Electricity: motive power systems – Periodic – repetitious or successive operations control of...
Reexamination Certificate
1999-06-30
2001-08-28
Nappi, Robert E. (Department: 2837)
Electricity: motive power systems
Periodic, repetitious or successive operations control of...
C318SDIG002, C015S250120
Reexamination Certificate
active
06281649
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to windshield wiper systems and, more particularly, to automotive windshield wiper system that utilize individual brushless dc motors for coordinated, but mechanically independent control of the windshield wipers.
BACKGROUND OF THE INVENTION
Automotive windshield wiper systems typically use a pair of motor driven wiper blades to clean the windshield. In most systems, a single motor is used with a mechanical linkage between the wiper blades so that the single motor provides simultaneous, synchronous reciprocation of the two wiper blades. Automotive vehicles also typically include a windshield washer system that sprays washer fluid onto the windshield to aid in the cleaning of the windshield by the wipers. The washer system can include a washer fluid reservoir to store the washer fluid, a pair of nozzles to spray the fluid onto the windshield, and a pump to supply the washer fluid to the nozzles. While these washer systems are commonly located in the engine compartment near the windshield wiper system itself, integration of the washer system and the windshield wiper system into a compact assembly can be difficult because of the moving mechanical linkages used to drive both wipers from a single motor.
Windshield wiper systems have been designed that utilize separate electric motors for each of the wipers. See, e.g., U.S. Pat. No. 4,585,980 to Gille et al., U.S. Pat. No. 4,665,488 to Graham et al., U.S. Pat. No. 4,900,995 To Wainwright, and U.S. Pat. No. 5,252,897 to Porter et al. While eliminating the mechanical linkage between the wipers, these dual motor system have at times been disfavored because operation of the two motors must be properly coordinated to prevent collisions between the two wipers. Coordination of the motors has been accomplished using position feedback by sensing, for example, the position of each motor's armature or by using position sensors on the wiper levels or the windshield itself, as in U.S. Pat. No. 5,157, 314 to Kühbauch.
In the field of motor controllers generally, motor position feedback has been used in brushless dc motors for commutation of the motor windings. This has sometimes been done using Hall Effect sensors, as in U.S. Pat. No. 4,680,515 to Crook, U.S. Pat. No. 4,723,100 to Horikawa et al., and U.S. Pat. No. 4,897,583 to Rees. The output of these Hall Effect sensors have also been used along with a clock oscillator to produce position and tachometer signals for operational control of the motor. See, for example, U.S. Pat. No. 4,415,844 to Mendenhall et al. and U.S. Pat. No. 4,717,864 to Fultz.
While suitable for use in windshield wiper systems, the use of the above-noted brushless dc motor controllers in a windshield wiper system that uses separate position sensors for coordination of the wipers can result in an unnecessarily complicated design.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a dual motor windshield wiper system that includes a windshield washing system all integrated into a single drop-in assembly. The assembly can include both wiper motors, a windshield washer fluid reservoir, a washer fluid pump, and at least one mounting member that supports the motors, fluid reservoir, and pump and that is adapted to attach the assembly to the vehicle.
In accordance with another aspect of the invention, the fluid reservoir can be located between the motors in the area that is typically used for the mechanical linkages required for a single motor system. The motors can be attached to separate mounting members and together can support the fluid reservoir between them. Alternatively, the reservoir can be attached to the one ore more mounting members and can provide the necessary support for the motors. The reservoir can have recesses in its outer surface that can be used as the motors' housings. The motors can be thermally coupled to the interior of the reservoir so that washer fluid within the reservoir operates as a heat sink to remove heat from the motors. Similarly, one or more power devices used by the windshield wiper system's control circuit can be thermally coupled to the interior of the reservoir to sink heat produced by the devices during use.
In accordance with another aspect of the invention, there is provided a dual motor windshield wiper system in which encoders are used to provide pulses indicative of angular displacements of the motors, with the pulses being used not only for commutation of the motors, but also for tracking the position of the wipers. This reduces the complexity of the control circuitry by using a single encoder for both commutation and position tracking.
In accordance with another aspect of the invention, the windshield wiper system includes a control circuit that is operable to automatically determine a park or home positions without the use of limit switches. This can be accomplished by rotating the wipers towards their home position until further rotation is obstructed by the cowl cover or some other part of the vehicle. The wipers can then be rotated upward by a small amount with current position of the wipers then being used as reference for determining the absolute position of the wipers during normal operation.
In accordance with another aspect of the invention, the control circuit can provide control of each wiper's position by comparing the actual position to target position values that are generated using acceleration, velocity, and deceleration values determined in accordance with the wiper speed selected by the vehicle operator.
In accordance with another aspect of the invention, the control circuit is operable to measure the current used by the motors and, using the measured current, is operable to determine an environmental condition of the windshield (e.g., wet, dry, icy). Outside air temperature and other sensed parameters can also be used along with motor current to determine the environmental condition of the windshield.
In accordance with yet another aspect of the invention, there is provided a windshield washer system having a control circuit operable to control the spray of washer fluid onto the windshield in accordance with at least one measured parameter. This parameter can be, for example, vehicle speed, so that overspray of the washer fluid can be avoided at higher speeds.
In accordance with another aspect of the invention, there is provided a windshield wiper system which includes a user-selectable intermittent mode of operation, wherein the control circuit is operable pause the motors each time the wipers reach either of their ends of their travel. For a windshield wiper system in which the wipers sweep up from the bottom center of the windshield to opposite sides of the windshield, this system is advantageous since the wipers do not obscure the driver's view in either their inboard or outboard position and can therefore be paused at each end of travel rather than only at the end of a complete cycle.
REFERENCES:
patent: 4123817 (1978-11-01), Hartery
patent: 4431954 (1984-02-01), Carperter et al.
patent: 4585980 (1986-04-01), Gille et al.
patent: 4665488 (1987-05-01), Graham et al.
patent: 4670695 (1987-06-01), Licata et al.
patent: 4723101 (1988-02-01), Bauer et al.
patent: 4745345 (1988-05-01), Petersen
patent: 4837474 (1989-06-01), Petersen et al.
patent: 4900995 (1990-02-01), Wainwright
patent: 4949000 (1990-08-01), Petersen
patent: 5216340 (1993-06-01), Welch
patent: 5241248 (1993-08-01), Forukoshi
patent: 5252897 (1993-10-01), Porter et al.
patent: 5271120 (1993-12-01), Eustache et al.
patent: 5291109 (1994-03-01), Peter
patent: 5355061 (1994-10-01), Forhan
patent: 5404085 (1995-04-01), Resch et al.
patent: 5561882 (1996-10-01), Eustache et al.
patent: 5568026 (1996-10-01), Welch
patent: 5569217 (1996-10-01), Luther
patent: 5659217 (1997-08-01), Petersen
patent: 5784749 (1998-07-01), Garbacik, Jr. et al.
patent: 5833441 (1998-11-01), Danish et al.
patent: 5874796 (1999-02-01), Petersen
patent: 1939453 (1971-02-01), None
patent: 3208121 A1 (1983-09-01), N
Ouellette Thomas J.
Prendergast William H.
Ziegler William E.
Duda Rina I.
McCord Winn Textron Inc.
Nappi Robert E.
Reising Ethington, Barnes, Kisselle, Learman & McCulloch, P.C.
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