Motor with cooling system

Abstract

The invention relates to a system and a method for an electric machine. In one example, an electric machine includes a rotor shaft having a central cavity, an oil inlet, and a tapered portion contoured to direct oil from the oil inlet to an oil outlet. The rotor shaft also includes an insert located outside the rotor shaft for guiding oil to the oil outlet. In this way, the motor can be effectively cooled, and therefore the operation efficiency of the machine is improved.

Description

Cross-reference search of related applications

[0001] This application claims priority to U.S. Provisional Application No. 63 / 579,871, filed on August 31, 2023, entitled "Electric Machine with Cooling System." The entire contents of the above application are now incorporated herein for reference. Technical Field

[0002] The present disclosure relates to an electric machine with a rotor shaft cooling system. Background Art

[0003] Electric motors used in electric vehicles (EVs) and other applications have attempted to improve motor efficiency using closed channel motor cooling, through which fluids flow. However, the inventors have recognized that certain closed channel motor cooling arrangements may cause pressure losses due to air entrainment in pressurized channels, thereby reducing cooling performance and motor efficiency. In addition, the inventors have recognized the desire to achieve high levels of motor cooling performance (e.g., particularly in non-pressurized environments). Summary of the invention

[0004] In view of the above problems, the inventors have developed an electric motor that at least partially overcomes the above problems. In one example, the electric motor includes a rotor shaft. The rotor shaft includes a central cavity, an oil inlet, a tapered portion, the cross-section of the tapered portion can guide oil from the oil inlet to the oil outlet, and an insert, which is located on the outer portion of the rotor shaft and is configured to guide oil to the oil outlet. In this way, the electric motor can be effectively cooled, thereby improving the operating efficiency of the machine.

[0005] In one example, the outer rotor shaft portion and the insert can be made of different metals. For example, the insert can be made of aluminum, while the outer rotor shaft portion can be made of steel. Using steel to make the outer rotor shaft portion can achieve the required strength and torque transfer capacity of the shaft. In addition, using this material structure in the rotor shaft, especially the aluminum insert, can reduce the weight of the shaft and improve thermal conductivity. In other examples, the insert can be made of copper to further improve thermal conductivity. However, using a copper insert will increase the weight of the machine compared to an aluminum insert. Therefore, the efficiency of the motor will be further improved.

[0006] In another example, the insert may include a plurality of grooves. The grooves may be linear or spiral. Constructing the insert in this manner may allow the insert to attract more oil flow in the axial direction toward the outlet of the rotor shaft, thereby further improving the cooling effect of the rotor shaft. Specifically, using spiral grooves may increase axial oil flow, further improving cooling performance.

[0007] In another example, a mechanical coupling interface can be formed between the outer surface of the insert and the inner surface of the outer shaft portion. The mechanical coupling of the insert and the outer shaft portion can reduce the thermal resistance between the components, thereby improving cooling performance. The mechanical coupling can be achieved by thermally conductive coupling agents, surface brazing, pushing the outer shaft portion radially inward when the insert is inside, and / or press fitting.

[0008] It should be understood that the above summary is intended to introduce in a simplified form the concepts that are further described in the detailed description. It is not intended to identify key or essential features of the claimed subject matter, the scope of which is solely determined by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 A schematic diagram of a vehicle including a motor is shown.

[0010] Figure 2 An example of an electric motor rotor shaft and cooling system is shown.

[0011] Figure 3-4 Shown Figure 2 Different views of the motor shown.

[0012] Figure 5-10 Different examples of serrations in motor inserts are shown.

[0013] Fig.11 Another example of a rotor shaft for an electric machine cooling system is shown.

[0014] Fig.12 Another example of a motor cooling system rotor shaft is shown.

[0015] Fig.13 Shows Fig.12 Detailed view of the rotor shaft section described in .

[0016] Figure 14-15 Shows Fig.12 Different views of the insert in the rotor shaft are shown.

