Apparatus for generating electrically distinguishable bipolar signals using a magnetic sensor and an oval wheel with teeth and notches in its minor and major axis

• US 4,180,753 A
• Filed: 06/30/1978
• Issued: 12/25/1979
• Est. Priority Date: 06/30/1978
• Status: Expired due to Term

• Current Assignee: Ford Motor Company
• Original Assignee: Ford Motor Company
• Inventors: Cook, James C. II
• Primary Examiner(s): Corcoran, Robert J.
• Assistant Examiner(s): Snow, Walter E.
• Application Number:
  US05/920,762
• Time in Patent Office: 543 Days
• Field of Search: 324/16 T, 324/166, 324/173, 324/174, 324/178, 324/179, 324/208, 340/347 P, 310/168, 310/155, 310/111, 310/DIG. 3, 123/148 E, 123/146.5 A
• US Class Current: 310/168
• CPC Class Codes: G01P 3/488 delivered by variable reluctance detectors

Abstract

This specification discloses an apparatus and method for providing electrically distinguishable signals occurring as a function of the position of a moving element. It is possible to identify a sub group of electrical signals from the remaining electrical signals or from the entire group. The electrical signals can be used altogether to determine a variable such as revolutions per minute of the movable element or, particular ones of the electrically distinguishable signals can be used for initiating a function such as the firing of spark plugs.

Claims

1. Pulse generating means for providing electrically distinguishable signals, said signals occurring as a function of position of a relatively movable element, said pulse generating means comprising:

a transducer means located on said relatively movable element for generating the electrically distinguishable signals;

a transducer receiving means located in energy transfer coupling with respect to said transducer means for providing the electrically distinguishable signals in response to passage of said transducer means past said transducer receiving means;

said transducer means including teeth means for projecting toward said transducer receiving means for generating an electrical signal of a first shape and notch means for receding away from said transducer receiving means for generating an electrical signal of a second shape, distinguishable from said first shape, each of said teeth means and notch means being sufficiently sized to be detected by said transducer receiving means;

said transducer means including a generally oval disc of a magnetic material having a major and a minor diameter, said projections for said teeth means extending outward from said disc along said minor diameter, said notch for said notch means extending radially inward along said major diameter, said notch and said projection having a generally rectangular shape and the periphery of said oval between an adjacent pair of notch means and teeth means being a continuous curve; and

including two teeth, one tooth being opposite from the other, and further including two notches, one notch being opposite from the other notch and each notch being positioned midway around the circumference of said oval between said two teeth; and

said transducer receiving means including a permanent magnet, an electrical pickup means coupled to said magnet for detecting changes in the magnetic flux, and said magnet being sufficiently close to a path of rotation for said teeth means and said notch means that movement of said teeth means and said notch means past said transducer receiver means causes a change of magnetic flux within pickup means

2. Pulse generating means as recited in claim 1 wherein said electrical pickup means includes a Hall effect device means for detecting magnetic flux, said Hall effect device including semiconductor means providing an electrical charge displacement in response to a magnetic field, and voltage measuring means for sensing the electric charge displacement within said semiconductor means.

3. Pulse generating means for providing electrically distinguishable signals of substantially equal magnitude comprising:

a rotating, generally oval ferro magnetic material, distinguishable signals occurring as a function of rotational position of said member, said member including a pair of opposing teeth extending outwardly from the generally oval shape of said member along the minor diameter of said member for rotating and aiding in the generation of a first signal shape, and said member including a pair of opposing notches extending inwardly from the generally oval shape of said member along the major diameter of said member for rotating and aiding in the generation of a second signal shape; and

a transducer receiving means located in energy transfer coupling with respect to said ferro magnetic material member, including a permanent magnet, a pole piece magnetically coupled to said permanent magnet, and an electrical wire coil coupled to said pole piece for detecting changes in the magnetic flux within said pole piece, and said pole piece being sufficiently close to a path of rotation for said teeth and notches past said pole piece so there is caused a change of magnetic flux within said pole piece and so that there is an induced current corresponding to said first signal shape when a tooth passes said pole piece and corresponding to said second signal shape when a notch passes said pole piece, said first and second signals being inverse of one another, and having a substantially equal magnitude.

4. Pulse generating means as recited in claim 3 wherein the diameter of said magnetic member is changing in magnitude between an adjacent tooth and notch, the curvature of the perimeter of said magnetic member being such as to provide a constant voltage output when the changing magnetic flux is detected by said transducer receiving means.

5. A method of generating electrically distinguishable signals of substantially equal magnitude, including the step of:

rotating a magnetic transducer having a generally oval shape;

positioning a pole piece of a permanent magnet near the transducer to provide a flux source for interaction with the transducer;

varying the magnetic reluctance of a flux path adjacent the flux source in a first direction by rotational movement of a protrusion extending from the minor diameter of the transducer, and varying the magnetic reluctance of a flux path in a second direction by rotational movement of a notch extending into the periphery of the transducer along the major diameter;

detecting changes in magnetic flux through the pole piece by measuring the current flow through a coil or wire around the pole piece;

adjusting the relative size and position of the magnetic transducer to the pole piece by changing the size, height and depth of the protrusion and notch so that the magnitudes of current flow in response to a protrusion the and a notch are substantially equal; and

distinguishing the passage of a protrusion the pole piece from the passage of a notch by the pole piece by analyzing the polarity of change of the current in the coil of wire.

6. A method as recited in Claim 5 wherein the step of generating a flux includes the steps of:

sequentially passing the periphery of the transducer associated with a decreasing diameter past the pole piece, passing a protrusion extending from the oval transducer past the pole piece, passing the periphery of the transducer associated with an increasing diameter past the pole piece thereby generating a flux change in the first direction; and

sequentially passing the periphery of the transducer associated with an increasing diameter past the pole piece, passing an notch in the periphery of the oval transducer past the pole piece, and passing the periphery of the transducer associated with a decreasing diameter past the pole piece thereby generating a flux change in the second direction.