Patent Application
20080242498
1. Field of the Invention
The invention relates to hybrid vehicle integrated transmission systems.
2. Discussion
In some hybrid vehicles, supplemental units, e.g., air conditioning compressors, power steering pumps, water pumps, oil pumps, etc., may be driven by the engine. In other hybrid vehicles, supplemental units may be driven by dedicated electric motors.
Embodiments of the invention may take the form of a hybrid vehicle including first and second power sources and a transmission. The transmission includes an input shaft, a drive shaft, and a rotationally powered accessory device. The transmission is mechanically connected with the first power source via the input shaft and operatively connected with the second power source. The drive shaft is configured to be selectively driven by at least one of the first and second power sources. The accessory device is configured to selectively receive rotational power from the drive shaft.
Embodiments of the invention may take the form of a transmission system for a vehicle including first and second power sources and a wheel. The system transfers power from at least one of the power sources to the wheel. The system includes an input shaft mechanically connected with the first power source and a drive shaft. The system also includes a rotationally powered accessory device. The drive shaft is configured to be selectively driven by at least one of the first and second power sources. The accessory device is configured to selectively receive rotational power from the drive shaft.
While exemplary embodiments in accordance with the invention are illustrated and disclosed, such disclosure should not be construed to limit the claims. It is anticipated that various modifications and alternative designs may be made without departing from the scope of the invention.
Accessory units driven by a vehicle engine may not receive power when the engine is off. Dedicated electric motors for powering accessory units may add cost and weight to hybrid vehicle systems.
In some embodiments of the invention, a Hybrid Electric Vehicle (HEV) transmission is used to drive an air conditioning compressor thus eliminating any separate air conditioning motor. In other embodiments of the invention, a transmission is used to drive accessory pumps, e.g., water pump, oil pump, power steering pump, etc.
If the engine is shut down, for example, while a driver is stepping on a brake, the hybrid motor may be disconnected from the powertrain via a clutch. The motor may then drive the accessory unit, e.g., air conditioning compressor, while the engine is stopped. If the driver no longer steps on the brake, the engine may be re-connected to the motor via the clutch.
In some embodiments, a belt or shaft transfers the HEV motor torque to one or more accessory units internal to the transmission. Merging accessory units into the transmission may reduce cost and weight associated with such systems and provide packaging flexibility.
Depending on the type of hybrid transmission, e.g., power split, the clutch may (1) disconnect the vehicle wheels from the HEV motor, (2) disconnect the engine from the HEV motor, (3) or two clutches may disconnect the motor from both the engine and the transmission. For example, when the engine shuts-down, the hybrid motor may be disengaged from the engine via the clutch. The motor may then drive the accessory unit while the engine is stopped. If a driver tips in, the clutch may re-engage the motor with the engine, enabling the engine to pull-up.
In some embodiments, for a given operating condition, the power demand at each accessory unit is determined. The power requirements of each system are added together. The motor is commanded to provide the total power requirement. Then, the power is distributed to the individual accessory units.
Embodiments of the invention may (1) allow accessory devices to be operated during hybrid engine shutdown, without adding additional electric motors to drive the accessory devices; (2) allow efficient accessory device operation by using power directly from an engine, motor, or wheels (during breaking), or any combination thereof; (3) allow reduced cost and compact sizing of accessory devices, due to integrated design, e.g., i.) a fully integrated accessory device can share components/systems with a transmission unit, such as walls, shafts, oil, etc., ii.) a concentric drive is not belt driven so as to eliminates side bearing loads thus allowing less costly/smaller bearing/shaft design, etc., (4) allow greater efficiency due to concentric design which eliminates accessory drive belt losses and side loading; (5) allow increased under hood space where accessories devices are typically located; (6) allow efficient and cost effective routing of fluid lines; and/or (7) eliminate some or all accessory drive belts.
Engine 32 may used to drive wheels 38. For example, engine clutch 30 is engaged with power shaft 22, motor 14 immobilizes the sun gear of planetary gear set 18 thus allowing the planet gears of planetary gear set 18 to rotate about the sun gear which, in turn, moves the ring gear of planetary gear set 18 thus driving wheels 38.
Battery 36 may be used to drive wheels 38. For example, engine 32 may be decoupled from power shaft 22 via engine clutch 30, motor 14 may turn the sun gear of planetary gear set 18 which, in turn, drives the planet gears and ring gear of planetary gear set 18 thus driving wheels 38.
Engine 32 and battery 36 may, in combination, be used to drive wheels 38. For example, the planetary gear set 18 may be turned by power from engine 32 and battery 36/motor 14 thus driving wheels 38.
Accessory unit(s) 26, e.g., power steering pump, air conditioner compressor, water pump, oil pump, alternator, etc., is driven by power shaft 22 if accessory clutch 28 is engaged. As described below, power shaft 22 may be selectively engaged with accessory clutch 28 and/or engine clutch 30 such that battery 36/motor 14 and/or engine 32 may provide power to accessory unit(s) 26.
In
Accessory clutch 28 and engine clutch 30 may be actuated using standard techniques. Multiple control strategies consistent with having accessory clutch 28 and engine clutch 30 may also be implemented to deliver power to accessory unit 26 from the desired sources. For example, any time vehicle 12 is on, yet engine 32 is shut down, accessory clutch 28 may be engaged and engine clutch 30 may be disengaged thus powering accessory unit 26 with power from battery 36 via motor 14.
While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and 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.