[0017] Figure 16-17 shows different views of a motor cooling system, Fig.12 The rotor shaft described in is installed in this system. DETAILED DESCRIPTION

[0018] A cooling system for an electric machine is described herein that has improved performance (e.g., enhanced thermal management), reduced weight, robust packaging, and efficient manufacturing over previous electric machine cooling systems. To achieve these characteristics, the cooling system in one example includes a rotor shaft insert in which oil is sprayed into a tapered portion of the rotor shaft. The oil forms a thin film that flows down the insert, which can be made of aluminum or other suitable material. To promote the flow of the oil film, the insert can include serrations to drive the oil flow.

[0019] Figure 1 A schematic diagram of a vehicle 100 is shown. In various examples, the vehicle may be a passenger vehicle, a commercial vehicle, an on-highway vehicle, or an off-highway vehicle.

[0020] In the vehicle example, the vehicle 100 includes a powertrain 102 with a gearbox 104 (e.g., a gearbox) and an electric motor 106. In this example, the electric motor 106 may be a traction motor. However, in other examples, the electric motor 106 may be included in other suitable systems, such as industrial machinery, agricultural systems, mining systems, etc.

[0021] When the electric machine 106 is a traction motor, the electric machine can be included in an electric drive system. In the electric drive example, under certain conditions, when the electric machine operates as a generator, power can flow from the transmission to the electric machine.

[0022] In the electric vehicle (EV) example, the electric vehicle can be an all-electric vehicle, such as a battery electric vehicle (BEV), as one example, or a hybrid electric vehicle (HEV) with an internal combustion engine, as another example.

[0023] The motor 106 includes a rotor 108, which electromagnetically interacts with a stator 110 to drive a rotor shaft 112 in the rotor to rotate. The motor 106 may further include a housing, bearings connected to the rotor shaft, and the like.

[0024] Generally speaking, the motor 106 can be a multi-phase alternating current (AC) motor. However, in other examples, the motor 106 can be a direct current (DC) motor. In the AC motor example, the motor 106 can be electrically connected to an inverter 114. The inverter 114 is used to convert DC power to AC power, and vice versa. However, in other examples, the motor 106 can be a DC motor (as described above), so the vehicle 100 can omit the inverter 114. The inverter 114 can receive electrical energy from one or more energy storage devices 116 (e.g., a traction battery, a capacitor, a combination thereof, etc.). Arrow 118 represents the transmission of electrical energy between the motor 106, the inverter 114, and the energy storage device 116, which may occur in different system operating modes.

[0025] The motor 106 includes a cooling system 120 (eg, a traction motor cooling system) that is integrated with the rotor shaft 112. A schematic diagram of the cooling system 120 is shown in FIG. Figure 1 However, the cooling system has a higher complexity. Figure 2 The details will be explained in detail.

[0026] The cooling system 120 includes an oil inlet 122 and an oil outlet 124. Arrow 126 indicates that oil flows from an oil source 128 to the oil inlet 122 in the cooling system 120, and arrow 130 indicates that oil flows out of the oil outlet 124 in the cooling system. In detail, the oil can be sprayed into the oil inlet 122 through a nozzle and / or other suitable device in the cooling system. The oil source 128 may include components such as an oil reservoir (such as an oil pan), a pump, a filter and / or a heat exchanger.

[0027] In addition, the gearbox 104 is mechanically connected to the axle assembly 134 to achieve torque transmission therebetween. In the illustrated example, the axle assembly 134 may include a differential 136, an axle shaft 138 and / or drive wheels 140.

[0028] like Figure 1 As shown, the vehicle 100 may further include a control system 190 with a controller 191 (such as a vehicle control unit (VCU)). The controller 191 may include a microcomputer whose components include a processor 192 (such as a microprocessor unit), input / output ports, and an electronic storage medium 194 for executable programs and calibration values ​​(such as a read-only memory chip, random access memory, keep-alive memory, data bus, etc.). The storage medium can be programmed with computer-readable data that represents instructions executable by the processor for performing the methods and control techniques described herein, as well as other variants that are expected but not specifically listed. Therefore, the control techniques, methods, etc. described herein can be stored as instructions in a non-transitory memory.

[0029] The controller 191 may receive various signals from sensors 195 coupled to different areas of the vehicle 100. For example, the sensors 195 may include pedal position sensors for detecting depression of operator actuation pedals such as an accelerator pedal and / or a brake pedal; speed sensors on the input and / or output shafts of a transmission; motor speed sensors, etc. Input devices 198 (e.g., an accelerator pedal, a brake pedal, a drive mode selector, a gear selector, combinations thereof, etc.) may further provide input signals indicative of the operator's system control intent.

