Electricity: measuring and testing – Magnetic – Displacement
Reexamination Certificate
1999-06-24
2001-11-20
Snow, Walter (Department: 2862)
Electricity: measuring and testing
Magnetic
Displacement
C324S207210, C324S165000
Reexamination Certificate
active
06320374
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to crankshaft target wheels, and more particularly to systems and methods for determining position and direction of rotation of rotating shafts with a single sensor.
BACKGROUND OF THE INVENTION
A target wheel is a disk that is engaged with a vehicle crankshaft and that is configured for inducing signals in one or more sensors positioned next to the target wheel, with the signals representing the angular position of the crankshaft. These position signals can be used in distributorless ignition systems that have selectively energized ignition coils that fire the spark plugs as appropriate for the angular position of the crankshaft. Moreover, the crankshaft angular position signals can be used for combustion control and diagnostic functions.
Examples of target wheels are set forth in, e.g., U.S. Pat. No. 5,754,042, incorporated herein by reference, and in co-pending U.S. patent application Ser. No. 09/250,826, filed Feb. 17, 1999, also incorporated herein by reference. Essentially, the edge of the disk-shaped wheel is varied along the periphery of the wheel in some fashion, e.g., by cutting slots in the periphery in a predetermined pattern. Usually, one or two sensors are used to detect the slots as they pass by the sensors, with the detected slot pattern being correlated to a crankshaft angular position and, when two sensors are used, also to a crankshaft direction of rotation. Unfortunately, when two sensors are used instead of one, as currently must be done to sense direction of crankshaft rotation, the cost and complexity of such systems is increased. The present invention has recognized the above-noted problems and has provided the below solutions to one or more of the above-noted problems.
SUMMARY OF THE INVENTION
A method for sensing the direction of motion, e.g., rotation, of a moving, e.g. rotating, body that defines a periphery and at least one peripheral anomaly includes providing a single sensor with first and second sensor elements, preferably by providing first and second magnetoresistor (MR) elements on a single MR die. First and second signals are respectively received from the elements, and then a magnitude that is related to the second signal is determined at a point in time that is contemporaneous with an edge related to the first signal. A direction signal is then generated in response which represents the direction of rotation of the rotating body.
In a preferred embodiment, a baseline magnitude is established, and the first and second signals establish respective first and second detection signals when an anomaly is sensed. The anomaly can be a slot, or tooth, or other magnetic mark on a target wheel of a crankshaft. The preferred method further includes establishing the position of the anomaly at a time when the first and second detection signals intersect each other.
As disclosed in greater detail below, the detection signals can define respective first and second detection signal magnitudes, and the method includes establishing a trigger magnitude. Further, the method includes establishing respective first and second square waves for the first and second detection signals, with each square wave being established for the period when the trigger magnitude is between the baseline magnitude and the respective detection signal magnitude. In a particularly preferred embodiment, the magnitude that is related to the second signal is a magnitude of the second square wave, and the edge that is related to the first signal is a leading edge or falling edge of the first square wave.
In another aspect, a device is disclosed to determine the direction of rotation of a crankshaft that is coupled to a trigger wheel having anomalies formed thereon. The device includes first and second anomaly detection signal generators generating respective first and second detection signals when an anomaly of the trigger wheel is juxtaposed with the signal generators. Each detection signal defines a respective first or second magnitude, and each detection signal also establishes a respective first or second edge. An electrical circuit receives the detection signals and identifies the second magnitude when the first edge is sensed, with the detection circuit generating a direction signal in response to sensing the first edge.
In still another aspect, an electrical circuit is disclosed for outputting a direction signal representative of the direction of rotation of a rotating shaft coupled to a wheel that bears peripheral anomalies. The circuit includes first and second sensor elements generating respective first and second detection signals when an anomaly is sensed. Means are provided for determining a magnitude related to the second signal at a point in time contemporaneous with an edge related to the first signal. Also, means generate a direction signal representative of the direction of rotation of the rotating body in response to the means for determining.
The details of the present invention, both as to its structure and operation, can best be understood in reference to the accompanying drawings, in which like reference numerals refer to like parts, and in which:
REFERENCES:
patent: 4370614 (1983-01-01), Kawada et al.
Lequesne Bruno Patrice Bernard
Schroeder Thaddeus
Delphi Technologies Inc.
Dobrowitsky Margaret A.
Snow Walter
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