Patent Application
20230105407
The present disclosure relates to electric machines, for use with electric and hybrid-electric vehicles, that are capable of acting either as a motor or as a generator.
Vehicles such as battery-electric vehicles and hybrid-electric vehicles contain a traction-battery assembly to act as an energy source. The traction-battery assembly, for example, is electrically connected to an electric machine that provides torque to driven wheels. The traction-battery assembly may include components and systems to assist in managing vehicle performance and operations. It may also include high-voltage components, and an air or liquid thermal-management system to control temperature.
Electric machines typically include a stator and a rotor that cooperate to convert electrical energy into mechanical motion or vice versa. Electric machines may include thermal-management systems to cool the stator, rotor, or both.
According to one embodiment, a vehicle electric machine includes a housing, a stator supporting windings and disposed in the housing. The stator defines axial cooling channels having first ends located on a first end face of the stator and second ends located on a second end face of the stator. A plug is disposed in the second end of one of the axial channels and having an orifice.
According to another embodiment, a vehicle electric machine includes a housing, a stator core disposed in the housing and having an inner diameter defining a plurality of slots, an outer diameter, and mounting ears each disposed radially outboard of the outer diameter and each defining at least one first cooling channel extending axially. Windings are disposed in the slots. An end cover defines a recessed cavity configured to receive the windings, a second cooling channel extending circumferentially around a perimeter of the cavity, and third cooling channels extending from the second cooling channel to the recessed cavity, wherein the end cover is connected to the housing such that the first cooling channels are in fluid communication with the second cooling channel.
According to yet another embodiment, a vehicle electric machine includes a housing, a stator core disposed in the housing and including mounting portions each defining at least one axial cooling channel, and windings disposed on the stator core. An end cover defines a recessed cavity configured to receive the winding and a circumferential cooling channel extending around a perimeter of the cavity. The end cover is connected to the housing such that the axial cooling channels are in fluid communication with the circumferential cooling channel. A plug disposed in one of the axial cooling channels and defines an orifice.
Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments can take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations.
Directional terms used herein are made with reference to the views and orientations shown in the exemplary figures. A central axis is shown in the figures and described below. Terms such as “outer” and “inner” are relative to the central axis. For example, an “outer” surface means that the surfaces faces away from the central axis, or is outboard of another “inner” surface. Terms such as “radial,” “diameter,” “circumference,” etc. also are relative to the central axis. The terms “front,” “rear,” “upper” and “lower” designate directions in the drawings to which reference is made. The terms, connected, attached, etc., refer to directly or indirectly connected, attached, etc., unless otherwise indicated explicitly or by context.
An example plugin-hybrid-electric vehicle (PHEV) is depicted in
The transmission 12 may be a power-split configuration. The transmission 12 includes the first electric machine 18 and a second electric machine 24. The second electric machine 24 may be an AC electric motor depicted as “generator” 24 in
The transmission 12 may include a planetary gear unit 26, which includes a sun gear 28, a planet carrier 30, and a ring gear 32. The sun gear 28 is connected to an output shaft of the second electric machine 24 for receiving generator torque. The planet carrier 30 is connected to an output shaft of the engine 20 for receiving engine torque. The planetary gear unit 26 combines the generator torque and the engine torque and provides a combined output torque about the ring gear 32. The planetary gear unit 26 functions as a continuously variable transmission, without any fixed or “step” ratios.
The transmission 12 may also include a one-way clutch (O.W.C.) and a generator brake 33. The O.W.C. is coupled to the output shaft of the engine 20 to only allow the output shaft to rotate in one direction. The O.W.C. prevents the transmission 12 from back-driving the engine 20. The generator brake 33 is coupled to the output shaft of the second electric machine 24. The generator brake 33 may be activated to “brake” or prevent rotation of the output shaft of the second electric machine 24 and of the sun gear 28. Alternatively, the O.W.C. and the generator brake 33 may be eliminated and replaced by control strategies for the engine 20 and the second electric machine 24.
The transmission 12 may further include a countershaft having intermediate gears including a first gear 34, a second gear 36 and a third gear 38. A planetary output gear 40 is connected to the ring gear 32. The planetary output gear 40 meshes with the first gear 34 for transferring torque between the planetary gear unit 26 and the countershaft. An output gear 42 is connected to an output shaft of the first electric machine 18. The output gear 42 meshes with the second gear 36 for transferring torque between the first electric machine 18 and the countershaft. A transmission output gear 44 is connected to a driveshaft 46. The driveshaft 46 is coupled to a pair of driven wheels 48 through a differential 50. The transmission output gear 44 meshes with the third gear 38 for transferring torque between the transmission 12 and the driven wheels 48.
The vehicle 16 includes an energy storage device, such as a traction battery 52 for storing electrical energy. The battery 52 is a high-voltage battery that is capable of outputting electrical power to operate the first electric machine 18 and the second electric machine 24. The battery 52 also receives electrical power from the first electric machine 18 and the second electric machine 24 when they are operating as generators. The battery 52 is a battery pack made up of several battery modules (not shown), where each battery module contains a plurality of battery cells (not shown). Other embodiments of the vehicle 16 contemplate different types of energy storage devices, such as capacitors and fuel cells (not shown) that supplement or replace the battery 52. A high-voltage bus electrically connects the battery 52 to the first electric machine 18 and to the second electric machine 24.