[0030] Received from Figure 1After receiving signals from various sensors 195, the controller 191 processes the received signals and uses various actuators 196 of the system components to adjust the components based on the received signals and the instructions stored in the memory of the controller 191. For example, the controller 191 can adjust the speed of the motor 106 by adjusting the inverter 114. For example, the controller 191 can determine that the speed of the motor should be adjusted and send instructions to the inverter to adjust the speed of the motor based on this determination. For example, other controllable components in the system can adjust sensor signals, control instructions, and actuators in a similar manner.

[0031] Figure 1 as well as Figure 2-17 An axis system is provided for reference in . In one example, the z-axis can be a vertical axis (e.g., parallel to the gravity axis), the x-axis can be a lateral axis (e.g., a horizontal axis), and / or the y-axis can be a longitudinal axis. However, in other examples, these axes may have other directions.

[0032] Figure 2 An example of a rotor shaft 200 with a cooling system 202 is shown. The rotor shaft 200 includes Figure 3-4 In the motor 203 shown, this will be discussed in more detail herein. In addition, it is understood that in one example, the rotor shaft 200 and the cooling system 202 may include Figure 1 However, in other examples, the rotor shaft 200 and the cooling system 202 may also be included in other suitable motors. The cross section of the rotor shaft 200 is as shown in FIG. Figure 2 shown. Figure 2 The cutting plane of the middle cross-sectional view passes through the rotation axis 250 of the rotor shaft. The other cross-sectional views described herein also have similar cutting planes.

[0033] The rotor shaft 200 includes a central cavity 204 through which the oil flows during operation of the motor. In the illustrated example, the rotor shaft 200 is composed of different parts. In detail, the rotor shaft 200 includes a tapered part 206, an insert part 208 and an outer part 210.

[0034] The tapered portion 206 includes an inlet 212 and the outer portion 210 includes an outlet 214. The inlet 212 is located at a first axial end of the rotor shaft 200 and the outlet 214 is located at a second axial end of the rotor shaft 200. As indicated by arrows 218, the inlet 212 and the outlet 214 are in fluid communication with an oil source 216. The oil source may include a pump, an oil reservoir, a filter, combinations thereof, and the like.

[0035] The oil source 216 may be configured to spray oil into the inlet 212. Thus, the oil source may include a nozzle and / or other suitable components for spraying oil into the inner cavity of the rotor shaft.

[0036] The tapered portion 206 includes an inner diameter 220 that tapers in an axial direction toward the inlet 212. Tapering the rotor portion in this manner increases the velocity of the oil droplets and propels them axially toward the outlet 214.

[0037] In the illustrated example, the insert 208 is circumferentially enclosed by the outer portion 210. However, other insert-type structures may also be used. The outer surface 240 of the insert 208 can be mechanically coupled to the inner surface 242 of the outer portion 210. Coupling these surfaces can reduce the thermal resistance between the components, thereby improving cooling performance. The mechanical coupling between the insert 208 and the outer portion 210 can be achieved by a thermally conductive coupling agent, brazing of the two surfaces (e.g., fully brazed), pushing the outer portion radially inward when the insert is inside, using a suitable press-fit method (e.g., ISO and / or ANSI press-fit techniques), a combination thereof, and the like.

[0038] like Figure 2 As shown, the insert 208 does not include an internally enclosed oil passage. The inner diameter of the insert 208 may include a plurality of grooves 222 (e.g., serrations). For example, the grooves 222 may be arranged in a spiral. In another example, the grooves may be arranged in a straight line. In other words, the grooves and grooves may have a zero helix angle or a non-zero helix angle.

[0039] The use of the grooves can increase the heat transfer from the rotor shaft to the oil, thereby improving the cooling performance of the system. In addition, the grooves can also enable the insert to effectively guide the oil axially toward the outlet 214.

[0040] Examples of different inserts are Figure 5-10 shown. Figure 5-10 The plugins shown can be used Figure 2-4 The rotor shaft 200 is shown. In addition, Figure 5 , Figure 7 and Fig. 9 Cross-sectional views of different inserts are depicted. Figure 6 , Figure 8 and Fig.10 Shown is a perspective view of the interior surface to show the surface contours.

