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Publication Number
US-9670972-B2
Publication Date
2017-06-06
Expiration Date
Abstract
In order to reduce torsional vibrations in a drive including a torque converter with a turbine and impeller, clutch slip speed of the drive is adjusted by manipulation of clutch pressure. This may be done in either closed loop mode or open loop mode by setting the clutch pressure to a predetermined value or continuously adjusting clutch pressure. Pressure is adjusted to produce a positively sloped function of sensed total torque of the clutch and turbine over the clutch slip speed. This produces extended service life of the drive train components, greater efficiency of the torque converter, and smoother operation of the drive.
Core Innovation
The invention relates to damping torsional vibrations in a drive line including a clutch by controlling a clutch slip speed of the clutch and an output shaft speed of the drive. The control maintains a positive slope of a total torque of the drive line versus the clutch slip speed, and the maintaining occurs at a slip speed less than about 30 rotations per minute. A total torque concept combines clutch torque and turbine torque for the drive line behavior.
A torque converter with an impeller and a turbine is provided, where the turbine torque and the clutch torque are engaged through the clutch. The invention monitors total torque including the clutch torque and the turbine torque and monitors clutch slip speed during operation. Total torque is continuously compared with clutch slip speed, and a clutch slip speed is maintained such that the total torque divided by clutch slip speed produces a positively sloped function over time, supporting damping of torsional vibrations.
A controller continuously compares total torque, including a sum of clutch torque added to a turbine torque, and the clutch slip speed during operation. The controller maintains the clutch slip speed so that the continuous comparison produces a positively sloped function of total torque over clutch slip speed. The disclosed approach is implemented without a use of a vibration absorbing coupling, and the maintaining of clutch slip speed can be performed with predetermined clutch pressure and/or closed-loop and open-loop control strategies, including use of a resonant frequency for determining predetermined clutch pressure.
Claims Coverage
The independent claims cover three aspects: a method that damps torsional vibrations by controlling clutch slip speed to maintain a positive torque-slope at low slip, a method that uses continuous comparison of total torque (clutch torque plus turbine torque) with clutch slip speed to maintain a positively sloped function over time, and a system that performs a controller-based continuous comparison to produce a positively sloped function while omitting a vibration absorbing coupling. The inventive concept centers on maintaining a positive slope relationship between total torque and clutch slip speed at slip speeds below about 30 rotations per minute.
Maintaining positive torque slope at low clutch slip speed
Controlling a clutch slip speed of the clutch and an output shaft speed of the drive while maintaining a positive slope of a total torque of the drive line versus the clutch slip speed, wherein the maintaining occurs at a slip speed of less than about 30 rotations per minute.
Continuously comparing total torque to clutch slip speed for positive slope function
Monitoring total torque including a clutch torque and a turbine torque; monitoring a clutch slip speed; continuously comparing total torque with clutch slip speed during operation; and maintaining a clutch slip speed such that the total torque divided by clutch slip speed produces a positively sloped function over time.
Controller maintaining clutch slip speed based on continuously compared positively sloped torque function
A controller that continuously compares a total torque, including a sum of clutch torque added to a turbine torque, and a clutch slip speed during operation of the drive; and maintains the clutch slip speed such that the continuous comparison of total torque and clutch slip speed produces a positively sloped function of total torque over clutch slip speed.
Collectively, the independent claims define torsional vibration damping by holding clutch slip speed so that a positively sloped relationship is maintained between total torque and clutch slip speed, using continuous torque/slip comparison in the converter drive line and/or controller-based maintenance without a vibration absorbing coupling, with operation restricted to slip speeds below about 30 rotations per minute.
Stated Advantages
Damping torsional vibrations in a drive line.
Without a use of a vibration absorbing coupling.
Extension of component life.
Improved torque converter efficiency.
Smoother operation by reducing torsional vibration spikes and smoothing torque waveforms.
Documented Applications
Reducing torsional vibrations in a drive line including a clutch.
Damping torsional vibrations in a drive line using a hydraulic torque converter with an impeller and a turbine and a lock-up clutch.
System operation during drive-line torsional vibration conditions where a resonant frequency concept may be used to determine predetermined clutch pressure.
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