Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2001-09-12
2004-08-17
Mullins, Burton (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C180S065230, C475S005000, C310S07500D, C310S092000, C310S112000
Reexamination Certificate
active
06777837
ABSTRACT:
INCORPORATION BY REFERENCE
The disclosure of Japanese Patent Application No. 2000-292979 filed on Sep. 26, 2000 is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a drive unit for a parallel-type hybrid vehicle wherein an engine and a motor are coupled for use as a power source, and more particularly to a hybrid-vehicle drive unit wherein a motor is fitted to an automatic transmission having a hydraulic power transmission.
2. Description of Related Art
Japanese Patent Application Laid-Open No. (“Kokai”) HEI 9-215270, discloses a drive unit for a parallel-type hybrid vehicle wherein a motor-generator is fitted to an automatic transmission equipped with a torque converter. The driving force of the motor-generator assists the driving force of the engine e.g. when the vehicle starts from a standstill or is accelerated. The motor-generator functions as a generator to supplement the effect of the engine brake when the vehicle runs down a slope or is braked, and wherein braking energy is regenerated to improve fuel efficiency and reduce exhaust emissions. Similar hybrid vehicle drive trains are disclosed in Japanese Patent Application Laid-Open No. (“Kokai”) HEI 5-30605, and Japanese Patent Application Laid-Open No. (“Kokai”) HEI 5-024447.
According to Kokai 9-215270, a motor housing for a motor-generator is sandwiched between an engine and a transmission housing containing the transmission and a torque converter. According to Kokai 5-30605, a motor-generator is disposed in a bypass between a turbine runner and a pump impeller of a torque converter. According to Kokai 5-024447, a motor-generator is directly mounted radially outside of a torque converter. Namely, the motor-generator is disposed in an automatic transmission that has substantially the same structure as a conventional automatic transmission, with a rotor supported radially outward of the cover of the torque converter.
In an internal combustion engine, pistons reciprocate due to explosive combustion of a fuel-air mixture in cylinder chambers to rotate a crank shaft. However, vibrations due to combustive explosion cause the crank shaft to rotate eccentrically (with deflection), preventing centering precision.
On the other hand, the efficiency of the motor-generator is enhanced in proportion to a decrease in clearance (air gap) between its stator and rotor, which, in turn, requires an increase in precision in radial support of the rotor, i.e., centering precision. Further, since the output of the motor-generator increases in proportion to an increase in the axial length of opposing surfaces of the stator and the rotor, the efficiency of the motor-generator is also greatly affected by precision in axial support of the rotor.
If the rotor is directly coupled to the crank shaft as in Kokai 9-215270, centering precision of the crank shaft directly affects centering precision of the rotor. Thus, the rotor needs to have an excess of air gap corresponding to the degree of eccentricity caused by explosive vibrations. Thus, the motor-generator decreases in efficiency, and requires a corresponding larger capacity.
Further, if the motor-generator is disposed between the turbine and the front cover of the torque converter as disclosed in Kokai 5-30605, the front cover is directly coupled with the crank shaft. Thus, centering precision of the crank shaft directly affects precision of the support position of the rotor. Also, since the torque converter undergoes deformation such as expansion or contraction due to changes in inlet pressure and centrifugal hydraulic pressure, the stator fixed to the pump impeller and the rotor fixed to the turbine runner are axially displaced relative to each other, and the motor suffers a corresponding decrease in efficiency. Thus, in order to obtain the required output, to offset the decrease in efficiency of the motor-generator, the motor-generator must be enlarged.
Further, if the motor-generator is directly mounted radially outside of the torque converter as disclosed in Kokai 5-024447, it is difficult to enlarge the diameter of the motor-generator owing to spatial restrictions such as vehicle height. It is difficult to provide a motor (generator) having the necessary output torque within such a limited space. Further, since the rotor of the motor-generator is directly supported radially outside of the cover of the torque converter, when the torque converter undergoes deformation, i.e., expansion or contraction due to changes in inlet pressure or centrifugal hydraulic pressure, there is the possibility of interference between the stator and the rotor. Thus, the rotor needs an excessive air gap corresponding to the expansion or contraction of the torque converter and the efficiency of the motor-generator is thereby decreased and requires a corresponding increase in capacity.
Further, the torque converter generates a great amount of heat. Thus, if the torque converter is integrated with the rotor, the permanent magnet of the motor may by demagnetized by heat from the torque converter. Furthermore, if the lock-up clutch and the rotor are located close to each other, the cover integrated with the rotor is magnetized due to the magnetic flux emitted from the permanent magnet of the rotor. As a result, iron powder dispersed in hydraulic fluid in the torque converter may accumulate in the lock-up clutch and obstruct operation of the lock-up clutch.
SUMMARY OF THE INVENTION
Thus an object of the invention is to provide a hybrid-vehicle drive unit capable of supporting a motor-generator with high precision, improving the efficiency of the motor-generator, and reducing the size of the motor-generator with independence from the influence of centering precision of the crank shaft of an engine, from deformation of the hydraulic power transmission, and so on.
To achieve the above-stated object, according to one aspect of the invention, there is provided a hybrid-vehicle drive unit comprising an engine, an automatic transmission having a hydraulic power transmission and an automatic speed-change mechanism, and a motor having a stator and a rotor that is coupled to an input section of the hydraulic power transmission. A motor housing for the motor is disposed between a housing of the hydraulic power transmission and the engine. The stator is fixed to the motor housing. The rotor is rotatably supported by the motor housing, and is disposed radially outside of the hydraulic power transmission with a predetermined clearance.
In the above arrangement, the rotor of the motor is independently supported by the housing of the motor, e.g., via the bearing, isolated from any affect of eccentric rotation of the crank shaft resulting from explosive vibrations of the engine or deformation of the hydraulic power transmission resulting from changes in inlet(charging) pressure or centrifugal hydraulic pressure.
According to the above aspect of the invention, the motor is separated with the stator fixed to the motor housing and with the rotor rotatably supported by the motor housing, and a predetermined clearance is left between the rotor and the torque converter. Thus, it is possible to provide support with high centering precision without influence by eccentric rotation of the crank shaft. The above-described construction also ensures a clearance (air gap) of high precision by preventing the rotor and the stator from interfering with each other due to expansion or contraction of the torque converter caused by changes in centrifugal hydraulic pressure and so on. Thus, the efficiency of the motor can be enhanced by narrowing (decreasing) the clearance, and the functions as described above can be performed reliably with a relatively compact structure. Further, since the predetermined clearance exists between the rotor and the torque converter, the permanent magnet is prevented from demagnetizing due to generation of heat within the torque converter. Furthermore, since the lock-up clutch and the rotor, which are disposed in the front cover of the torque co
Amano Masaya
Hasebe Masahiro
Nakamura Seiji
Omote Kenji
Shinohara Keiichi
Aisin AW Co. Ltd.
Lorusso, Loud & Kelly
Mullins Burton
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