[0041] Figure 5-6 A first example of an insert 500 is shown. The insert 500 includes an inner surface 502 which, in the illustrated example, does not include any grooves or serrations. The inner diameter 504 of the insert may remain constant along its length.

[0042] Figure 7-8A second example of an insert 700 is shown. The inner surface 702 of the insert 700 includes a groove 704. The groove 704 is a straight section along the central axis of the insert. Likewise, the inner diameter 706 of the insert can remain constant along its length. In addition, the groove 704 can have a curved inner profile 708.

[0043] Figure 9-10 A third example of an insert 900 is shown. The inner surface 902 of the insert 900 includes a groove 904. The groove 904 is spirally shaped along the central axis of the insert. Likewise, the inner diameter 906 of the insert may remain constant along its length.

[0044] Back to Figure 2 , the conical portion 206 and the outer portion 210 can be made of a different metal than the insert 208. For example, the conical portion 206 and the outer portion 210 can be made of steel. Also, in this example, the insert 208 can be made of aluminum. Aluminum has a better thermal conductivity and is lighter than steel. Therefore, when an aluminum insert is used in a cooling system, the weight of the rotor shaft can be reduced and the heat transfer capacity of the shaft can be improved.

[0045] In the illustrated example, the tapered portion 206 includes a flange 224. However, in another example, the tapered portion may omit the flange. Specifically, in the illustrated example, the flange 224 is in coplanar contact with an axial end 226 of the insert 208 and an axial end 228 of the outer portion 210. The flange 224 may be welded and / or otherwise connected to the axial end of the insert and the outer portion of the rotor shaft. However, in other examples, the tapered portion may have other suitable profiles.

[0046] The outer portion 210 may include an internal spline portion 230 that may connect the rotor shaft to a downstream component, such as a gearbox shaft. However, other suitable rotor shaft connection interfaces may be used in other examples.

[0047] A stepped interface 232 may be formed between the outer portion 210 and the insert 208 to facilitate positioning the insert in a desired position when the insert is installed. However, other profiles of the rotor shaft are also contemplated.

[0048] By designing the conical portion 206, the insert portion 208 and the outer portion 210 on the rotor shaft, the rotor shaft can be manufactured more efficiently as needed. In addition, in a specific example, the internal closed oil passage can be omitted on the rotor shaft, thereby reducing the cooling loss caused by air stagnation. In addition, the oil inside the rotor shaft 200 can be maintained within a certain oil film thickness when passing through the shaft, thereby reducing the loss of oil flow through the rotor shaft. Figure 2The rotating axis 250 of the rotor shaft 200 is provided for reference. In the illustrated example, the insert 208 does not include a closed oil passage. In detail, during operation of the cooling system, an oil film is formed on the inner diameter of the insert, and air can flow radially inward from the oil film through the insert. In this way, the cooling system can achieve a higher cooling effect than other rotor cooling systems.

[0049] Figure 3 A cross-sectional view of the motor 203 is shown. The conical portion 206 of the rotor shaft 200 is again shown. A conduit inlet 300 may be provided within the conical portion 206. The conduit inlet 300 may include an oil passage 302 that delivers oil to a nozzle 304 (e.g., a radial nozzle). The nozzle 304 in turn delivers oil to the conical portion 206. Specifically, the nozzle 304 sprays the oil toward the wall of the conical portion 206. It will be appreciated that the oil within the conical portion and the insert may not be pressurized.

[0050] The angle 305 between the central axis of the nozzle 304 and the central axis 307 of the pipeline inlet 300 is as follows: Figure 3 In the illustrated example, angle 305 is 90°. However, other suitable nozzle angles may be used in other examples.

[0051] As the rotor rotates at high speed in an unpressurized environment, the oil film thickness increases 309. The rear cover 306 may include an oil conduit 308 that delivers oil to the pipe inlet 300 through an oil conduit outlet 330. A seal 310 may be provided between the pipe inlet 300 and the rear cover 306 to reduce the chance of oil leaking into undesirable parts of the machine. In other words, the seal 310 helps retain the oil in the rotor shaft.

