Speed control for a window wiper system
AssigneeUnited Technologies Automotive, Inc.
InventorsDavid L. Juzswik, John E. Lahiff
Life of this patent
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Abstract
A window wiper control system provides accurate regulation and/or profiling of wiper speed. A desired interval corresponding with the preselected speed or speed profile is stored; a reference signal is provided to indicate a reference position of the wiper and is used to measure the actual interval of a wiper stroke or cycle. The actual interval is compared with the desired interval and an appropriate adjustment is made in a pulse-width modulation signal for effecting a desired speed and interval. The pulse-width modulation signal preferably has a relatively-low repetition rate. The wiper speed may be profiled to include acceleration and deceleration, and the intervals of acceleration and deceleration may be lengthened substantially to provide an apparent dwell.
Claims24
An improved control for a window wiper system having a wiper motor for driving at least one wiper in a wiping cycle between inner and outer reversing positions and means responsive to a control signal for regulating a supply of electrical power to the motor, the improvement wherein said control comprises:
- means for providing an electrical signal indicating the presence of the wiper at a reference position,
- electronic signal processing means including means for storing a preselected time value representative of the interval for a wiping cycle at a desired wiping speed profile, timing means for responding to the signal indicative of the wiper being at said reference position to time the interval actually required for the wiper to complete a wiping cycle, means for comparing the actual wiping cycle interval with the desired wiping cycle interval to determine a .DELTA. interval representative of the difference, if any, therebetween, and means for providing pulse-width modulated control signals, said pulse-width modulated control signals being initially of a preselected nominal value and thereafter of a value adjusted to minimize said .DELTA. interval;
- and
- means for applying said pulse-width modulated control signal to said means for regulating the supply of power to the wiper motor, thereby to regulate the speed of the wiper motor.
Dependencies are inferred from the claim text.