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US 4,544,870 AGranted
Intermittant windshield wiper control system with improved motor speed control
AssigneeRobert W. Kearns
InventorsRobert W. Kearns, Timothy B. Kearns
Life of this patent
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AssigneeRobert W. Kearns
InventorsRobert W. Kearns, Timothy B. Kearns
Estimating the term…
In an intermittent windshield wiper system in which the time between wiping cycles depends upon the degree of dryness of the windshield and upon the speed of the wiper blades on the downstroke of the wiping cycle toward the dwell position of the wiper blades, a circuit is provided to regulate the speed of the motor on the down stroke making use of the same transistor device that is used in controlling the energization of the motor to achieve intermittent operation. The motor is a three-brush motor and speed regulation is achieved by deriving signals from one or two of the brushes and applying it to the input electrode of the transistor device. The regulated speed of the motor can be manually controlled to provide a manual adjustment to the sensitivity of the system to the degree of dryness of the windshield. The motor may be electrodynamically braked at the end of each wiping cycle and the electrodynamic braking circuit is also used to apply reverse current to the motor when the windshield wiper system is turned off to drive the windshield wiper blades to a depressed park position.
In an intermittent windshield wiper system comprising a motor connected to drive a windshield wiper through repeating wiping cycles over a windshield, each wiping cycle including an upstroke at the start of the wiping cycle and down stroke at the end of the wiping cycle, an amplifying device, switch means driven by said motor having a RUN position and a DWELL position and moving to said DWELL position at the end of each wiping cycle, and circuit means responsive to said switch means to cause said amplifying device to energize said motor intermittently to cause said wiper to stop for dwell periods at the ends of successive wiping cycles;
A motor speed control system comprising a threebrush motor having first, second and third brushes, an amplifying device having output electrodes connected to said third brush in a circuit to control the energization of said motor between said first brush and said third brush and having an input electrode, said amplifying device controlling the current flow from its output electrodes in accordance with the signal applied to said input electrode, means to apply a signal derived from said second brush to said input electrode to regulate the speed of said motor and means to apply a signal derived from said third brush to said input signal to regulate the speed of said motor.
In an intermittent windshield wiper system having an electric motor for driving a windshield wiper through repeating wiping cycles, manual control means having an ON position and an OFF position, and circuit means for energizing said motor to drive said wipers intermittently, stopping for dwell periods at the ends of successive wiping cycles when said manual control means is in said ON position, and for driving the wiper means to complete a wiping cycle during which said manual control means is switched to said OFF position, and automatically reversing the direction of current through the electric motor at the end of the last wiping cycle to drive the wiper to a depressed park position, the improvement wherein said circuit means includes a current path connected across the armature of said motor, control means for closing said current path at the ends of successive wiping cycles to electrodynamically brake said motor to a stop at the ends of such successive wiping cycles and to open said switch means before the end of said dwell period when said manual control means is in said ON position, said control means connecting said armature in series with said current path to cause current flow through said armature in the reverse direction at the end of said last wiping cycle during which said manual control means is switched to said OFF position to drive said wiper to said depressed park position.
Dependencies are inferred from the claim text.