The vehicle includes a battery energy control module (BECM) 54 for controlling the battery 52. The BECM 54 receives input that is indicative of vehicle conditions and battery conditions, such as battery temperature, voltage and current. The BECM 54 calculates and estimates battery parameters, such as battery state of charge and the battery power capability. The BECM 54 provides output (BSOC, Pcap) that is indicative of a battery state of charge (BSOC) and a battery power capability (Pcap) to other vehicle systems and controllers.
The vehicle 16 includes a DC-DC converter or variable voltage converter (VVC) 10 and an inverter 56. The VVC 10 and the inverter 56 are electrically connected between the traction battery 52 and the first electric machine 18, and between the battery 52 and the second electric machine 24. The VVC 10 “boosts” or increases the voltage potential of the electrical power provided by the battery 52. The VVC 10 also “bucks” or decreases the voltage potential of the electrical power provided to the battery 52, according to one or more embodiments. The inverter 56 inverts the DC power supplied by the main battery 52 (through the VVC 10) to AC power for operating the electric machines 18, 24. The inverter 56 also rectifies AC power provided by the electric machines 18, 24, to DC for charging the traction battery 52. Other embodiments of the transmission 12 include multiple inverters (not shown), such as one invertor associated with each electric machine 18, 24. The VVC 10 includes an inductor assembly 14.
The transmission 12 includes a transmission control module (TCM) 58 for controlling the electric machines 18, 24, the VVC 10 and the inverter 56. The TCM 58 is configured to monitor, among other things, the position, speed, and power consumption of the electric machines 18, 24. The TCM 58 also monitors electrical parameters (e.g., voltage and current) at various locations within the VVC 10 and the inverter 56. The TCM 58 provides output signals corresponding to this information to other vehicle systems.
The vehicle 16 includes a vehicle system controller (VSC) 60 that communicates with other vehicle systems and controllers for coordinating their function. Although it is shown as a single controller, the VSC 60 may include multiple controllers that may be used to control multiple vehicle systems according to an overall vehicle control logic, or software.
The vehicle controllers, including the VSC 60 and the TCM 58 generally includes any number of microprocessors, ASICs, ICs, memory (e.g., FLASH, ROM, RAM, EPROM and/or EEPROM) and software code to co-act with one another to perform a series of operations. The controllers also include predetermined data, or “look up tables” that are based on calculations and test data and stored within the memory. The VSC 60 communicates with other vehicle systems and controllers (e.g., the BECM 54 and the TCM 58) over one or more wired or wireless vehicle connections using common bus protocols (e.g., CAN and LIN). The VSC 60 receives input (PRND) that represents a current position of the transmission 12 (e.g., park, reverse, neutral or drive). The VSC 60 also receives input (APP) that represents an accelerator pedal position. The VSC 60 provides output that represents a desired wheel torque, desired engine speed, and generator brake command to the TCM 58, and contactor control to the BECM 54.
The vehicle 16 includes an engine control module (ECM) 64 for controlling the engine 20. The VSC 60 provides output (desired engine torque) to the ECM 64 that is based on a number of input signals including APP, and corresponds to a driver's request for vehicle propulsion.
If the vehicle 16 is a PHEV, the battery 52 may periodically receive AC energy from an external power supply or grid, via a charge port 66. The vehicle 16 also includes an on-board charger 68, which receives the AC energy from the charge port 66. The charger 68 is an AC/DC converter which converts the received AC energy into DC energy suitable for charging the battery 52. In turn, the charger 68 supplies the DC energy to the battery 52 during recharging. Although illustrated and described in the context of a PHEV 16, it is understood that the electric machines 18, 24 may be implemented on other types of electric vehicles, such as a hybrid-electric vehicle or a fully electric vehicle.
Referring to
Each lamination 78 includes an inner diameter defining a plurality of teeth extending radially inward toward the inner diameter. Adjacent teeth cooperate to define slots. The teeth and the slots of each lamination 78 are aligned with adjacent laminations to define stator teeth 93 and stator slots 94 extending axially through the stator core 80 between the opposing end faces 112. The end faces 112, 113 define the opposing ends of the core 80 and are formed by the first and last laminations of the stator core 80. A plurality of windings (also known as coils, wires, or conductors) 96 are wrapped around the stator core 80 and are disposed within the stator slots 94. The windings 96 may be disposed in an insulating material (not shown). Portions of the windings 96 generally extend in an axial direction along the stator slots 94. At the end faces 112, 113 of the stator core, the windings bend to extend circumferentially around the end faces 112, 113 of the stator core 80 forming the end windings 98. The windings may be of the distributed, concentrated, or hairpin type.
A rotor 72 is disposed within the cavity 88. The rotor 72 is fixed to a shaft 76 that is operably connected to the gearbox. When current is supplied to the stator 74, a magnetic field is created causing the rotor 72 to spin within the stator 74 generating a torque that is supplied to the gear box via one or more shafts.
