Patent Application
20100013329
The invention herein resides in the art of hybrid vehicles, particularly of the type adapted for implementation of alternate drive sources. Particularly, the invention relates to a module including an electric drive motor adapted for selective interconnection with the drive shaft of a vehicle to alternatingly provide an electric motor or heat engine as the power source for the vehicle drive mechanism. Specifically the invention relates to a post transmission hybrid drive module having parallel motor and output shafts, the output shaft being interconnected with the drive shaft of a vehicle and the motor shaft being selectively engageable with the output shaft.
The cost of heat sources for the engines typically employed for driving vehicles has given rise to an acute need for alternative fuels or hybrid vehicles, adapted for implementation of various fuel sources. Presently, the most advantageous type of an alternate fuel vehicle is the hybrid vehicle, which, in its most common sense, employs a diesel or gas powered engine and an electric motor as alternative power sources. Prior attempts to achieve this combination have generally met with disappointment, being either excessively costly or under powered in providing motive force. Moreover, the packaging of alternative power sources has been given to complexities that have yet to be overcome, resulting in vehicles that are not only costly, but given to service and maintenance problems. Moreover, presently known electric motors and their methods of implementation have been fraught with power output that is inconsistent with the bulk, size, weight and cost of the motor being implemented.
The instant invention provides a module for use with electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles and other applications requiring high performance, light weight, and economical electric motors and/or generators. It is known that the alternating current (AC) induction motor is the simplest and least expensive type of electric motor for vehicle traction drives. The advent of Flux Vector inverter drive controls provides for variable frequency control up to very high speeds for standard induction motors. Standard motors are typically wound for the common 60 hertz frequency that is used in the United States, or 50 hertz, which is used for the most part in the remainder of the world. High frequency motor invertor drives can operate into the range of 200 to 400 hertz, resulting in motor speeds up to 12,000 rpm for common four pole motors that normally run at 1,800 rpm. A properly matched controller and high speed motor can produce 3 to 5 times the peak power from a similarly sized standard AC induction motor. Further, with effective cooling such a motor can produce 5-10 times the continuous power rating of a standard fan cooled motor and even well beyond that of water jacket cooled motors. Particularly problematic is the need for removal of the heat in the rotor core and stator windings to achieve high continuous power.
It is well known that an AC induction motor commonly uses a “squirrel cage” rotor as its only rotating part. In overall shape, the rotor is a cylinder mounted on a shaft. Internally, it contains axial or longitudinal conductive bars of aluminum or copper set in grooves or holes in the rotor laminations and connected at both ends by shorting rings of aluminum or copper to form a cage-like conductive structure. The core of the rotor is built up of a stack of iron laminations. The field winding in the stator of an induction motor sets up a rotating magnetic field around the rotor. The relative motion between this field and the rotation of the rotor induces electric current flow in the conductive bars. In turn, these currents flowing lengthwise in the conductors react with the magnetic field of the motor stator windings to produce a force acting at a tangent to the rotor, resulting in torque to turn the motor shaft. In effect, the rotor is carried around with a magnetic field, but at a slightly slower rate of rotation. The difference in speed is called “slip” and increases with load.
In light of the foregoing, it is an aspect of the invention to provide an oil cooled electric drive module for hybrid vehicles that can significantly reduce the weight and cost of electric motors for vehicle traction drives.
A further aspect of the invention is the provision of an oil cooled electric drive module for hybrid vehicles that employs a high speed motor with a gear reduction capable of matching the output speed with desired vehicle speed at which the electric drive is most useful.
Still a further aspect of the invention is the provision of an oil cooled electric drive module for hybrid vehicles that is particularly adapted for implementation with vehicles such as urban buses, refuse trucks, and the like, having a staged gear reduction achieving the desired match between motor speed an output drive speed.
Yet a further aspect of the invention is the provision of an oil cooled electric drive module for hybrid vehicles which may be quickly and effectively engaged and disengaged with the vehicle drive shaft.
Another aspect of the invention is the provision of an oil cooled electric drive module for hybrid vehicles that is efficiently cooled by implementation of a coanda effect distribution of cooling oil across the rotor and stator of the motor and its housing.
Still a further aspect of the invention is the provision of an oil cooled electric drive module for hybrid vehicles that employs a rotary union on the motor drive shaft with axial and radial passages for motor cooling oil to optimize the cooling effect.
An additional aspect of the invention is the provision of an oil cooled electric drive module for hybrid vehicles that includes the implementation of a heat exchanger to optimize cooling efficiency.
