Internal-combustion engines – Vibration compensating device
Reexamination Certificate
2000-03-31
2001-09-11
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Vibration compensating device
Reexamination Certificate
active
06286473
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a system for damping engine speed oscillations and more particularly, to a system which utilizes a starter/alternator to damp crankshaft speed oscillations within a hybrid electric vehicle, thereby providing improved idle quality and fuel economy.
BACKGROUND OF THE INTENTION
The periodic fuel combustion processes within an internal combustion engine and the generally nonlinear engine geometry result in torque disturbances and crankshaft speed oscillations. These crankshaft speed oscillations adversely effect the smoothness and quality of the vehicle's ride, cause increased noise, vibration and harshness (“NVH”), and undesirably reduce fuel economy. Typically, a conventional “passive” flywheel is coupled to the end of the crankshaft to reduce the pulsation of the crankshaft speed.
Conventional flywheels are relatively massive and undesirably increase the overall weight and packing space of the vehicle's engine, and undesirably reduce fuel economy. Additionally, the effectiveness of flywheels in damping crankshaft speed oscillations is severely limited since conventional flywheels are “passive”, devices and are incapable of adjusting to changing operating conditions and circumstances.
There is therefore a need for a system for damping crankshaft speed oscillations which overcomes the drawbacks of prior systems and methods and which utilizes an active supplemental torque source such as a starter-alternator to attenuate crankshaft speed oscillations.
SUMMARY OF THE INVENTION
It is a first object of the invention to provide a system for damping engine crankshaft speed oscillations which overcomes the previously delineated drawbacks of prior methods, apparatuses, and devices.
It is a second object of the invention to provide a system which utilizes a supplemental torque source to damp engine crankshaft speed oscillations.
It is a third object of the invention to provide a system which is adapted for use within a hybrid electric vehicle and which utilizes a starter/alternator to actively damp engine crankshaft speed oscillations.
It is a fourth object of the invention to provide a system for damping engine crankshaft oscillations which includes a variable inverse notch filter and a variable lead compensator to attenuate crankshaft speed oscillations at a desired disturbance frequency.
According to a first aspect of the present invention, a system is provided for use in combination with a vehicle including an engine which drives a crankshaft at a first speed. The system is effective to damp oscillations in the first speed and includes an electric machine which is operatively coupled to the crankshaft and which is effective to selectively provide torque to the crankshaft, effective to alter the first speed; a sensor which measures the first speed and which generates a first signal based upon the measured first speed; and a controller which is communicatively coupled to the electric machine and to the sensor. The controller is effective to receive the first signal and, based upon the first signal, to communicate a second signal to the electric machine, the second signal being effective to cause the electric machine to selectively provide torque to the crankshaft, effective to alter the first speed in a manner which substantially attenuates the oscillations.
According to a second aspect of the present invention, a method is provided for damping speed oscillations in an engine having a crankshaft which rotates at a first speed, said method comprising the steps of providing a supplemental torque source; mounting said supplemental torque source on said crankshaft; measuring said first speed; generating a first signal corresponding to said measured first speed; processing said first signal by use of a variable parameter notch filter, effective to generate a second signal; utilizing said second signal to generate an output signal; and communicating said output signal to said supplemental torque source effective to cause said supplemental torque source to selectively provide torque to said crankshaft, said torque being effective to alter said first speed, thereby substantially attenuating said speed oscillations.
Further objects, features, and advantages of the invention will become apparent from the following detailed description of the preferred embodiment of the invention and by reference to the following drawings.
REFERENCES:
patent: 4699097 (1987-10-01), Tanaka et al.
patent: 4862009 (1989-08-01), King
patent: 4922869 (1990-05-01), Kadomukai et al.
patent: 5033425 (1991-07-01), Kadomukai et al.
patent: 6085723 (2000-07-01), Pels et al.
patent: 11-325 168 (1999-11-01), None
Ford Global Tech.
Ford Global Tech., Inc.
Kamen Noah P.
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