[0052] The duct inlet 300 includes a flange 311 in contact with a portion 313 of the housing 319. In the illustrated example, the seal 310 is arranged axially outward from the interface between the flange 311 and the housing 313. The seal 310 specifically includes surfaces 315 and 317 in contact with the stepped surface in the housing 319. The seal 310 may also include a portion 321 in sealing contact with an extension portion 323 of the tapered portion 206. In this way, the seal plays a role in sealing the oil in the rotor shaft. In addition, in the illustrated example, the duct inlet 300 is circumferentially surrounded by the extension portion 323.

[0053] Arrow 312 indicates the general oil flow through the rear cover 306, the duct inlet 300 and the nozzle 304. However, it is understood that the oil flow pattern may be more complex. After the oil forms an oil film with a thickness of 309 on the wall of the tapered portion, the oil flows axially toward the insert and then passes through the insert.

[0054] In the illustrated example, the inner diameter 314 of the tapered portion 206 increases in the axial direction 316 to allow for efficient distribution of oil along the inner surface 318 , thereby increasing cooling of the rotor shaft.

[0055] The bearing 320 can be coupled to an outer surface 322 of the tapered portion 206. In the illustrated example, the bearing 320 includes an outer race 324, roller elements 326, and an inner race 328.

[0056] Figure 4 Another cross-sectional view of the motor 203 is shown. The figure shows the rotor core 400 in the motor. The rotor core 400 is connected to the rotor shaft 200. Arrow 401 indicates that heat is transferred from the rotor core 400 to the rotor shaft 200. In a high-speed rotating environment, oil flows from the small diameter part to the large diameter part.

[0057] Again, the film thickness 309 is shown. However, as shown, the oil film thickness 309 extends into the insert 208. Most of the heat transfer from the oil may occur at the oil film thickness. Arrow 402 indicates the general direction of oil flow through the insert 208.

[0058] Fig.11 Another example of a rotor shaft 1100 is shown. The cross section of the rotor shaft 1100 is as shown in FIG. Fig.11 As shown. The rotor shaft 1100 again includes a tapered portion 1102, an outer portion 1104 and an insert 1106. It is understood that the rotor shaft 1100 can be used in any motor cooling system or cooling system combination described herein. The insert 1106 includes a flange 1108 that is in coplanar contact with the flange 1110 of the tapered portion 1102.

[0059] Fig.12 FIG. 1 shows another example of a rotor shaft 1200 that may be included in any of the electric machine cooling systems or cooling system combinations described herein. A cross-section of the rotor shaft 1200 is shown in FIG. Fig.12 1200. The rotor shaft 1200 also includes a central cavity 1202 through which oil flows during operation of the motor. Arrow 1204 indicates the general direction of oil flow through the central cavity. Arrow 1207 indicates the direction of lubricating oil flow through lubrication passage 1209, which will be discussed in detail herein. An oil collector 1211 for lubrication passage 1209 may be formed in outer portion 1208.

[0060] In the illustrated example, the rotor shaft 1200 is formed by different parts. In detail, the rotor shaft 1200 includes a tapered portion 1205, an insert portion 1206, and an outer portion 1208. Also, the tapered portion 1205 and the outer portion 1208 may be made of steel, and the insert portion may be made of aluminum.

[0061] In the illustrated example, a portion 1210 of the tapered portion 1205 engages a portion of the outer portion 1208. An O-ring 1212 may be mounted at an interface 1213 between the insert 1206, the tapered portion 1205, and the outer portion 1208.

[0062] A weld 1214 (eg, a laser weld) can be formed at an interface 1216 between the tapered portion 1205 and the outer portion 1208. The tapered portion 1205 can include a stepped portion 1215 that matches a groove 1217 in the outer portion 1208.

[0063] Thermal grease 1218 may be provided at the interface 1220 formed between the outer portion 1208 and the insert 1206. The O-ring 1212 may reduce the chance of grease contamination when welding the tapered portion to the outer portion.

[0064] The outer portion 1208 also includes a set of output shaft splines 1222, which are contoured to match the output shaft. The outer portion 1208 also includes another set of splines 1224. The splines 1224 are contoured to rotationally lock the insert 1206 in place when inserted into the outer portion 1208. In detail, one end 1226 of the insert 1206 is deformed by the splines 1224 when the insert is engaged with the outer portion.

