Patent Application
20140266527
One or more embodiments relate to an inductor assembly of a DC-DC converter, and structure for supporting the inductor assembly inside of a transmission housing.
The term “electric vehicle” as used herein, includes vehicles having an electric machine for vehicle propulsion, such as battery electric vehicles (BEV), hybrid electric vehicles (HEV), and plug-in hybrid electric vehicles (PHEV). A BEV includes an electric machine, wherein the energy source for the electric machine is a battery that is re-chargeable from an external electric grid. In a BEV, the battery is the source of energy for vehicle propulsion. A HEV includes an internal combustion engine and one or more electric machines, wherein the energy source for the engine is fuel and the energy source for the electric machine is a battery. In a HEV, the engine is the main source of energy for vehicle propulsion with the battery providing supplemental energy for vehicle propulsion (the battery buffers fuel energy and recovers kinematic energy in electric form). A PHEV is like a HEV, but the PHEV has a larger capacity battery that is rechargeable from the external electric grid. In a PHEV, the battery is the main source of energy for vehicle propulsion until the battery depletes to a low energy level, at which time the PHEV operates like a HEV for vehicle propulsion.
Electric vehicles may include a voltage converter (DC-DC converter) connected between the battery and the electric machine. Electric vehicles that have AC electric machines also include an inverter connected between the DC-DC converter and each electric machine. A voltage converter increases (“boosts”) or decreases (“bucks”) the voltage potential to facilitate torque capability optimization. The DC-DC converter includes an inductor (or reactor) assembly, switches and diodes. A typical inductor assembly includes a conductive coil that is wound around a magnetic core. The inductor assembly generates heat as current flows through the coil. An existing method for cooling the DC-DC converter by circulating fluid through a conduit that is proximate to the inductor is disclosed in U.S. 2004/0045749 to Jaura et al.
In one embodiment, a vehicle is provided with a transmission and an inductor assembly that is mounted within a chamber of the transmission. The inductor assembly includes an insulator having first and second portions that are oriented toward each other. Each portion includes a base, a support extending from the base, and a spool extending transversely from the support to engage the other portion. Each spool includes an external surface for supporting a coil and a cavity extending therethrough for receiving a core.
In another embodiment, an inductor assembly is provided with a coil, a core, and an insulator that mounted within a transmission chamber. The insulator includes first and second portions oriented toward each other. Each portion includes a base, a support extending from the base, and a spool extending transversely from the support to engage the spool of the other portion. Each spool includes an external surface for supporting the coil and a cavity extending therethrough for receiving the core.
In yet another embodiment, a transmission that defines a chamber is provided. The transmission includes an inductor assembly that is mounted within the chamber. The inductor assembly includes an insulator having first and second portions that are oriented toward each other. Each portion includes a base, a support extending from the base, and a spool extending transversely from the support to engage the other portion. Each spool includes an external surface for supporting a coil and a cavity extending therethrough for receiving a core.
As such, the transmission and the inductor assembly provide advantages over existing systems, by providing structure to support the coil and the core while facilitating direct cooling of the coil and the core using transmission fluid.
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may 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.
With reference to
Referring to
The transmission 12 has a power-split configuration, according to one or more embodiments. The transmission 12 includes the first electric machine 18 and a second electric machine 24. The second electric machine 24 is an AC electric motor according to one or more embodiments, and depicted as the “generator” 24 in
The transmission 12 includes 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 also includes a one-way clutch (O.W.C.) and a generator brake 33, according to one or more embodiments. 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. In other embodiments, the O.W.C. and the generator brake 33 are eliminated, and replaced by control strategies for the engine 20 and the second electric machine 24.
The transmission 12 includes 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 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 to other vehicle systems and controllers.
The transmission 12 includes the VVC 10 and an inverter 56. The VVC 10 and the inverter 56 are electrically connected between the main 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 by 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 main battery 52. Other embodiments of the transmission 12 include multiple inverters (not shown), such as one inverter associated with each electric machine 18, 24.