Yet a further aspect of the invention is the provision of an oil cooled electric drive module for hybrid vehicles that includes a manifold connected to and driven by the motor output shaft to optimize shifting speed and efficiency between power sources.
Still a further aspect of the invention is the provision of an oil cooled electric drive module for hybrid vehicles that includes a motor driven pump that provides for the actuation pressure for shifting between power sources, and the flow of oil through a heat exchanger mechanism.
Yet a further aspect of the invention is the provision of an oil cooled electric drive module for hybrid vehicles that is readily conducive to implementation with presently known heated vehicles, providing an auxiliary driving force for such vehicles.
The foregoing and other aspects of the invention that will become apparent as the detailed description proceeds are achieved by a post transmission parallel hybrid drive module for vehicles, comprising: an AC induction motor having a motor shaft extending therethrough, said motor shaft having a rotor attached thereto, said rotor being received within an array of stator windings, and said motor shaft having a passage therein for passing cooling oil over opposite ends of said rotor and onto said stator windings; a sump adjacent said motor for receiving cooling oil from said windings; an output shaft passing through said sump, said output shaft adapted at opposite ends thereof for interposition within a drive shaft of a vehicle; and a gear assembly interposed between said motor shaft and output shaft for selective driving engagement therebetween.
Other aspects of the invention are attained by a post transmission parallel hybrid drive module for a vehicle, comprising: an AC induction motor having a motor shaft extending therethrough, said motor shaft having a rotor attached thereto, said rotor being received within an array of stator windings, and said motor receiving cooling oil over opposite ends of said rotor and onto said stator windings; a sump adjacent said motor for receiving cooling oil from said windings; an output shaft passing through said sump and adapted at opposite ends thereof for interposition within a drive shaft of a vehicle; and a gear assembly interposed between said motor shaft and output shaft for selective driving engagement therebetween.
Still further aspects of the invention are attained by a post transmission parallel hybrid drive module for a vehicle, comprising: an AC induction motor having a motor shaft extending therethrough, said motor shaft having a rotor attached thereto, said rotor being received within an array of stator windings about a stator core, said motor receiving cooling oil over opposite ends of said rotor and onto said stator windings, and said stator core having a circumferential passage thereabout receiving cooling oil about a circumferential surface of said stator core; a sump adjacent said motor for receiving cooling oil from said windings and stator core; an output shaft adapted at opposite ends thereof for interposition within a drive shaft of a vehicle; and a gear assembly interposed between said motor shaft and output shaft for selective driving engagement therebetween.
For a complete understanding of the various aspects of the invention, reference should be made to the following detailed description and accompanying drawings wherein:
Referring now to the drawings and more particularly
Received within the housing 12, comprising halves 12a and 12b, is a drive shaft or output shaft 18, having respective ends 18a, 18b adapted for interconnection with the drive shaft of a vehicle. In other words, the drive shaft 18 is adapted to be interposed within the drive shaft of the vehicle, beyond the vehicle's transmission, and interconnected therewith through universal joints or the like at 18a and 18b. Also received within the housing 12 and maintained in parallel relationship to the drive shaft 18, is a motor shaft 20 of a motor having a squirrel cage configuration. The motor includes a stator core 22 having stator windings 24 thereabout in standard fashion, the stator core and windings being fixedly retained in the housing 12. A rotor base 26, of standard fashion, is connected to the motor shaft 20 and is rotatable therewith. In standard fashion, conducive bars 28 extend axially across the rotor base 22 and are interconnected as by shorting rings 30 at the lateral ends thereof.
Appropriate bearings 32 are provided at opposite ends of the motor shaft 20 for rotational support. A speed sensing bearing 34, appropriately encoded or otherwise graduated for producing signals corresponding to rotational speed, is provided at one end of the motor shaft 20. At the opposite end, an oil distribution ring assembly or rotary union is attached to the motor shaft 20 and is provide in communication with an axial bore 38 extending thereinto. The axial bore 38 extends to and communicates with a radial bore 40 that extends outwardly into communication with the outer circumferential surface of the motor shaft 20. A plurality of axial splines or reliefs 42 are provided in the circumferential surface of the motor shaft 20 and extend between end rings 44, provided at each end of the rotor base. The end rings 44 are in the form of annular disks, washers, deflectors or the like. This structure and arrangement provides an important pathway for cooling oil to enter the motor shaft 20 at the oil distribution ring or rotary union 36, to pass through the axial bore 38, outwardly through the radial bore 40, and into the space between the shaft 20 and rotor base 26. The plurality of axial splines or reliefs 42 provided in the circumferential surface of the shaft 20 direct the cooling oil outwardly between the shaft and rotor base to the end rings 44, where the cooling oil is redirected radially by such deflectors at the end of the rotor. There, the cooling oil is centrifugally spun outwardly with a coanda effect that coats the aluminum or copper shorting rings 30 on the end faces of the rotor. This oil is centrifugally thrown off of the rotor directly into the stator windings 24 to then flow downwardly through the motor to drain holes 46 in the aluminum housing 12 and into a recovery and recirculating sump 48, that receives the drive shaft 18. A drain 50 is provided within the sump 48 to return the cooling oil to an appropriate pump, auxiliary heat exchanger, or the like for redistribution back through the assembly 10 or other units associated with the vehicle.