[0065] The inner diameter of the insert 1206 has a plurality of grooves and serrations 1228. The grooves and serrations 1228 have a straight profile, with the grooves extending in the axial direction of the inner diameter of the insert.

[0066] In the illustrated example, lubrication passage 1209 is formed in outer portion 1208 downstream of the interface between the outer portion and insert 1206. Lubrication passage 1209 delivers oil to rotor shaft bearing 1600, as shown in FIG. Fig.16 This article will discuss this in more detail. Fig.11 Provided in Fig.13 The boundary 1250 of the detailed view is provided for reference.

[0067] Fig.13 A detailed view of a portion of the rotor shaft 1200 is shown, particularly the outer portion 1208 including the lubrication passage 1209. In the illustration, the outer portion 1208 includes an undercut 1300. The undercut 1300 allows a portion 1302 of the insert 1206 to deform, thereby axially locking the insert 1206 to the outer portion 1208. As previously described, the end 1226 of the insert 1206 deforms when inserted into the spline 1224, thereby rotationally locking the insert 1206 relative to the outer portion 1208. Fig.13 An outlet 1304 of the lubrication passage 1209 is further illustrated.

[0068] Figure 14-15 The front view and the back view of the insert 1206 are shown respectively. Figure 14-15 Again, grooves and serrations 1228 are shown at the inner diameter of the insert 1206. In the illustrated example, the grooves and serrations are axially aligned. However, as described above, the grooves and serrations may have other profiles.

[0069] Fig.16 A cross-sectional view of the rotor shaft 1200 coupled to the motor 1602 is shown. Specifically, Fig.16 The drive side 1603 of the motor 1602 is shown. The bearing 1600 is connected to the outer circumference of the outer part 1208. The bearing 1600 is a ball bearing having an inner race 1604, an outer race 1606 and balls 1608 between the races. The lubrication channel 1209 opens into an area 1610 located axially inside the bearing 1600. The oil collector 1211 that supplies oil to the lubrication channel 1209 is again as shown. Fig.16 In this way, the bearing 1600 can obtain the required oil flow.

[0070] Rotating seal 1612 is coupled to outer portion 1208 at a location inboard of bearing and region 1610. In the illustrated example, grounding ring 1614 is coupled to outer portion 1208 at a location axially inboard of rotating seal 1612.

[0071] The bearing housing 1616 encloses the bearing 1600, the rotating seal 1612 and the grounding ring 1614. In detail, the respective portions of the bearing 1600, the rotating seal 1612 and the grounding ring 1614 are in coplanar contact with the inner surface 1618 of the housing 1616.

[0072] Fig.17 Another cross-sectional view of another portion of the motor 1602 is shown. The figure again shows the tapered portion 1205, the insert portion 1206 and the outer portion 1208 of the rotor shaft 1200. The bearing 1700 is connected to the outer circumference of the tapered portion 1205. In the example, the bearing 1700 is a ball bearing. In the example, the rotary seal 1702 is connected to the insert 1206. In addition, in the illustrated example, the oil nozzle 1704 is embedded in the housing 1616. Therefore, the oil entering the central cavity 1202 of the rotor shaft 1200 flows from the oil nozzle 1704 into the central cavity. As previously described, the pump drives the oil flow through the rotor cooling system.

[0073] Figure 1-17 The description provides a method for rotating the rotor shaft of an electric motor according to system operating conditions. For example, a controller may send a command to an inverter to cause the rotor to rotate or increase the speed of the machine. In response, the inverter may transmit alternating current to the motor to cause the motor to rotate. The technical effect of the method described herein is to effectively cool the rotor shaft of the motor to improve the efficiency and service life of the motor.