The core 80 includes an inner diameter 104 and an outer diameter 106 that are each concentric with the centerline 75. Mounting ears 108 are disposed radially outboard of the outer diameter 106. In the illustrated embodiment, the stator core 80 includes four mounting ears 108. The addition of the mounting ears 108 to the outer diameter 106 creates a generally rectangular cross section. Each of the mounting ears 108 may include an arcuate outer surface 110 and a tab 111 with a bolt hole 115. One or more cooling channels 114 are defined in at least one of the mounting ears 108. The cooling channel(s) 114 extends in the axial direction of the stator core 80 and may extend completely through the core 80 from the first end face 112 to the second end face 115. In the illustrated embodiment, each of the mounting ears 108 includes a plurality of cooling channels 114. The axial channels 114 may have a circular cross section, as shown, or any other suitable shape. As shown, the cooling channels of each ear 108 are grouped into first and second sets 116 and 118 on opposite sides of the tab 111. (Used herein, a “set” includes one or more cooling channels.) In the illustrated embodiment, each set includes a plurality of small circular channels 114, however, these may replace with a single enlarged channel. Each of the cooling channels 114 may be set at a same radial distance from the centerline 75. That is, the inner most points 120 of the cooling channels 114 may all lie on a common circle. A radial distance between the center of the core 80, e.g., centerline 75, and an inner most points 120 of cooling channels 114 is greater than the radial distance between the center of the core and the outer diameter 106. This places the coolant channels 114 out of the yoke portion (region between the outer diameter and the base of the teeth) of the stator core 80. By moving the cooling channels 114 radially outboard of the yoke portion, the flux path of the electric machine is less affected than in designs having cooling channels extending through the yoke portion. Each of the laminations 78 include individual features that cooperate to form the mounting ears and their associated features described above.
The stator core 80 is received within a housing 130 having a sidewall 132 and a cavity 136 configured to receive the stator core 80. The cavity 136 has a shape that substantially matches the shape of the stator core 80. In the illustrated embodiment, the housing 130 has an insertion end 135 and a bottom end 137 that is at least semi-enclosed to include a shoulder or stop for the stator core 80. The stator core 80 is received within the housing 130 through the insertion end 135 and bottoms out on the shoulder/stop.
Referring to
The diameter of the circumferential cooling channel 162 is sized so that the channel 162 is disposed over the axial channels 114 when the end cover 150 is attached to the housing 130. One or more seals or gaskets (not shown) may be applied between the end cover 150 and the housing 130 and/or the stator core 80 to retain the fluid within the desired channels and passages.
Referring to
A first of the plugs 184 includes a semi-spherical (domed) head 186 defining at least one orifice 188 (multiple in the illustrated embodiment). The orifice 188 extends through the head 186 and is in fluid communication with the axial channel 114. The orifice 188 permits fluid flow through the plug 184. The size, number, and location of the orifices 188 can be adjusted to achieve a desired flow rate, velocity, and pressure of the fluid in the axial channel 114. The orifices 188 may also be used to direct the fluid exiting the axial channel 114. For example, one or more of the orifices 188 may be aimed to spray fluid onto the end windings 98.
A second type of plug 190 may include a flat head 192 that defines a single orifice 194. The orifice 194 may be a rectangular slot formed on a central region of the head 192. Alternatively, the plug 190 may include a plurality of orifices that are either slots, circular holes, or the like. The head 192 may be raised from the end face 113 of the stator core.
A third type of plug 196 may include a head 198 that is fully received within the channel 114 so that the outer surface 200 of the head 198 is flush with the end face 113 (or alternatively 112). In the illustrated embodiment, the plug 196 includes a single orifice in the form of a circular hole 202. This, of course, is just one embodiment. The third plug 196 may include multiple orifices in other embodiments. Additionally, the hole 202 need not be centered so shown.
Another type of plug 204 is configured to block multiple axial channels 114. This type of plug includes an upper plate 206 and posts (not visible) that are received within the individual axial channels 114. The upper plate 206 defines orifices 208 that are in fluid communication with the axial channels allowing the fluid to flow from the axial channels and onto the end windings. In the illustrated embodiment, each orifice 208 is associated with one of the axial channels, however, the upper plate 206 may define multiple orifices associated with each channel 114.
The plugs may be retained within the cooling channels by a variety of different mechanisms. In one embodiment, an adhesive or sealant may be used to retain the plugs within the cooling channels 114. In another embodiment, the plugs may be mechanically joined to the stator core 80 by interference fit, threads, or the like. In some embodiments, an insert may be used to secure the plug to the stator core. For example, an insert may be first assembled within the axial slot. The insert element may include a tapered opening that gradually reduces is in diameter. The plug is receivable within this tapered opening and is secured by interference fit. Alternatively, the insert may define threads that engage with threads of the plug. The plugs of this type may only partially extend into the axial cooling channels 114.
In other embodiments, the plugs may extend a length of the axial cooling channels.
Referring to
While example embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments can be combined to form further embodiments of the invention that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes can include, but are not limited to strength, durability, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and can be desirable for particular applications.