The invention employs a gear reduction set between the motor shaft 20 and output shaft 18 to tailor the motor speed to a desired output speed. In one embodiment, the gear set includes a first stage helical gear 52 in driving connection through gear teeth with the motor shaft 20. Those skilled in the art will understand that the first stage helical gear 52 is connected through an appropriate gear drive shaft ( shown in
The mechanical disconnect mechanism 56 is operatively connected to a splined collar 58 that is interposed between the second stage helical gear 54 and the output shaft 18. The collar 58 is axially slidable with regard to both the output shaft 18 and gear 54 to selectively engage and disengage the two. An actuator arm 60 is interconnected with the mechanical disconnect mechanism 56 and driven by a hydraulic piston 62 upon a slide 76, as shown. The piston 62 is received by a hydraulic cylinder 64, having dual cavities to both extend and retract the piston 64 with respect thereto. Accordingly, the piston 62 is capable of engaging and disengaging the collar 58 through the disconnect mechanism 56 and associated actuator arm 60. A solenoid valve 66 is electrically operated to selectively actuate the piston 64 in either the engage or disengage direction.
As shown in
In use, it will be appreciated that the solenoid valves 66 may be employed to selectively engage/disengage the motor drive from the output shaft 18. The timing of the engagement/disengagement is achieved by correlation of the outputs of the speed sensing bearings 34, 70. When disengaged, the output shaft 18 is driven solely by the heat engine of the vehicle. When engaged, the motor drive mechanism either provides sole power to the vehicle (in which case the heat engines are disengaged from the output shaft 18) or the motor is used to supplement that power. Of key importance is the ability to provide an AC motor structure that can be effectively cooled in order to ensure optimum efficiency in a small, light weight, cost effective envelope. The provision of an oil distribution ring assembly or rotary union 36 in association with axial and radial bores 38, 40, coupled with the implementation of axial splines or reliefs 42 and end ring deflectors 44 to provide a coanda sheeting of cooling oil across the end surface of the rotor which is then centrifugally spun outwardly onto the stator of the motor, and its housing, providing for effective cooling that optimizes motor performance.
As shown in
A pair of permanent holding magnets 102, 104 is employed to hold the actuator arm 60 in a desired position, once moved by the piston 62. Accordingly, the piston, cylinders, and solenoid valve 66 are employed to move the actuator arm 60 to either engage or disengage the output shaft 18 with the second stage gear 54, and the actuator arm 60 is then maintained in that position by an appropriate holding magnet 102, 104 such that the hydraulic pressure can be released, and not reapplied until opposite shifting is desired. In that regard, proximity sensors 106, 108 are provided in association with the actuator arm 60 or other associated movable element, to sense that the desired shifting has occurred and then signal through an appropriate control mechanism that the solenoid valves 66 can be released for removal of the hydraulic pressure.
The instant invention further contemplates that an auxiliary heat exchanger 110 may be interposed between the pressure relief valve 94 and the sump 48 for further cooling efficiency. The heat exchanger 110 may be of any suitable nature, such as a radiator, finned housing, cooling jacket or the like. The necessity of transferring heat from the motor assembly to the ambient is of primary importance to ensure optimum effective operation of the motor. In keeping with such efforts to maximize and optimize cooling of the drive motor, it is further contemplated as a portion of the cooling oil recirculation that the output of the pump 90 or heat exchanger 110 might also provide additional cooling to the stator core 22 and windings 24. To that end, as shown in
Thus it can be seen that the various aspects of the invention have been attained by the structures and combinations thereof presented herein. While in accordance with the patent statutes only the best mode and preferred embodiments of the invention have been presented and described in detail, the invention is not limited thereto or thereby. Accordingly, for an appreciation of the true scope and breadth of the invention reference should be made to the following claims.