[0074] In addition to the schematically depicted components, Figure 2-17 Drawn approximately to scale. However, other relative component sizes may be used in other examples. Figure 1-17 Configuration examples of relative positioning of various components are shown. If the elements shown in the figure are in direct contact or directly coupled to each other, then at least in one example, these elements can be referred to as direct contact or direct coupling, respectively. Similarly, at least in one example, the elements shown as adjacent or adjacent to each other can be adjacent or adjacent to each other, respectively. For example, elements that are in face-to-face contact with each other can be referred to as face-to-face contact elements. Another example is that, at least in one example, the elements are placed separately from each other, with only space in the middle and no other elements, which can be referred to as being placed separately from each other. For example, relative to each other, the elements displayed above / below each other, relative to both sides of each other, or relative to the left / right side of each other can be referred to as such elements. In addition, as shown in the figure, in at least one example, the topmost element or element point can be referred to as the "top" of the element, and the bottommost element or element point can be referred to as the "bottom" of the element. The top / bottom, upper / lower, upper / lower used in this article can be relative to the vertical axis in the figure to describe the positioning of each element in the figure relative to each other. Therefore, in one example, the element displayed above other elements is vertically positioned above other elements. For another example, the shapes of the elements depicted in the figure may be referred to as having these shapes (such as circular, linear, planar, curved, rounded, chamfered, beveled, or similar shapes). In addition, in one example, elements that are coaxial with each other may be referred to as coaxial elements. In addition, at least in one example, elements that are shown to intersect with each other may be referred to as intersecting elements or intersecting with each other. In addition, in one example, elements that are displayed within another element or displayed outside another element may be referred to as intersecting elements. In other examples, elements that are offset from each other may also be referred to as such. Even further, elements that are coaxial or parallel to each other may also be referred to as such elements. Further, the axis around which the element rotates may be referred to as a rotation axis. Elements that are fixedly coupled to each other may be referred to as rotation axes.

[0075] The present invention will be further described below. In one aspect, the present invention provides an electric motor, comprising a rotor shaft, the rotor shaft comprising a central cavity; an oil inlet; a tapered portion for directing oil from the oil inlet to the oil outlet; and an insert, the insert being located in a cross section of an outer rotor shaft for directing oil to the oil outlet. In one example, the outer rotor shaft portion and the insert may be made of different metals. In addition, in one example, the insert may be made of aluminum. In another example, the rotor shaft may be made of steel. In addition, in one example, the axial end of the insert may be connected to the axial end of the tapered portion. In addition, in one example, the insert may include a plurality of serrations. In addition, in one example, the insert may form a spiral or linear groove between the plurality of serrations. Further, in one example, the inner diameter of the tapered portion of the rotor shaft may decrease in an axial direction extending toward the oil inlet. In addition, in one example, the electric motor may be a traction motor in an electric drive system. In one example, the motor cooling system may further include a first rotating seal coupled to the outer portion of the rotor shaft drive side; and a second rotating seal coupled to the tapered portion. In another example, the insert may include a plurality of serrations and grooves; the plurality of serrations and grooves may be spiral or linear. Additionally, in one example, the outer rotor shaft portion may include a set of splines for rotationally locking the insert to the outer rotor shaft portion.

[0076] In another aspect, a method for operating an electric motor is provided, the method comprising rotating a rotor shaft; wherein the rotation of the rotor shaft causes oil to flow from an oil inlet to a tapered portion of the rotor shaft, from the tapered portion of the rotor shaft to an insert located in a central cavity of the rotor shaft, and from the insert to an oil outlet; wherein the rotor shaft and the insert are made of different metals. In one example, the insert may include a plurality of serrations, the serrations being spiral or linear. Additionally, in one example, the insert may be made of aluminum and the rotor shaft may be made of steel.

[0077] In another aspect, a traction motor is provided, the motor comprising a rotor shaft, the rotor shaft comprising: a central cavity; a tapered portion having an oil inlet and an inner diameter that gradually decreases in an axial direction and extends toward the oil inlet; and an insert, the insert being located at an outer portion of the rotor shaft and comprising a plurality of serrations, the serrations forming a pattern that can direct oil to the oil outlet; wherein the outer portion of the rotor shaft and the insert are made of different metals. In one example, the rotor shaft can be made of steel and the insert is made of aluminum. In addition, in one example, the tapered portion can include a flange that shares contact with an axial end surface of the insert. In addition, in one example, the flange can be in coplanar contact with the outer portion of the rotor shaft. In addition, in one example, the outer surface of the insert can be mechanically coupled to the inner surface of the rotating shaft. In addition, in one example, the pattern can be a spiral pattern or a linear pattern. In another example, the mechanical coupling can include one or more of welding, coupling, brazing, and press fitting. In another example, the insert can include no internally enclosed oil passage.