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 a braking system (not shown) which includes a brake pedal, a booster, a master cylinder, as well as mechanical connections to the driven wheels 48, to effect friction braking. The braking system also includes position sensors, pressure sensors, or some combination thereof for providing information such as brake pedal position (BPP) that corresponds to a driver request for brake torque. The braking system also includes a brake system control module (BSCM) 62 that communicates with the VSC 60 to coordinate regenerative braking and friction braking. The BSCM 62 provides a regenerative braking command to the VSC 60, according to one embodiment.
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.
The vehicle 16 is configured as a plug-in hybrid electric vehicle (PHEV) according to one or more embodiments. The battery 52 periodically receives 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 embodiments of the VVC 10 may be implemented on other types of electric vehicles, such as a HEV or a BEV.
With reference to
Referring back to
The transmission 12 includes fluid 96 such as oil, for lubricating and cooling the gears located within the transmission chamber 92 (e.g., the intermediate gears 34, 36, 38). The transmission chamber 92 is sealed to retain the fluid 96. The transmission 12 also includes pumps and conduits (not shown) for circulating the fluid 96 through the chamber 92.
Rotating elements (e.g., gears and shafts) may displace or “splash” fluid 96 on other components. Such a “splash” region is referenced by letter “A” in
The transmission 12 includes nozzles 98 for directly spraying the transmission fluid 96 on components within the housing 90, according to one or more embodiments. Such a “spray” region is referenced by letter “B” in
Further, the transmission fluid 96 accumulates within a lower portion of the chamber 92. Such an “immersion” region is referenced by letter “C” in
The thermal resistance of the heat transfer path from the conductor 110 to the coolant flowing through the passage 124 of the cold plate 120 is high. The thermal grease 122, the potting compound 118 and the cold plate 120 contribute significantly to this resistance. As a result, the thermal performance of this potted inductor assembly 104 is limited, and the temperature of the inductor assembly 104 at various locations increases may exceed predetermined temperature limits at high electrical power loads. In one or more embodiments, a controller (e.g., the TCM of
The temperature of the inductor assembly 104 depends on the amount of current flowing through the conductor 110 and the voltage potential across the conductor 110. Recent trends in electric vehicles include higher current capability of the inductor. For example, increased battery power for the extended electric range in PHEVs and reduced battery cells for the same power in HEVs result in increased inductor current rating in electric vehicles. Additionally, reduced battery voltage also leads to an increase in the inductor AC losses due to a higher magnitude of high frequency ripple current. Therefore, due to additional heat generation, the temperature of the inductor assembly 104 will generally increase and if heat is not dissipated, the inductor temperature may exceed predetermined limits. One solution is to increase the cross-sectional area of the conductor coil to reduce inductor loss and also improve heat dissipation (due to more surface area). However, such changes will increase the overall size of the inductor assembly. A larger inductor assembly may be difficult to package in all vehicle applications, and larger components affect vehicle fuel economy and cost.
Rather than increase the size of the inductor assembly 104, to improve the inductor thermal performance and thermal capacity, the inductor assembly 104 may be mounted within the transmission chamber 92 and directly cooled using transmission fluid 96 as described with reference to
Referring to
The core 212 is formed in a dual “C” configuration, according to the illustrated embodiment. The core 212 includes a first end 216, a second end 218 that are each formed in a curved shape. The core 212 also includes a first leg 220 and a second leg 222 for interconnecting the first end 216 to the second end 218 to collectively form a ring shaped core 212. Each leg 220, 222 includes a plurality of core elements 224 that are spaced apart to define air gaps. (
Referring to
As shown in
The core 212 is assembled by first assembling the first and second legs 220, 222 which includes attaching the core elements 224 and ceramic spacers 226 together using an adhesive or laminate. The first end 216 of the core 212 is then attached to the legs 220, 222. A core 212 sub-assembly, including the first end 216 and the legs 220, 222 is translated toward the conductor 210 and insulator 214, such that the legs 220, 222 are inserted into the corresponding first and second spools 240, 240′, 242, 242′. The second end 218 of the core 212 is then attached to a distal end of each leg 220, 222 using an adhesive or laminate. In one or more embodiments, a strap 228 (shown in
With reference to
The core 812 is similar to the core 212 described above with reference to
The conductor 210 and the insulator 814 are disposed within the recess 802. The insulator 814 is similar to the insulator 214 described above with reference to
As described above, the insulator 814 is formed of an electrically insulating polymeric material, such as PPS and physically separates the electrically conductive conductor 210 from the core 812. The transmission 12 is formed a electrically conductive material, such as an aluminum. To avoid any electrical losses due to mounting the core 812 to the transmission 12, an electrically insulative material (not shown) may be disposed between each of the first end 816 and the second end 818 and the transmission 12.
