial direction.

[0020] The balancing disk with multiple shoulders will be suitable for guiding channels corresponding to the shoulders and having different radial distances through the rotor laminated core, and thus dissipating heat near the permanent magnets in an optimal manner. Description of the Drawings

[0021] Figure 1 The electric machine is shown in a sectional view,

[0022] Figure 2 The same sectional view showing the oil drainage guide is shown,

[0023] Figure 3 and Figure 4 A plan view of the front side of the electric machine is shown,

[0024] Figure 5 A longitudinal section through the rotor balancing disk is shown,

[0025] Figure 6 A plan view of the rotor laminated core within the stator is shown. Detailed Description of the Invention

[0026] In Figure 1 and Figure 2 the electric machine 1 is shown in a longitudinal sectional view. The electric machine includes two main components: a rotor 2 and a stator 3. The stator 3 has winding ends 4 on both sides.

[0027] The rotor 2 consists of a rotor laminated core 9 mounted on a shaft 8. The shaft 8 is led out of a housing (not shown) at the front side V of the electric machine 1. Channels 5 are arranged within the rotor laminated core 9 and extend along the axis A. The number of channels 5 here should be adapted according to the cooling problem.

[0028] The channels 5 extend along the radius r, for example, at uniformly spaced radial distances from each other, or are distributed circumferentially at different radii r.

[0029] The rotor laminated core 9 is provided with terminal plates on both the front side portion V and the rear side portion R, and the terminal plates cover the rotor laminated core. The terminal plate on the front side portion V is formed as a balance disk 7 having structural members, and an unstructured terminal plate 6 is provided on the rear side portion R.

[0030] A cooling channel 10 is provided in the shaft 8 of the rotor 2, and the cooling channel 10 extends from the front side portion V to the rear side portion R.

[0031] The shaft 8 has a lateral hole 11 in a first plane E1 and a lateral hole 12 in a second plane E2 which is axially spaced from the first plane by a certain distance. The lateral hole 11 is provided in a single plane E3 on the rear side portion R of the electric machine 1.

[0032] In the plane E1, oil is sprayed onto the winding end 4 from the channel 10 via the lateral hole 11 and the free space by centrifugal force. In the plane E2, oil is sprayed from the channel 10 and the lateral hole 12 onto the structural members formed on the balance disk 7 and is guided to the channel 5 of the rotor lamination 9 via the structural members.

[0033] In Figure 2 the oil flow is indicated by arrows. The winding end 4 is cooled via the lateral holes 11 on both the front side portion V and the rear side portion R of the electric machine. The cooling oil rushes out from the opening 11 and contacts the winding end 4 via the path 13. Since the delivery of the oil depends on the rotational speed of the shaft 8 and the available amount of oil, the cooling of the winding end 4 on the rear side portion R of the electric machine is sometimes weaker because no more oil arrives.

[0034] However, due to the newly introduced cooling oil path 14, the winding end 4 on the rear side portion R of the electric machine 1 is also sufficiently cooled. The cooling oil path 14 initially extends radially from the lateral hole 12 of the shaft 8, contacts the structural members of the balance disk 7 - which will be described in more detail below, deflects and is guided along the channel 5 of the rotor lamination 9. This part of the cooling oil leaves on the rear side portion R of the electric machine 1 and rushes out in the direction of the winding end 4 on the rear side of the electric machine.

[0035] Permanent magnets (not shown in the figure) are embedded in the rotor lamination 9 and are spatially located near the channel 5. The heat of the permanent magnets is dissipated into the channel 5 by the cooling oil.

[0036] Figure 3 and Figure 4 shows a view of the front side portion V of the electric machine 1. In Figure 5 a cross - section through the balance disk 7 shown in Figure 3 can be seen.

[0037] The balancing disk 7 in the exemplary embodiment has a shoulder 15 in which the thickness D of the balancing disk is actually halved. Thus, an edge is formed, the thickness of which is approximately half of the thickness of the balancing disk. The depth of the shoulder 15 is adaptively modified according to the specific embodiment of the balancing disk and the cooling channel 5.

[0038] The balancing disk 7 additionally has axial cutouts in the form of recesses 16 through which the oil impinging on the shoulder 15 is axially guided to the rotor 2 and through the channel 5.

[0039] To optimize the cooling of the electric machine, the balancing disk 7 collects a portion of the oil quantity and axially guides this portion of the oil quantity through the rotor 2. The remaining oil is sprayed via the transverse opening 11 onto the winding ends and cools the stator.

[0040] Figure 6 An alternative solution is shown that is not limited to a specific channel type.

[0041] The figure shows the winding ends 4 arranged around the rotor laminated core 9. The permanent magnets 20 are incorporated in the rotor laminated core 9 in a typical arrangement. A group of permanent magnets 20 is placed along the outer circumference of the rotor laminated core 9; other permanent magnets are arranged in a V-shape so as to taper alternately inwards and outwards. Thus, mounting areas 21 and 22 are provided in the triangular spaces between two permanent magnets 20.

[0042] The channels 5 are formed in the mounting area 21 in a manner distributed over the entire circumference having a first radius r1. Additionally, channels 5a are provided along the circumference having a radius r2, and in this example, the channels 5a have a smaller inner diameter than the channels 5.

[0043] Another advantageous arrangement uses channels that are arranged in the mounting area 22 and adjacent to three permanent magnets 20.

[0044] To enable all channels 5, 5a to be supplied with oil, the balancing disk must be adaptively modified accordingly by additional shoulders 15 and recesses 16 along the circumferences having radii r1, r2, etc.

Claims

1. An electric machine (1), said electric machine (1) having a stator (3) and a rotor (2), wherein, The rotor (2) has a rotor laminated core (9) mounted on a shaft (8), wherein the shaft (8) includes an oil passage (10), and wherein the rotor laminated core (9) has a passage (5) parallel to the axis (A) of the shaft (8) and a terminal plate at an end of the rotor laminated core (9), wherein the oil passage (10) has transverse holes (11, 12) which are arranged in planes spaced apart from each other axially on the front side (V) of the electric machine (1), and the transverse holes (11, 12) supply a first cooling oil path and a second cooling oil path, and a first plane (E2) in the plane extends within the thickness (D) of the terminal plate designed as a balance disk (7), and a second plane (E1) extends in the region of the winding ends (4) of the stator (3) outside the balance disk (7), characterized in that the second cooling oil path is guided via the oil passage (10) and the transverse hole (12), wherein oil jets out from the oil passage (10) and the transverse hole (12) and is guided via the balance disk (7) onto the passage (5) of the rotor laminated core (9) on the front side (V), and the balance disk (7) has at least one circumferential shoulder (15), in which an orifice or recess (16) leading to the passage (5) in the rotor laminated core is provided along the radially inner periphery of the shoulder, and the orifice or the recess (16) guides the oil impinging on the shoulder (15) axially to the rotor (2), and a plurality of shoulders (15) have staggered depths and are arranged at a distance from each other radially, and passages (5) having different radial distances (r1, r2) corresponding to the shoulders (15) pass through the rotor laminated core (9).

2. The electric machine (1) according to claim 1, characterized in that, The first cooling oil path extends along the oil passage (10) through the transverse hole (11) in the front side (V) of the electric machine and the transverse hole (11) in the rear side (R), and the discharged cooling oil flushes onto the winding ends (4).

3. The electric machine (1) according to claim 1, characterized in that, The depth of the shoulder (15) is up to half of the thickness (D) of the balance disk (7).

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