[0078] Note that the control and estimation routine examples included herein may be used in a variety of system (e.g., transmission) configurations. The control methods and routines disclosed herein may be stored as executable instructions in a non-transitory memory and may be executed by a control system including a controller in combination with an electronic controller and various sensors, actuators, and other system hardware. Thus, the actions, operations, and / or functions described may graphically represent code to be programmed into a non-transitory memory of a computer-readable storage medium in a vehicle and / or powertrain control system.

[0079] Although various embodiments are described above, it should be understood that these embodiments are examples only and not limitations. It is obvious to those familiar with the relevant technology that the disclosed subject matter can be embodied in other specific forms without departing from the spirit of the subject matter. Therefore, the embodiments described above should be regarded as illustrative and not restrictive in all respects. Therefore, the configurations and routines disclosed herein are exemplary in nature, and these specific examples should not be regarded as restrictive because there can be many changes. For example, the above-mentioned technology can be applied to various systems. In a specific example, the above-mentioned technology can be applied to a power system including different types of propulsion sources, including different types of traction motors, internal combustion engines and / or transmissions. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of various systems and configurations, as well as other features, functions and / or characteristics disclosed herein.

[0080] The following claims particularly point out certain combinations and subcombinations regarded as novel and non-obvious. The claims may refer to "an" element or a "first" element or the equivalent. The claims should be understood to include one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amendment of the present claims or by presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, are also deemed to be included in the subject matter of the present disclosure.

Claims

1. A motor cooling system, comprising: A rotor shaft, the rotor shaft comprising: Central cavity; Oil inlet; a tapered portion that guides oil from the oil inlet to the oil outlet; and An insert is located within the outer rotor shaft portion, the insert directing oil to the oil outlet.

2. The motor cooling system according to claim 1, characterized in that: The outer rotor shaft portion and the insert are made of different metals.

3. The motor cooling system according to claim 2, characterized in that: The insert is made of aluminum and the outer rotor shaft portion is made of steel.

4. The motor cooling system according to claim 1, characterized in that: Also includes: a first rotary seal coupled to the outer rotor shaft portion on a drive side of the rotor shaft; as well as A second rotary seal is connected to the tapered portion.

5. The motor cooling system according to claim 1, characterized in that: An axial end of the insert is adjacent to an axial end of the tapered portion.

6. The motor cooling system according to claim 1, characterized in that: The insert includes a plurality of serrations and grooves; and The plurality of saw teeth and grooves are in a spiral or linear shape.

7. The motor cooling system according to claim 1, characterized in that: The outer rotor shaft portion includes a set of splines that rotationally lock the insert relative to the outer rotor shaft portion.

8. The motor cooling system according to claim 1, characterized in that: The inner diameter of the tapered portion gradually decreases in the axial direction extending toward the oil inlet.

9. The motor cooling system according to claim 1, characterized in that: The electric machine is a traction motor in an electric drive system.

10. The motor cooling system according to claim 1, characterized in that: The insert does not include an internally enclosed oil passage.

11. The motor cooling system according to claim 1, characterized in that: The tapered portion comprises a flange which shares contact with an axial end face of the insert; and / or The flange is in coplanar contact with the outer side of the rotor shaft.

12. The motor cooling system according to claim 1, characterized in that: The outer surface of the insert is mechanically coupled to the inner surface of the outer rotor shaft portion; and / or The mechanical coupling includes one or more of welding, coupling, brazing and press fitting.

13. A method for operating a motor with a cooling system, comprising: rotating the rotor shaft; wherein rotation of the rotor shaft causes oil to flow from the oil inlet to the tapered portion of the rotor shaft, from the tapered portion of the rotor shaft to the insert located in the central cavity of the rotor shaft, and from the insert to the oil outlet; and The rotor shaft and the insert are made of different metals.

14. The method according to claim 13, characterized in that The insert includes a plurality of saw teeth, and the plurality of saw teeth are in a spiral shape or a linear shape.

15. The method according to claim 13, characterized in that The insert is made of aluminum and the rotor shaft is made of steel.

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