Referring to
The inductor assembly 904 is sized to engage the wall 903 within the recess 902 for both maintaining the core 212 in a ring shape, and for mounting the inductor assembly 904 to the transmission. The inductor assembly 904 is sized such that a longitudinal length of the core 212 corresponds to a longitudinal length of the recess 902 to provide an interference fit, or minimal clearance. However, the costs associated with manufacturing the inductor assembly 904 and the structure 900 at such dimensions may make such a design cost-prohibitive.
With reference to
The structure 1000 also includes a spring, such as a spring clip 1006, that is mounted to a first inner surface 1008 of the wall 1003. The inductor assembly 904 is sized such that the second end 218 of the core engages the spring clip 1006. The spring clip 1006 imparts a longitudinal force upon the core 212 such that the first end 216 of the core engages a second inner surface 1110 of the wall 1003, for both maintaining the core 212 in a ring shape, and for mounting the inductor assembly 904 to the transmission. The spring clip 1006 elastically deforms in the longitudinal direction to compensate for tolerance variations in the longitudinal length of the core 212, which reduces the costs associated with manufacturing the inductor assembly 904 and the structure 1000 as compared to the structure 900 illustrated in
Referring to
The inductor assembly 904 is cooled by the transmission fluid 96 within the transmission 12. Heat transfers by conduction from the conductor 210 and the core 212 through the insulative material 1118 and then to wall 1003. The transmission fluid 96 contacts the wall 1003, as well as the conductor 210 and the core 212. Heat transfers from the wall 1003, as well as the conductor 210 and the core 212 to the transmission fluid 96.
The thermal resistance of the heat transfer path from the non-potted inductor assembly 904 to the transmission fluid 96 is low as compared to the thermal resistance of the potted inductor assembly 104 depicted in
With reference to
Referring to
With reference to
The receptacle 1702 includes a base 1706 and a sidewall 1708 extending transversely from an outer periphery of the base 1706. The base 1706 includes a plurality of flanges 1710 with holes 1712 formed through for receiving fasteners for mounting the receptacle 1702 to the transmission. The sidewall 1708 defines a cavity 1714 for receiving the inductor assembly 1704. The structure 1700 includes adhesive material, such as potting material 1716 that is disposed within the cavity 1714 to encase a lower portion of the inductor assembly 1704. The potting material 1716 secures the partially potted inductor assembly 1704 to the receptacle 1702 while leaving an upper portion of the inductor assembly 1704 exposed for receiving the transmission fluid 96.
The thermal resistance of the heat transfer path from the partially potted inductor assembly 1704 to the transmission fluid 96 is low as compared to the thermal resistance of the fully potted inductor assembly 104 depicted in
As such the non-potted inductor assembly 14, 804, 904, and the partially potted inductor assembly 1704 provides advantages over existing fully potted inductor assemblies, such as inductor assembly 104, by facilitating direct cooling of the conductor and core using transmission fluid. The transmission 12 and/or the inductor assembly 14 include additional structure 200, 800, 900, 1300, 1700 for supporting the inductor assembly 14, 804, 904, 1704 to compensate for the decreased potting material.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.
