Electricity: battery or capacitor charging or discharging – Battery or cell charging – With thermal condition detection
Reexamination Certificate
2000-09-27
2001-08-07
Wong, Peter S. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell charging
With thermal condition detection
C320S129000, C219S201000
Reexamination Certificate
active
06271648
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method of preconditioning a battery to improve cold temperature starting of a vehicle and more particularly, to a method of preconditioning a battery to improve cold temperature starting of a hybrid electric vehicle which selectively operates the vehicle's integrated starter/generator to heat the core of the battery prior to starting the vehicle.
BACKGROUND OF THE INVENTION
Hybrid electric vehicles (“HEVs”) utilize both an internal combustion engine and one or more electric machines (e.g., motors/generators) to generate power and torque. The electric motor/generator within a hybrid electric vehicle provides the vehicle with additional degrees of freedom in delivering the driver-demanded torque and is also typically used to start the vehicle's engine.
One type of hybrid electric vehicle utilizes an integrated starter/alternator or starter/generator which functions as both a motor and a generator. The starter/generator typically provides a variety of functions and benefits, including but not limited to starting the vehicle's engine; generating and providing electrical power to vehicle systems and components; providing additional torque to the vehicle's engine during heavy accelerations; assisting in and/or performing the braking functions of the vehicle, thereby capturing the kinetic energy of the moving vehicle; and stopping or “shutting off” the vehicle's engine during idling and decelerating states or conditions, thereby improving the vehicle's overall fuel economy.
In order to start the vehicle's engine, the starter/generator receives power from an onboard electrical power supply such as a battery. In one type of hybrid electric vehicle, a rechargeable forty-two volt (42 V) battery, such as a lead acid or nickel-metal-hydride battery, is used to supply electrical power to the starter/generator. While these types of batteries are often effective to provide the requisite electrical charge to power the starter/generator, they suffer from some drawbacks.
For example and without limitation, during cold temperature starting conditions, these batteries provide only limited performance. The power pulse capability for a typical forty-two volt battery at −20 degrees Celsius is often less than fifty percent of its power pulse capability at 20 degrees Celsius. Therefore, if a typical forty-two volt battery is sized to meet cost and weight constraints, it may have marginal cold temperature pulse discharge performance and may be unable to meet engine cranking loads.
Efforts have been made to overcome the cold temperature starting limitations associated with these types of batteries. These efforts include utilizing different battery technologies in parallel, self-heating the battery core by use of resistive elements, and providing an auxiliary climate control system for the battery. These efforts, however, have not produced satisfactory results. For example, the utilization of different battery technologies requires additional costly and complex electronics to address battery management issues. Furthermore, the use of resistive elements and auxiliary climate control systems results in an excessive amount of battery self-discharge which adversely impacts the fuel economy gains that are provided by the starter/generator.
There is therefore a need for a method of preconditioning a battery to improve cold temperature starting of a hybrid electric vehicle which overcomes the drawbacks of prior methods, strategies and systems.
SUMMARY OF THE INVENTION
It is a first object of the invention to provide a method of preconditioning a battery to improve cold temperature starting of a hybrid electric vehicle which overcomes at least some of the previously delineated drawbacks of prior emissions reducing methods and strategies.
It is a second object of the invention to provide a method of preconditioning a battery to improve cold temperature starting of a hybrid electric vehicle which selectively operates the vehicle's starter/generator to heat the battery core.
It is a third object of the invention to provide a method of improving cold temperature starting of a hybrid electric vehicle which utilizes the vehicle's starter/generator to remove static friction within the vehicle's engine, thereby reducing the torque required to start the engine.
It is a fourth object of the invention to provide a method of preconditioning a battery to improve cold temperature starting of a hybrid electric vehicle which provides for a faster application of fuel and spark within the engine.
According to a first aspect of the present invention, a method is provided for improving cold temperature starting of a vehicle having a battery, an engine, and an electric machine which is coupled to the battery and which is attached to the crankshaft of the engine. The method includes the steps of: detecting a cold temperature starting condition; and selectively providing torque pulsations to the crankshaft by use of the electric machine during the cold temperature starting condition, the torque pulsations being effective to draw power from the battery effective to heat the battery and to remove static friction within the engine, thereby reducing the torque required to crank the engine.
According to a second aspect of the present invention, a method of preconditioning a battery is provided. The battery is disposed within a vehicle having an engine and a starter/generator which is operatively coupled to the battery and the engine. The method includes the steps of: detecting a cold temperature starting condition; and selectively activating the starter/generator effective to draw power from the battery, thereby heating the battery, the selective activation of the starter/generator being further effective to generate torque pulsations which remove static friction within the engine, thereby reducing the torque required to crank the engine.
These and other features, aspects, and advantages of the invention will become apparent by reading the following specification and by reference to the following drawings.
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patent: 5362942 (1994-11-01), Vanderslice, Jr. et al.
patent: 5990660 (1999-11-01), Meissner
patent: 5990661 (1999-11-01), Ashtiani et al.
patent: 6072301 (2000-06-01), Ashtiani et al.
Ford Global Tech. Inc
Ford Global Tech., Inc.
Toatley , Jr. Gregory J.
Wong Peter S.
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